CDA Journal - December 2020: Dental Student Research

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Dental Student Research So Ran Kwon, DDS, MS, PhD, MS

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D E C E M B E R 2020

Vol 48 Nº 12

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Dec. 2020

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d e pa r t m e n t s

638 Thank You to the 2020 Reviewers 639 Guest Editorial/Questioning Our Role in Health Care in Response to COVID-19

641 Impressions 705 RM Matters/Hostility in the Workplace Escalates if Left Unchecked 707 Regulatory Compliance/Employer Obligations To Provide Vaccinations

709 Ethics/He Wants You To Do What? Ethical Issues of Providing Second Opinions

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710 Tech Trends f e at u r e s

645 Dental Student Research An introduction to the issue.

So Ran Kwon, DDS, MS, PhD, MS

647 Dentin Bonding in Class V Lesions and the Influence of the Patient’s Age on Bond Strength This in vitro study evaluates the influence of patients’ ages on shear bond strength of composites to dentin in cervical lesions comparing acid-etching and self-etching systems.

Harley Grandin, DDS; Jim Milani, DDS; Mouchumi Bhattacharyya, PhD; and Karen A. Schulze, DDS, PhD

655 Digital Imaging Filters and Their Effect on Detecting Root Resorption This study evaluates the sensitivity of various radiographic software filters in the detection of root resorption.

Jeries Nader Qoborsi, BS; Shant Oroojian, BSc; Jason Bajwa, BSc; Ambrose I. Obhade, BDS, DDS; Gina D. Roque-Torres, PhD; and Dwight Rice, DDS

661 Assessment of a Pediatric Population Using Telehealth Training in Predoctoral Dental Education This article aims to increase the dental workforce and quantify outcomes of telehealth curriculum by integrating predoctoral dental students in the delivery of asynchronous teledentistry.

Analia Tahir, BS; Krystle P. Rapisura, DMD, MS; T. Jamie Parado, DDS; Keith R. Boyer, DDS; Luis G. Robinson, MS; and Marisa K. Watanabe, DDS, MS

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published by the California Dental Association 1201 K St., 14th Floor Sacramento, CA 95814 800.232.7645 cda.org

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John L. Blake, DDS Secretary secretary@cda.org Steven J. Kend, DDS Treasurer treasurer@cda.org Debra S. Finney, MS, DDS Speaker of the House speaker@cda.org R. Del Brunner, DDS Immediate Past President pastpresident@cda.org

Volume 48 Number 12 December 2020

Brian K. Shue, DDS, CDE Associate Editor Gayle Mathe, RDH Senior Editor

Blake Ellington Tech Trends Editor

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Charles N. Bertolami, DDS, DMedSc, Herman Robert Fox dean, NYU College of Dentistry, New York

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So Ran Kwon, DDS, MS, PhD, MS Guest Editor Andrea LaMattina, CDE Publications Manager Kristi Parker Johnson Senior Communications Specialist

The Journal of the California Dental Association (ISSN 1043–2256) is published monthly by the California Dental Association, 1201 K St., 14th Floor, Sacramento, CA 95814, 916.554.5950. The California Dental Association holds the copyright for all articles and artwork published herein.

Steven W. Friedrichsen, DDS, professor and dean, Western University of Health Sciences College of Dental Medicine, Pomona, Calif.

Mina Habibian, DMD, MSc, PhD, associate professor of clinical dentistry, Herman Ostrow School of Dentistry of USC, Los Angeles Robert Handysides, DDS, dean and associate professor, department of endodontics, Loma Linda University School of Dentistry, Loma Linda, Calif.

Bradley Henson, DDS, PhD , associate dean for research and biomedical sciences and associate professor, Western University of Health Sciences College of Dental Medicine, Pomona, Calif.

Paul Krebsbach, DDS, PhD, dean and professor, section of periodontics, University of California, Los Angeles, School of Dentistry Jayanth Kumar, DDS, MPH, state dental director, Sacramento, Calif.

Lucinda J. Lyon, BSDH, DDS, EdD, associate dean, oral health education, University of the Pacific, Arthur A. Dugoni School of Dentistry, San Francisco Nader A. Nadershahi, DDS, MBA, EdD, dean, University of the Pacific, Arthur A. Dugoni School of Dentistry, San Francisco Francisco Ramos-Gomez, DDS, MS, MPH, professor, section of pediatric dentistry and director, UCLA Center for Children’s Oral Health, University of California, Los Angeles, School of Dentistry Michael Reddy, DMD, DMSc, dean, University of California, San Francisco, School of Dentistry

The Journal of the California Dental Association is published under the supervision of CDA’s editorial staff. Neither the editorial staff, the editor, nor the association are responsible for any expression of opinion or statement of fact, all of which are published solely on the authority of the author whose name is indicated. The association reserves the right to illustrate, reduce, revise or reject any manuscript submitted. Articles are considered for publication on condition that they are contributed solely to the Journal of the California Dental Association. The association does not assume liability for the content of advertisements, nor do advertisements constitute endorsement or approval of advertised products or services.

Avishai Sadan, DMD, dean, Herman Ostrow School of Dentistry of USC, Los Angeles

Copyright 2020 by the California Dental Association. All rights reserved.

Brian J. Swann, DDS, MPH, chief, oral health services, Cambridge Health Alliance; assistant professor, oral health policy and epidemiology, Harvard School of Dental Medicine, Boston

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Harold Slavkin, DDS, dean and professor emeritus, division of biomedical sciences, Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry of USC, Los Angeles

Richard W. Valachovic, DMD, MPH, president emeritus, American Dental Education Association, Washington, D.C.

DEC. 2020

TABLE OF CONTENTS C D A J O U R N A L , V O L 4 8 , NÂş 12

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671 Streptococcus sanguinis Proteins Involved in Interspecies Binding to Fusobacterium nucleatum In this study, a mutant library was screened to identify the Streptococcus sanguinis proteins involved in binding to Fusobacterium nucleatum during biofilm formation.

Emily Duong, BS; Jenny Truong, BS; Mario Pizarro Rojas, BS; Bruno P. Lima, PhD; Ping Xu, PhD; Bhumika Shokeen, PhD; and Renate Lux, PhD

681 Surface Roughness of 3D Printed Discs Infused With Gold-Coated Titanium Oxide Nanofibers The purpose of this study was to synthesize titanium oxide nanofibers and gold-coated titanium oxide nanofibers, disperse them into the resin matrix to 3D printed composite discs and evaluate the change in surface roughness associated with repeated UV light activation over time.

Brittany Watu, BS, DDS; Clayton Tran, BS, DDS; Ellin Choi, BS, DDS; Alyson Drew, BS, DDSc; Udochukwu Oyoyo, MPH; Ryan Sinclair, PhD; Christopher C. Perry, PhD; and So Ran Kwon, DDS, MS, PhD, MS

689 Vulnerability of a young adult dental population in Los Angeles This study discusses how dentists need to identify, understand and include vulnerabilities created by adverse childhood experiences and unhealthy behaviors in comprehensive patient care.

Kenneth J. Glenn, BS; Christina Light, BS; Rassilee Sharma, BS; Kelly Nguyen, BS; Hongfei Chen, DDS, PhD; Todd Franke, MSW, PhD; and Shane N. White, BDentSc, MS, MA, PhD

697 A Tribute to Dr. Bob

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Reviewers

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Thank You to the 2020 Reviewers The Journal of the California Dental Association is grateful for the many professionals who formally reviewed manuscripts in 2020 and offered their recommendations. We extend our thanks to those who are instrumental in helping us produce this award-winning scientific publication.

Kenneth Abramovitch, DDS Matt Allen, DDS Pamela Alston, DDS, MA Clarisa Amarillas Gastelum, DDS, MS Sowmya Ananthan, BDS, DMD, MSD Shawn R. Anderson, DDS, MSD Leif K. Bakland, DDS Wade M. Banner, DMD Nicole Barkhordar, DDS, MEd Jane R. Barrow, MS Joyce Bassett, DDS Karen Becerra, DDS, MPH Phyllis Beemsterboer, MS, Ed D, FACD Ken Berley, DDS, JD, DABDSM Louis Berman, DDS Beatriz Bezerra, DDS, PhD Patrick Blahut, DDS, MPH John L. Blake, DDS Wanda Borges, PhD, RN, ANP-BC Donald L. Branam, BS, PharmD Carolyn Brown, DDS Michael E. Cadra, DMD, MD Jean Marie Calvo, DDS, MPH Paulo Camargo, DDS, MS, MBA Nicholas Caplanis, DMD, MS Megan L. Casey, RN, BSN, MPH David W. Chambers, EdM, MBA, PhD Jennifer Chang, DDS, MSD Kai Chiao Joe Chang, DDS, MS David A. Chernin, DMD, MLS Christina Chi, DDS Russell Christensen, DDS Paul K. Chu, DDS Alma Clark, DDS Donald Clem, DDS Stephen T. Connelly, DDS, MD, PhD Leopoldo P. Correa, BDS, MS Darren P. Cox, DDS. MBA Jean L. Creasey, DDS David R. Cummings, DDS Michael John Danford, DDS Robert A. Danforth, DDS Nancy Dewhirst, RDH Raymond Dionne, DDS, PhD Mark Donaldson, PharmD Evelyn Donate-Bartfield, PhD 638 D ECEMBER

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Bruce Donoff, DMD, MD Gerald I. Drury, DDS Rena D’Souza, DDS, MS, PhD Steve Duffin, DDS Nejat Duzgunes, PhD Joel P. Epstein, DMD, MSD, FRCD(C), Dip ABOM Yuwei Fan, PhD Fariborz A. Farnad, DMD James Fedusenko, DDS, RN Alan L. Felsenfeld. DDS Leticia Ferreira, DDS, MS Steven Friedrichsen, DDS Danielle Furgeson, RDH, MS, DHSC Sangeeta Gajendra, DDS, MPH, MS Steven I. Ganzberg, DMD, MS Jack D. Gerrow, DDS, MS, MEd, Cert Pros Anita Gohel, BDS, PhD Anupama Grandhi, DDS Shailee Gupta, DDS, MPH Mina Habibian, DMD, MS, PhD Marc Hayashi, DMD Reza Heshmati, DDS, MPH, MS Alice Horowitz, PhD Michelle Hurlbutt, RDH, MSDH, DHSc Mohammed A. Husain, DDS Nicola P.T. Innes, PhD, BDS, BSc, BMSc Lisa Itaya, DDS Shankar Iyer, DDS, MDS Kenneth J. Jacobs, DDS Peter Jacobsen, DDS, PhD Poonam Jain, BDS, MS, MPH Daniel Jenkins, DDS Larry E. Jenson, DDS, MA Kyle Jones, DDS, PhD David M. Kadar, DDS Richard T. Kao, DDS, PhD Cristin E. Kearns, DDS, MBA Kevin Keating, DDS Steven J. Kend, DDS Junad Khan, BDS, MSD, MPH, PhD Chun K. Kim, DDS Gary D. Klasser, DMD Perry Klokkevold, DDS, MS Anne Koerber, DDS, PhD Jens Kreth, PhD

Satish Kumar, DMD, MDSc, MS Jensog Le, DDS Michael J. Lee, DMD, MS Natasha A. Lee, DDS Stuart E. Lieblich, DMD Brent Lin, DMD Cindy, Lyon, RDH, DDS, EdD Monty MacNeil, DDS, MDentSc Ilay Maden, BDS, MSc, PhD Stanley F. Malamed, DDS Sanjay M. Mallya, BDS, MDS, PhD Stanley Markman, DDS Michael Marshall, DDS, HDS Keith A. Mays, DDS, MS, PhD Kimberly K. McFarland, DDS, MHSA Diana Messadi, DDS, MMSc, DMSc Peter G. Meyerhof, DDS, PhD Peter Milgrom, DDS Shelley Miyasaki, DDS, PhD Jean Moore, DrPH, MSN Alireza Moshaverinia, DDS, MS, PhD Sherry Mostofi, JD Richard P. Mungo, DDS, MSD, MeD Theodore A. Murray Jr., DDS Asma Muzaffar, DDS, MS, MPH Nader A. Nadershahi, DDS, MBA, EdD Linda Neuhauser, DrPH, MPH Ichiro Nishimura, DDS, DMD Man Wai Ng, DDS, MPH Marcel Noujeim, DDS, MS Brian Novy, DDS Busuyi Olotu, MSPharm, PhD Gregory Olson, DDS, MS Ali Oromchian, JD, LLM Daniel L. Orr, DDS, MS, PhD, JD, MD Joan Otomo-Corgel, DDS, MPH Udochukwu Oyoyo, MPH Mariela Padilla, DDS, MEd Tejas Patel, DMD, BDS Michael Perry, DDS Lucila Piasecki, MS, PhD Patricia Podolak, DDS, MPH Peter John Polverini, DDS, DMSc

Fred Quarnstrom, DDS Lori Rainchuso, DHSc, MS, RDH Robin L. Reisz, DDS Lindsey A. Robinson, DDS Alvin Rosenblum, DDS Lindsay Rosenfeld, ScD, ScM David Lawrence Rothman, DDS Mohammad Sabeti, DDS Elise Sarvas, DDS, MSD, MPH Roberto Savignano, MS, PhD Steven E. Schonfeld, DDS, PhD Charlotte L. Senseny, DMD Ya Shen, DDS, PhD Frederic J. Sherman, DDS Yooseok Shin, DDS, MS, PhD Charles Shuler, BSc, DMD, PhD Rebeka G. Silva, DMD Steven Silverstein, DMD, MPH Krikor Simonian, DDS, DABP James D. Stephens, DDS Stanley R. Surabian, DDS, JD Thomas Tanbonliong Jr., DDS Antonia Teruel, DDS, MS, PhD Gina Thornton-Evans, DDS, MPH Oluwabunmi Tokede, DDS, MPH Thanh Tam Ton, DDS, MS, MPH Richard D. Trushkowsky, DDS Richard W. Valachovic, DMD, MPH Suvendra Vijayan, BDS, MPH, MS Marisa K. Watanabe, DDS, MS Walter Weber, DDS Jane A. Weintraub, DDS, MPH Kimberly G. Whippy, DMD Bruce L. Whitcher, DDS Cun-Yu Wong, DDS, PhD Tim Wright, DDS, MS Christine D. Wu, PhD Juan Fernando Yepes, DDS, MD, MPH, MS, DrPH Andrew Young, DDS, MSD Douglas A. Young, DDS, EdD, MBA, MS Zhe Zhong, DDS, PhD Anthony J. Ziebert, DDS, MS Every effort was made to ensure the accuracy of the list of contributors.

If you discover an error or omission, please accept our apologies.

Guest Editorial

C D A J O U R N A L , V O L 4 8 , Nº 12

Questioning Our Role in Health Care in Response to COVID-19 Alex Fisher, DMD

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t feels strange to say, but I feel very lucky right now. In the face of an unprecedented pandemic ripping apart the fabric of our society, workplaces and daily lives, my life has resumed largely as if nothing changed. My family is healthy, and my office is perhaps busier and more productive than before COVID-19 took hold, only now I wear a mask when I enter the office in addition to when I’m working. Reopening our office has been, for the most part, uneventful.

When I began reflecting on our reopening, it wasn’t the day-to-day minutiae that felt important to me.

This has been an eye-opening, scary, unclear time for everyone, and for me the expectation was always that we should return to work as a pillar of safety for our community. We pride ourselves on being true communitybased health providers, many of us developing long-lasting relationships with our patients. What keeps coming up as the most important consideration of being an early career dental provider in a pandemic-present world is how can we better serve our community?

One of the things I’ve struggled with at times, as I’m sure many others have, is garnering the respect of patients. We all want patients to recognize that although we’re relatively new to the profession, we are their doctors. Some of us wear a white coat with our degree plastered on our chest, while for others, we grow a COVID-19-quarantine mustache in the hopes that no one asks if we’re old enough to be a dentist anymore (just me?). But the more you practice, the more you realize that ultimately, the respect comes from doing the right thing and being an active participant and educator in the oral-systemic health

We all want patients to recognize that although we’re relatively new to the profession, we are their doctors.

decisions of our patients. Now, more than ever, I think it’s important that we consider all aspects of health.

In April it was announced that the ADA was advocating for the federal government to grant liability immunity to dental providers when performing COVID-19 tests. While many providers have shied away from becoming testers, this brings about a natural, important progression of duties as dentists. We tend to see our patients with far more regularity than primary care physicians. We are at a much higher risk for transmission based on the use of our high-speed handpieces, cavitrons and working in the oral cavity. Why shouldn’t we be testing?

And this leads to broader questions regarding the scope of our practice. We are all aware, as dental providers, that we have a responsibility to perform oral cancer screenings routinely for our patients.

Knowing what we know regarding HPV and its link to rising oropharyngeal cancers, would it be appropriate to begin administering HPV vaccinations in our offices? I think it’s a logical next step. And is it enough to tell patients to cut down on sugar intake or should nutritionists and dietitians play a role in our general offices for nutritional counseling?

It’s very easy to stick to what we know in our line of work. The demands of working in or running a dental office are massive, and keeping current with dental

continuing education, new technologies and treatments could be a job in itself.

But maybe the pause in our normal operations can be a perfect opportunity to reconsider what exactly we can provide to our patients. Where can we do more?

Right now, it’s important to be a resource for our patients, to inform them of their oral health in the era of COVID-19.

It’s important to stay current on the latest guidelines and to be sympathetic to patients’ concerns and questions.

It’s important to lead our teams and to reinforce the science of why we do the things we do. Moving forward, hopefully we can find a way to exercise a broader scope of dentistry that incorporates a more systemic approach to health care. n Alex Fisher, DMD is a New Dentist Now guest blogger who graduated from Rutgers School of Dental Medicine in 2017. He is an associate general dentist and the sole clinical provider in a private practice in Montclair, New Jersey. He is an active ADA, AGD and AACD member and continues his learning with preeminent higher dental education programs.

This guest editorial, republished with permission, originally appeared Aug. 11, 2020, in ADA New Dentist Now, newdentistblog.ada.org.

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TOGETHER WE ARE LIMITLESS

Membership renewal is now open.

Be an active member of the community that amplifies your voice, takes action and drives results for dentistry. This year, we’ve delivered trusted guidance, actionable resources and advocacy success. Together, we’re stronger navigating what’s next.

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Impressions

C D A J O U R N A L , V O L 4 8 , Nº 12

Oral Cancer Pain Predicts Metastasis

Histological image of an oral carcinoma cuniculatum (4X).

(Credit: Mandana Donoghue)

While most patients reported some pain, those who suffered with the most pain were more likely to have cancer that spread to lymph nodes in the neck.

Oral cancer is more likely to spread in patients experiencing high levels of pain, according to a recent study in the journal Scientific Reports. The study’s research team from the New York University (NYU) College of Dentistry found genetic and cellular clues as to why metastatic oral cancers are so painful.

Previous research suggests that patients with metastatic oral cancer experience more pain than those whose cancer has not spread. The new study helps researchers understand why.

When oral cancer metastasizes, spreading to lymph nodes in the neck, a patient’s chance of survival is cut by half. However, it’s often unclear through imaging and physical assessment if oral cancer has spread, leaving surgeons struggling with whether to preemptively remove lymph nodes — an invasive procedure termed prophylactic neck dissection — during surgery to remove the oral cancer. While most oral cancer surgeries include a prophylactic neck dissection, research shows that up to 70% are unnecessary.

In their study, the researchers first documented the pain experienced by 72 oral cancer patients before surgery using an oral cancer pain questionnaire developed by the investigators.

While most patients reported some pain, those who suffered with the most pain were more likely to have cancer that spread to lymph nodes in the neck. This observation suggests that patients with less pain are at low risk of metastasis and will rarely benefit from a neck dissection.

To begin to understand why metastatic cancers are more painful, the investigators looked for differences in gene expression between metastatic cancers from patients with high levels of pain compared to nonmetastatic cancers from patients not experiencing pain. Cancer pain is attributed to the release of mediators from cancers that sensitize nerves near the cancer.

Forty genes were identified that were more highly expressed in painful metastatic cancers, suggesting that they promote metastasis and mediate cancer pain. Many of these genes are found in exosomes, small vesicles that break away from a cell and can be taken up by other cells, revealing a potential mechanism for how cancers communicate with nerves.

Next, the team undertook laboratory experiments to study exosomes found in the extracellular fluid of oral cancer cells grown in the lab. When this extracellular fluid was injected into animal models, it produced pain, but when the cancer-derived exosomes in the fluid were removed, it did not cause pain. This suggests that exosomes from cancer may be responsible for oral cancer pain.

Now, with a deeper understanding of why metastatic oral cancers are painful, the researchers point to several potential clinical applications for their research, including a biomarker for oral cancer metastasis to help with surgical decision-making and future testing options.

Learn more about this study in Scientific Reports (2020); doi.org/10.1038/s41598-020-71298-y. n D ECEMBER 2 0 2 0

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Researchers Identify Cell Populations in Teeth Light Stimulation Makes Bones Heavier Bone health is a dynamic process of continual remodeling controlled by multiple factors. Sclerostin, a glycoprotein coded by the gene SOST, is produced by bone cells and suppresses bone formation. Now, researchers at Tokyo Medical and Dental University have shown that laser irradiation, by inhibiting sclerostin expression without inducing inflammation, shows promise as a new treatment modality for osteoporosis. The study was published in the Federation of American Societies for Experimental Biology (FASEB) Journal.

The research team knew that in periodontal surgery, bone that underwent controlled destruction using a specific type of laser known as an Er:YAG laser healed faster than bone subjected to conventional bur drilling. Thus, they wondered whether Er:YAG laser irradiation modified SOST expression in bone. “We set out to compare comprehensive and sequential gene expression and biological healing responses in laser-ablated, burdrilled and untreated bone as well as investigating the biostimulation effect of an Er:YAG laser on osteogenic cells,” said Yujin Ohsugi, PhD, lead author.

Using microarray analysis, the researchers first studied gene expression patterns in rat skull bones during healing at six, 24 and 72 hours after drilling or laser treatment. Immunohistochemical analysis at one day was performed to detect sclerostin expression. Additionally, oseteogenic cell cultures were irradiated in vitro and assessed for cell death and sclerostin concentration.

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New knowledge on the cellular makeup and growth of teeth can expedite developments in regenerative dentistry as well as the treatment of tooth sensitivity.

Using a single-cell RNA sequencing method and genetic tracing, researchers at Karolinska Institutet in Sweden, the Medical University of Vienna in Austria and Harvard University have identified and characterized all cell populations in mouse teeth and in the young growing and adult human teeth. The research was published in Nature Communications.

“From stem cells to the completely differentiated adult cells, we were able to decipher the differentiation pathways of odontoblasts, which give rise to dentine — the hard tissue closest to the pulp — and ameloblasts, which give rise to the enamel,” the authors said.

“We also discovered new cell types and cell layers in teeth that can have a part to play in tooth sensitivity.”

Some of the finds can also explain certain complicated aspects of the immune system in teeth, and others shed new light on the formation of tooth enamel.

The results have been made publicly accessible in the form of searchable interactive, user-friendly atlases of mouse and human teeth, which researchers believe should prove to be a useful resource not only for dental biologists but also for researchers interested in development and regenerative biology in general.

“We hope and believe that our work can form the basis of new approaches to tomorrow’s dentistry,” the authors said. “Specifically, it can expedite the fast expanding field of regenerative dentistry.”

Learn more about this study in Nature Communications (2020); doi.org/10.1038/ s41467-020-18512-7.

Schematic drawing summarizing validation and mapping of the observed cellular subpopulations back onto the incisor tissue preparations. (Credit: Krivanek et al. Creative Commons license.)

The research team confirmed decreased sclerostin expression after laser irradiation both in vivo and in vitro.

“Interestingly, sequential microarray analysis revealed a clear distinction in the gene expression pattern between burdrilled and laser-ablated bones at 24 hours, with the former alone showing enriched inflammation-related pathways,” said Sayaka Katagiri, PhD, corresponding author. “Significantly, at six hours following laser ablation, the Hippo signaling pathway that limits tissue

overgrowth was enriched but inflammation-related pathways remained unaffected, suggesting that laser irradiation worked thorough mechanical biostimulation.”

The finding that mechanical stimulation of laser irradiation inhibits the pathways that suppress bone regeneration without provoking inflammation may aid development of laser-based therapeutic methods.

Read more about this study in FASEB Journal (2020); doi/10.1096/fj.202001032R.

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Botox for TMJD May Not Lead to Bone Loss Botox injections to manage jaw and facial pain do not result in clinically significant changes in the jawbone when used short term and in low doses, according to researchers at NYU College of Dentistry.

However, they found evidence of bone loss when higher doses were used.

The researchers, whose findings are published in the Journal of Oral Rehabilitation, call for further clinical studies to track bone- and muscle-related changes with long-term use of Botox for temporomandibular muscle and joint disorders (TMJD).

Tumor Progression Relies on Microenvironment Researchers from Tokyo Medical and Dental University and Niigata University discovered that the proteins transforming growth factor-β (TGF-β) and tumor necrosis factor alpha (TNF-α) promote the development of cancer-associated fibroblasts, which in turn contribute to tumor progression. The study was published in Cancer Science.

The goal of this study was to investigate how the tumor microenvironment contributes to tumor progression. To achieve their goal, the researchers focused on the protein TNF-α, a known cytokine secreted by inflammatory cells. Because tumors are often infiltrated by inflammatory cells, the tumor microenvironment contains high levels of TNF-α. To understand the roles of TNF-α in TGF-β-induced EndMT, the researchers treated human endothelial cells with TGF-β, TNF-α or both. TGF-β robustly induced EndMT as shown through increased expression of various markers of CAFs as well as a transition toward a CAF morphology of the human endothelial cells. However, interestingly enough, TNF-α enhanced the molecular effects of TGF-β.

Because one of the main biological functions of CAFs is to secrete proteins into the tumor microenvironment and induce tumor progression, the researchers next cultured human oral cancer cells in the presence of the proteins secreted from EndMT-derived CAFs. The researchers found that oral cancer cells underwent epithelial-mesenchymal transition (EMT). Because EMT is a hallmark of tumor progression and metastasis, these results demonstrated that the proteins secreted by CAFs contribute to tumor progression. The researchers also found that these effects of CAFs on tumor progression was suppressed by inhibition of TGF-β, suggesting that TGF-β protein secreted from CAFs induced EMT. “These are striking results that identify a molecular mechanism underlying the role of the tumor microenvironment in tumor biology,” said the authors. “We hope that our findings will aid in the development of novel cancer therapies.”

Learn more about this study in Cancer Science (2020); doi.org/10.1111/ cas.14455.

Fluorescence immunostaining for SM22α (magenta) and nuclei (blue). (Image © 2020 Cancer Science published by John Wiley & Son)

Botox (or botulinum toxin), an FDA-approved injectable drug known for its wrinkle-reducing capabilities, is approved to treat certain muscle and pain disorders, including migraines. It works in part by temporarily paralyzing or weakening muscles. In the U.S., a Phase 3 clinical trial is currently underway to study the use of Botox to treat TMJD, but in the meantime, it is increasingly being used off-label.

Thus far, small studies using Botox to treat TMJD in humans have had mixed results. In animal studies, Botox injections in jaw muscles have led to major bone loss in the jaw. This is thought to be due to the muscles not being used to exert force needed for bone remodeling, but Botox may also have a direct effect on bone resorption.

The NYU study included 79 women with TMJD affecting their facial muscles: 35 of whom received Botox injections (between two and five rounds in the past year) and 44 who were not treated with Botox but may have used other TMJD treatments. Using specialized CT scans, the researchers measured participants’ jawbone density and volume.

The researchers found that jawbone density and volume were similar between women who had Botox injections to treat their TMJD and those who did not. While most study participants were given relatively low doses of Botox — smaller than in most clinical trials for TMJD — individuals who received higher doses of Botox were more likely to have lower bone density. Read more of this study in the Journal of Oral Rehabilitation (2020); doi.org/10.1111/joor.13087.

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introduction C D A J O U R N A L , V O L 4 8 , Nº 12

Dental Student Research So Ran Kwon, DDS, MS, PhD, MS

GUEST EDITOR So Ran Kwon, DDS, MS, PhD, MS, is a professor and director of the student research program at the Loma Linda University School of Dentistry.

Conflict of Interest Disclosure: None reported.

E

very year, the Journal of the California Dental Association highlights student research and papers from dental schools in California. Additionally, the CDA Presents convention provides a dedicated Table Clinic for dental students to present their research and compete for several awards. These platforms not only provide great opportunities for our students to share their research efforts but also allow them to interact with peers and oral health care professionals. I sincerely thank CDA for these special considerations.

This year, invitations were sent out to six California dental schools, and as a result this issue features six excellent submissions from the University of California, Los Angeles, School of Dentistry, the University of the Pacific, Arthur A. Dugoni School of Dentistry, the Loma Linda University School of Dentistry and the Western University of Health Sciences College of Dental Medicine.

It is immensely exciting that the student research topics cover: ■ Clinical research “Dentin Bonding in Class V Lesions and the Influence of the Patient’s Age on Bond Strength” from UOP and “Digital Imaging Filters and Their Effect on Detecting Root Resorption” from Loma Linda.

■ Educational research “Assessment of a Pediatric Population Using Telehealth Training in Predoctoral Dental Education” from Western.

Basic science research “Streptococcus sanguinis Proteins Involved in Interspecies Binding to Fusobacterium nucleatum” from UCLA. ■ Nanomaterial science “Surface Roughness of 3D Printed Discs Infused With Gold-Coated Titanium Oxide Nanofibers” from Loma Linda.

■ Community studies “Vulnerability of a Young Adult Dental Population in Los Angeles” from UCLA. The articles clearly demonstrate the commitment of our students to expand dental knowledge through research. We applaud our students and their faculty mentors in their passion to further dental research and, ultimately, improve patient care.

The challenges of the current pandemic have brought many restrictions to our dental community. However, it is my personal hope that despite these circumstances, all six California dental schools will come together and collaborate to promote student research endeavors and enhance the field of dentistry.

I hope you enjoy reading this issue that shows beyond a doubt how this new generation of dental students will lead and advance dentistry to its future. n ■

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dentin bonding C D A J O U R N A L , V O L 4 8 , Nº 12

Dentin Bonding in Class V Lesions and the Influence of the Patient’s Age on Bond Strength Harley Grandin, DDS; Jim Milani, DDS; Mouchumi Bhattacharyya, PhD; and Karen A. Schulze, DDS, PhD

a b s t r a c t The aim of this in vitro study was to evaluate the influence of patients’

age (up to 40 years old, 40-60 years old, 60-plus years old) on shear bond strength (SBS) of composites to dentin in cervical lesions comparing acid-etching and self-etching systems. The self-etching materials performed the same in all age groups. For the acid-etching materials, a significant increase in bond strength could be found in the 60-plus age group.

AUTHORS Harley Grandin, DDS, studied dentistry at the University of the Pacific, Arthur A. Dugoni School of Dentistry in San Francisco.

He is currently enrolled in the endodontics residency program at the University of Illinois, Chicago, College of Dentistry.

Conflict of Interest Disclosure: None reported.

Jim Milani, DDS, is an associate professor in the department of preventive and restorative dentistry at the University of the Pacific, Arthur A. Dugoni School of Dentistry in San Francisco.

He teaches clinical as well as preclinical courses.

Conflict of Interest Disclosure: None reported.

Mouchumi Bhattacharyya, PhD, is a professor in the department of mathematics in the College of the Pacific at the University of the Pacific in Stockton.

Conflict of Interest Disclosure: None reported.

Karen A. Schulze, DDS, PhD, is an associate professor in the department of preventive and restorative dentistry at the University of the Pacific, Arthur A. Dugoni School of Dentistry in San Francisco. She is the director of clinical research and teaches clinical courses and conducts research.

Conflict of Interest Disclosure: None reported.

D

entin has a complex histology that changes with its proximity to the pulp, with time and in response to the disease processes.

A honeycomb-like structure formed by intertubular and peritubular mineralized collagen creates fluid-filled tubules that become more narrow as they travel from the pulp to the dentinoenamel junction.1 Because of this unique and variable structure, bonding to dentin requires a different approach than bonding to enamel.2 One of the early impediments to dentin bonding was the presence of a smear layer resulting from preparation of the tooth. The smear layer covers the dentin and occludes the tubules preventing the formation of the hybrid layer — a mixture of bonding agent and the collagen meshwork that allows the composite to adhere.3 Early

bonding systems attempting dentin bonding failed to remove the smear layer and, therefore, failed to achieve a bond strong enough to resist the contraction stress caused by the polymerization of the overlying composite.4 While we have found a way to manage the smear layer, carious and sclerotic dentin still present a similar barrier to predictable dentin bonding.5,6 Furthermore, the majority of laboratory tests on dentin bond strength are performed on healthy and nonsclerotic dentin, which does not accurately model the clinical use of dentin bonding systems.7 Dentin from younger patients has different morphology while dentin from older patients shows a more sclerotic surface. Sclerotic dentin appears more translucent and very glossy due to calcification of the dentinal tubules as a result of injury or normal aging (FIGURE 1) .

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FIGURE 1. Noncarious cervical lesions in adult teeth.

The structure of sclerotic dentin is characterized by occluded dentin tubules. A combination of bacterial activity and host response leads to obliteration of the dentinal tubules with rhombohedral, whitlockite crystallites referred to as sclerotic casts.5 Moreover, these sclerotic casts are more resistant to acid conditioning, and they also block the tubules, thereby inhibiting the formation of resin tags.8,9 As teeth age, the pulp responds to stressors such as caries, restorative procedures or occlusal trauma by forming tertiary/ reparative dentin, narrowing or completely occluding the tubules with whitlockite.10–12 While in theory, this tubular occlusion should impair dentin bond strength, studies have failed to draw consistent conclusions.

In general, studies consistently demonstrate thinner hybrid layers with voids in older and sclerotic dentin but fail to show a significant difference in tensile bond strength when subjected to Instron testing.8,13,14 This tubular occlusion also appears in noncarious cervical lesions (NCCLs) but is compounded by a hypermineralized surface layer.16 Bacteria colonizing the wedgeshaped lesions lower the pH in the presence of fermentable carbohydrates demineralizing the root surface. Once 648 D ECEMBER

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the food source is depleted, pH levels rise and the surface remineralizes.

Over time, a hypermineralized layer of entombed bacteria and denatured collagen builds up16 creating a surface that is highly resistant to current etching techniques.9 In sum, dentin bonding is altered by both the formation of tertiary dentin as part of aging and carious activity and by the presence of a hypermineralized surface layer in NCCLs.17 Studies have repeatedly shown that dental adhesives form weaker bonds to caries-affected dentin and NCCLs; however, studies regarding the effects of aging on adhesive bond strengths have been mixed.12–14,18–20

Background on Dentin Bonding Protocols

Current bonding systems rely on two principles to achieve a sufficient bond: Acid-etching (total etching) of the dentin to remove the smear layer and “wetting” of the now decalcified collagen meshwork with an amphiphilic molecule to achieve a hybrid layer with resin tags extending into the tubules.21 With total etch systems, the phosphoric acid must be washed off, and the degree of drying plays a significant role in the strength of the bond — overdrying will collapse the collagen meshwork, overwetting will inhibit the polymerization.22 Self-etch systems are thought to simplify this by combining a weaker, self-limiting acid with the primer, thus eliminating the need for a rinse.23 Unlike total-etch systems that remove the smear layer, selfetch systems incorporate the smear layer into the hybrid layer.24 Self-etch systems have a smaller hybrid layer and better adaptation to the dentin tubules with fewer voids in comparison

to total-etch systems.25 These voids are of clinical significance in that they are implicated in postoperative sensitivity.26 While self-etch adhesives have demonstrated superior bond strength to dentin in many studies, they fail to produce predictable bond strength to sclerotic dentin that occurs mainly in cervical lesions.16 The purpose of this study was to evaluate the bond strength in class V lesions between human dentin from different age groups and composites that were followed by either an acid-etching or a self-etching adhesive protocol. The presented study uses commercially available adhesive products and a more defined pool of extracted premolars from three different age groups. The null hypothesis of this study is that the age of the patient has no influence on the bond strength of composite to dentin in class V lesions.

Research Study

A total of 36 freshly extracted human upper premolars were collected and sorted by three different age groups (from patients aged 39 or younger; 12 premolars, group Young), patients aged 40–60; 12 premolars, group Mid) and patients aged 61 and older; 12 premolars, group Older). All of the Older premolars had significant cervical defects in a wedge-shaped dimension. The extracted premolars from the Young and Mid groups had minimal or no lesions and needed some preparation in the class V location. These teeth were gently ground flat by hand on carbide paper (320 grit) at the facial cementoenamel junction area of the tooth to expose a dentin surface with a 3 mm x 3 mm2 area. All teeth were embedded into acrylic resin (Jet Tray, Lang Dental Manufacturing Co. Inc., Wheeling,

C D A J O U R N A L , V O L 4 8 , Nº 12

Ill.) using a cylinder mold. The surfaces of six specimens from each age group were treated with self-etching adhesive material (Peak SE, Ultradent Products Inc., South Jordan, Utah) called SE and another six specimens for each age group were treated with acid-etching adhesive material (OptiBond Solo Plus, Kerr, Brea, Calif.) called AE. The materials were applied according to manufacturers’ instructions. All specimens were prepared by one provider. A special bonding clamp (Ultradent Products Inc.) served as a mold for the flowable composite (experimental material from Ultradent Products Inc.) that was inserted and light cured to fabricate a composite rod (2.3 mm in diameter) perpendicular to the dentin surface (FIGURES 2–5). The shear bond strength (SBS) was evaluated in megapascals (MPa) at a cross head speed of 1 mm per min using the Ultratester (Ultradent Products Inc.). FIGURE 6 shows the preparation of the specimens. The Kruskal-Wallis test (for non-normal data) and one-way ANOVA test (for normal data) were used to analyze the data for statistically significant difference at a 95% confidence interval.

The SBS test results are 33.2 (± 10.4), 33.4 (± 10.6) and 32 (± 6.5) MPa for Young SE, Mid SE and Older SE, respectively. With a p-value of 0.89, the groups failed to demonstrate a statistically significant difference among the groups meaning the results are very similar and vary only a minimal amount of 1.4 MPa (blue columns in FIGURE 7 ). The results for the AE tests are as follows: 29.8 (± 3.2), 32.8 (± 10.8) and 42.6 (± 7.1) MPa for Young, Mid and Older, respectively. This test revealed that an acid-etching procedure in group Older AE showed not significantly higher bond strength compared to

FIGURE 2 . Bonding clamp and materials for the

FIGURE 3 . Application of etchant to the sample.

research study.

FIGURE 4 . Placement of composite to the sample.

FIGURE 5 . Light curing of the composite.

Mid AE (p = 0.098) and Young AE (p = 0.272). There was no significant difference (p = 0.999) between Young AE and Young SE and also no significant difference found (p = 0.928) between Mid AE and Mid SE. The only significant difference was determined among Older AE and Older SE (p = 0.0223). In summary, these results indicate no detectable difference in self-etching mode among all age groups but a significantly stronger bond when using the acidetching protocol in older individuals.

phosphoric acid prior to applying a self-etching primer. Other approaches have been a self-etching technique and a selective-etching technique.

However, studies have failed to show improved bond strength to sclerotic dentin irrespective of preconditioning technique.13,18 Each treatment either failed to penetrate the hypermineralized layer and bond to the underlying dentin or the bond was only with the hypermineralized layer or the overlying microbial matrix.5 This failure to adequately penetrate the hypermineralized layer with resulting voids in the hybrid layer and a deficiency in resin tag formation is one explanation for the weak links that are responsible for reduced bond strength to sclerotic dentin.

One drawback in the study design is that for the Older group, the existing exposed sclerotic dentin surface was used, while for the Mid

Discussion

Attempts at bonding to sclerotic dentin have focused on removing the hypermineralized layer to clear occluded dentinal tubules and create a suitable surface for the primer and adhesive to infiltrate.27 One approach to achieve this has been to condition the sclerotic dentin with

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dentin bonding C D A J O U R N A L , V O L 4 8 , Nº 12

Groups

Roots Roots cut cutoff, off, buccal surface ground flat flat ground

Embedded with Embedded with acrylic acrylic acid acid

Compositerod rod Adhesive Adhesive application application on Composite created in in aa clamp exposed surface on exposed surface created

with SBS testing testing with Ultratester Ultratester

OLDER Older

Mid MID

YOUNG Young

FIGURE 6 . Sample preparation in a diagram.

MPa 60

SSD

50 40 30 20 10 0

< 40 years old

40–60 years old

60+ years old

SSD = statistically significant different self-etch acid-etch FIGURE 7. Shear bond strength between dentin (from different age groups) and composite using a self-etch and acid-etch system.

and Younger groups, all bonding areas had to be mechanically created.

Nevertheless, the attempt was made to finish all samples on carbide paper the same way in order to create the same type and size of smear layer.

The authors noticed a much smaller standard deviation for the Younger AE group than for all other groups. This shows a more precise result. For the younger patient group, the phosphoric etching step creates a very predictable result on SBS. The reason practitioners 650 D ECEMBER

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avoid the etching step in young people is the potential sensitivity.

When it comes to managing the hypermineralized layer of NCCLs, methods include preserving the layer,28 increasing lengths of acidetching time13 or attempting complete removal of it.13,18 It is possible that the only way to completely remove the hypermineralized layer and underlying sclerotic dentin is by mechanical means with a bur.5 This is complicated by the fact that the

deepest aspect of NCCLs also have the thickest hypermineralized layer increasing the potential for a pulp exposure depending on the dimensions of the lesion.19 One generally accepted method to improve the predictability of restorations involving sclerotic dentin is to incorporate beveled, acidetched enamel at the cavosurface.20 Creating mechanical retention into the prep is another way of increasing the lifespan of the restoration.29 While composite has the potential to produce a more aesthetic and durable restoration, our ability to achieve a reliable bond to sclerotic dentin limits its use. Currently, resin-modified glass ionomer cements, either as a base or complete restoration, have been shown to produce more predictable results compared to composite over longitudinal studies.30–32 To improve the life span of a class V composite restoration, this study found that the patient’s age must be considered when choosing a bonding system instead of using one bonding technique across all patient age ranges.

By categorizing your patients into three age groups (39 and younger, 40–60 and 61 or older) and using the bonding technique for that age group as described in this paper, the lifespan for the class V composite is likely to

C D A J O U R N A L , V O L 4 8 , Nº 12

TABLE

Clinical Guidelines for Class V Treatments in Regard to Bonding Protocols Percent weight loss vs. titratable acidity

Patient age

Suggested bonding protocol for class V lesions

40 and younger

Self-etching protocol on dentin Acid-etching protocol on beveled enamel

40–60

Self-etching protocol on dentin Acid-etching protocol on beveled enamel

60 and older

} }

Reason

equals selective etch technique

Highly sensitive dentin

equals selective etch technique

Medium sensitive dentin

Acid-etching protocol on both dentin and enamel

Low sensitivity on dentin

Note: Bracket represents the selective etching technique.

improve compared to using the same bonding system for all patient ages.

The increase in SBS in the AE Older group is likely due to the greater ability of the phosphoric acid etch to disrupt and prepare the sclerotic, acid-etch resistant dentin that is most prominent in this older population even though other studies have shown no differences in age groups.14 It is also possible that the sclerotic dentin behaves more like enamel than dentin due to its higher inorganic content.

Thus, because the dentin in the older group is more highly mineralized, the use of acid-etch technique is justified (TABLE) . Most importantly, when it comes to managing NCCLs, it is important to determine the etiology (erosion, abrasion and/or abfraction) to prevent the formation of these lesions in the first place.

More studies need to be done to identify if mechanical pretreatment such as air abrasion or other influences have an effect on SBS in class V lesions in vitro. In the recent years, many clinical studies on NCCLs have been published.33–36 Most of them are short-term studies (up to three years) showing no differences of the materials used.34 Using an ultrasound probe for application34 had increased the success rate while optical coherence tomography has demonstrated the superior performance of selective etching on NCCLs.35 Only very few studies show long-term clinical results

after nine-plus years of staying in situ.36 The null hypothesis was rejected in this study because teeth from patients aged 60 or older exhibited statistically significantly higher bond strength when the acid-etching protocol was used compared to the Young and Mid groups. It was also determined that the Older AE group had significantly higher bond strength statistically than the Older SE group. The etching step on sclerotic dentin seemed to be the key to the highly successful SBS result.

Clinical Significance

This in vitro study showed that for the testing group 60 + years old, the acid-etching protocol on cervical lesions resulted in significantly higher SBS than the self-etching protocol. Universal or self-etching techniques can be used with younger or middle-aged patients. n

ACKNOWLEDGMENT The authors thank Warden Noble, DDS, MS, MSED, and Jon Draper for their help with the images. Furthermore, we thank Ultradent and 3M for supplying the materials for this study.

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2. Pashley DH. Clinical correlations of dentin structure and function. J Prosthet Dent 1991 Dec;66(6):777–781. doi: 10.1016/0022-3913(91)90414-r.

3. Tao L, Pashley DH, Boyd L. The effect of different types of smear layers on dentin and enamel bond strengths. Dent Mater 1988 Aug;4(4):208–216. doi: 10.1016/s01095641(88)80066-6.

4. Davidson CL, de Gee AJ, Feilzer A. The competition

between the composite-dentin bond strength and the polymerization contraction stress. J Dent Res 1984 Dec;63(12):1396–19. doi: 10.1177/00220345840630121101.

5. Tay FR, Pashley DH. Resin bonding to cervical sclerotic dentin: A review. J Dent 2004 Mar;32(3):173–96. doi: 10.1016/j.jdent.2003.10.009.

6. Yoshiyama M, Tay FR, Doi J, Nishitani Y, Yamada T, Itou K, Carvalho RM, Nakajima M, Pashley DH. Bonding of self-etch and total-etch adhesives to carious dentin. J Dent Res 2002 Aug;81(8):556–60. doi: 10.1177/154405910208100811.

7. Perdigão J. Dentin bonding as a function of dentin structure. Dent Clin North Am 2002 Apr;46(2):277–301. doi: 10.1016/s0011-8532(01)00008-8.

8. Prati C, Chersoni S, Mongiorgi R, Montanari G, Pashley DH. Thickness and morphology of resin-infiltrated dentin layer in young, old and sclerotic dentin. Oper Dent 1999 Mar–Apr;24(2):66–72.

9. Gwinnett AJ, Jendresen M. Micromorphologic features of cervical erosion after acid conditioning and its relation with composite resin. J Dent Res 1978 Apr;7:543–549. doi: 10.1177/00220345780570040101.

10. Stanley HR, Pereira JC, Spiegel E, Broom C, Schultz M. The detection and prevalence of reactive and physiologic sclerotic dentin, reparative dentin and dead tracts beneath various types of dental lesions according to tooth surface and age. J Oral Pathol 1983 Aug;12(4):257–289. doi: 10.1111/j.1600-0714.1983.tb00338.x.

11. Duke ES, Lindemuth J. Variability of clinical dentin substrates. Am J Dent 1991 Oct;4(5):241–246.

12. Ryou H, Romberg E, Pashley DH, Tay FR, Arola D. Importance of age on the dynamic mechanical behavior of intertubular and peritubular dentin. J Mech Behav Biomed Mater 2015 Feb;42:229–42. doi: 10.1016/j. jmbbm.2014.11.021.

13. Lopes GC, Vieira LC, Araújo E, Bruggmann T, Zucco J, Oliveira G. Effect of dentin age and acid etching time on dentin bonding. J Adhes Dent 2011 Apr;13(2):139–45. doi: 10.3290/j.jad.a19028.

14. Burrow MF, Takakura H, Nakajima M, Inai N, Tagami J, Takatsu T. The influence of age and depth of dentin on bonding. Dent Mater 1994 Jul;10(4):241–246. doi: 10.1016/0109-5641(94)90068-x.

15. Kawakami T, Takei N, Eda S. Crystals closing tubules in sclerosed coronal dentin of the aged. In: Shimono M, Maeda T, Suda H, Takahashi K, eds. Proceedings of the International Conference on Dentin/Pulp Complex 1995 Resin bonding to cervical sclerotic dentin: A review 193 and the International Meeting on Clinical Topics of Dentin/ Pulp Complex. Osaka: Quintessence; 1996:285–286.

16. Duke ES, Lindemuth J. Polymeric adhesion to dentin: Contrasting substrates. Am J Dent 1990 Dec;3:24–270.

17. Peridgão J. Dentin bonding — Variables related to the clinical situation and the substrate treatment. Dent Mater 2010 Feb;26(2):e24–e37. doi:10.1016/j. dental.2009.11.149.

18. Kwong SM, Cheung GS, Kei LH, Itthagarun A, Smales RJ, Tay FR, Pashley DH. Micro-tensile bond strengths to sclerotic dentin using a self-etching and a total-etching technique. Dent Mater 2002 Jul;18(5):359–369. doi: 10.1016/s0109-5641(01)00051-3.

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B, Carvalho RM, Johnson MH, Pashley DH. Regional strengths of bonding agents to cervical sclerotic root dentin. J Dent Res 1996 Jun;75(6):1404–1413. doi: 10.1177/00220345960750061201.

20. Van Meerbeek B, Braem M, Lambrechts P, Vanherle G. Two-year clinical evaluation of two dentine-adhesive systems in cervical lesions. J Dent 1993 Aug;21(4):195– 202. doi:10.1016/0300-5712(93)90126-b.

21. Pashley DH, Carvalho RM. Dentine permeability and dentine adhesion. J Dent 1997 Sep;25(5):355–372. doi: 10.1016/s0300-5712(96)00057-7.

22. Yamamoto K, Suzuki K, Suwa S, Miyaji H, Hirose Y, Inoue M. Effects of surface wetness of etched dentin on bonding durability of a total-etch adhesive system: Comparison of conventional and dumbbell-shaped specimens. Dent Mater 2005 Jun;24(2):187–94. doi: 10.4012/dmj.24.187.

23. Tay FR, Pashley DH. Have dentin adhesives become too hydrophilic? J Can Dent Assoc 2003 Dec;69(11):726–31.

24. Tay FR, Pashley DH. Aggressiveness of contemporary self-etching adhesives. Part I. Depth of penetration beyond dentin smear layers. Dent Mater 2001 Jul;17(4):296–308. doi:10.1016/s0109-5641(00)00087-7.

25. Hegde MN, Hegde P, Chandra CR. Morphological evaluation of new total etching and self-etching adhesive system interfaces with dentin. J Conserv Dent 2012 Apr;15(2):151–5. doi: 10.4103/0972-0707.94589.

26. Unemori M, Matsuya Y, Akashi A, Goto Y, Akamine A. Composite resin restoration and postoperative sensitivity: Clinical follow-up in an undergraduate program.

J Dent 2001 Jan;29(1):7–13. doi:10.1016/s03005712(00)00037-3.

27. Eick JD, Gwinnett AJ, Pashley DH, Robinson SJ. Current concepts on adhesion to dentin. Crit Rev Oral Biol Med 1997;8(3):306–335. doi:10.1177/ 10454411970080030501.

28. Tani C, Itoh K, Hisamitsu H, Wakumoto S. Efficacy of dentin bonding to cervical defects. Dent Mater 2001 Dec;20(4):359–368. doi: 10.4012/dmj.20.359.

29. Kim SY, Lee KW, Seong SR, Lee MA, Lee IB, Son HH, Kim HY, Oh MH, Cho BH. Two-year clinical effectiveness of adhesives and retention form on resin composite restorations of non-carious cervical lesions. Oper Dent 2009 Sep–Oct;34(5):507–515. doi: 10.2341/08-006C. 30. Franco EB, Benetti AR, Ishikiriama SK, Santiago SL, Lauris JRP, Jorge MFF, Navarro MFL. 5-year clinical performance of resin composite versus resin modified glass ionomer restorative system in non-carious cervical lesions. Oper Dent 2006 Jul–Aug;31(4):403–408. doi: 10.2341/05-87.

31. Tyas MJ. The Class V lesion — aetiology and restoration.

Aust Dent J 1995 Jun;40(3):167–170. doi: 10.1111/ j.1834-7819.1995.tb05631.x.

32. Fagundes TC, Barata TJE, Bresciani E, Santiago SI, Franco EB, Lauris JRP, Navarro MF. Seven-year clinical performance of resin composite versus resin-modified glass ionomer restorations in noncarious cervical lesions.

Oper Dent 2014 Nov–Dec;39(6)578–587. doi: 10.2341/13-054-C. 33. Rocha AC, Salas MS, Masotti AS, da Rosa W, Zanchi CH, Lund RG. A randomized double-blind clinical trial of dentin surface treatments for composite restorations in noncarious cervical lesions: A 36-month evaluation.

Oper Dent 2019 Mar–Apr;44(2):114–126. doi:10.2341/17-308-C.

34. Oz FD, Kutuk ZB, Ozturk C, Soleimani R, Gurgan S. An 18-month clinical evaluation of three different universal adhesives used with a universal flowable composite resin in the restoration of non-carious cervical lesions. Clin Oral Investig 2019 Mar;23(3):1443–1452. doi:10.1007/ s00784-018-2571-2.

35. Haak R, Hähnel M, Schneider H, Rosolowski M, Park KJ, Ziebolz D, Haefer M. Clinical and OCT outcomes of a universal adhesive in a randomized clinical trial after 12 months. J Dent 2019 Nov;90:103200. doi:10.1016/j. jdent.2019.103200.

36. Peumans M, Wouters L, De Munck J, Van Meerbeek B, Van Landuyt K. Nine-year clinical performance of a HEMA-free one-step self-etch adhesive in noncarious cervical lesions. J Adhes Dent 2018;20(3):195–203. doi:10.3290/j.jad.a40630.

THE CORRESPONDING AUTHOR, Harley Grandin, DDS, can be reached at grandindds@gmail.com.

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digital imaging filters C D A J O U R N A L , V O L 4 8 , NÂş 12

Digital Imaging Filters and Their Effect on Detecting Root Resorption Jeries Nader Qoborsi, BS; Shant Oroojian, BSc; Jason Bajwa, BSc; Ambrose I. Obhade, BDS, DDS; Gina D. Roque-Torres, PhD; and Dwight Rice, DDS

a bstr a c t Objectives: Advances in radiographic imaging software are making a significant impact on diagnosis and treatment planning in dentistry. Root resorption (RR) has multigenic etiologies and can lead to tooth loss if not diagnosed and treated early.

This study evaluated the sensitivity of various radiographic software filters in the detection of RR. Methods: Twenty-nine teeth were evaluated using complementary metal-oxide semiconductor (CMOS) digital X-ray images. Common dental imaging software was used to create four modified images of each dental exposure. The four modified images used filters: invert, edge enhance, dentin-to-enamel junction (D to E) and endo. The original, unfiltered image was also evaluated. Three observers evaluated a total of 145 images for RR using a five-point scale.

Results: Through the use of receiver operating characteristic (ROC) curves, these data showed that specific filters were better at detecting RR than a 50/50 chance.

The most accurate ROC was observed with the endo filter (AUC = .950; 95% CI: .869,.1.0). The least accurate ROC was observed with the D to E filter (AU = .758; 95% CI: .551, .965).

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Conclusion: The endo filter had the highest accuracy in detecting RR and the D to E filter was the least accurate of the filters tested in this study. The use of the endo filter has the potential to improve RR treatment prognosis because of the filter’s capability of earlier RR detection.

Key words: radiography, digital radiography, endodontic diagnosis, diagnostic imaging, imaging filters, root resorption, early diagnosis.

AUTHORS Jeries Nader Qoborsi, BS, is a fourth-year dental student at Loma Linda University and has been involved in predoctoral dental research since his second year of dental school. His interests include dental research, orthodontics, surgery and dental anesthesiology.

Shant Oroojian, BS, is a fourth-year dental student at Loma Linda University and completed research on the circadian rhythm at the University of California, Irvine, before completing research at LLU. His main focus relates to digital imaging filters and their effect on detecting interproximal caries.

Jason Bajwa, BS, is a fourth-year dental student at Loma Linda University.

He has great interest in the life sciences and a passion for making an impact in the dental field.

Ambrose I. Obhade, BDS, DDS, has worked with other student research candidates on digital imaging filters and their effect on detecting apical root resorption. He now practices general dentistry at a community dental center in Rolla, Mo. Gina D. Roque Torres, DDS, MSc, PhD, was a visiting researcher in the orthodontics and dentofacial orthopedics department at Loma Linda University and is currently an assistant professor in the Center for Dental Research. She is experienced in oral radiology and orthodontics and dentofacial orthopedics.

Dwight Rice, DDS, is a professor in the division of general dentistry and the Center for Dental Research at Loma Linda University. In addition, he is a professor in the school of graduate studies. He is experienced in several areas of X-ray imaging.

Conflict of Interest Disclosure: None reported for all authors.

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R

oot resorption (RR) in the scope of this study is defined as the pathologic inflammatory pathway by which clastic cells cause the loss of dentin and/or cementum from a tooth’s root anatomy. The rate of progression varies depending on the etiology, severity and locus.1,2 RR can be caused by many factors such as orthodontic treatment, cysts, acute trauma, periapical inflammation, third molar impaction, periodontal infection and idiopathic elements.3 Finding and removing the cause is a critical first step in the treatment of RR.2,3 RR is categorized according to the type of resorptive process as well as the site of initiation of the resorption (internal and external).2 External RR originates in the periodontium and is defined radiographically by loss of cementum and/ or dentin, loss of periodontal ligament space and lamina dura as well as a persistent or progressive radiolucent area in the bone adjacent to the resorbed area of the tooth.2 Orthodontic forces have been implicated as the most common etiology of external RR, sometimes to a severe degree.

It is especially common in the maxillary incisors.1 External RR is often of minor consequence to the average orthodontic patient with resorption of less than 2.5 mm.

However, in about 1% to 5% of orthodontic patients, severe external RR is defined as exceeding 4 mm or one-third of the original root length. This causes an increased crown-root ratio and may lead to tooth mobility.4 Patients with RR often present

with no symptoms unless it is very late in the progression of the disease process in which case pain and mobility may be present.3 RR is commonly discovered incidentally at recall appointments during radiographic examinations1–3 and is usually found at the advanced stage.

Periapical radiography is currently the main method of diagnosing RR;5 however, it is not sufficiently reliable in many cases for an accurate diagnosis of RR.5,6 This modality does not adequately describe the extent of the lesion.5,6 Due to the asymptomatic nature of RR as well as the incidental findings at checkup appointments,1 it can be difficult to adequately diagnose this condition and properly manage RR. If RR is diagnosed at an advanced stage, the only treatment is extraction.1,3 Early diagnosis is especially important in specific cases such as cervical RR and inflammatory RR.7 Clinicians mostly rely on digital imaging filters and adjustments of contrast and brightness for the radiographic interpretation of RR.5 Eye fatigue is a common problem faced by clinicians who diagnose disease from radiographic images.8 Through the use of filters, diagnosing RR will become a faster process, decreasing the amount of time spent looking at the radiograph and thus decreasing eye fatigue and erroneous diagnosis.8 The use of cone beam computed tomography (CBCT) for 3D visualization has also been utilized,11 but CBCT exposes the patient to significantly higher doses of

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1A

1D

1B

1E

FIGURE S 1. Images showing the different filters used by investigators. Original (1A), dentin to enamel (1B),

endo (1C), invert (1D) and edge enhance 5 (1E).

radiation relative to periapical radiographs.8 It is imperative to use accurate selection criteria and appropriately adjust exposure and field of view parameters. The benefits must outweigh the risks to the patients; CBCT should not be used on a routine basis and not without prior clinical examination.9 This research aims to find a filter that can be used at routine examination appointments to achieve similar results to higher-quality images with less radiation exposure. It is expected that a more favorable tooth prognosis will occur due to early detection. While it is clear that CBCT is superior to conventional periapical radiography, caution is advised with the use of CBCT due to significantly higher radiation exposure. Therefore, this research aimed to test multiple filters with settings unique to each filter to improve the likelihood of an early diagnosis of RR on periapical radiographic examinations.

The hypothesis was that radiographs processed with a filter can increase the confidence and reliability in distinguishing positive RR. The null hypothesis of this research was that there will be no statistically significant difference between these existing filters in the detection of RR.

Materials and Methods Sample Selection and Image Acquisition

Digital radiographic images were obtained with a CMOS sensor (Digora Toto system, Soredex, Tuusula, Finland) and a Focus X-ray source (Instrumentarium, Tuusula, Finland), operating at 70kVp, 7mA and 0.063s. All the images were saved in tagged image file format (TIFF) format. Before the study, the teeth were imaged by CBCT to verify RR. An experienced oral radiologist evaluated the images confirming RR using multiplanar reconstruction images. This evaluation was used as the gold standard for diagnosis prior to evaluation of bidimensional images.10,11 CBCT volumes were captured using the Veraviewepocs 3De (J. Morita USA, Irvine, Calif.).

Thus, the selected exposure time was the smallest possible to produce an image of good quality for dental evaluation (following the ALARA principle), presenting average density and contrast.

Image Preparation and Assessment

Twenty-nine individual CMOS digital X-ray images of teeth with possible RR were selected for this study. To

1C standardize initial images, the gray values of the density scale were measured using software Image J (National Institutes of Health, Bethesda, Md.). Once density and contrast were standardized, four different digital imaging filters were processed: invert, edge enhance-5, endo and D to E. Microsoft PowerPoint (Redmond, Wash.) was used to view images captured from the MiPACS dental enterprise viewer software 3.2.1 (Medicor imaging, Charlotte, N.C. ). The PowerPoint presentation used a dark background.

One hundred forty-five images were produced, randomized and rated. On each radiograph, observers had to evaluate the presence of RR using a five-point ordinal grading scale of absent (1), probably absent (2), uncertain (3), probably present (4) and present (5) (FIGURES 1) .

Three third-year dental students with specific training in identifying RR evaluated and scored the images. The students did not have previous knowledge of the adjustments made using the filters.

Each student analyzed the radiographic images independently in a dimly lit room with a calibrated medical-grade MDRC-2120 monitor Barco (Kortrijk, Belgium). The monitor was set at 1600 by 1200 pixel, 60-Hz 8-bit to assess for RR using the five-point scale. The use of image manipulation tools was not allowed, except for the zoom tool.

Observers were oriented to assess a maximum of 25 images per day and to have an interval of a minimum of three days between images assessments in order to avoid visual fatigue. Reevaluation of the images took place 15 days after the end of the primary assessment to verify the reproducibility of the evaluations. â&#x20AC;&#x192;D ECEMBER 2 0 2 0

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TABLE

ROC Curve of Averaged Results of All Readers to the Different Image Filter Types Filter

Statistical Analysis

Intra- and interobserver agreement was calculated by the weighted Kappa test.

Kappa result ranges between < 0.00, no agreement; 0.00–0.20, poor agreement; 0.21–0.40, reasonable agreement; 0.41–0.60, moderate agreement; 0.61– 0.80, good agreement; and 0.81–1.00, excellent agreement. The area under the receiver operating characteristic (ROC) curve was calculated along with its 95% confidence interval (CI) to represent a point estimate of diagnostic accuracy.

Sensitivity and specificity values were also obtained. Diagnosis values were compared by two-way ANOVA with the post hoc Tukey test. The level of significance was set at p < 0.05. The data were analyzed using the SPSS statistical package v.22 (IBM Corp, Armonk, N.Y.). The differences were based on quantitative comparisons and correlation assessments with a significance of 5%.

Results

Mean and range Kappa values have excellent agreement (0.81–1.00). The highest mean values for the intraobserver agreement was found between all the observers. In the same way, this agreement was shown when comparing the filters.

The TABLE summarizes the diagnostic values related to the detection of the different RR distributed according to the image filters. No differences were found between the diagnostic values of the four filters (p > 0.05). All of the ROC curves showed that students and the average of the students are operating at better than the chance for detecting RR. The most accurate ROC was observed with the endo filter (AUC = .950; 95% CI: .869,.1.0). The least accurate ROC was observed with the D to E filter (AU = .758; 95% CI: .551,.965) (FIGURE 2) . The overall results showed low values of area under the ROC curve and sensitivity of the periapical radiography in the detection of RR with a filter, which has as an aim to evaluate changes in the crown.

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Endo

Area

.950

Standard error

.041

Asymptotic 95% confidence interval

lower bound

upper bound

.869

1.000

Invert

.819

.086

.652

.987

Edge enhance

.814

.094

.629

.999

Original

.789

.097

.599

.979

D to E

.758

.106

.551

.965

Discussion

Radiographic digital systems, compared to conventional radiographs obtained on films, allow image post-processing, including the use of different filters and image storage.

It is known that digital radiography should be saved as a TIFF to avoid the loss of information. This format has the highest digital file size and avoids loss of information that often occurs with compressing.12 The application of digital imaging filters for diagnostic purposes, though a fairly recent development, holds great potential for the early detection of asymptomatic pathologies such as RR. This holds true because RR is typically diagnosed by imaging in the late stage and usually by coincidence. Other similar studies have focused on the effect of brightness and contrast variation for detecting RR but produced low accuracy.5,13 The results of another study suggested that digital contrast and density enhancement improved external RR detection.14 To achieve the goal of early detection of RR without increasing radiation dose, this study analyzed the different filters used to determine which filter gave the most accurate ROC. The original nofilter group served as a control group. The invert image filter was used to rule out eye fatigue. The edge enhance-5 filter was used to enhance borders between structures. The endofilter was used as a high-contrast filter. The D to E filter was used to accentuate the border between different mineralized structures such as the cementum and dentin in the roots of teeth.

The results from this study showed that the endo filter had the highest ROC while the D to E filter showed the

lowest ROC. The endo filter also had the lowest standard error. In this study, the diagnostic values of using digital imaging filters for the assessment of RR was found to be statistically significant. Thus, we reject the null hypothesis and accept the original hypothesis that there is a statistical difference between the filters in the diagnosis of RR. The endo filter holds promise in improving the diagnosis of RR. This filter is not only costeffective but also requires little additional training to implement into the clinician’s diagnostic workup. Early detection and prevention of problems of this nature have the potential to lower the chance of iatrogenic lawsuits that are on the rise for dental and medical practitioners.4 The results of this study support the use of this filter to more easily and decisively discern the radiographic determinants of RR. If RR is detected early, it could help in the finding and elimination of the etiology that can lead to favorable outcomes for the involved tooth. Filters can be utilized by oral surgeons, oral medicine specialists, orthodontists, endodontists, periodontists, general dentists or any clinician involved in the diagnosis and treatment of the root and/or its accessory periodontium.

Early diagnosis, removal of the cause and proper treatment of the resorbed root are imperative to maintaining the stability and longevity of the dentition.

Existing research regarding the detection of RR suggests that there are limitations in the diagnostic capacity of raw intraoral periapical radiographs to diagnose RR.14 The superiority of CBCT to periapical imaging to diagnose RR is widely agreed upon in the literature.14–19

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ROC Curves

FIGURE 2 . ROC curve of averaged results of all readers of the filters.

This is because CBCT can depict the tooth in three dimensions with very minimal distortions, artifacts and superimposition of anatomical structures seen in conventional periapical radiography.11,15 A study noted the impracticality of CBCT imaging for paraclinical examination to diagnose all RR due to a large amount of radiation dose to the patient.8,11 One way of reducing the CBCT radiation dose is to use a smaller field of view. The use of 180- and 360-degree rotation to the X-ray source showed no significant difference.16 Another study showed that high-contrast in comparison to low-contrast CBCT showed superiority in diagnosing lateral resorption defects.14 This study also discusses that longer exposure time and higher exposure quantity can

positively influence the detection of RR.8 Another study compared raw images with adjustment to contrast and brightness on the detection of periapical lesions. It found no significant differences when using contrast and brightness; however, the observers preferred low brightness with high contrast.13 Current literature offers minimal information on imaging software filters and their capacity for diagnosing RR. Imaging filters can affect the diagnosis of root resorption depending on which type of filter is applied. With this in mind, judicious usage is suggested to achieve optimum outcomes with low exposure to the patient at routine oral evaluations.

Advanced imaging may be warranted in special circumstances after the primary

clinical examination. This type of imaging software could also be useful in low socioeconomic locations or regions without access to advanced imaging. This is a cost-effective modality that requires minimal training to implement but can yield great clinic outcomes for patients.

In future studies, a larger sample size and a greater number of participants in different areas of clinical expertise and specialty are warranted. This would produce a stronger baseline and may further corroborate that the endo filter is significantly useful in the diagnosis of RR. One cautionary factor the clinician should note is that the endo filter was found to be useful in the specific diagnosis of RR only; if this same filter is used for caries, for â&#x20AC;&#x192;D ECEMBER 2 0 2 0

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example, false negatives may appear on the crown of the tooth and lead to misdiagnosis.

Future research is needed using various image filters for different clinical diagnostic tasks to validate their benefits.

Conclusion

The endo filter holds significant promise in improving the diagnosis of RR when compared with the other filters. n ACKNOWLEDGMENTS This study earned second place in the 2019 CDA Presents Table Clinic Competition: Clinical Research category and placed first at the Loma Linda University One Homecoming Research Exhibition.

This study was funded by the LLUSD Student Research Program.

REFERENCES 1. Raza M, Pasha S, Valli S. Nonsurgical management of horizontal root fracture associated external root resorption and internal root resorption. Indian J Dent Sci 2016;8(3):150. doi:10.4103/0976-4003.191722.

2. Abbott P. Treatment of external apical inflammatory root resorption. Australian Endodontic Newsletter.2010;17(3):22–26. doi:10.1111/j.1747-4477.1992.tb00320.x.

3. Dewan K, Fairbrother K, Kapur S. Multiple idiopathic external apical root resorption: A literature review. J Conserv Dent 2015 Jan–Feb;41(7):586–595. doi:10.12968/denu.2014.41.7.586.

Accessed Jan. 2, 2020.

4. Justus R. Prevention of external apical root resorption during orthodontic treatment. Clin Dent Rev 2018 Oct;2:23. doi:10.1007/s41894-018-0035-3. Accessed Jan. 2, 2020.

5. Nascimento EHL, Gaêta-Araujo H, Galvão NS, Moreira-Souza L, Oliveira-Santos C, Freitas DQ. Effect of brightness and contrast

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variation for detectability of root resorption lesions in digital intraoral radiographs. Clin Oral Investig 2019 Aug;23(8):3379– 3386. doi: 10.1007/s00784-018-2764-8. Epub 2018 Dec 7.

Accessed Jan. 2, 2020.

6. Barbosa dos Santos J, Castillo JFM, Nishiyama CK, Esper LA, de Castro Pinto L, Pinheiro CR. External root resorption: Diagnosis and treatment. Clinical case report. J Dent Health Oral Disord Ther 2018;9(2). doi:10.15406/jdhodt.2018.09.00350.

7. Safi Y, Ghaedsharaf S, Aziz A, Hosseinpour S, Mortazavi H. Effect of field of view on detection of external root resorption in cone beam computed tomography. Iran Endod J Spring 2017;12(2):179–184. doi:10.22037/iej.2017.35.

8. Maeda E, Yoshikawa T, Hayashi N, et al. Radiology readingcaused fatigue and measurement of eye strain with critical flicker fusion frequency. Jpn J Radiol 2011 Aug;29(7):483–7. doi: 10.1007/s11604-011-0585-7. Epub 2011 Sep 1.

9. Creanga AG, Geha H, Sankar V, Teixeira FB, McMahan CA, Noujeim M. Accuracy of digital periapical radiography and cone beam computed tomography in detecting external root resorption.

Imaging Sci Dent 2015 Sep;45(3):153–158. doi: 10.5624/ isd.2015.45.3.153.

10. Lima T, Gamba T, Zaia A, Soares A. Evaluation of cone beam computed tomography and periapical radiography in the diagnosis of root resorption. Aust Dent J 2016 Dec;61(4): 425–431. doi: 10.1111/adj.12407.

11. Levin MD, Jong G. The use of CBCT in the diagnosis and management of root resorption. In: Fayed M, Johnson BR, eds.

3D Imaging in Endodontics. Cham, Switzerland: Springer Nature; 2016:131–143. doi:10.1007/978-3-319-31466-2_7.

12. Provedel LF, et al. Effects of image compression on linear measurements of digital panoramic radiographs. Braz Dent J 2016 Sep;27(6):757–760. doi:10.1590/01036440201601157.

13. Nascimento EH, Gaêta-Araujo H, Vasconcelos KF, et al.

Influence of brightness and contrast adjustments on the diagnosis of proximal caries lesions. Dentomaxillofac Radiol 2018 Dec;47(8):20180100. doi: 10.1259/dmfr.20180100. Epub 2018 Jun 15.

14. Ponder SN, Benavides E, Kapila S, Hatch NE. Quantification of external root resorption by low- vs. high-resolution cone-beam computed tomography and periapical radiography: A volumetric and linear analysis. Am J Orthod Dentofacial Orthop 143:77–91. doi.org/10.1016/j.ajodo.2012.08.023.

15. Kamburoǧlu K, Barenboim SF, Kaffe I. Comparison of conventional film with different digital and digitally filtered images in the detection of simulated internal resorption cavities — an ex vivo study in human cadaver jaws. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008 Jun;105(6):790–7. doi: 10.1016/j.tripleo.2007.05.030. Epub 2007 Oct 17.

16. Durack C, Patel S, Davies J, Wilson R, Mannocci F. Diagnostic accuracy of small volume cone beam computed tomography and intraoral periapical radiography for the detection of simulated external inflammatory root resorption. Int Endod J 2011 Feb;44(2):136–47. doi: 10.1111/j.1365-2591.2010.01819.x.

Epub 2010 Nov 17.

17. Darcey J, Qualtrough A. Resorption: Part 1. Pathology, classification and aetiology. Br Dent J 2013 May;214(9):439– 51. doi: 10.1038/sj.bdj.2013.431.

18. Lima TF, Gamba TO, Zaia AA, Soares AJ. Evaluation of cone beam computed tomography and periapical radiography in the diagnosis of root resorption. Aust Dent J 2016 Dec;61(4):425– 431. doi: 10.1111/adj.12407.

19. Laux M, Abbott PV, Pajarola G, Nair PNR. Apical inflammatory root resorption: A correlative radiographic and histological assessment. Int Endod J 2000 Nov;33(6):483–93. doi: 10.1046/j.1365-2591.2000.00338.x.

THE CORRESPONDING AUTHOR, Jeries Nader Qoborsi, BS, can be reached at jqoborsi@llu.edu.

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Assessment of a Pediatric Population Using Telehealth Training in Predoctoral Dental Education Analia Tahir, BS; Krystle P. Rapisura, DMD, MS; T. Jamie Parado, DDS; Keith R. Boyer, DDS; Luis G. Robinson, MS; and Marisa K. Watanabe, DDS, MS

a b s t r a c t This article aims to increase dental workforce and quantify outcomes

of telehealth curriculum by integrating predoctoral dental students in the delivery of asynchronous teledentistry. Preliminary data from the quality improvement process suggests that over 90% of recommended treatment plans coincided between onpremise and off-premise, second-year predoctoral dental students. This initial data establishes a quantitative measurement for telehealth and supports the incorporation of teledentistry into predoctoral dental curriculum for its use in clinical practice.

AUTHORS Analia Tahir, BS, is a DMD 2021 candidate in the College of Dental Medicine at Western University of Health Sciences with an interest in community-based and clinical research.

Krystle P. Rapisura, DMD, MS, is an assistant professor and assistant dean for community patient care in the College of Dental Medicine at Western University of Health Sciences and a diplomate of the American Board of Pediatric Dentistry. She manages the WesternU CDM school-based oral health centers and is an overseeing pediatric faculty for the college.

T. Jamie Parado, DDS, is an assistant professor in the College of Dental Medicine at Western University of Health Sciences and a diplomate of the American Board of Pediatric Dentistry. One of her key areas of interest is in interprofessional education and interprofessional collaborative practice, and she is the liaison for WesternU CDM. Keith R. Boyer, DDS, is an associate professor in the College of Dental Medicine at Western University of Health Sciences and a diplomate of the American Board of Endodontics.

He was drawn into the academic environment

because of his desire for continuous learning and to share that knowledge with colleagues and future dentists.

Luis G. Robinson, MS, received his Master of Science in medical sciences from the Graduate College of Biomedical Sciences and is a DMD 2024 candidate in the College of Dental Medicine at Western University of Health Sciences with an interest in public health and bridging the gap in access to care.

Marisa K. Watanabe, DDS, MS, is an associate professor and associate dean for community partnerships and access to care in the College of Dental Medicine at Western University of Health Sciences. She oversees the entire community-based dental education curriculum for the college and focuses her research on prevention and intervention for persons throughout the lifespan.

Conflict of Interest Disclosure: None reported for any of the authors.

T

eledentistry, though initially conceptualized in the late 1980s, was first named by Cook and colleagues in 1997.1 In more recent times, teledentistry has become known as the “use of health information technology and telecommunications for oral care, consultation, education and public awareness with the broad goal of improving oral health.” 2 Slowly, teledentistry has evolved for use in periodontal screenings, specialty consultations, patient and provider education, referrals and care within the dental specialties of oral and maxillofacial surgery, pediatric dentistry, oral medicine and orthodontics.3–10 Teledentistry technology has notably been used in California and Alaska, D ECEMBER 2 0 2 0

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although other states are following suit.11 In 2010, the first virtual dental home program was created in California to deliver integrated oral, general, educational and social services to underserved and vulnerable populations.12 Moreover, teledentistry was signed into California law as reimbursable

by Medi-Cal in September 2014.

Despite its acceptance into some states’ legislatures, telehealth technology remains underutilized.13 Teledentistry has known potential to reduce cost and barriers to oral health care, improve oral health outcomes, increase use of dental resources and lead to the establishment of a dental home, especially for the underserved pediatric population.14 Additionally, teledentistry has been shown to be practical and cost-effective while improving access and increased oral health care use, especially among disadvantaged or rural populations.15 The use of teledentistry can be one of four formats: asynchronous, synchronous, remote patient monitoring (RPM) and mobile oral health care services.2 Asynchronous teledentistry is also known as “store and forward” and is defined as the transmission of a patient’s oral images that are not used in real time.

Synchronous teledentistry is the transmission of a patient’s oral images using real-time interactive modalities, such as in live video interactions.

RPM is defined as the connection of electronic instruments directly to the patient to record personal health and medical information remotely.

Mobile oral health care services refer to the use of mobile technology, such as text messages and smartphone applications, to track and manage patients’ oral health conditions.

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Teledentistry may be utilized to promote early intervention and preventive services by shifting delivery of these services from the physical dental office to other allied professionals within a targeted population or community.2,11 For example, the virtual dental home program incorporates registered dental hygienists in alternative practice (RDHAP) settings, registered dental hygienists in public health programs and registered dental assistants in extended functions (RDAEF) to gather

One way to integrate teledentistry into the global oral health landscape is to make it an essential component of dental education curriculum. clinical and radiographic data from patients in the community.16 The information is then electronically transmitted to the supervising dentist who creates a dental treatment plan that authorizes the RDHAP/RDAEF to provide preventive services and place interim therapeutic restorations under general supervision. This model of asynchronous teledentistry has solidified California’s role as a leader in telehealth advancements.

In the changing climate of dentistry and the modernization of technology and integration of telehealth, teledentistry has become more widely accepted as a feasible adjunct to conventional clinical dentistry and opens portals for those who lack dental services. Most

recently, the COVID-19 pandemic has accelerated the use of teledentistry within traditional dental practices, while also highlighting the need for greater knowledge and training to incorporate telehealth into dentistry.

One such way to integrate teledentistry into the global oral health landscape and increase the telehealth workforce is to make it an essential component of dental education curriculum.

In rural or urban areas with high poverty-stricken pediatric populations, teledentistry not only minimizes disruptions in a child’s education, but also addresses several social determinants of health barriers for parents such as transportation and missed work that may lead to lower income. As Healthy People 2020 describes, as a person ages, the most influential social determinants will shift — for children, the social and community contexts that include physical, cognitive and socialemotional foundations, lay the groundwork for health, learning and overall well-being.17 As children progress through adolescence to adulthood and then as aging adults, other key social determinants play a bigger influence in life, specifically in access to health care. Knowing that family income affects a child’s physical, mental, behavioral and cognitive health, it is imperative to provide alternative care modalities that currently address the barriers that prevent children from attaining health equity.

With 20.8% of persons living in poverty in El Monte, Calif., compared to 14.2% in overall Los Angeles County and 12.8% in California according to the 2019 U.S. Census,18 children in El Monte are at a higher disadvantage in accessing basic heath

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necessities, including oral health.

Therefore, the Western University of Health Sciences, College of Dental Medicine (WesternU CDM), in conjunction with Mountain View School District (MVSD) and El Monte City School District (EMCSD) in El Monte, established a unique asynchronous “hub-and-spoke” teledentistry model utilizing secondyear predoctoral dental students as both the on-premise providers (spoke) and off-premise providers (hub).

In this model, the WesternU CDM Jeff Seymour Family Center (JSFC) dental clinic, located in the EMCSD, represents the “hub” — a comprehensive school-based oral health center. The MVSD Head Start main site is the “spoke,” where clinical and radiographic data gathering, in addition to preventive care, is provided by second-year predoctoral dental students. The uniqueness of this model is twofold.

First, though a freeway and 3.8 miles separate the hub and spoke, most of the families whose children attend the MVSD Head Start program at the main location utilize public transportation or walk as their means of transportation. Thus, the 3.8 miles (which by car is approximately only 10 minutes) translates to a 45-minute excursion comprising multiple bus transfers and additional traveling on foot or to at least an hour walk between the hub and spoke for parents and their young children. Due to this barrier, less than 70% of MVSD Head Start children assessed in an oral health screening in 2018 initiated dental treatment beyond preventive care. To mitigate and address the transportation challenge that parents faced in previous years, in 2019 MVSD provided transportation for children

requiring treatment beyond prevention between their main teledentistry site and the JSFC dental clinic.

Secondly, in order to appropriately graduate trained clinicians in teledentistry, the predoctoral dental students need to establish foundational clinical and behavioral knowledge, learn how to perform all allied dental personnel functions and roles in a teledentistry setting and understand the clinician’s role of assessing clinical and radiographic findings to establish a diagnosis and treatment plan in a

The goal ... was to introduce a measurable quality improvement process that quantifies the outcomes of telehealth curriculum in dental education.

and treatment planning. Through the clinical application of teledentistry by second-year predoctoral dental students as on-premise versus off-premise dental providers, preliminary data was evaluated for similarities in treatment recommendations for the children in the MVSD Head Start program.

The objective of this clinical quality improvement process was to determine if at least a 90% agreement in treatment plan recommendations existed between the on-premise and off-premise, second-year dental providers. With limited research published about training the dental workforce utilizing teledentistry with predoctoral dental students, these measurable outcomes further support the integration of teledentistry into predoctoral dental programs in preparation for implementation in clinical practice, while also addressing barriers in access to care.

Methodology pediatric teledentistry environment.

The methodology section below further outlines the calibration and integration of predoctoral dental students as the dental workforce in teledentistry.

Therefore, the goal of this assessment was to introduce a measurable quality improvement process that quantifies the outcomes of telehealth curriculum in dental education. Quality improvement is defined as the “systematic and continuous actions that lead to measurable improvement in health care services and the health status of targeted patient groups.”19 By associating a measurable outcome with telehealth, it was a means to assess the improvement of students’ telehealth clinical and radiographic diagnoses

The patient population consisted of nine pediatric patients aged 3–6 with no underlying medical conditions. A target population of 24 second-year predoctoral dental students calibrated in performing dental examinations were randomly divided into two groups: nine on-premise providers examined the patients at the MVSD Head Start program (control) and 15 off-premise providers assessed patient data outside the MVSD Head Start program (variable). Fewer on-premise providers participated due to patient cancellations; hence, multiple off-premise students independently assessed the same onpremise patients as noted in TABLE 1 .

Each on-premise predoctoral dental student was paired with one pediatric patient to provide a face D ECEMBER 2 0 2 0

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TABLE 1

Number of Providers Who Assessed Each Patient Patient

Number of on-premise providers

Number of off-premise providers

1

1

4

2

1

1

3

1

1

4

1

1

5

1

1

6

1

1

7

1

1

8

1

2

9

1

3

Total number of providers

9

15

Note that multiple off-premise students independently assessed the same on-premise patients (e.g., patients 1, 8 and 9) due to on-premise patient cancellations.

to-face clinical examination. Onpremise dental students utilized a digital single-lens reflex (DSLR) camera for extraoral and intraoral clinical photographs. During the examination, the on-premise dental students evaluated all erupted teeth (primary and permanent) and noted missing dentition in each pediatric patient with a range of 20–24 teeth per patient. Based on the principles of as low as reasonably achievable (ALARA) and guidelines set by the American Academy of Pediatric Dentistry, the on-premise dental providers provided a minimum of two-bitewing radiographs per patient and optional periapical radiographs if interproximal contacts were not present or suspicious clinical/ radiographic findings required more information. For each pediatric patient assessed on-premise, all five surfaces (occlusal, buccal/ facial, lingual, mesial and distal) of erupted teeth were evaluated.

The on-premise dental students also recorded existing restorations, clinical findings via the International Caries Detection Assessment System (ICDAS), radiographic findings via the American Dental Association Caries Classification System (ADA CCS) and soft tissue pathologies and/ 664 D ECEMBER

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or abnormalities onto a comprehensive treatment record worksheet. TABLE 2 is a visual summary of the ICDAS and the ADA CCS. The collected patient information was then transferred into the Health Insurance Portability and Accountability Act (HIPAA)compliant electronic health record axiUm. After evaluating the pediatric patient, the on-premise dental students independently created a recommended treatment plan for their paired patient, which was utilized as the control to compare with the findings of the offpremise dental students. The extraoral and intraoral clinical photographs and radiographs were then uploaded to axiUm and were subsequently used for remote assessment by the offpremise predoctoral dental students.

FIGURES 1A–1F are examples of intraoral photographs that include a patient’s full smile, occlusal photographs of maxillary and mandibular arch and anterior maxillary and mandibular lingual surfaces. Additional pictures (not shown) were taken of the left and right buccal corridors, additional lingual anterior and posterior and close-ups of posterior occlusal surfaces.

The asynchronous mode of teledentistry was employed for this project. The off-premise predoctoral dental students were provided with

the medical and dental history of the patient, clinical photographs performed with the DSLR camera and corresponding radiographs of the pediatric patient via axiUm. Each off-premise dental student independently recorded their findings onto their own comprehensive treatment record worksheet, following the same instructions as described for the control group. As the goal was to assess the similarities and differences of the off-premise dental student recommended treatment plan based on clinical and radiographic findings gathered and their respective diagnoses, these off-premise findings, diagnoses and treatment plans were considered the variable group.

For the purposes of this comparison that focuses on the similarities and differences in treatment recommendations, staining, ICDAS 0, 1 and 2 were categorized together as a single finding during the analysis of results. The reason for grouping staining, ICDAS 0, 1 and 2 is that the findings’ corresponding diagnoses lead to preventive treatment recommendations (i.e., reevaluation at the next recare appointment, remineralization with fluoride application and/or sealants).

Similarly, ADA CCS radiographic findings E1 and E2 were categorized together because both led to preventive treatment recommendations such as remineralization through use of fluoride, at-home behavior modification or reevaluation at the next recare appointment (TABLE 3) .

To evaluate the agreement between on-premise and-off-premise student providers in overall treatment plan recommendations, the off-premise dental student records were compared tooth by tooth to the on-premise dental students in four categories:

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TABLE 2

ICDAS dental descriptions

Sound

First visual change in enamel

Distinct visual change in enamel

Localized enamel breakdown

Underlying dentin shadow

Distinct cavity with visible dentin

Extensive cavity with visible dentin

ICDAS detection code

0

1

2

3

4

5

6

Sound

Outer ½ of enamel

Inner ½ of enamel

Outer ⅓ of dentin

Middle ⅓ of dentin

Inner ⅓ of dentin

E0

E1

E2

D1

D2

D3

ICDAS visualization

ADA CCS radiographic description ADA CCS radiographic interpretation Radiographic visualization

TABLE 3

Categorization of ICDAS Clinical and ADA CCS Radiographic Findings Corresponding to Diagnoses and Treatment Recommendations Clinical findings (ICDAS)

Radiographic findings (ADA CCS)

Diagnosis

0

0

Sound/staining

1

E1

2

E2

3

D1

4

D2

5

D3

Recommendations

Incipient decay

Prevention (sealants, fluoride, reevaluation)

Primary decay

Treatment

6

TABLE 4

Observed Agreement of Off-Premise Records as Compared to the On-Premise Records for All Nine Pediatric Patients Combined Category

Total off-premise score

Total number of Percent agreement on-premise records (%)

Existing restorations

277

307

90.2

Clinical findings

281

317

88.6

Radiographic findings

271

309

87.7

Soft tissue lesions

124

135

91.9

Treatment plan recommendations

282

302

93.4

existing restorations, clinical findings, radiographic findings and soft tissue pathologies/abnormalities. If the off-premise dental student recorded the same finding(s) as the on-premise individual on a specific tooth, they received a score of 1 for each corresponding findings that matched. If the off-premise individual did not record the same findings as the on-premise individual, they received a score of 0 for those corresponding findings. For instance, for Patient 2 on tooth No. E, the on-premise provider recorded a mesial ICDAS 1, while the off-premise provider recorded a mesial ICDAS 3.

In this case, the off-premise provider received a score of 0 out of 1 for this tooth because the finding differed from that of the on-premise student.

Similarly, if the on-premise dental student recorded “no clinical finding” on a particular tooth and the off-premise dental student also recorded “no clinical finding” on the same tooth, the offpremise dental student would receive a score of 1 out of 1 for that tooth.

After comparison between onpremise and off-premise dental students was completed, prior to any treatment, the on-premise and off-premise D ECEMBER 2 0 2 0

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FIGURE S 1A–1F. A patient’s full smile, occlusal photographs of maxillary and mandibular arch and anterior maxillary and mandibular lingual surfaces.

overseeing faculty reviewed all findings, diagnoses and treatment plans with their respective students and reconciled any discrepancies prior to rendering patient treatment.

Preliminary data analysis was conducted using Microsoft Excel, and IRB is currently under review for future research.

Preliminary Results

Preliminary data results were analyzed in the areas of 1) existing restorations; 2) clinical findings; 3) radiographic findings; and 4) soft tissue lesions in order to compare treatment plan recommendations between on-premise and off-premise dental providers. The total off-premise score was divided by the total number of on-premise records for each category. The percentage calculated represents the observed agreement of the off-premise records as compared to the on-premise records for all nine pediatric patients combined (TABLE 4) .

Existing Restorations, Clinical Findings, Radiographic Findings and Soft Tissue Lesions

The total off-premise score inclusive of all nine pediatric patients in the 666 D ECEMBER

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existing restorations category was 277. The total number of on-premise records inclusive of all nine pediatric patients in the existing restorations category was 307. The percent observed agreement of off-premise to on-premise records for existing restorations was 277/307 (90.2%).

The total off-premise score inclusive of all nine pediatric patients in the clinical-findings category was 281. The total number of on-premise records inclusive of all nine pediatric patients in the clinical-findings category was 317. The percent observed agreement of off-premise to on-premise records for clinical findings was 281/317 (88.6%).

The total off-premise score inclusive of all nine pediatric patients in the radiographic-findings category scoring was 271. The total number of on-premise records inclusive of all nine pediatric patients in the radiographic-findings category scoring was 309. The percent observed agreement of off-premise to on-premise records for radiographic findings was 271/309 (87.7%).

The total off-premise score inclusive of all nine pediatric patients in the soft tissue lesions category was 124. The total number of on-premise records

inclusive of all nine pediatric patients in the soft tissue lesions category was 135.

The percent observed agreement of the off-premise to on-premise records for soft tissue lesions was 124/135 (91.9%).

Overall Comparison of Recommended Treatment Plans

The total off-premise score inclusive of all nine pediatric patients in the recommended treatment plan category was 282. The total number of onpremise records inclusive of all nine pediatric patients in the recommended treatment plan category was 302. The percent observed agreement of the off-premise to the on-premise records for recommended treatment plans was 282/302 (93.4%).

Discussion Clinical Impact

The use of asynchronous teledentistry in this project addresses social determinants of health barriers for the pediatric population at the MVSD Head Start program and suggests positive learning opportunities for dental students. Not only are the predoctoral dental students able to implement their acquired pediatric

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clinical dental knowledge, but they are able to see firsthand the limitations in access to dental care in an underserved area. Specifically, in a teledentistry setting, the predoctoral dental students are also able to further understand the logistics and challenges of working remotely. For instance, the predoctoral dental students acquire a better understanding of the role of all potential allied dental personnel, as WesternU CDM currently has RDAs, RDAEFs, RDHs and RDHAPs who participate in the teledentistry clinic. Furthermore, the MVSD Head Start Program site incorporates an interprofessional aspect by virtue of working with health technicians, social workers and nurses. These learning opportunities synthesize students’ foundational knowledge with clinical dentistry.

Beginning in their first year, the predoctoral students are provided with the fundamentals when treating the pediatric population. By integrating virtual patients as early as their first year and throughout their fouryear dental school journey, students manage information that parallels the same data gathered and assessed during asynchronous teledentistry.

As an example, the development of virtual patients obtained from teledentistry patient records are compiled and applied in areas such as the pediatric simulated clinical exam (SCE). This pediatric SCE allows for dental students to demonstrate the application of their knowledge at a particular point in time as well as confirm calibration among students prior to entering the comprehensive school-based oral health centers.

This project indicates that adding a clinical hands-on teledentistry rotation to predoctoral curriculum

is a valuable means of increasing competency in both health promotion and patient care assessment, diagnosis and treatment planning.

Unfortunately, there is limited research focusing on comparing oral health findings and recommended treatment plans between dental providers on-premise versus offpremise and even fewer studies evaluating the integration of predoctoral dental students in the teledentistry workforce. Prior studies

Students remarked that use of photographs during virtual patient cases would also be helpful in diagnosing soft tissue lesions.

have shown an insignificant increase in cavities diagnosed with the use of teledentistry.15,20 Whether or not the findings were false positive or not is unclear; however, with a primary caries diagnosis, a treatment plan will vastly differ based on a noncarious or incipient caries diagnosis.17,21 Evaluation of the existing restorations suggest that the off-premise dental students had the most difficulty identifying occlusal sealants from the intraoral photographs. The need for calibrated and improved photographs will in turn support the predoctoral dental students off-premise to better identify the sealants and, ultimately, improve diagnosing and treatment recommendations. The present project similarly found a discrepancy between ICDAS 2 incipient decay

and ICDAS 3 primary decay, which indicates the lower percentage of observed agreement in the clinical findings scoring category. This may lead to a more aggressive treatment plan, shifting from a sealant to a preventive resin restoration.

For radiographic interpretation and diagnoses, a lower percentage of agreement was noted between onpremise and off-premise dental students (87.7%). The largest discrepancy was noted in the discernment of E0 (sound) versus E1 lesions between onpremise and off-premise dental student providers. This led to treatment recommendations of remineralization modalities for the incipient decay rather than reassessment at subsequent recare appointments for sound dentition. This observation suggests that both on-premise and off-premise student providers erred on overdiagnosing, knowing that preventive modalities such as fluoride varnish and other remineralizing agents would be beneficial for the child. It was also noted that the radiographic findings’ lower scoring percentage between on-premise and off-premise providers may be attributed to overlapping proximal contacts, which emphasizes the need for improved diagnostic radiographs to obtain accurate treatment recommendations.

While evaluating the soft tissue findings, off-premise dental students recorded slightly more findings than that of their on-premise peers, particularly in erythematous areas, where they noted descriptions such as “trauma” or “inflammation” instead of “no findings.” On-premise students noted that managing patient behavior combined with the inability to have stationary snapshots increased the difficulty of in-person observation of D ECEMBER 2 0 2 0

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these soft tissue lesions. This feedback suggests the need to increase focus on behavior guidance in clinical calibration to ensure sufficient time is allotted to evaluate soft tissue lesions in live patients. Students remarked that use of photographs during virtual patient cases as part of their training and calibration in both synchronous and asynchronous teledentistry would also be helpful in diagnosing soft tissue lesions.

It is understood that there will be variations in findings and diagnoses as dentistry has an element of subjectivity; however, these preliminary results are similar to other studies showing that there is no significant difference between the traditional in-person examination versus teledentistry clinical findings.5,15,20 From an educational perspective, this assessment suggests that the foundational knowledge obtained preclinically by the dental students in treatment recommendations (based on ICDAS and ADA CCS lesions) is upheld among the second-year dental students who participated in the project.

Outcomes from the quality assessment further support the need for calibration among dental providers, particularly in pediatric behavior management, to ensure all photographs and radiographs are diagnostic, leading to more accurate diagnoses and treatment planning.

Health Policy and Workforce Development

The expansion of telehealth into nonprofit community clinics, federally qualified health centers and dental institutions provides a delivery system in which dental providers become essential to decreasing health inequity 668 D ECEMBER

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among underserved populations. Not only has the current pandemic brought teledentistry to the forefront of dental care, but it has highlighted the increased need to maintain the telehealth delivery system as part of mainstream dentistry.22 From Health and Human Services to state governments, new policies and executive orders promote the use of telehealth. For instance, the California Department of Public Health released guidelines on temporary Medi-Cal Dental Teledentistry Flexibilities.23 As of March 25, 2020, the Current Dental

The current pandemic brought teledentistry to the forefront of dental care, but it has highlighted the increased need to maintain the telehealth delivery system as part of mainstream dentistry.

Terminology (CDT) code D9430 in California can now be utilized for a live telephone or teleconference call with a patient in lieu of the in-person office visit as long as the appropriate documentation meets the required consultation prerequisite.23 With the MVSD Head Start program currently closed due to pandemic physical distancing requirements, the asynchronous/ store-and-forward method is currently suspended. Nonetheless, predoctoral dental students will continue maximizing their teledentistry proficiency by engaging in synchronous teledentistry. These students will work with faculty to converse with patients in real time regarding oral health care; the synchronous modality of

teledentistry will combine the students’ learned behavioral sciences with clinical assessment and triaging. This supports the Association of State and Territorial Dental Directors’ “10 Essential Public Health Services to Promote Oral Health,” which states that oral health programs should provide assurance that the public and private oral health workforce is adequate and competent.24 Therefore, with California Proposition 56 tobacco tax dollars distributed among the different local departments of public health, local oral health plans such as Los Angeles County’s Community Oral Health Improvement Plan (LACOHIP) specifically addresses workforce development and capacity. More specifically, Strategy C, Objective 4 of LACOHIP calls for an action plan to “encourage dental professional training programs to increase rotations working with underserved communities and special needs populations.”25 According to the Health Resources and Services Administration, telehealth specifically is “critical in rural and other remote areas that lack sufficient health care services.”26 By marrying these two concepts, not only are dental institutions strengthening the training programs for future dental providers, but also increasing the workforce capacity in much-needed areas.

Limitations

This project includes two limitations: a small sample size and the inclusion of nondiagnostic clinical photographs. The small sample size of nine pediatric patients and 24 dental student providers is too small to test for significant comparisons.

In addition, as some intraoral clinical photographs uploaded to

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axiUm showed large amounts of saliva present, it was difficult for the off-premise dental providers to confidently diagnose and recommend treatment. These limitations should be considered in future studies to ensure that the data can be generalized to a larger population and that all photographs are of diagnostic quality for more accurate diagnoses and treatment planning.

Future Prospective

In dental education, teledentistry has strong potential to be used as a tool for calibration when comparing students’ dental knowledge. Though this project evaluates only secondyear predoctoral students, continuous quality improvement processes in subsequent years of telehealth curriculum can result in greater calibration by making comparisons between predoctoral students in different years. For example, the teledentistry treatment plans created by a second-year student can be compared and contrasted with a later treatment plan by that same student in their senior year. These comparison datasets will help improve curriculum and further tailor dental education to the prevailing health climate.

Teledentistry will continue to shape the field of dentistry, and this initial assessment of quantifying the process and outcomes of telehealth in dental education has far-reaching ramifications for the future of oral health care, particularly in light of the current pandemic. Institutional review board approval is being pursued to continue research in improving the telehealth process in dental education as well as investigating the various nonrestorative treatment modalities that complement teledentistry.

Conclusion

These quality improvement outcome measures suggest that teledentistry can be applied as early as the second year of the dental curriculum for diagnosis and treatment planning of a pediatric patient population at a remote site. Though the findings varied slightly between off-premise and on-premise providers, greater than 90% of recommended treatment plans coincided, validating the fidelity of teledentistry in predoctoral dental education and its use in clinical practice. n ACKNOWLEDGMENTS This project is supported by the Health Resources and Services Administration (HRSA) of the U.S. Department of Health and Human Services (HHS) under grant number D85HP30837 Predoctoral Pediatric Training in General Dentistry and Dental Hygiene for the grant amount $1,499,999, with 0% match from nongovernmental sources.

This information or content and conclusions are those of the authors and should not be construed as the official position or policy of nor should any endorsements be inferred by HRSA, HHS or the U.S. government. The authors acknowledge WesternU CDM’s Dean Steven Friedrichsen, DDS, and Bradley Henson, DDS, PhD, for their support in continued research in the community.

REFERENCES 1. Chen J-W, Hobdell MH, Dunn K, et al. Teledentistry and its use in dental education. J Am Dent Assoc 2003 Mar;134(3):342–6. doi: 10.14219/jada. archive.2003.0164.

2. Daniel SJ, Kumar S. Teledentistry: A key component in access to care. J Evid Based Dent Pract 2014 Jun;14 Suppl:201–8. doi: 10.1016/j.jebdp.2014.02.008.

Epub 2014 Mar 5.

3. Kvedar J, Coye MJ, Everett W. Connected health: A review of technologies and strategies to improve patient care with telemedicine and telehealth. Health Aff (Millwood) 2014 Feb;33(2):194–9. doi: 10.1377/ hlthaff.2013.0992.

4. Ojima M, Hanioka T, Kuboniwa M, et al.

Development of web-based intervention system for periodontal health: A pilot study in the workplace. Med Inform Internet Med 2003 Dec;28(4):291–8. doi: 10.1080/14639230310001617823.

5. Kopycka-Kedzierawski DT, Billings RJ. Comparative effectiveness study to assess two examination modalities used to detect dental caries in preschool urban children.

Telemed J E Health 2013 Nov;19(11):834–40. doi: 10.1089/tmj.2013.0012. Epub 2013 Sep 21.

6. Berndt J, Leone P, King G. Using teledentistry to provide interceptive orthodontic services to disadvantaged children.

Am J Orthod Dentofacial Orthop 2008 Nov;134(5):700– 6. doi: 10.1016/j.ajodo.2007.12.023.

7. Birur PN, Sunny SP, Jena S, et al. Mobile health application for remote oral cancer surveillance. J Am Dent Assoc 2015 Dec;146(12):886–894. doi: 10.1016/j. adaj.2015.05.020.

8. Haron N, Zain RB, Nabillah WM, et al. Mobile phone imaging in low resource settings for early detection of oral cancer and concordance with clinical oral examination.

Telemed J E Health 2017 Mar;23(3):192–199. doi: 10.1089/tmj.2016.0128. Epub 2016 Aug 19.

9. Nickenig HJ, Wichmann M, Schlegel A, et al. Use of telemedicine for pre-implant dental assessment — a comparative study. J Telemed Telecare 2008;14(2):93–7. doi: 10.1258/jtt.2007.070806.

10. Simon L, Friedland B. Interstate practice of dental teleradiology in the United States: The effect of licensing requirements on oral and maxillofacial radiologists’ practice patterns. Telemed J E Health 2016 Jun;22(6):541–545. doi: 10.1089/tmj.2015.0162. Epub 2015 Dec 22.

11. Howell S. Teledentistry: How technology can facilitate access to care: Association of State and Territorial Dental Directors; 2019. www.astdd.org/docs/teledentistryhow-technology-can-facilitate-access-to-care-3-4-19.pdf Accessed May 12, 2020.

12. Glassman P, Helgeson M, Kattlove J. Using telehealth technologies to improve oral health for vulnerable and underserved populations. J Calif Dent Assoc 2012 Jul;40(7):579–585.

13. Public Health Institute, Center for Connected Health Policy. State telehealth laws and reimbursement policies: A comprehensive scan of the 50 states and the District of Columbia. 2020. www.cchpca.org/sites/default/ files/2020-05/CCHP_%2050_STATE_REPORT_ SPRING_2020_FINAL.pdf. Accessed May 10, 2020.

14. Kopycka-Kedzierawski DT, McLaren SW, Billings RJ. Advancement of teledentistry at the University of Rochester’s Eastman Institute For Oral Health. Health Aff (Millwood) 2018 Dec;37(12):1960–1966. doi: 10.1377/hlthaff.2018.05102.

15. Kopycka-Kedzierawski DT, Billings RJ, McConnochie KM. Dental screening of preschool children using teledentistry: A feasibility study. Pediatr Dent 2007 May–Jun;29(3): 209–213.

16. Glassman P, Harrington M, Mertz E, et al. The virtual dental home: Implications for policy and strategy. J Calif Dent Assoc 2012 Jul;40(7):605–611.

17. Healthy People 2020: Social Determinants Life Stages and Determinants. Washington, DC: U.S. Department of Health and Human Services, Office of Disease Prevention and Health Promotion; 2020. www.healthypeople. gov/2020/leading-health-indicators/2020-lhi-topics/ Social-Determinants/determinants. Accessed May 12, 2020.

18. United States Census Bureau as of July 1, 2019.

Washington, D.C.: U.S. Department of Commerce. www.census.gov/quickfacts/fact/table/US/PST045219.

Accessed Sept. 10, 2020.

19. Health Resources & Services Administration Quality Improvement. U.S. Department of Health and Human Services, Health Resources and Services Administration; 2011. www.hrsa.gov/sites/default/files/quality/ D ECEMBER 2 0 2 0

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toolbox/508pdfs/qualityimprovement.pdf. Accessed Sept. 9, 2020.

20. Queyroux A, Saricassapian B, Herzog D, et al.

Accuracy of teledentistry for diagnosing dental pathology using direct examination as a gold standard: Results of the tel-e-dent study of older adults living in nursing homes.

J Am Med Dir Assoc 2017 Jun 1;18(6):528–532. doi: 10.1016/j.jamda.2016.12.082. Epub 2017 Feb 22.

21. International Caries Detection and Assessment System (ICDAS). International Caries Classification and Management System. www.iccms-web.com/content/icdas.

Accessed May 12, 2020.

22. Glassman P, Jacob M, Boynes S. Teledentistry: Providing alternative care during a public health crisis. Presented at Dentaquest Partnership for Oral Health Advancement Webinar, April 6, 2020.

23. Department of Health Care Services. New COVID-19 guidance regarding dental emergency care and teledentistry flexibilities. dental.dhcs.ca.gov/

DC_documents/providers/provider_bulletins/Volume_36_ Number_10.pdf. Accessed May 10, 2020.

24. California Department of Public Health. California oral health plan 2018–2028. www.cdph.ca.gov/Documents/ California%20Oral%20Health%20Plan%202018%20 FINAL%201%205%202018.pdf. Accessed May 10, 2020.

25. Los Angeles County Department of Public Health Oral Health Program. Community Oral Health Improvement Plan 2019–2023. publichealth.lacounty.gov/ohp/docs/ LACDPH_COHIP.pdf. Accessed May 11, 2020.

26. Health Resources & Services Administration. Telehealth Programs. Washington, D.C.: www.hrsa.gov/rural-health/ telehealth. Accessed May 12, 2020.

THE CORRESPONDING AUTHOR, Marisa K. Watanabe, DDS, MS, can be reached at mwatanabe@westernu.edu.

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Streptococcus sanguinis Proteins Involved in Interspecies Binding to Fusobacterium nucleatum Emily Duong, BS; Jenny Truong, BS; Mario Pizarro Rojas, BS; Bruno P. Lima, PhD; Ping Xu, PhD; Bhumika Shokeen, PhD; and Renate Lux, PhD

a b s t r a c t In this study, a mutant library was screened to identify the Streptococcus

sanguinis proteins involved in binding to Fusobacterium nucleatum during biofilm formation. Seven mutants showed a significant defect in the interaction with F. nucleatum, and the affected genes encoded the adhesins SspD and CrpA, three proteins with pleiotropic function (YidC, SrtB and DltB), a predicted stomatin/ prohibitin-like membrane protease subunit and a hypothetical protein. These proteins could serve as therapeutic targets to prevent biofilm-related oral diseases.

AUTHORS Emily Duong, BS, is a dental student at the University of California, Los Angeles, School of Dentistry.

Conflict of Interest Disclosure: None reported.

Jenny Truong, BS, is a dental student at the Tufts University School of Dental Medicine.

Conflict of Interest Disclosure: None reported.

Mario Pizarro Rojas, BS, is in the master’s program in the department of chemistry and biochemistry at California State University, Los Angeles.

Conflict of Interest Disclosure: None reported.

Ping Xu, PhD, is a professor at the Virginia Commonwealth University School of Dentistry, Philips Institute for Oral Health Research.

Conflict of Interest Disclosure: None reported.

Renate Lux, PhD, is a professor in the section of periodontics at the University of California, Los Angeles, School of Dentistry.

Conflict of Interest Disclosure: None reported.

Bruno P. Lima, PhD, is a research associate at the University of Minnesota School of Dentistry in the department of diagnostic and biological sciences.

Conflict of Interest Disclosure: None reported.

Bhumika Shokeen, PhD, an assistant project scientist in the section of periodontics at the University of California, Los Angeles, School of Dentistry.

Conflict of Interest Disclosure: None reported.

The first two authors contributed equally to this study.

D

ental plaque is defined as a multispecies bacterial biofilm formed on the tooth enamel surface.1,2 Complex cell-to-cell interactions between bacterial community members as well as with the host define and drive the ecology of the oral cavity. With the advent of high-throughput sequencing, there is increasing evidence that supports the polymicrobial nature of oral diseases.3,4 In health, the community is in homeostasis and very resilient to changes. Disruptions of this equilibrium, however, promote dysbiosis and may shift the microbial community toward disease. The onset and progression of disease is largely dependent D ECEMBER 2 0 2 0

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upon interspecies binding and signaling as well as metabolic cross-feeding.5 Commensal bacteria support oral health by inhibiting the growth of pathogenic species without hampering the host. A well-documented commensal in the oral community is Streptococcus sanguinis.

Previous studies established that this oral Streptococcus species is highly abundant in health and significantly lower in sites with caries and periodontal disease.6–9 The gram-positive, facultative anaerobe S. sanguinis was originally classified as a member of the mitis group of streptococci,10,11 but a recent study suggested a reclassification to the sanguinis group along with the closely related Streptococcus gordonii.12 As an initial colonizer of the tooth enamel surface, this species is a key player in oral biofilm development.13 It competes with other streptococcal species in the community for colonization and, once established, delays the onset of pathogenic streptococci.14 One of the important binding partners for S. sanguinis is the bridging organism Fusobacterium nucleatum, which enables recruitment of a wide variety of other microbial species into the biofilm.15 Influenced by its interaction with “friends” or “foes,” the opportunistic pathogen F. nucleatum can contribute to the oral community shifts from commensalism to dysbiosis.16,17 Thus, unraveling the molecular mechanisms governing interspecies binding within the oral biofilm can pave the way for future therapeutic targets to maintain or even reestablish homeostasis.

Several adhesins involved in the interaction between streptococci and F. nucleatum have been characterized on a molecular level. A previous study in our lab identified SpaP as the adhesin for binding of Streptococcus mutans to one of the fusobacterial subspecies.18 Interestingly, the SpaP homologues, 672 D ECEMBER

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SspA and SspB, were implicated in S. gordonii binding to F. nucleatum.19 In addition, we established the role of two fusobacterial outer membrane proteins, RadD and CmpA, as the adhesins that mediate interactions with streptococci.

RadD acts as the main adhesin involved in interspecies binding with S. sanguinis and other oral Streptococcus species,20 while CmpA serves as additional adhesin for attachment to S. gordonii.21 Similar to the closely related species Streptococcus gordonii, S. sanguinis is also known to possess adhesins responsible for its binding

Several adhesins involved in the interaction between streptococci and F. nucleatum have been characterized on a molecular level.

to other microorganisms within the oral biofilm.22–25 However, S. sanguinis adhesins that specifically recognize F. nucleatum remain unknown and are the focus of this study.

In order to identify the genes encoding protein(s) of S. sanguinis that are involved in the interaction with F. nucleatum, we performed a comprehensive screen of an existing S. sanguinis mutant library.26 Mutants defective in binding were further assessed for their role in integration of F. nucleatum into an already established S. sanguinis biofilm. This allowed the identification of several candidate genes implicated in the interspecies interaction between S. sanguinis and F. nucleatum.

Their role could be further explored for relevance in oral homeostasis, a cornerstone of oral health.

Materials and Methods Bacteria Strains and Growth Conditions

Streptococcus sanguinis (strain SK36) was grown on Todd Hewitt (TH) agar or broth (Difco Labs, Detroit), while the S. sanguinis mutants26 were grown in TH with kanamycin at a concentration of 500 μg/ mL (Fisher Scientific, Hampton, N.H.).

Fusobacterium nucleatum (ATCC 23726) and a wild-type derivative of F. nucleatum conferring thiamphenicol resistance (Fnn_ WT_CIC27) were grown on Columbia Broth (CB) and CB supplemented with thiamphenicol (5 μg/mL), respectively.

All cultures were grown at 37 C in anaerobic conditions (nitrogen 80%, carbon dioxide 10%, hydrogen 10%).

Coaggregation Assay Visual Coaggregation

The mutant library of S. sanguinis was screened by visual coaggregation as previously described by Kaplan et al.20 with adaptations to a 96-well plate format.

Briefly, overnight cultures of the mutant derivatives were inoculated from a 96-well format stock to a 96-well plate for growth in TH supplemented with kanamycin, while the wild-type S. sanguinis and wild-type F. nucleatum were grown in TH and CB, respectively. The cultures were pelleted at 5,000 rpm for 10 minutes, washed twice with 1X coaggregation buffer (CAB; 150 mM/L NaCl, 1 mM/L Tris/ HCl pH 8, 0.1 mM/L CaCl2 and 0.1 mM/L MgCl2) and resuspended in 200 μL of 1X coaggregation buffer. The optical density at 600 nm (OD600 nm) was measured using a plate reader, and the cells were resuspended in 1X CAB to an OD600 nm of 2.0 (2.0 × 109 cells/mL). Suspensions of wild-type S. sanguinis and its mutant derivatives in CAB were then combined at a 1:1 ratio with F. nucleatum to a total volume of 200 μL in 96-well plates.

Upon addition of the second partner strain, the mixtures were immediately

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vortexed for 10 seconds and left for 10 minutes for coaggregation display. For visual scoring, a system by Cisar et al.28 was employed, where a score of “0” indicated no visible coaggregation and a score of “4” indicated complete visible coaggregation with a clear supernatant. To observe the coaggregates in the 96-well plate format, a magnifying glass was used.

Quantitative Coaggregation

A quantitative coaggregation assay was performed similar to the above-mentioned protocol except for the following minor modifications: equal volumes of 2 x 109 cells/mL of the test strains in 1X CAB were combined in a total volume of 400 μL in micro centrifuge tubes (MCTs). Spectrophotometric OD600 nm readings were taken immediately after the addition of the second partner strain and vortexing (ODt= 0 minute) and after 10 minutes of coincubation (ODt= 10 minutes).

The percent coaggregation was determined by calculating [(ODt= 0 minute – ODt= 10 minutes)/ODt= 0 minute] x 100.

Monospecies Biofilm Growth and Biomass Determination Monospecies Biofilm

For monospecies biofilm growth, overnight cultures of wild-type S. sanguinis or mutant strains were adjusted to 1 x 107 cells/mL, and 50 μL of this suspension was seeded into 48-well culture plates (Thermo Fisher Scientific, Waltham, Mass.) containing 450 μL of TH supplemented with 0.5% sucrose and 0.5% mannose. The biofilms were grown for 15–17 hours at 37 C under anaerobic conditions (nitrogen 80%, carbon dioxide 10%, hydrogen 10%).

Biomass Determination

Biofilm biomass was evaluated using the crystal violet assay according to published protocols.29 Briefly, supernatants

were removed from each well and washed with 500 μL of sterile phosphate-buffered saline (PBS) twice. Plates were inverted and air-dried. Next, attached bacteria were fixed at room temperature for 15 minutes by adding 500 μL of methanol into each well. The biofilms were then stained with a 500 μL aqueous solution of 0.5% crystal violet (Thermo Fisher Scientific) for 15 minutes at room temperature followed by careful rinsing with distilled water. Bound crystal violet on the biofilm was extracted by adding 500 μl of 95% ethanol. The optical density of each

The optical density of each well was measured and was represented relative to negative control wells that contained only TH medium.

well was measured at 570 nm and was represented relative to negative control wells that contained only TH medium.

Dual-Species Biofilms and Colony Forming Unit Analysis Dual-Species Biofilm

For dual-species biofilm development, the biofilm of wild-type S. sanguinis and its mutant derivatives were grown prior to the addition of the F. nucleatum derivative Fnn_WT_CIC.27 Briefly, overnight cultures of S. sanguinis wild-type and mutant derivatives were adjusted to 1 x 107 cells/mL. In a 48-well culture plate, 50 μL of this suspension along with 450 μL of TH supplemented with 0.5% sucrose and 0.5% mannose was seeded. The 48-well plates were incubated for 15–17 hours at 37 C under anaerobic conditions

(nitrogen 80%, carbon dioxide 10%, hydrogen 10%) to allow biofilm growth.

Simultaneously, the F. nucleatum strain Fnn_WT_CIC27 was grown anaerobically in CB at 37 C. The F. nucleatum overnight culture was then resuspended in 1X PBS to a concentration of 5 x 108 cells/mL (0.5 OD600 nm). After washing the wildtype S. sanguinis and mutant biofilms with 1X PBS, 500 μL (5 x 108 cells) of the F. nucleatum culture was added into each well and incubated further for 15–17 hours at 37 C in anaerobic conditions.

CFU Analysis

To determine the ratio of F. nucleatum integration into the biofilms, the supernatant was removed and the biofilms were resuspended in 200 μL 1X PBS after a gentle wash with 1X PBS to remove planktonic cells. The suspended biofilm cells were serially diluted and distributed onto CB plates with thiamphenicol for CFU determination of F. nucleatum.

Similarly, the serial dilutions were placed on TH plates with kanamycin or without kanamycin for mutants and wild-type S. sanguinis, respectively.

Colonies were counted after incubation under anaerobic conditions at 37 C for one to two days for S. sanguinis and three to five days for F. nucleatum.

Statistical Analysis

One-way ANOVA was performed to determine statistical significance using GraphPad Prism 8.0 (version 2016, Microsoft, Seattle).

Results Identification of S. sanguinis gene(s) Involved in the Interaction With F. nucleatum

For the identification of genes involved in binding of S. sanguinis to its partner species F. nucleatum, an S. sanguinis mutant library of 2,270 genes26 was D ECEMBER 2 0 2 0

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TABLE

Visual Coaggregation Screening of Selected S. sanguinis SK36 Mutants With F. nucleatum Strain

Affected protein (KEGG database)

Assigned function

Visual coaggregation score (scale 0–4)*

SK36

None

SSA_0022

SrtB

Surface protein cell wall anchor

2

SSA_0094

LysM type protein

Cell wall metabolism

2

SSA_0303

SspC

Surface protein C

2

SSA_0904

CrpA

CshA-like fibrillary surface protein A

2

SSA_0905

CrpB

CshA-like fibrillary surface protein B

2

SSA_0906

CrpC

CshA-like fibrillary surface protein C

2

SSA_0956

SspD

Surface protein D

2

SSA_1049

PotB

Spermidine/putrescin transport system

2–3

SSA_1101

HlyD secretion protein

Multi-drug-resistance efflux pump

2–3

SSA_1307

TrkH2

Trk transport membrane spanning protein

2

SSA_1788

Receptor (integral)

Integral membrane protein

2

SSA_1792

YidC

Oxa-like protein precursor

1

SSA_1965

—

Stomatin/prohibitin like membrane protease

1

SSA_1984

SD-repeat like protein

Cell surface SD repeat containing protein

2

SSA_2067

Hypothetical protein

Hypothetical

2

SSA_2121

Anchor protein

Cell wall surface anchor family protein

2

SSA_2333

DltB

Membrane protein involved in D-alanine transport

1

SSA_2343

Hypothetical protein

Putative membrane protein

2

3

*The visual coaggregation score is based on the scale described by Cisar et al.28 The scale ranges from 0 = no coaggregation with all cells remaining in suspension to 4 = maximum coaggregation with no visible cells remaining in suspension.

screened via a large-scale visual coaggregation assay. The coaggregation assay is a well-established in vitro method for assessing the binding between two species. High levels of coaggregate formation are the result of intercellular binding, while cells remaining in suspension indicate a lack of physical interaction between the species tested.

The large-scale visual coaggregation assays were conducted in a 96-well plate format, and after three consecutive rounds of library screening, 18 mutants with potential defects in interaction were 674 D ECEMBER

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identified (TABLE) . Further quantitative evaluation of the coaggregation ability of these mutants was conducted for confirmation of candidates (FIGURE 1) . Of the 18 original mutants identified, eight mutants were confirmed to have significant defect in interaction with F. nucleatum compared to the wild-type S. sanguinis (75.7 ± 1.4), suggesting a role of these genes in the binding. Specifically, these mutants included ΔsrtB (48.0 ± 5.1), ΔsspC (49.0 ± 3.8), ΔcrpA (46.3 ± 3.8), ΔsspD (56.3 ± 3.3), ΔyidC (31.6 ± 3.3), ΔdltB (35.6 ± 6.2), along with ΔSSA_1965

(56.6 ± 5.0) and ΔSSA_2343 (51.6 ± 4.4), which lack a predicted stomatin/ prohibitin-like membrane protease subunit and a hypothetical protein, respectively.

Monospecies Biofilm Formation of S. sanguinis Mutant Derivatives

The eight S. sanguinis mutant derivatives that showed significant defects in coaggregation compared to the wild-type (FIGURE 1) were further characterized for their biofilm formation phenotype. This was achieved by using crystal violet staining for the assessment of biomass of the biofilms (FIGURE 2) . Of the eight mutants, a statistically significant increase in biomass compared to the wild-type (100%) was evident for ΔcrpA (212.3 ± 31.4), ΔdltB (205.0 ± 25.2) and ΔSSA_2343 (311.1 ± 15.6). Though a higher biomass was also observed for ΔsspD (161.6 ± 23.6), it was not statistically significant. In contrast, an apparent, albeit statistically not significant, reduction in biomass was noted for ΔsrtB (81.3 ± 4.4), ΔsspC (76.3 ± 4.5), ΔyidC (39.7 ± 3.9) and ΔSSA_1965 (81.0 ± 3.6).

F. nucleatum Integration Into S. sanguinis Biofilms

Next, we tested the ability of the above eight mutants to allow for integration of F. nucleatum into S. sanguinis biofilms. To follow the reported sequence of colonization in the oral cavity, F. nucleatum cells were added to previously established S. sanguinis biofilms for coincubation as described in the materials and methods section.

CFUs of each species were determined to calculate the ratio of F. nucleatum to S. sanguinis cells present in the dual-species biofilm. All mutants with the exception of ΔsspC showed a significant reduction in F. nucleatum incorporation compared to the wild-type (FIGURE 3) , suggesting a role in interspecies interaction. These

C D A J O U R N A L , V O L 4 8 , Nº 12

100

80

% Coagregation

*

* *

*

60

*

*

*

* *

40

30

W T ΔS Δs SA rtB _0 09 3 Δs sp C Δc rp A Δc rp B Δc rp C Δs sp D ΔS Δp SA otB ΔS _11 SA 01 ΔS _13 SA 07 _1 78 8 ΔS Δy SA idC _ ΔS 196 SA 5 ΔS _1 SA 984 ΔS _20 SA 67 _2 12 1 ΔS Δd SA ltB _2 34 3

0

FIGURE 1. Quantitative coaggregation of wild-type S. sanguinis SK36 (green) and selected mutant derivatives with F. nucleatum ATCC 23726. Detailed information for the mutants is summarized in the TABLE. Mutants exhibiting a significant defect in coaggregation are shown as orange bars and the rest are depicted as gray bars.

Data are presented as mean of percentage coaggregation and standard error of mean of three independent experiments (*represents p ≤ 0.05).

% Mutant / WT (OD570 nm)

400

* 300

*

*

200 WT

100

ΔS SA _19 65 ΔS SA _2 34 3

Δd ltB

Δy idC

Δs spD

Δc rpA

Δs spC

Δs rtB

0

FIGURE 2 . Biofilm biomass of S. sanguinis SK36 wild-type (WT) and selected mutant derivatives. The biomass

was assessed by crystal violet assay. Data are presented as percentage of mean of the optical density at 570 nm compared to WT. The WT level is indicated as a dotted line (---). The data represent the mean and standard error of mean of three independent experiments (*represents p ≤ 0.05).

included the mutants of the predicted stomatin/prohibitin-like membrane protease subunit SSA_1965 (0.22) and the hypothetical protein SSA_2343 (0.45), mutants of genes encoding proteins with a likely pleiotropic affect; srtB (0.37), yidC (0.34), dltB (0.34) and the adhesins coding genes sspD (0.27) and crpA (0.41). The mutant derivative lacking sspC (1.45) integrated more cells of F. nucleatum compared to WT (0.86), which was statistically significant.

Discussion

Adherence is a critical ability of bacteria for colonization and biofilm formation. The mutual interaction of diverse microbial species within the oral cavity enables maturation of the complex biofilm. As one of the pioneer colonizers, S. sanguinis lays a foundation for biofilm development by recruiting other microbial species.13,15 Of the species binding to S. sanguinis, F. nucleatum is an important bridging organism that further shapes the microbial community composition.13,30,31 While we previously demonstrated that F. nucleatum binds to S. sanguinis via the adhesin RadD,20 the respective adhesins/receptors of S. sanguinis are still unknown. In this study, we found that mutants defective in genes encoding the adhesins SspD and CrpA or those with membrane-associated pleiotropic functions (srtB, dltB and yidC) had the most drastic effect on the interaction with S. sanguinis. In addition, we identified genes predicted to encode a stomatin/ prohibitin-like membrane protease subunit and a hypothetical protein (SSA_1965 and SSA_2343) that might play a role in S. sanguinis binding to F. nucleatum.

Extensive screening of an S. sanguinis mutant library26 for strains defective in attachment to F. nucleatum yielded 18 candidate mutants (TABLE) . Further analysis by quantitative coaggregation D ECEMBER 2 0 2 0

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2.0

*

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Fn:Ss Ratio

1.0

*

*

0.5

*

*

* *

*

Δd ltB ΔS SA _19 65 ΔS SA _2 34 3

Δy idC

Δs spD

Δc rpA

Δs spC

Δs rtB

W

T

0.0

FIGURE 3 . Analysis of F. nucleatum ATCC 23726 (Fn) integration into S. sanguinis (Ss) SK 36 biofilms. Data

Peptidoglycan

are presented as the ratio of the number of Fn cells to Ss cells as determined by colony forming units. The data represent the mean and standard error of mean of three biological replicates (* represents p ≤ 0.05).

Lipoteichoic acid Teichoic acid

SrtB

YidC

DltB

SSA_1965

Periplasmic space

Cytoplasmic membrane

confirmed eight of these candidate mutants as being significantly impaired in interspecies binding (FIGURE 1) . Consistent with functions involved in attachment, the affected genes were mostly associated with cell surface or membrane functions (TABLE) . More detailed characterization revealed higher biomass accumulation for biofilms formed by the ΔsspD, ΔcrpA, ΔdltB and ΔSSA_2343 mutants compared to wild-type (FIGURE 2) . Another study has observed a similar increase in biomass upon deletion of adhesin encoding genes and found that this defect can lead to overexpression of other attachment-related genes.32 In contrast, a decrease in the biofilm formation was observed for mutant derivatives defective in genes with pleiotropic effects on membraneinsertion of proteins such as yidC and srtB. In other bacterial species, YidC is well documented as an important facilitator for the insertion of cell wall proteins.33–36 Biofilm formation is decreased in strains lacking yidC, including the oral bacterium S. mutans,37 due to defects in cell wall display of multiple proteins. Similarly, we observed reduced biofilm production in the ΔsrtB mutant, which does not produce sortase B, the enzyme responsible for anchoring LPXTG motif-containing surface proteins including adhesins to the cell wall of gram-positive bacterial species.38,39 On the other hand, increased biofilm formation was observed for the ΔdltB mutant. DltB was previously described for its role in transferring D-alanine to the lipoteichoic acids (LTAs) on the cell wall of bacteria40,41 and was attributed to the modification of cell surface charges in Streptococcus agalactiae.42 Thus, the elevated biofilm biomass produced by the dltB defective strain could be the result of altered charges on the S. sanguinis cell surface.

1.5

SSA_2343

FIGURE 4 . Schematic of the S. sanguinis cell wall depicting the key proteins involved in the interaction with F. nucleatum. The sortase SrtB and the insertase YidC, both of which have key functions in proper localization of distinct groups of membrane proteins, are localized in the cytoplasmic membrane. SrtB is inserted in the outer leaflet with its enzymatic activity occurring in the peptidoglycan layer and YidC spans the cytoplasmic membrane. Another protein with pleiotropic function is DltB, which is integral to the cytoplasmic membrane and transfers D-alanine (shown in pink circles) to the lipoteichoic acid during transport to the peptidoglycan layer.

The adhesins CrpA and SspD are shown anchored to the surface after cleavage of the LPXTG motif by SrtB. The predicted stomatin/prohibitin-like membrane protease subunit SSA_1965 and the hypothetical protein SSA_2343 are indicated in their predicted membrane-associated location.

C D A J O U R N A L , V O L 4 8 , Nº 12

Additionally, we analyzed the integration of F. nucleatum into already established S. sanguinis biofilm. Consistent with our results for the coaggregation assay (FIGURE 1) , we found that lack of the genes with pleiotropic effect (ΔyidC, ΔsrtB, ΔdltB) had the most drastic impact on the F. nucleatum integration (FIGURE 3) . Interestingly, all of these genes are implicated in cell wall biogenesis and thus play an indirect role in the adherence of F. nucleatum (FIGURE 4) . As detailed previously, YidC acts as an insertase for cell wall proteins,33,36,43 SrtB anchors proteins to the cell surface,38,39 and DltB is required for incorporation of D-alanine into LTAs40 changing the cell surface and cell wall of S. sanguinis. Not surprisingly, mutants in sspD and crpA, which encode adhesins, exhibited a reduced ability to integrate F. nucleatum into the S. sanguinis biofilm demonstrating their role in binding. A similar phenotype was observed for the mutants defective in the predicted stomatin/prohibitin-like membrane protease subunit SSA_1965 and the hypothetical protein SSA_2343.

In contrast, the ΔsspC mutant displayed a significant increase in F. nucleatum integration. The adhesins SspC and SspD belong to the AgI/II family, and their corresponding S. gordonii orthologs are known to be involved in interspecies interaction.44,45 Though our results strongly suggest a role of SspD in attachment of S. sanguinis to F. nucleatum, SspC is likely not directly involved in the binding. An earlier study demonstrated that deletion of the adhesins can potentially lead to an increased expression of other adhesins32 that could explain the ΔsspC phenotype. Similarly, the CshA adhesin of S. gordonii,46 an ortholog of CrpA, has been known to play a role in binding with other oral bacteria.47,48 Consistent with the findings of this study, we demonstrated that CrpA acts as an

important adhesin in the interaction of F. nucleatum and S. sanguinis.

Similar to their orthologs SspA/B and CshA/B in S. gordonii, SspC/D and CrpA of S. sanguinis are SrtB-dependent surface proteins containing the LPXTGmotif.45,49–51 In our study, the main adhesins (SspD and CrpA) that are involved in attachment to F. nucleatum are both sortase B dependent. Hence, the mutant strain deficient in srtB in S. sanguinis likely affects SspD and CrpA linkage to the peptidoglycan layer, which leads to reduced binding to F. nucleatum.

The S. sanguinis mutant lacking SspC, another SrtB-dependent adhesin, however, exhibited contrasting behavior of reduced coaggregation with F. nucleatum but enhanced fusobacterial integration with this partner species. The function of SspC in adherence to F. nucleatum is thus inconclusive. As mentioned earlier, the role of dltB and yidC in S. sanguinis interaction with its fusobacterial partner species is likely indirect. It will be interesting to further investigate whether DltB and YidC affect the adhesins, SspD and CrpA, identified in this study or a different group of adhesins.

However, as this study was performed with only one wild-type strain of the F. nucleatum subspecies nucleatum, future analyses should include the investigation of their role in binding to other fusobacterial strains and subspecies.

Complementation of mutant strains would further validate the identified candidate genes, and addition of saliva to the biofilm experiments would evaluate the influence of this important oral fluid on the interaction between F. nucleatum and its partner species S. sanguinis.

Conclusions

In conclusion, this study revealed two adhesins, SspD and CrpA, with potential roles in the binding of S. sanguinis and

F. nucleatum. Additionally, three genes encoding pleiotropic functions for insertion of proteins in the cell wall, srtB, yidC and dltB, along with the genes encoding the predicted stomatin/ prohibitin-like membrane protease subunit SSA_1965 and the hypothetical protein SSA_2343 exhibited a substantial role in the interaction. Overall, it is evident that multiple adhesins mediate this association of an early colonizer (S. sanguinis) and an intermediate colonizer (F. nucleatum).

As a true commensal, S. sanguinis lives in harmony with the host and contributes to oral homeostasis. The identification of the proteins that support building a network of partner species upholding this beneficial microbial community can pave the way for future therapeutic interventions to prevent or mitigate oral diseases. n ACKNOWLEDGMENTS This study was supported in part by NIH grant DE021108 to RL. We thank members of the Lux and Tran laboratories for discussion.

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29. Zmantar T, Kouidhi B, Miladi H, Mahdouani K, Bakhrouf A. A microtiter plate assay for Staphylococcus aureus biofilm quantification at various pH levels and hydrogen peroxide supplementation. New Microbiol 2010 Apr;33(2):137–45.

30. Kolenbrander PE. Oral microbial communities: Biofilms, interactions and genetic systems. Annu Rev Microbiol 2000;54:413–37. doi: 10.1146/annurev.micro.54.1.413.

31. Lancy P Jr., Dirienzo JM, Appelbaum B, Rosan B, Holt SC. Corncob formation between Fusobacterium nucleatum and Streptococcus sanguis. Infect Immun 1983 Apr;40(1):303–9. doi: 10.1128/IAI.40.1.303-309.1983.

32. Zhang Y, Lei Y, Nobbs A, Khammanivong A, Herzberg MC. Inactivation of Streptococcus gordonii SspAB alters expression of multiple adhesin genes. Infect Immun 2005 Jun;73(6):3351–7. doi: 10.1128/IAI.73.6.3351-3357.2005.

33. Hennon SW, Soman R, Zhu L, Dalbey RE. YidC/Alb3/Oxa1 Family of Insertases. J Biol Chem 2015 Jun;290(24):14866– 74. doi: 10.1074/jbc.R115.638171.

34. Wu ZC, de Keyzer J, Berrelkamp-Lahpor GA, Driessen AJ. Interaction of Streptococcus mutans YidC1 and YidC2 with translating and nontranslating ribosomes. J Bacteriol 2013 Oct;195(19):4545–51. doi: 10.1128/JB.00792-13.

35. Serek J, Bauer-Manz G, Struhalla G, et al. Escherichia coli YidC is a membrane insertase for Sec-independent proteins.

EMBO J 2004 Jan 28;23(2):294–301. doi: 10.1038/ sj.emboj.7600063.

36. Samuelson JC, Chen M, Jiang F, et al. YidC mediates membrane protein insertion in bacteria. Nature 2000 Aug 10;406(6796):637–41. doi: 10.1038/35020586.

37. Palmer SR, Ren Z, Hwang G, et al. Streptococcus mutans yidC1 and yidC2 impact cell envelope biogenesis, the biofilm matrix and biofilm biophysical properties. J Bacteriol 2018 Dec 7;201(1):e00396–18. doi: 10.1128/JB.00396-18. Print 2019 Jan 1.

38. Mazmanian SK, Ton-That H, Schneewind O. Sortasecatalysed anchoring of surface proteins to the cell wall of Staphylococcus aureus. Mol Microbiol 2001 Jun;40(5):1049– 57. doi: 10.1046/j.1365-2958.2001.02411.x.

39. Novick RP. Sortase: The surface protein anchoring transpeptidase and the LPXTG motif. Trends Microbiol 2000

Apr;8(4):148–51. doi: 10.1016/s0966-842x(00)01741-8.

40. Neuhaus FC, Heaton MP, Debabov DV, Zhang Q. The dlt operon in the biosynthesis of D-alanyl-lipoteichoic acid in Lactobacillus casei. Microb Drug Resist Spring 1996;2(1):77– 84. doi: 10.1089/mdr.1996.2.77.

41. Clemans DL, Kolenbrander PE, Debabov DV, et al. Insertional inactivation of genes responsible for the D-alanylation of lipoteichoic acid in Streptococcus gordonii DL1 (Challis) affects intrageneric coaggregations. Infect Immun 1999 May;67(5):2464–74. doi: 10.1128/IAI.67.5.24642474.1999.

42. Poyart C, Lamy MC, Boumaila C, Fiedler F, Trieu-Cuot P. Regulation of D-alanyl-lipoteichoic acid biosynthesis in Streptococcus agalactiae involves a novel two-component regulatory system. J Bacteriol 2001 Nov;183(21):6324–34. doi: 10.1128/JB.183.21.6324-6334.2001.

43. Dalbey RE, Kuhn A. How YidC inserts and folds proteins across a membrane. Nat Struct Mol Biol 2014 May;21(5):435–6. doi.org/10.1038/nsmb.2823.

44. Demuth DR, Duan Y, Brooks W, et al. Tandem genes encode cell-surface polypeptides SspA and SspB which mediate adhesion of the oral bacterium Streptococcus gordonii to human and bacterial receptors. Mol Microbiol 1996 Apr;20(2):403– 13. doi: 10.1111/j.1365-2958.1996.tb02627.x.

45. Jenkinson HF, Demuth DR. Structure, function and immunogenicity of streptococcal antigen I/II polypeptides. Mol Microbiol 1997 Jan;23(2):183–90. doi: 10.1046/j.13652958.1997.2021577.x.

46. McNab R, Forbes H, Handley PS, et al. Cell wall-anchored CshA polypeptide (259 kilodaltons) in Streptococcus gordonii forms surface fibrils that confer hydrophobic and adhesive properties. J Bacteriol 1999 May;181(10):3087–95. doi: 10.1128/JB.181.10.3087-3095.1999.

47. McNab R, Jenkinson HF, Loach DM, Tannock GW. Cell-surface-associated polypeptides CshA and CshB of high molecular mass are colonization determinants in the oral bacterium Streptococcus gordonii. Mol Microbiol 1994 Nov;14(4):743–54. doi: 10.1111/j.1365-2958.1994. tb01311.x.

48. McNab R, Holmes AR, Clarke JM, Tannock GW, Jenkinson HF. Cell surface polypeptide CshA mediates binding of Streptococcus gordonii to other oral bacteria and to immobilized fibronectin. Infect Immun 1996 Oct;64(10):4204–10.

49. Holmes AR, Gilbert C, Wells JM, Jenkinson HF. Binding properties of Streptococcus gordonii SspA and SspB (antigen I/II family) polypeptides expressed on the cell surface of Lactococcus lactis MG1363. Infect Immun 1998 Oct;66(10):4633–9.

50. Jakubovics NS, Stromberg N, van Dolleweerd CJ, Kelly CG, Jenkinson HF. Differential binding specificities of oral streptococcal antigen I/II family adhesins for human or bacterial ligands. Mol Microbiol 2005 Mar;55(5):1591–605. doi: 10.1111/j.1365-2958.2005.04495.x.

51. McNab R, Jenkinson HF. Altered adherence properties of a Streptococcus gordonii hppA (oligopeptide permease) mutant result from transcriptional effects on cshA adhesin gene expression. Microbiology 1998 Jan;144 (Pt 1):127–36. doi: 10.1099/00221287-144-1-127.

THE CORRESPONDING AUTHORS, Renate Lux, PhD, and Bhumika Shokeen, PhD, can be reached at rlux@dentistry.ucla.edu and bhumikas@ucla.edu.

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Surface Roughness of 3D Printed Discs Infused With Gold-Coated Titanium Oxide Nanofibers Brittany Watu, BS, DDS; Clayton Tran, BS, DDS; Ellin Choi, BS, DDS; Alyson Drew, BS, DDSc; Udochukwu Oyoyo, MPH; Ryan Sinclair, PhD; Christopher C. Perry, PhD; and So Ran Kwon, DDS, MS, PhD, MS

a b s t r a c t Advances in nanotechnology and 3D printing are making significant

impacts on dentistry. The purpose of this study was to synthesize titanium oxide nanofibers and gold-coated titanium oxide nanofibers, disperse them into the resin matrix to 3D print composite discs and evaluate the change in surface roughness associated with repeated UV-light activation over time. The infusion of nanomaterials and prolonged UV-light activation did not adversely affect the surface roughness properties of the 3D printed material.

AUTHORS Brittany Watu, BS, DDS, is a recent graduate of the Loma Linda University School of Dentistry.

Conflict of Interest Disclosure: None reported.

Ellin Choi, BS, DDS, is a recent graduate of the Loma Linda University School of Dentistry.

Conflict of Interest Disclosure: None reported.

Clayton Tran, BS, DDS, is a recent graduate of the Loma Linda University School of Dentistry.

Conflict of Interest Disclosure: None reported.

Alyson Drew, BS, DDSc, is a dental student at the Loma Linda University School of Dentistry.

Conflict of Interest Disclosure: None reported.

Udochukwu Oyoyo, MPH, is an assistant professor at the Loma Linda University School of Dentistry.

Conflict of Interest Disclosure: None reported.

Ryan Sinclair, PhD, is an associate professor at the Loma Linda University School of Public Health.

Conflict of Interest Disclosure: None reported.

Christopher C. Perry, PhD, is an assistant professor in the division of biochemistry at the Loma Linda University School of Medicine.

Conflict of Interest Disclosure: None reported.

So Ran Kwon, DDS, MS, PhD, MS, is a professor and director of the student research program at the Loma Linda University School of Dentistry.

Conflict of Interest Disclosure: None reported.

N

anomaterials are emerging as a new therapeutic strategy for the treatment of bacterial infections and the prevention of biofilm formation.1 These nanomaterials offer many advantages over traditional therapies, including reduced toxicity and a lower risk of developing resistance by bacteria. Titanium dioxide (TiO2) nanoparticles and nanofibers are known photocatalysts that activate and promote hydroxyl formation, which essentially initiates oxidation. Titanium dioxide is a natural oxide of titanium with low toxicity and negligible biological effects and is found in food products, cosmetics â&#x20AC;&#x192;D ECEMBER 2 0 2 0

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Synthesis

Sonication

3D printing

Washing and drying

Irradiation and profilometry

FIGURE 1. Diagram of experimental set-up.

and pharmaceutical products.2 TiO2 nanomaterials serve as ideal carriers for other metals such as silver or gold that when irradiated with UV light have shown to generate reactive oxygen species that disrupt the biofilm.3,4 Gold nanoparticles have received widespread interest because of their highly controlled optical and electrical properties.5 In the medical field, gold nanoparticles are applied in aiding drug delivery to target areas and as therapeutic and diagnostic agents.6 Properties of materials change as their size approaches the nanoscale and as the percentage of atoms at the surface of a material becomes significant. Thus, gold nanoparticles and conjugates have known antibacterial functions especially against multi-drug-resistant bacteria.5,7 In the oral health care industry, gold nanoparticles have been incorporated into toothbrush bristles, as their antibacterial properties aid in reducing contamination and plaque scores.8,9 In our previous study, we compared the oxidation potential of synthesized TiO2 nanofibers and gold-coated TiO2 nanofibers (Au-TiO2 nanofibers).10 The coating of Au to the TiO2 nanofibers scaffold exerted a synergistic effect that resulted in increased oxidation potential and a 1.6 times faster degradation rate of the tested dye.

This was attributed to gold’s plasmonic resonances that strongly absorb in the visible and near-infrared region.10 682 D ECEMBER

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3D printing became recognized in dentistry with the introduction of CAD/ CAM technology in the 1970s.11 With this innovation, 3D printing continued to flourish throughout all fields within dentistry. In prosthodontics and implant dentistry, it provided printed complete denture prosthesis, removable partial metal frameworks and surgical implant guides.12 More specifically for implants, 3D-printed surgical guides allow implants to be placed in an optimal position with reduced chance of surgical complications.13 The progression continued into areas of oral and maxillofacial surgery for anatomical models and surgical guides to clear aligners in orthodontics.14,15 Furthermore, 3D printing has been used to fabricate oral health care products such as sports mouthguards and toothbrush aids that allow ease of handling.16,17 3D printing is a significant advancement that will become of increasing importance in dentistry to develop new materials and more predictable, less-invasive and less-costly procedures for patients.

Our previous studies have shown that Au-TiO2 nanofibers have higher oxidation potential than TiO2 nanofibers.10 Although dispersion of functional inorganic nanomaterials within the polymer matrix is known to impart bactericidal activity to the composite, there is scarce information on how the photocatalytic activity will affect the 3D printed polymer matrix over time.

Surface topography plays an important part

in understanding the nature of material surfaces.18 Material degradation can occur through a physically applied force or via reaction with the environment such as light, liquids and gas that can cause an increase or decrease in surface roughness.

Thus, measuring potential changes in surface roughness of materials that contain functional inorganic nanomaterials is a central issue that needs to be addressed to confirm their dimensional stability over time.19 There are several methods such as profilometry, atomic force microscopy or scanning electron microscopy to measure surface roughness. Of these methods, contact profilometry is commonly used for dental materials.20 The purpose of this study was to synthesize gold-coated Au-TiO2 nanofibers, disperse them into the resin matrix of 3D printed composite discs and evaluate the change in surface roughness associated with repeated UVlight activation over time using contact profilometry. The null hypothesis tested was that there would be no difference in surface roughness among the different groups tested.

Materials and Methods Synthesis of Au TiO2 Nanofibers

The experimental set-up from synthesis to 3D printing and surface roughness measurement is illustrated in FIGURE 1 .

Anatase titanium (IV) oxide (SigmaAldrich, St. Louis) anatase nanoparticles (crystallite size ≈ 25 nm; surface area

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45–55 m2 g–1) was the starting material.

Hydrogen tetrachloroaurate (III) trihydrate (HAuCl4 .3H2O), trisodium citrate (HOC(COONa)(CH2COONa)2·2H2O) and oxalic acid were purchased from Sigma-Aldrich. One gram of TiO2 anatase nanoparticle powder was suspended in 5 M NaOH (20 mL, using ultrapure water; 18.2 MΩ cm−1 resistivity) and placed in a stainless-steel enclosed Teflon autoclave (100 mL volume size) containing a Tefloncoated stir bar as previously described.21 The Teflon autoclave was ≈ 2∕3 submerged in an oil bath at ~120–130 C (autoclave internal temperature ~ 170 C) on a magnetic hot plate with continuous stirring for approximately 48 to 72 hours. We used a base concentration range and temperature that is known to synthesize titanate nanofibers.22 Stirring with a Teflon-coated stir bar was required to get fibers. After the excess base was removed with aqueous acid and washed with water, the sample was vacuum filtered and annealed at 400 C. Gold nanoparticles (≈ 10 nm) were synthesized based upon the protocol by Vikesland et al.23 Briefly, 100 µL of Au3+ (100 mM) and 20 ul of 1 M NaOH were added to 20 mL of water. The solution was brought to a boil and allowed to boil for five minutes before adding 600 µL of 100 mM trisodium citrate (3 mM final concentration). This solution was refluxed for another 15 minutes and allowed to cool to room temperature.

TiO2 nanofibers were characterized and further coated with gold nanoparticles using photocolloidal deposition method using oxalic acid as the hole scavenger.

Briefly, 50 mg of TiO2 nanofiber solution was suspended in 20 mL Au nanoparticle solution and 0.5 mL of 0.1 M oxalic acid added in a Pyrex round-bottomed flask.

The solution was purged with Ar for five minutes. Then the solution was irradiated with 365 nm UV light for 30 to 40 minutes while under constant Ar purging. This

solution was centrifuged, the supernatant removed and the remaining solid nanofibers dried at ≈ 120 C. Finally, the nanofibers were suspended under sonication to give ≈ 0.5 mg/mL concentration and imaged with transmission electron microscopy (TEM: FEI TitanX, Thermo Fisher Scientific, Waltham, Mass.).

Additionally, Fourier-transform infrared spectroscopy (FT/IR-4100, Jasco, Easton, Md.) was performed to obtain infrared spectrum absorption of the disc surface.

Polymer Infusion With TiO2 Nanofibers and Au-TiO2 Nanofibers

On completion of TiO 2 nanofibers and Au-TiO2 nanofibers synthesis, the pulverized form of each material was weighed and transferred to 50 mL plastic centrifuge tubes. Forty milliliters of organic acrylonitrile butadiene styrene (ABS) compound resin (EP200-V420, Bucktown Polymers, Chicago) was added to tubes to create three experimental groups as follows: 1) negative control (NC): Polymer without nanomaterials; 2) TiO 2 NF: TiO 2 nanofibers and polymer mixture at a concentration of 0.05 gm/mL; and 3) Au TiO 2 NF: Au TiO 2 nanofibers and polymer mixture at a concentration of 0.01 gm/mL. The final concentration of each mixture was based on pilot studies determining optimal concentration for antimicrobial activity.

The mixtures were then mixed with a sonicator (60 Sonic Dismembrator, ThermoFisher Scientific) for 60 seconds to yield a homogenous mixture of nanomaterials throughout the resin.

3D Printing of Resin Composite Discs

A total of 36 resin discs were printed with the photon UV LCD 3D printer (Anycubic, Shenzhen, China) using acrylonitrile butadiene styrene (ABS) resin. The ABS thermoplastic polymer

was compromised of the monomer units acrylonitrile, butadiene and styrene. Acrylonitrile provides chemical resistance and impact resistance, butadiene provides toughness and impact resistance and styrene gives rigidity and easy postprocessing.24 Each solution was poured into the printing well using an STL file with the disc dimensions of 7 x 3mm to yield 12 discs per group. Once printed, discs were removed from the printing platform, washed with 99% isopropyl alcohol by vortexing for 30 seconds, dried and stored in single-unit containers.

Surface Roughness Measurements and UV Activation

Surface measurements were made using a contact type profilometer (Mitutoyo Surftest, SV-2000, Andover, U.K.). In each group, discs were divided into two subcategories: UV activation or non-UV activation.

Surface roughness (Ra) was measured at three time points: baseline (T1), UV activation of four hours (T2) and 20 hours (T3). UV light irradiation at 365 nm was performed at room temperature (Spectroline, Spectronics Corp., Westbury, N.Y.). Surface roughness was measured along the X-axis with a preset evaluation length of 4 mm.

Three scans were conducted from at least 100z-values across the scan as calculated by software and averaged.25 The Kruskal-Wallis procedure was used to compare the change in surface roughness among the experimental groups. All post hoc comparisons were conducted with Bonferroni corrections of the Mann-Whitney or Wilcoxon signed-rank test, where appropriate. All tests of significance were two-sided and conducted at an alpha level of 0.05 with SAS v 9.1.3 (SAS Institute, Cary, N.C.).

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Baseline Surface Roughness (Ra) Measurements

FIGURE 2 . Transmission electron microscope image of gold-coated titanium oxide nanofibers.

TABLE

Surface Roughness (Ra) at Baseline and Surface Roughness Change (ΔRa) Relative to Baseline at 4 hrs and 20 hrs UV-Activation [Mean (SD)]

NC-UV

NC

TiO2NF_ UV

TiO2NF

Au TiO2NF_ UV

Au TiO2NF

p-value*

Baseline Ra

0.09 (0.03)

0.11 (0.04)

0.05 (0.02)

0.07 (0.04)

0.08 (0.02)

0.08 (0.01)

0.053

ΔRa at T2

–0.03 (0.03)

–0.01 (0.03)

0.01 (0.01)

0.01 (0.04)

0.02 (0.04)

0.01 (0.02)

0.147

ΔRa at T3

0.00 (0.05)

–0.02 (0.04)

0.02 (0.02)

0.01 (0.04)

0.03 (0.03)

0.01 (0.02)

0.232

*Kruskal-Wallis test

Discussion

Results Characterization of Au TiO2 Nanofibers

TEM was used to characterize the proper synthesis of Au TiO2 nanofibers.

A solution was drop-cast onto ultrathin carbon support and imaged. FIGURE 2 shows the scaffold of TiO2 nanofibers that serves as a carrier for scattered gold nanoparticles that appear as black dots with an average size of 20 nm in diameter.

Fourier-Transform Infrared Spectroscopy (FTIR)

FIGURE 3 shows the attenuate total reflection Fourier-transform infrared (ATR-FTIR) spectra of TiO2 nanofibers impregnated acrylonitrile-butadiene styrene (ABS) 3D printed disks referenced against native polymer. By referencing against native ABS, changes associated with the addition of TiO2 nanofibers were compared.

The ATR-FTIR bands of ABS have peaks that are associated with acrylonitrile

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Descriptive statistics of mean surface roughness (Ra) at baseline and surface roughness change (ΔRa) relative to baseline after four hours and 20 hours of UV activation are summarized in the TABLE. Mean Ra ranged from 0.05 to 0.11 μm at baseline. There was no statistically significant difference in baseline Ra, ΔRa at T2 and ΔRa at T3 among the six groups (p = 0.053, p = 0.147, p = 0.232 respectively). The distribution of ΔRa at T3 by group is illustrated in FIGURE 4 . Although there was no statistically significant difference among the groups, when comparing within each subgroup, the UV-activated group tended to have a greater surface roughness change compared to their respective non-UV-activated group.

2020

(CN stretch ~2240 cm–1; obscured by background CO2 bands), butadiene and styrene (C-C ring modes ~1600, 1580, 1490 cm–1; CH2 scissor modes ~1450 cm–1; CH deformation 970, 910 cm–1) groups. Prominent peaks associated with surface oxidation were observed with TiO2 nanofibers, namely the production of carboxylic acids (~1700 cm–1 (C = O) and ~ 3500 cm–1 broad (OH) stretch modes.

The presence of Au has the same effect and does not alter the chemical characteristics of the surface. Notably, samples containing TiO2 nanofibers have (C = C) stretch peaks at 1408 and 1508 cm–1, where these bands are associated with increased unsaturation.

UV irradiation during curing generates electron-hole charge carriers in TiO2 that combine with oxygen and residual water to produce reaction oxygen species (–•O 2, H2O2, •OH). This results in partial oxidation and increased unsaturation of the polymer surface when TiO2 is present.

The blending of nanotechnology and 3D printing offers an innovative platform for dental applications.26,27 Therefore, thorough research on safety aspects and anticipated beneficial effects to target areas is highly warranted. The use of titanium dioxide is not new in dentistry, as it is commonly applied to enhance the white color and brightness of toothpaste.28 It also has a significant role in tooth whitening as a photocatalyst to promote hydroxyl radical formation and enhance whitening outcomes in conjunction with hydrogen peroxide and a light-activating source at 405 nm.29 Several studies have shown that the addition of titanium dioxide in tooth whitening products enables adequate whitening results and reduced tooth sensitivity compared to highly concentrated hydrogen peroxide whitening products.29–34 Recently, titanium dioxide nanomaterials attracted great attention, as selective titanium dioxide surface coatings on dental

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FIGURE 3 . Attenuated total reflectance infrared spectra of TiO2 nanofibers (solid line) and Au coated TiO2 nanofibers (dashed line) impregnated ABS disks. Spectra were

referenced against unmodified ABS disks.

DELTA Rz T3-T1

0.05

0.00

-0.05 NC_UV

NC

TiO2 NF_UV

TiO2 NF

Au TiO2 NF_UV

Au TiO2 NF

Group FIGURE 4 . Boxplots of difference in surface roughness (ΔRa) by group.

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implants are in development to exert antibacterial and protein adsorption properties.35 Our study builds on the knowledge that titanium oxide nanofibers’ oxidation potential can be enhanced by coating gold nanoparticles onto the 3D scaffold. Furthermore, when infusing the gold-coated nanomaterials into a resin matrix, it exhibits antimicrobial activity.8,9 However, there is scarce information on the stability of the printed resin matrix with prolonged cycles of UV-light activation. The additional antimicrobial effect of new dental materials with added nanomaterials is promising in preventing multifactorial biofilm diseases such as dental caries and periodontal disease. However, it is important to recognize that surface roughness values greater than 0.2 microns lead to increased plaque accumulation.36 Furthermore, dramatic colonization would occur beginning at 2 microns. Therefore, it is critical to assess the dimensional stability of newly developed dental materials to avoid inadvertent surface roughness changes that may enhance accumulation of bacteria.37 Based on our results, we accepted our null hypothesis because there were no differences in surface roughness changes among the differently treated groups. In fact, there was only a minor change in all groups regardless of composition and UV-light activation. It is important to note that roughness measurements were performed on the micrometer scale. This constraint means that caution is required in the interpretation of results, as measurements with more sensitive equipment that would detect differences at the nanometer scale could have potentially yielded different results.

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The findings of our study open opportunities and prompt for future research into blending 3D printing with nanotechnology. It is important to realize several significant challenges to make significant advancements. First, we used light activation in the ultraviolet range, as we used a 365 nm light source.

In order to envision novel dental applications, synthesized na-nomaterials need to be activated by simple LED lights in the visible light spectrum.

Second, the photocatalytic activity and resulting antimicrobial characteristics of metal oxide nanomaterials are only effective at the surface. Thus, the most stable and cost-effective method for creating a reactive surface needs to be determined. Third, there is a need to demonstrate the degree of dispersion within the resin and localization of the nanomaterials on the surface where they are intended to exert antimicrobial activity. Fourth, it is desirable to use a printer and material that does not require UV-light activation. Lastly, nanomaterials are prone to passivation from various factors. Therefore, it is crucial to create a robust coating that has recycling stability so that antimicrobial activity is sustainable on a long-term basis.38–40 Once these challenges have been addressed, the antimicrobial properties of this technique will have broad applications in the oral health care industry, such as for use in personal protective equipment or dental device scaffolds that may have unique self-cleaning properties.

Conclusion

Within the limitations of this study, we conclude that TiO 2 nanofibers or Au-TiO 2 nanofibers can successfully be infused into 3D printed discs and retain stable surface characteristics, even after prolonged UV-light activation. n

ACKNOWLEDGMENT This study was supported by the Loma Linda University School of Dentistry Student Research Program Fund and Loma Linda University GRASP Grant # 2170315. The authors thank Dr. Frances Allen at the University of California, Berkeley, for taking the TEM images.

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8. Durgesh P, Sridharan S, Prabhu SK, Rao R, Rudresh V, H Bangalore D. Microbial contamination and plaque scores of nanogold-coated toothbrush. Int J Dent Hyg 2020 Aug;18(3):278–284. doi: 10.1111/idh.12433. Epub 2020 Mar 23.

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10. Watu B, Choi E, Tran C, Perry C, Sinclair R, Nick K, Kwon S. Effect of gold coating on oxidation potential of titanium-oxide nanofiber. J Dent Res 2020; 99(Spec Iss A):#0589.

11. Tarika M, Kohli A. 3D printing in dentistry — An overview.

ASDS 2019;3(6):35–41.

12. Dawood A, Marti Marti B, Sauret-Jackson V, Darwood A. 3D printing in dentistry. Br Dent J 2015 Dec;219(11):521–9. doi: 10.1038/sj.bdj.2015.914.

13. Vlahović Z, Mikić M. 3D printing guide implant placement: A case report. Balk J Dent Med 2017;21. doi.org/10.1515/ bjdm-2017-0010.

14. Oberoi G, Nitsch S, Edelmayer M, Janjić K, Müller AS, Agis H. 3D printing-encompassing the facets of dentistry. Front Bioeng Biotechnol 2018 Nov 22;6:172. doi: 10.3389/ fbioe.2018.00172. eCollection 2018.

15. Yilmaz A, Badria AF, Huri PY, Huri G. 3D-printed surgical

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guides. Ann Jt 2019;4(25). doi: 10.21037/aoj.2019.02.04.

16. Yanagi T, Kakura K, Tsuzuki T, Isshi K, Taniguchi Y, Hirofuji T, Kido H, Yoneda M. Fabrication of mouthguard using digital technology. Dentistry, an open access journal 2019;9(1). doi: 10.4172/2161-1122.1000531.

17. Gallup N, Bow JK, Pearce JM. Economic potential for distributed manufacturing of adaptive aids for arthritis patients in the U.S. Geriatrics (Basel) 2018 Dec 6;3(4)89. doi: 10.3390/ geriatrics3040089.

18. Poon CY, Bhushan B. Comparison of surface roughness measurements by stylus profiler, AFM and noncontact optical profile. Wear 1995;190:76–88. doi.org/10.1016/00431648(95)06697-7.

19. White CC, White KM, Pickett JE. Service Life Prediction of Polymers and Plastics Exposed to Outdoor Weathering. 1st ed.

Cambridge, Mass: Elsevier Inc.; 2018:19–34.

20. Whitehead SA, Shearer AC, Watts DC, Wilson NHF. Comparison of methods for measuring surface roughness of ceramic. J Oral Rehabil 1995 Jun;22(6):421–7. doi: 10.1111/ j.1365-2842.1995.tb00795.x.

21. Allard MM, Merlos SN, Springer BN, Cooper J, Zhang GY, Boskovic DS, et al. Role of TiO2 Anatase Surface Morphology on Organophosphorus Interfacial Chemistry. J Phys Chem C 2018;122(51):29237–48. doi.org/10.1021/acs.jpcc.8b08641.

22. Kasuga T, Hiramatsu M, Hoson A, Sekino T, Niihara K. Formation of titanium oxide nanotube. Langmuir 1998;14(12):3160–3. doi.org/10.1021/la9713816.

23. Leng W, Pati P, Vikesland PJ. Room temperature seed mediated growth of gold nanoparticles: Mechanistic investigations and life cycle assessment. Environ Sci: Nano 2015;2(5):440–453. doi: 10.1039/C5EN00026B. 24. Zhang H, Cai L, Golub M. et al. Tensile, creep and fatigue behaviors of 3D-printed acrylonitrile butadiene styrene. J Mater Eng Perform 2018; 27:57–62. doi.org/10.1007/s11665-0172961-7.

25. Kwon SR, Wang J, Oyoyo U, Li Y. Evaluation of bleaching efficacy and erosion potential of four different over-the-counter bleaching products. Am J Dent 2013 Dec;26(6):356–60.

26. Bhavikatti SK, Bhardwaj S, Prabhuji ML. Current applications of nanotechnology in dentistry: A review. Gen Dent 2014 Jul–Aug;62(4):72–7.

27. Priyadarsini S, Mukherjee S, Mishra M. Nanoparticles used in dentistry: A review. J Oral Biol Craniofac Res Jan–Apr 2018;8(1):58–67. doi: 10.1016/j.jobcr.2017.12.004. Epub 2017 Dec 7.

28. Rompelberg C, Heringa MB, van Donkersgoed G, Drijvers J, Roos A, Westenbrink S, Peters R, van Bemmel G, Brand W, Oomen AG. Oral intake of added titanium dioxide and its nanofraction from food products, food supplements and toothpaste by the Dutch population. Nanotoxicology 2016 Dec;10(10):1404–1414. doi: 10.1080/17435390.2016.1222457. Epub 2016 Sep 13.

29. Lee JY, Lee ES, Kang SM, Kim BI. Application of quantitative light-induced fluorescence technology for tooth bleaching treatment and its assessment: An in vitro study. Photodiagnosis Photodyn Ther 2019 Mar;25:208–213. doi: 10.1016/j.pdpdt.2018.12.001.

Epub 2018 Dec 4.

30. Kurzmann C, Verheyen J, Coto M, Kumar RV, Divitini G, Shokoohi-Tabrizi HA, Verheyen P, De Moor RJG, Moritz A, Agis H. In vitro evaluation of experimental light activated gels for tooth bleaching. Photochem Photobiol Sci 2019 May 15;18(5):1009– 1019. doi: 10.1039/c8pp00223a.

31. Bortolatto JF, Trevisan TC, Bernardi PS, Fernandez E, Dovigo LN, Loguercio AD, Batista de Oliveira Junior O, Pretel H. A novel

approach for in-office tooth bleaching with 6% H2O2/TiO_N and LED/laser system-a controlled, triple-blinded, randomized clinical trial. Lasers Med Sci 2016 Apr;31(3):437–44. doi: 10.1007/ s10103-016-1866-2. Epub 2016 Jan 21.

32. Cuppini M, Leitune VCB, Souza M, Alves AK, Samuel SMW, Collares FM. In vitro evaluation of visible light-activated titanium dioxide photocatalysis for in-office dental bleaching. Dent Mater J 2019 Feb 8;38(1):68–74. doi: 10.4012/dmj.2017-199. Epub 2018 Nov 17.

33. Tano E, Otsuki M, Kato J, Sadr A, Ikeda M, Tagami J. Effects of 405 nm diode laser on titanium oxide bleaching activation.

Photomed Laser Surg 2012 Nov;30(11):648–54. doi: 10.1089/ pho.2012.3273. Epub 2012 Sep 24.

34. Martín J, Vildósola P, Bersezio C, Herrera A, Bortolatto J, Saad JR, Oliveira OB Jr., Fernández E. Effectiveness of 6% hydrogen peroxide concentration for tooth bleaching — a double-blind, randomized clinical trial. J Dent 2015 Aug;43(8):965–72. doi: 10.1016/j.jdent.2015.05.011. Epub 2015 Jun 6.

35. Sawada R, Katou Y, Shibata H, Katayama M, Nonami T. Evaluation of photocatalytic and protein adsorption properties of anodized titanium plate immersed in simulated body fluid. Int J Biomater 2019 Jul 1;2019:7826373. doi. org/10.1155/2019/7826373.

36. Bollen CML, Lambrechts P, Quirynen M. Comparison of surface roughness of oral hard materials to the threshold surface roughness for bacterial plaque retention: A review of the literature. Dent Mater 1997 Jul;13(4):258–69. doi: 10.1016/s0109-5641(97)80038-3.

37. Quirynen M, Marechal M, Busscher HJ, et al. The influence of surface-free energy and surface roughness on early plaque formation. An in vivo study in man. J Clin Periodont 1990;17:138– 144. doi: 10.1111/j.1600-051x.1990.tb01077.x.

38. Liao C, Li Y, Tjong SC. Visible-light active titanium dioxide nanomaterials with bactericidal properties. Nanomaterials (Basel) 2020 Jan;10(1):E124. doi: 10.3390/nano10010124.

39. Noman MT, Ashraf MA, Ali A. Synthesis and applications of nano-TiO2: A review. Environ Sci Pollut Res Int 2019 Feb;26(4):3262–3291. doi: 10.1007/s11356-018-3884-z.

Epub 2018 Dec 6.

40. Veerachandra K, Hunh Y, Hung YC. Using photocatalyst metal oxides as antimicrobial surface coatings to ensure food safetyopportunities and challenges. Comp Rev Food Sci Food Safety 2017;16:617–631. doi.org/10.1111/1541-4337.12267.

THE CORRESPONDING AUTHOR, Brittany Watu, BS, DDS, can be reached at bwatu@llu.edu.

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patient vulnerability C D A J O U R N A L , V O L 4 8 , NÂş 12

Vulnerability of a Young Adult Dental Population in Los Angeles Christina Light, BS; Kenneth J. Glenn, BS; Rassilee Sharma, BS; Kelly Nguyen, BS; Hongfei Chen, DDS, PhD; Todd Franke, MSW, PhD; and Shane N. White, BDentSc, MS, MA, PhD

a b s t r a c t A survey found high levels of vulnerability in a Los Angeles young

adult dental population presenting for third molar extraction. A high proportion of them suffered abusive incidents as children, lived in nonnutritive households, were exposed to violence and were fiscally disadvantaged. The young adults had high prevalence of cigarette, alcohol and street-drug use as well as behavioral health issues, depression, nervousness and anxiety. Dentists should be aware of such vulnerabilities and their long-term consequences.

AUTHORS Christina Light, BS, is a student at the University of California, Los Angeles, School of Dentistry.

Conflict of Interest Disclosure: None reported.

Rassilee Sharma, BS, is a student at the University of California, Los Angeles, School of Dentistry.

Conflict of Interest Disclosure: None reported.

Hongfei Chen, DDS, PhD, is a visiting scholar at the University of California, Los Angeles, School of Dentistry.

Conflict of Interest Disclosure: None reported.

Kenneth J. Glenn, BS, is a student at the University of California, Los Angeles, School of Dentistry.

Conflict of Interest Disclosure: None reported.

Kelly Nguyen, BS, is a student at the University of California, Los Angeles, School of Dentistry.

Conflict of Interest Disclosure: None reported.

Todd Franke, MSW, PhD, is a professor at the University of California, Los Angeles, Luskin School of Public Affairs, UCLA Pritzker Center for Strengthening Children and Families.

Conflict of Interest Disclosure: None reported.

Shane N. White, BDentSc, MS, MA, PhD, is a professor at the University of California, Los Angeles, School of Dentistry.

Conflict of Interest Disclosure: None reported.

A

llostatic load is the concept that cumulative stress and wear and tear on physiological regulatory systems over a lifetime may predispose to disease and other vulnerabilities.1 Some stressors are abrupt, such as an assault; some may be episodic, such as physical abuse; others such as poor nutrition are longer or continual. Their profound effects may not be visible or known to health care providers.

Early-life exposures and experiences may have enduring impacts on adult health trajectories. Stress has a major influence on neural, physiological and physical development and health. Lower socioeconomic status and harsh or chaotic and nonnutritive childhood environments are linked to health risks, including â&#x20AC;&#x192;D ECEMBER 2 0 2 0

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patient vulnerability C D A J O U R N A L , V O L 4 8 , Nº 12

TABLE 1

Adverse Childhood Experiences by Percentage

increased risks of infection, multiple chronic conditions and cardiovascular disease as well as early death.2–5 Neglect and abuse during childhood have a long-term impact on adult health trajectories.6 Allostatic load, including physical abuse, may lead to increased rates of depression, anxiety and suicidality in younger adults.7,8 Adverse childhood experiences (ACEs) are associated with negative health risk behaviors in young adults, including excessive alcohol use.9,10 Interventions are capable of modifying maladaptive protective responses to adverse childhood experiences, such as drinking, smoking and substance abuse.11 A surprisingly high proportion of adult health issues, including obesity, heavy drinking, pulmonary disease and depression, are attributable to adverse childhood experiences.12 Identification of patients at high risk for deterioration in mental health, for example, would be beneficial.7 Caries is associated with ACEs.13 Inadequate, infrequent dental care is also associated with ACEs.14 Dentists recognize high caries rates and infrequent attendance; they address the disease itself and its direct cause — a sugary acidogenic diet. However, there is less awareness of caries’ association with a broader ACE and the impact of those experiences on health behaviors and trajectories of dental patients.

Some biomarkers of ACEs are well known to dentists. Linear enamel hypoplasias are indicative of abrupt severe physiological stresses received during tooth formation.15 Hutchinson’s teeth are signs of congenital syphilis.

Early childhood baby bottle syndrome, also known as early childhood caries (ECC), is indicative of inappropriate nutrition and prolonged and multiple exposures to sugary acidogenic 690 D ECEMBER

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Never

Once/ Twice

Sometimes

Often

Swear at you or put you down?

45

15

21

18

Make you afraid of being physically hurt?

50

21

17

11

Push, grab, slap you?

53

26

11

10

Hit you so hard you had marks or were injured?

73

12

9

5

Push, slap, grab your mother or stepmother?

74

14

10

1

Kick, bite, hit your mother or stepmother?

88

9

3

Hit your mother or stepmother repeatedly?

93

5

2

Threaten your mother or stepmother with a knife or gun?

96

4

Use a knife or gun to hurt your mother or stepmother?

99

1

No

Yes

Your parents divorced?

62

38

You involved in serious family arguments?

47

53

Anyone in your household mentally ill?

70

30

Anyone in your household an alcoholic?

73

27

Anyone in your household a street-drug user?

84

16

Anyone in your household attempt suicide?

92

8

Anyone in your household in prison?

81

19

A. As an 8- to 11-year-old, how often did a parent:

B. As an 8- to 11-year-old were:

liquids. Likewise, high caries rates in older children are indicative of inappropriate nutritional practice.

These signs are visible; they alert the dentist to the likelihood that the child is experiencing adversity or a nonnutritive environment. However, most ACEs do not leave visible traces.

Just as ACEs may not be visible, current heath behaviors and vulnerabilities may not be fully expressed or ascertained by health care providers. Frank answers about such socially stigmatized topics such as alcohol use, alcoholism or addictions may be difficult to elicit. Accurate knowledge about illicit drug usage or experience of violence may be even more difficult to obtain. Hence, the vulnerability of individuals or populations may often be unknown

or underestimated. This has profound implications for care and well-being.

The purpose of this study was to measure childhood exposure to adverse experiences and current exposure to alcohol, tobacco and illicit drug use of a young adult Los Angeles dental population.

Materials and Methods Patient Population

Patients presenting for extraction of lower third molars were recruited at the UCLA School of Dentistry Oral and Maxillofacial Surgery Clinic. All serially consenting patients requiring third molar extractions between June 2011 and September 2013 were included. Subjects were aged 18 or older and able to provide informed consent. Although a convenience sample, patients presenting for wisdom

C D A J O U R N A L , V O L 4 8 , Nº 12

TABLE 2

Childhood Exposure to Violence by Percentage Experience as an 8- to 11-year-old:

No

Yes

Seen someone punched

47

53

Punched or kicked

59

41

Heard gunshots

69

31

Seen assault

92

8

Assaulted with a knife

94

6

Shot by gun

97

3

tooth extraction are overwhelmingly young adults, which are the focus of this study. In order to ensure absolute patient confidentiality, no personal identifiers or data that could potentially be used to infer identity were collected.

A sample size of 100 was attained, sufficient to meet the study aim, but not sufficient to analyze associations between adverse childhood experiences and young adult health care behaviors.16 This clinic is believed to serve a socioeconomically diverse patient population because it both provides specialty services to fiscally disadvantaged patients covered by Medi-Cal and is surrounded by several of the most affluent communities in Los Angeles and the nation. According to patient registration data, the UCLA School of Dentistry patient population for the 2012–13 financial year was: 50% male/ female, < 1% transgender and < 1% other. For the same year, patients described their race as Asian, 10%; African American, 11%; Caucasian, 50%; Hispanic, 20%; undescribed, 5%; Native American < 1%; other, 3%; Persian, 3%; and Pacific Islander, < 1%.

There is no reason to believe that the pool of patients in the oral surgery clinic differed from the overall school of dentistry pool. Some caution should be used in making comparisons to census because the categories used by the school and censuses differ. Data collected as part of the study provided additional demographic description, perceived financial status and homeownership (TABLE 3) . Spanish speakers represented a significant part

of the patient pool; the study documents were translated into Spanish and interpreters were available.

Some selection and response biases may have occurred. It is possible that the least advantaged felt less comfortable with the intrusive and personal nature of the questions, were less likely to provide consent or were less able to provide accurate information. It is possible that, even with all the steps taken to assure anonymity, some subjects biased their responses with the aim of protecting their abusers. It is possible that the least advantaged were less likely to seek and identify care at the UCLA School of Dentistry. It is also possible that young adults attending other clinics within the school, for example orthodontics or the emergency clinic, might have had different life experiences.

Subject Recruitment

Institutional Review Board approval was obtained (UCLA IRB #10-001874). Subjects were recruited using a posted flyer; interested patients contacted the clinic receptionist.

Next, recruiters used a short eligibility screening, according to a standardized script to determine eligibility. Finally, completion of informed consent occurred in a private room. Subjects were given a $20 gift card upon consent, whether or not they completed the subsequent study questionnaire.

Questionnaire

Questionnaires were used to identify and quantify childhood stressors. The questionnaire first directed subjects

to when they were 8–11 years old and included questions adapted to these years from the widely used Adverse Childhood Experience Scale, including measures of abuse, neglect and household dysfunction.17 The ACE questionnaire was initially developed by Vincent Felitti of Kaiser Permanente’s San Diego Department of Preventive Medicine in 1985; it became a widely used instrument that has since been adopted by the U.S. Centers for Disease Control and Prevention.18 Secondly, the questionnaire addressed childhood exposure to violence. Thirdly, the questionnaire examined childhood socioeconomic condition, parental social class, parental education, parental homeownership, housing quality and care of the house and child.2,19 Fourthly, the questionnaire examined the current status of personal health including alcohol use and illicit drug use as well as questions from the standard UCLA School of Dentistry health questionnaire.17 Finally, the questionnaire asked about the reason for extraction, prophylactic/preventive or pain/infection (Question: Why are you having your wisdom tooth/ teeth extracted? Answers: Current pain; prevention of future problems).

The previously established questionnaire components were designed to capture experienced major life events, trauma and long-term environmental conditions.2,17,19 These questions were also originally designed so as to be as easy as possible for the subject to accurately remember and respond and were previously used for self-administered completion without any guidance. The questionnaires were completed immediately after completion of the standard UCLA School of Dentistry Health questionnaire with a trained clinic staff member in attendance to assist subjects as needed.

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patient vulnerability C D A J O U R N A L , V O L 4 8 , Nº 12

TABLE 3

Childhood Economic Environment

by Percentage What was your parent’s approximate income?

Due to the sensitivity of the personal data, no personal identifiers were included, so even if subpoenaed, the questionnaires could never be related to an individual participant or used to imply identity. The questionnaires were cataloged by unique, random bar codes.

Results Adverse Childhood Experiences

Adverse childhood experiences were extremely common (TABLE 1, A) . A majority of the subjects were subjected to abuse as children, ranging from 53% being put down or sworn at to 27% being hit so hard as to be injured or to leave marks. A majority of the subjects never or infrequently were abused; nonetheless, many received occasional to frequent abuse — 14% to 39% depending on type of abuse. Abuse of the subjects’ mothers or stepmothers was less frequent than abuse of the children.

Many subjects, if not most, grew up in nonnutritive households (TABLE 1, B).

A majority of the subjects had been involved in serious family arguments.

Mental illness, alcoholism, street-drug use, suicide attempts and prison incarceration among household members were relatively common; these situations were reported by 8% to 30% of the study participants.

Childhood Exposure to Violence

Exposure to violence was frequent A majority of children were exposed to violence, from 53% seeing someone being punched to 30% hearing or seeing a gunshot.

Many children received violence, from 41% being punched to 6% being assaulted with a knife and 3% being shot. Follow-up questions fortunately revealed that almost all of the injuries were described as being minor. The assaulters were overwhelmingly strangers or sometimes someone met (TABLE 2) .

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for the first time, and the assaults were overwhelmingly at or near school.

Childhood Economic Environment

The study subjects represented a broad economic diverse economic spectrum (TABLE 3) . Parental income was spread across all income brackets, but the lower and middle ranges dominated.

Likewise, the subjects’ comparison of their families’ relative financial status was broadly distributed but dominated by the lower and middle ranges. Many grew up in fiscally disadvantaged situations, with 48% having a parental income of less than $50,000. A large majority — 67% — lacked family homeownership, more than contemporaneous census data described — 54% — for all households in Los Angeles County.

Young Adult Heath Issues

A variety of unhealthful behaviors were widely used (TABLE 4 A) . Smoking was common. Not surprisingly, alcohol was used by a majority — 56%; notably, 9% of the subjects considered themselves to be alcoholics. Street-drug use was common — 41%, but use of cocaine and injected drugs was rare at 3% and 2% respectively.

Behavioral health issues were common, (TABLE 4 B) . Depression, feelings of depression, nervousness and anxiety were reported by onefifth to one-third of the subjects, consistent with 35% reporting having received psychological counseling.

A quarter of the subjects described the reason for the extraction of their third molars as being due to current pain, but twice as many subjects described prevention of future problems as being the reason and the remainder gave both reasons (TABLE 4 C) . Hence, almost threequarters of the subjects were motivated to seek extraction for preventive reasons and almost half were in pain.

0–25,000

28

> 25,000–50,000

22

> 50,000–75,000

28

> 75,000–100,000

9

> 100,000

12

Family financials compared to the average: A lot better off

6

Somewhat better off

20

A little better off

20

Same

28

A little worse off

11

Somewhat worse off

9

A lot worse off

5

Parental financials compared to yours now: A lot better off

11

Somewhat better off

13

A little better off

13

Same

22

A little worse off

19

Somewhat worse off

10

A lot worse off

10

Did parents own a home?

Yes

33

No

67

Discussion

Dentists and other health care providers must be aware that many young adults have received substantial adverse experiences, been disadvantaged in multiple dimensions and are extremely vulnerable (TABLES 1–3) . Such vulnerabilities may not be outwardly obvious. They may not even be known to or understood by the patient. Some known issues may not be expressed, even when directly questioned by a health care provider. The patient may be embarrassed, afraid for themselves, afraid of or for their abuser, scared of the legal implications of a truthful answer or may not appreciate the relevance of the question to their care and well-

C D A J O U R N A L , V O L 4 8 , Nº 12

TABLE 4

Young Adult Health Issues by Percentage A. Health behaviors – do/are/have you used: Cigarettes?

20

Alcohol?

56

An alcoholic?

9

Street drugs?

41

Cocaine recently?

3

Intravenous drugs?

2

Prescription/nonprescription/ recreational drugs recently?

36

B. Behavioral health – have you had or felt: Depression or felt down?

33

Depressed?

21

Trouble with nervousness?

30

Anxious?

25

Psychological counseling?

35

C. Reason for extraction of wisdom teeth: Pain

24

Prevention

52

Both

21

being. The absolute confidentiality of this study, which did not record any personal identifiers, may have provided a secure environment for the participants to more fully describe their experiences and behaviors than in routine health care environments.

Dentists must understand that young adults have a high prevalence of unhealthy behaviors (TABLE 4 A) .

Cigarette, alcohol and street-drug use are extremely common. Nine percent described themselves as being alcoholics.

Although street-drug use was common, only a couple reported using cocaine or intravenous drugs; nonetheless, it is particularly important that these patients are identified and supported. Likewise, dentists must appreciate that young adults have a high prevalence of behavioral health issues (TABLE 4 B) . Depression, nervousness and anxiety are common, and a third had received psychological counseling. Again, these patients should be identified and supported.

In medicine, especially pediatrics, there is a newfound focus on assessing risks associated with risky behaviors and mental health-related concerns including depression. The dental office is an opportune place to assess and make appropriate referrals to services and those who could provide support. Early intervention or targeted prevention are beneficial; just as in a more tangible disease such as caries, failure to act preemptively may lead to worsening of the condition, sometimes irreversibly. Incorporation of comprehensive risk assessment into the dental curriculum would allow dental students to gain valuable practice that can have career-long application.

The dental profession must identify, understand and support the vulnerable and guide patients to appropriate intercession by our health care partners.

Dentists may not think to routinely probe for adverse childhood experiences, unhealthy behaviors or behavioral health issues beyond the questions on a routine medical history form. The questions listed in TABLES 1–4 may provide ideas and direction to dentists as they take patient histories. Although routine comprehensive screening for ACEs may be helpful in the future, it may currently be premature.7,20 Dentists can provide a list of local resources for the vulnerable and those who could benefit from support or interventions.

Treating patients with poor health behaviors presents many challenges. A dentist renders services that address the patient’s chief dental complaint and overall oral health. Although the legal scope of dental practice is narrow, a failure to address poor health behaviors falls short of comprehensive or holistic care.

Recognizing, advising and referring to an appropriate caregiver are important for the success of the current treatment,

maintenance of oral health and overall health. Treatment of a patient with disfiguring linear enamel hypoplasias or rampant caries is not just technical exercise, but necessitates understanding of the patient’s vulnerabilities and behaviors, including referral to appropriate sources of support, whether a psychologist, social worker or medical provider.

How does a dentist incorporate the process of recognition, intervention and referral? If the necessary behavioral changes are a matter such as reducing alcohol consumption, one way to implement the change would be to include the recommendation and referral in a treatment plan. This would allow the doctor to present the change in an objective nonjudgmental manner, an awareness and expectation would be recorded and the behavioral change would be framed in terms of the patient’s own presenting complaint and the overall treatment plan.

Access to care is very important when it comes to rectifying some of the extrinsic and intrinsic forces affecting young adult Angelinos. It was heartening that a majority of this patient sample were seeking third molar extraction to prevent future problems and located access to care at a dental school clinic.

However, based on this sample and census data, a high proportion of the millions of young Angelinos are living in poverty, where elective dental care is likely seen as superfluous to more basic needs. Obviously, society must do better in its 56-year-old war on poverty and in providing broader access to health care. Nonetheless, the dental profession has its own responsibility to change perceptions among young adults and to serve more lower-income patients so that the dentist is in a position to act as a conduit between the disadvantaged young adult and D ECEMBER 2 0 2 0

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a source of help. The elimination of adverse childhood experiences must be a goal for governments, policymakers and all of us as individuals.

In 2012 when this data were collected, 12% of all American families were living below the poverty-line threshold of $18,300 for a family of three. In California, 17% lived below the poverty level, and in the city of Los Angeles, 19% of the population lived below the poverty line, consistent with our sample (TABLE 3) .21 Stratification among the living wage and the impoverished expands even more when race/ethnicity are examined. At the time of data collection, in the city of Los Angeles, African Americans, Latinos and Native Americans were more than twice as likely as whites to live below the poverty-level threshold.21 In 2012, 11% of whites had an income below poverty, while 25% of African Americans, Latinos and Native Americans had incomes below the poverty level. Considering that the city of Los Angeles is comprised of only 9% African Americans and 0.2% Native Americans, these poverty-level threshold disparities are truly astonishing.21 According to 2019 census data, the percentage of the Los Angeles city population that lived below poverty level had decreased across the board, but racial disparities remained unchanged. African Americans and Latinos were still twice as likely to live below the poverty level than whites; disparities have persisted.21 The unequal impacts of race and ethnicity on patient vulnerability must not be underestimated.

Conclusions

A young adult Los Angeles dental patient population suffered abusive incidents as children, lived in nonnutritive households, witnessed or suffered from violence and were fiscally disadvantaged as children, all of which likely predispose 694 D ECEMBER

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them to adverse adult health trajectories.

This young adult population had high prevalences of unhealthy behaviors, cigarette, alcohol and street-drug use as well as high prevalences of behavioral health issues, depression, nervousness and anxiety, along with psychological counseling. Dentists need to identify, understand and include vulnerabilities created by adverse childhood experiences and unhealthful behaviors in comprehensive patient care. n ACKNOWLEDGMENTS The authors are grateful for support from NIH NIDA grant R21 DA031571. They are most appreciative of the efforts of all the faculty, staff and residents of the UCLA Oral and Maxillofacial Surgery Clinic in their gracious and invaluable support of this study.

REFERENCES 1. McEwen BS, Stellar E. Stress and the individual.

Mechanisms leading to disease. Arch Int Med 1993 Sep 27;153(18):2093–101.

2. Cohen S, Doyle WJ, Turner RB, et al. Childhood socioeconomic status and host resistance to infectious illness in adulthood. Psychosom Med Jul–Aug 2004;66(4):553–8. doi: 10.1097/01.psy.0000126200.05189.d3.

3. Karlamangla AS, Singer BH, Williams DR, et al. Impact of socioeconomic status on longitudinal accumulation of cardiovascular risk in young adults: The CARDIA Study (USA).

Soc Sci Med 2005 Mar;60(5):999–1015. doi: 10.1016/j. socscimed.2004.06.056.

4. Lehman BJ, Taylor SE, Kiefe CI, et al. Relation of childhood socioeconomic status and family environment to adult metabolic functioning in the CARDIA study. Psychosom Med Nov–Dec 2005;67(6):846–54. doi: 10.1097/01. psy.0000188443.48405.eb.

5. Danese A, McEwen BS. Adverse childhood experiences, allostasis, allostatic load and age-related disease. Physiol Behav 2012 Apr 12;106(1):29–39. doi: 10.1016/j. physbeh.2011.08.019. Epub 2011 Aug 25.

6. Widom CS, Horan J, Brzustowicz L. Childhood maltreatment predicts allostatic load in adulthood. Child Abuse Negl 2015 Sep;47:59–69. doi: 10.1016/j.chiabu.2015.01.016. Epub 2015 Feb 18.

7. Karatekin C. Adverse childhood experiences (ACEs), stress and mental health in college students. Stress Health 2018 Feb;34(1):36–45. doi: 10.1002/smi.2761. Epub 2017 May 16.

8. Scheuer S, Wiggert N, Bruckl TM, et al. Childhood abuse and depression in adulthood: The mediating role of allostatic load. Psychoneuroendocrinology 2018:94:134–42. doi. org/10.1016/j.psyneuen.2018.04.020.

9. Lee RD, Chen J. Adverse childhood experiences, mental health and excessive alcohol use: Examination of race/ethnicity and sex differences. Child Abuse Negl 2017 Jul;69:40–48. doi: 10.1016/j.chiabu.2017.04.004. Epub 2017 Apr 28.

10. Wiehn J, Hornberg C, Fischer F. How adverse childhood

experiences relate to single and multiple health risk behaviours in German public university students: A cross-sectional analysis.

BMC Public Health 2018 Aug 13;18(1):1005. doi: 10.1186/ s12889-018-5926–3.

11. Chandler GE, Roberts SJ, Chiodo L. Resilience intervention for young adults with adverse childhood experiences. J Am Psychiatr Nurses Assoc Nov–Dec 2015;21(6):406–16. doi: 10.1177/1078390315620609.

12. Merrick MT, Ford DC, Ports KA, et al. Vital signs: Estimated proportion of adult health problems attributable to adverse childhood experiences and implications for prevention — 25 states, 2015–2017. Morb Mortal Wkly Rep 2019:68(44):999–1005. doi: dx.doi.org/10.15585/mmwr. mm6844e1external icon.

13. Bright MA, Alford SM, Hinojosa MS, et al. Adverse childhood experiences and dental health in children and adolescents. Community Dent Oral Epidemiol 2015 Jun;43(3):193–9. doi: 10.1111/cdoe.12137. Epub 2014 Nov 21.

14. Crouch E, Radcliff E, Nelson J, et al. The experience of adverse childhood experiences and dental care in childhood.

Community Dent Oral Epidemiol 2018 Oct;46(5):442–448. doi: 10.1111/cdoe.12389. Epub 2018 Jun 6.

15. Rose JC, Armelagos GJ, Lallo JW. Histological enamel indicator of childhood stress in prehistoric skeletal samples.

Am J Phys Anthropol 1978 Nov;49(4):511–6. doi: 10.1002/ ajpa.1330490411.

16. Sharma R, Lohiya S, Rajabi P, et al. Prevalence of enamel markings on third molars. J Calif Dent Assoc 2016 Aug;44(8):499–505.

17. Dube SR, Felitti VJ, Dong M, et al. Childhood abuse, neglect and household dysfunction and the risk of illicit drug use: The adverse childhood experiences study. Pediatrics 2003 Mar;111(3):564–72. doi: 10.1542/peds.111.3.564.

18. Felitti VJ, Anda RF, Nordenberg D, et al. Relationship of childhood abuse and household dysfunction to many of the leading causes of death in adults: The Adverse Childhood Experiences (ACE) Study. Am J Prev Med 1998 May;14(4):245–58. doi: 10.1016/s0749-3797(98)00017-8.

19. Kuh D, Hardy R, Langenberg C, et al. Mortality in adults aged 26–54 years related to socioeconomic conditions in childhood and adulthood: Postwar birth cohort study. BMJ 2002 Nov 9;325(7372):1076–1080. doi: 10.1136/ bmj.325.7372.1076.

20. Finkelhor D. Screening for adverse childhood experiences (ACEs): Cautions and suggestions. Child Abuse Negl 2018 Nov;85:174–179. doi: 10.1016/j.chiabu.2017.07.016.

Epub 2017 Aug 4.

21. United States Census Bureau. Poverty Status in the Past 12 Months of Families. Survey/Program: American Community Survey. TableID: S1702. ACS 5-Year Estimates Subject Tables. data.census.gov/cedsci/table?q=poverty%20california%20 &g=0400000US06&hidePreview=false&tid=ACSST1Y2012.

S1702&t=Poverty&vintage=2018&layer=VT_2018_040_00_ PP_D1&cid=S1701_C01_001E. Accessed Aug. 8, 2020.

THE CORRESPONDING AUTHOR, Shane N. White, BDentSc, MS, MA, PhD, can be reached at snwhite@dentistry.ucla.edu.

CARROLL &COMPANY 4407 SAN MATEO GP Exceptional 5-operatory San Mateo practice in popular health provider neighborhood generating significant daily business draw. Beautiful 2,200 sq. ft. seller-owned facility, handsomely ING GR $1.4M, average overhead equipped to highest standards.DAverage N 61%. Seasoned and loyal staff. Seller willing to help for a smooth PE transition.

4366 SONOMA COUNTY Fabulous practice and location within one of the North Bay’s gems of a town. Classically beautiful and well appointed office with 4 ops in 1,425 sq. ft. Fantastic storefront location on a well traveled road, walking distance to the pedestrian-friendly center of downtown. 900+ active patients, all fee-for-service. Not a Delta Dental Premier Provider. 4 doctor days/week and 4 hygiene days/week. Last two years average GR $865K with average adj. net of $407K. Seller will help for smooth transition. Asking $450K. 4420 OAKLAND GP Seller retiring, offering 35 years of goodwill.

Quaint Oakland location near the Grand Lake District. Charming and well appointed, this 4 op office has great visibility on a busy thoroughfare. Loyal staff and LDstable patient base with 2,160 active SO $988K with an adjusted net of $385K. 4 patients. Average GR over doctor days & 8 hygiene days per week with an emphasis on restorative and preventative care. Hygiene department generates over 50% of production. Terrific upside potential for a buyer. Asking $710K. 4394 SANTA CRUZ GP Retiring seller offering 33+ years of goodwill in stunning 1,534 sq. ft. facility with 4 fully-equipped ops. Pristine leasehold improvements/gorgeous cabinetry make this a must-see! Prime corner location with dedicated parking lot, situated in one of the most desirable areas of Santa Cruz, close to shoreline and tourist attractions. 2019 GR $887K with adj. net of $353K. 1,500+ active patients with average of 19 new patients/month. Seller works 3+ days/week with 5+ days of hygiene.

Asking $729K. 4405 LOS GATOS GP 30 year practice in beautiful modern, office and desireable location with two 5 year options to extend lease. $1.2M LD average gross receipts with 56% SO average overhead. Asking $986K. 4422 SOUTH BAY GP 30+ year practice in the heart of Silicon Valley in a gorgeous modern 2,680 sq. ft. office with 7 fully-equipped ops. Digital xray and Panorex, well-maintaned and upgraded equipment. 5.5 doctor days per week, and 8 days of hygiene per week. Loyal & stable patient base. Located in highyly desirable area with approximately 2,000 active patients. $2.2M average Gross Receipts. Asking $1,629,000.

4406 PALO ALTO GP Offering 50+ years of goodwill in growing practice close to Stanford University. Great Palo Alto location with incredible visibility. 7 ops in recently remodeled 2,152 sq. ft. office. 1,400+ active patients. Pre-Covid hygiene schedule LD running at 8 days/week. 2019 GR SOServices provided are typical of practice $1.5M+ with adj. net of $518K. with emphasis on Restorative dentistry. Asking $1,185,000.

4399 SAN JOSE GP Gorgeous office in pristine condition located on a well-traveled thoroughfare withO incredible views of the eastern foothills.

LD Approx. 2,000 active patientsSwith 12-13 new patients per month.

Approx. 8 hygiene days/week. Average GR $1.3M. Asking $977K.

carroll.company

dental@carrollandco.info

C D A J O U R N A L , V O L 4 8 , Nº 12

“Matching the Right Dentist to the Right Practice”

4418 PALO ALTO GP Palo Alto practice offering 75 years of goodwill.

Located in highly desirable neighborhood, just a short walk from downtown. Clean, crisp, charming, and well appointed 3 op office with lots of natural light. Approximately 750-800 active patients (all truly feefor-service). 2020 annualized GR $1M+ with adjusted net of $470K+. 3 doctor days and 3 hygiene days per week with upside potential.

Emphasis on Restorative dentistry. Asking $670K.

4392 SAN JOSE GP Offering 40+ years of goodwill. Excellent location in

beautiful bldg on well-traveled thoroughfare. 6+ ops in 1,882 sq. ft. Lots of natural light with views of the eastern foothills. 1,800 active patients. 8 hygiene days/wk. Average GR $900K with adj. net of $295K. Terrific upside potential. Asking $558K. Owners will help for smooth transition.

4415 WATSONVILLE GP & BLDG Offering 35 yrs of goodwill in the growing coastal community of Watsonville. Charming and renovated 4 op office in 1,320 sq. ft. Approx.

450 active patients with an average of 10 new patients/mo. Incredible LD management systems in place. Endo, Oral upside potential with excellent SO Surgery and all Ortho procedures referred out. Last 2 yrs average Gross Receipts $275K with average adj net of $159K on just 1.5 doctor days/ week. Bldg condo is also available for purchase. Asking price $175K for practice and $300K for condo.

4416 SF FACILITY Located on Lyon street, closest major cross street Lombard. 1,600 sq. ft. turn-key dental facility. This street level space has over $350,000 of improvements completed for professional use and ready to go as a dental office. Asking $35K. 4421 SAN BRUNO FACILITY 670 square foot 3 op facility with a reception area, a private office, a lab area, a sterilization area and a storage area. Located in prime location in a high-traffic area. Asking $40K. 4362 MARIN COUNTY GP 36 years of goodwill, Seller-owned 1,550 square foot facility with 5 fully-equipped ops. Prime position in charming town; desirable area known for temperate weather, easy, outdoor living and natural beauty. No Delta Premier patients. Excellent reputation and word-of-mouth referrals. Retiring seller will help for smooth transition. Average Gross Receipts last 2 yrs is $450K. Asking $248K for the practice. Bldg condo is available for purchase.

4375 LOS GATOS DENTAL FACILITY Unique opportunity in highly desirable area! Seller offering two full suites of state-of-the-art equipment and modern, 2-operatory facility including furniture, fixtures and leasehold assets in medical office building adjacent to Los Gatos Community Hospital. Asking $250K.

Mike Carroll

Pamela Carroll-Gardiner

Mary McEvoy Carroll

CalRE# - 00777682

(650) 362-7004

(650) 362-7007 D ECEMBER 2 0 2 0

695

Specialists in the Sale and Appraisal of Dental Practices

Serving California Dentists since 1966 How much is your practice worth??

PPS extends Heartfelt Wishes to You and Your Family for Peace, Love and Gratitude during this Holiday Season NORTHERN CALIFORNIA (415) 899-8580 – (800) 422-2818 Raymond and Edna Irving Ray@PPSsellsDDS.com www.PPSsellsDDS.com

Practices Wanted

SOUTHERN CALIFORNIA

(714) 832-0230 – (800) 695-2732 Thomas Fitterer and Dean George PPSincnet@aol.com www.PPSDental.com

California DRE License 1422122

California DRE License 324962

6185 CHICO – SACRAMENTO’S NORTH VALLEY Highly regarded as evidenced by 6-days of Hygiene. Revenues average $470,000 per year.

4-ops, attractive setting. Retain the 2-Hygienists and the patients shall continue.

6184 SAN FRANCISCO’S EAST BAY – LAMORINDA AREA Unique opportunity to practice in high income area. Revenues have averaged $390,000 a year on part-time basis. Highly regarded. 3-days of Hygiene.

Excellent candidate to go out-of-network.

6183 REDWOOD CITY Collected $730,000 in 2019. 4-day Hygiene schedule. 5-ops, paperless, digital Pano. Ideal for nearby Dentist seeking larger facility, or perfect acquisition by nearby Dentist who vertically integrates the goodwill into their office. Seller shall become the Pied Piper by continuing in an association for up to a year for transition.

6182 NAPA / SOLANO COUNTY Collections last three years have averaged $1,000,000. 2019’s Available Profits totaled $374,000. Current annualized performance trending $1.1 Million. All specialty work referred.

4-Hygiene days. Paperless charting. Well-designed office. Great location.

Great staff. Perfect platform to provide additional services and immediately improve the performance.

6181 CARMEL VALLEY’S “THE VILLAGE” - START-UP 48-year history providing dental care at this $1 +Million location. Equipped & furnished 4-ops. Only practice in Village. Next practice 10-minutes away.

Landlord is daughter of original dentist who worked as Hygienist and later Manager. Closed April. Purchase equipment & furnishings; enter into Lease, open doors, patients return. Operate out-of-network Full Price $19,750.

6180 SAN FRANCISCO’S LOWER PACIFIC HEIGHTS Collected $796,500 in 2019 with Available Profits of $391,500 in 2019 with 9-weeks off. 2020 trending collections of $810,000 with Available Profits of $425,000.

Fees shall continue! $258,000 spent in décor, delivery systems & technology.

Average adjusted gross income per household in this zip code is $286,800.

6177 MONTEREY BAY AREA - SALINAS Exceptional opportunity to create a full-service practice. Under-performing practice collected $935,000 in 2019. Current annualization is $1+ Million in collections. 7-days of Hygiene. Has averaged 130-new patients/year the last 2-years. Housed in beautiful 6-op building. Free-standing condo included in package sale.

Perfect platform to bring in specialists.

6176 SANTA CRUZ Delta PPO practice seeks Successor skilled in implants. Last 2-years averaged $1,180,000 in Collections and $735,000 in Available Profits. $480,000 invested in technology. 4-days of Hygiene. Full Price $650,000. Compare to similar nearby "For Sale" practice asking $1,350,000 with another brokerage.

6174 HUMBOLDT COUNTY’S UNIVERSITY COMMUNITY – ARCATA Best location, great foundation. Owner voted “Best Dentist” in 2020 Reader’s Poll. Owner works 3-day week by choice. 2019 collected $360,000. Receives new patient calls constantly, and which are turned away.

Practice will be full-time by simply working 5-days if that is your intent. Full Price $30,000.

6172 WALNUT CREEK – OUT-OF-NETWORK 2019 collected $850,000 with Profits of $430,000. 4-days of Hygiene. Great Downtown location. Seller shall work-back to assist in transition.

6171 SANTA ROSA Great DNA in long-established practice. Strong patient foundation per 6+ day Hygiene Schedule. 2019 collected $990,000 with Available Profits of $338,000. Great Team. 2020 is doing extremely well.

6165 ROSEVILLE ORTHO – OUT-OF-NETWORK Stanford Ranch. $455,000 invested in build-out, furnishings, computers and equipment. 3-chair Bay. Digital Pan with Ceph. Averages 3 New Patients per month. Full Price $125,000.

Great Time to Think about Change. Not doing the Type of Dentistry You would like to do? Look to Tom Fitterer & PPS to plan your future.

D

SOL

BEAUMONT/ BANNING 26,000 new homes planned. 2 retiring Dentists; buy one or both. 2,000 sq.ft. condo. Hygiene booked. Live in Palm Springs or Redlands.

CULVER CITY Grossed $853,000 in 2019. Referred 55 Endo; 28 Perio; 60 OS & Implant cases last year. Loyal Patients.

EAST LOS ANGELES Long established. 2 days grossing near $200,000 cash. Full Price $150,000.

GP INNOVATOR Grossing $1.7 Million; Nets $1+ Million. Unusual opportunity. Very Conservative, Refers out a lot.

HEMET Includes apt & dental building. Long established. Beautiful 5 ops.

Open part-time. Will do $500,000.

KOREAN DENTIST SOUGHT FOR 2 YEAR APPENTICESHIP Learn while working. Implants, OS. Airplane provided. Great pay while learning to produce $2 Million/year by Senior Korean Maestro. Call Tom Fitterer.

KOREATOWN Low overhead. No Denti-Cal. PPO & Cash. Grossing $250,000. Full Price $150,000.

LA HABRA Huge shopping Center. 6 Ops. Seller will work back.

LA MIRADA $5,000/mth HMO check. Collects $569,000. 7 ops; 2,700 sq.ft.; rent $2,800. Entire 10,000 sq.ft. building For Sale. No vacancies.

LAGUNA NIGUEL Hi visibility shopping center. 3-ops Husband / Wife work part-time. Grossing $414,000. Needs more Doctor days.

LAGUNA WOODS Did $1 Million in 2019, will do $1+ Million. Shopping plaza completed $6 Million remodel. New tenants will be patient magnets. $5,000/mth HMO. 4-ops, rent $3,831. Successor double shifts with present crew. Near Leisure World and affluent new growth. Implant DDS will net 500k working 3 days.

ORANGE COUNTY Merger candidate. Near Chapman and Tustin Streets. 4 ops. Merge or grow. PT owner grossing $400,000.

PALM DESERT Hi identity on Highway 111. 2 days grosses $300,000. Full Price $150,000.

PALM SPRINGS Grossing $1.5 Million. Specialists gross $300,000. Pay Owner $150,000. Shall pay rent and practice loan. 8-ops. Full Price $875,000.

PASADENA Busy shopping center near large medical center. Grossing near $1 Million. If your lease is up, merge.

PASADENA Husband DDS / Wife Hygienist have small practice to merge.

Lost lease.

PICO RIVERA Paramount and Whittier. High visibility shopping center. 4 ops. Grossing $200,000. $4,000/month HMO check.

REDLANDS Near City Hall. Rent $1,400. No patients but ready to go. 3 ops plumbed 2 equipped. Full Price $50,000.

RIVERSIDE 215 FREEWAY High visibility real estate. Make Implant & Family Dental Center. Riverside or Colton dentist should move here. 250,000 autos pass daily.

THOUSAND OAKS Grossing $1 Million. One Partner willing to work back 3-to-5 years. 5-ops. Refers lots Specialists.

TORRANCE HMO check of $5,000/month. 70,000+ autos pass popular intersection per day. Entrance to Palos Verde. 6 ops in hi visibility dental office. Gorgeous. Grossing $700,000+.

UPLAND 3 ops. Grossing $330,000. 3 days Hygiene. 5 Star Yelp Reviews.

Tribute

C D A J O U R N A L , V O L 4 8 , Nº 12

A Tribute to Dr. Bob When more than a year ago we began planning a Journal issue commemorating CDA’s 150th anniversary, we obviously had no idea what was to come in 2020. A looming pandemic was not on our radar — or the world’s radar, for that matter.

We knew what we wanted to include in the anniversary issue, such as a timeline of the history of organized dentistry in California and a look at the future of our profession. But we also wanted to honor Dr. Robert “Bob” Horsman, my good friend and fellow dentist who wrote an opinion column for the Journal for almost 40 years and who turned 100 years young this year. Dr. Bob, as his column was titled, retired from writing in 2014 but occasionally sent new columns until 2015. So, it was hard to imagine a CDA anniversary issue that didn’t include him.

Ultimately, as COVID-19 emerged with all the challenges that came with it, we decided to run a tribute to Dr. Bob in another issue later in the year, after the 150th anniversary issue was published in March, so that we could give him the attention he deserves. I think it’s appropriate that we end 2020 now with some laughs courtesy of Dr. Bob — we could all use some humor right now, I’m sure. Aside from his often-hilarious takes on dentistry, Dr. Bob also provides valuable insight into the important issues and challenges dentists have faced in the past — some of which we still deal with today. His columns — written in first person and often brutally honest — are a reflection of late 20th and early 21st century dentistry from a boots-on-the-ground perspective.

We are eternally grateful to have had the opportunity to share this view with our readers all these years. So as a final nod to CDA’s 150th anniversary, to a historic 2020 and to the many thoughts and words Dr. Bob contributed to the Journal, the editorial team chose some favorite Dr. Bob quotes from his many columns. Some are funny, others insightful, but all are pure Dr. Bob. Thank you, Dr. Bob, for your friendship and your writing.

And happy anniversary CDA. It’s been a long and interesting 150th year. Here’s to healthier horizons in 2021!

— Kerry K. Carney, DDS, CDE

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1995

American history is replete with references to the “Minute Men,” guys who were faster by at least 59 minutes than the “Man of the Hour.”

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Because folks back then didn’t have an anchorperson, two stooges and a weatherfool on a choice of 121 channels to gorge them with input, they had ample time to play whist and dance the Bunny Hug at early discos until their celluloid collars melted.

1996

Lose the use of your hands and what’s left for you? — nothing but the lecture circuit, a scam that’s already been thought of by hundreds of your colleagues to the point where in a few years there will be nobody left to do the actual work; they’re all out lecturing to each other.

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I take another slug of Swiss Mocha, straight, no creamer, wet my finger to pick up the last crumbs of the prune Danish I had for breakfast and wonder again if I’m doing the right thing staying aloof from the PPO wars.

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The Tooth Fairy, dentistry’s mostcherished myth next to the spiritual belief held by some dentists that if you tell patients to floss, they will, is still alive and flourishing.

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There’s no use in denying that there are patients who, for one reason or another, have the ability to instantly create in us everything from migraines to bleeding ulcers just by having their names appear on the appointment book.

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Many’s the day when, after a disheartening round of resurrecting bombed out molars, I’ve muttered to nobody in particular, “Well, that’s it! I’m going to get a job with Proctor & Gamble writing ad copy for Crest.” But I never do; the payment’s due on the intraoral camera.

1997

When I was a naval cadet returning from liberty, it was the duty officer’s job to walk slowly down the line of disheveled cadets, sniffing each lad’s breath for telltale signs of alcohol, then dealing out suitable punishment for infractions of the rules. It was there that I learned that the efficacy of breath mints is overrated. I never envied him his job and can only assume that this duty is performed by specially trained dogs in today’s modern Navy.

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The point is, this building has been declared an unofficial designated fivestar AAA rest stop for all pigeons in the Southwest United States, particularly those with severe gastrointestinal disorders.

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I will refer whenever possible those patients who were put on earth specifically to torment me personally and who have completed all the human development they ever plan to do by age seven, including those who watch “The Price Is Right” and “The Newlywed Game” on purpose.

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Your little recall card, unless it is stapled to a $20 bill, is going the way of the rest of the junk mail. It doesn’t matter that the little molar on the front is brightly bleating, “Your six months are up, time for your checkup and cleaning.” He’s going down with the mattress ads, the specials on eggplant and the Sale of the Century at Manny’s House of Fabric Remnants.

1998

Dentistry’s main claim to pioneering was when OSHA and “60 Minutes” singled us out as potential generators of a host of bad things.

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A notice posted on the reception room door advising would-be hit men that all we’ve got is 500 patient records with outstanding balances and if you want to take a crack at collecting these accounts, good luck! is probably not going to suffice.

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Without the people who unselfishly devote their professional lives to pushing the envelope of R&D — research and development to we laypeople — we’d still be using one-fluted burs made from pot metal, trying to cope with nondesigner toothbrush handles and denying the public the benefits of carbamide peroxide.

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Born of the same wisdom that ordered the Swine Flu fiasco, the conclusion was reached that those missing patients would appear if only there were more dentists.

This would result in a dual benefit — lower the cost of dental treatment through competition while making it available to the missing 50% via appealing ads placed in the Yellow Pages and colorful fliers placed beneath windshield wipers.

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I am now comfortably in that period that lies beyond Geezer Plus; I am a Super Geezer, formally called an “old-timer.” If there is any geriatric nomenclature above that, it falls into the field of paleontology, and I don’t want to know about it.

1999

It is important that the public can readily differentiate dentists from other professional

C D A J O U R N A L , V O L 4 8 , Nº 12

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persons such as those employed in the service of the Good Humor Company.

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When the first man discovered sugar cane tasted better than bamboo, civilization started its long downhill slide that made the advent of dentists inevitable.

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When people first meet me, they often comment, “Bob, you’re much older than I thought!” To which I reply, “I owe it all to dentistry. Before I became a dentist, I was half this age and looked a lot younger than that.”

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Why we have been so lax in this department is a puzzlement. Looking back in the dental literature and advertising of 20 years ago, references to bad breath and its deleterious effect on the nation’s social structure and the ensuing depletion of the ozone layer are conspicuously absent.

2000 My inflatable punching dummy came with a complete kit of interchangeable visages, such as lab faces, staff faces, IRS and OSHA faces and a nice selection of generic patient faces.

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Actuarially speaking, the trauma of the first bridge shortened every dental student’s life by 10 years and reduced his skeletal being to the consistency of jellied consommé. Even today, the memory of it is a moment of nostalgia laced with masochism.

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An aptitude test taken at my high school sometime early in the last century indicated clearly that my particular talents uniquely qualified me for a position either demonstrating Amway’s personal hygiene products or as a supernumerary census taker.

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As dentists, we can immediately see the advantage of combining human DNA with, say, that of a shark. Of all our various organs, none suffer such a deficit in engineering know-how as the human dentition.

2001 The appointment is the basic unit of my practice. You may procure one by the telephone; you may procure one by the personal appearance; you may procure one by the proxy. Once made, understand this: No contract is more sacred; not that of the marriage, not that of the court summons. I say to you, do not break it, but leave it as it is. Unless declared legally dead, dishonor not the appointment, nor tarry more than four minutes beyond the time of obligation.

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Fruit flies with the altered gene who normally would have been on assisted care in rest homes were seen out skateboarding.

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One hundred thousand or so dentists have fruitlessly tried to put the sentence “The square of the length of the hypotenuse of a right triangle equals the sum of the squares of the lengths of the other two sides” out of their minds. Not once during a 40-year practice has this ever come up, either in a clinical or social setting.

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Leeches may be on the verge of a comeback more successful than John Travolta’s.

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Intervention on behalf of the beleaguered mouse population by the SPCA, the ACLU and other alphabet-heavy entities has made news coming from mousedom scarce anyway.

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We’ve never had any complaints about our office, in fact we had one lady state emphatically, “This place smells just like a dentist’s office,” which we took as a highest form of compliment.

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More and more people are being seen by fewer and fewer health care providers until in the very near future, everybody will be seen by nobody.

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The culmination of all the great minds of dentistry since the beginning of time — the fruition of dental intellect — has peaked with some pathetic technique to make teeth whiter in one hour. This is our most impressive triumph since the introduction of flavored floss.

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The placebo effect is alive and well and not nearly so messy as real surgery.

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The surgeon general should require warning labels to be placed on these products stating that the contents will go directly to the hips.

2003 Early on, many general practitioners, realizing that there was just too much to know about human dentition and the medical ramifications thereof, wisely restricted their practices to specialized areas. This allowed them to know more and more about less and less and drive a better make of car.

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You will recall the famous “Undercover Cat Sting” of 1988 when animal groomer Cindy Collins suffered arrest and detention for performing a prophy on an

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undercover kitty sent in by the Department of Consumer Affairs to discourage this sort of thing by non-veterinarians.

Younger actors such as Frank Sinatra were quick to recognize the advantage of capping all their upper anterior teeth with porcelain the shade of an upright Kelvinator, giving them the appearance of a youth just getting used to wearing long pants.

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Even into the late Renaissance period, this belief in worms as the causative agent of dental caries was firmly held. Many reputable and prominent authorities of the day supported the theory in spite of the worms’ vigorous denial that they had anything to with the problem. “Okay,” they admitted, “we may have messed up some produce and littered the sidewalks after a rain, sure, but living in a hollow tooth? Get real!”

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Years ago, two patients genetically programmed to hate each other on sight, met quite by accident in our reception room. When this encounter left the area frigid enough in which to hang meat, we realized privacy had become our top priority next to departing the premises at 5 p.m.

2004 Statistics are more pliable than facts and are, in fact, like witnesses; you can always get them to testify for either side.

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For many years an unholy alliance between the dental schools, the State Board of Dental Examiners and the International Gold Foil Cartel mandated that candidates for licensure demonstrate that they could, by God, pound in a gold foil a sadistic examiner couldn’t flip out after repeated tries.

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Teeth are the most durable parts of the human body, with the possible exception of crow’s feet and love handles.

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2005 The one-on-one time with your personal health provider is variously estimated to be between 45 seconds and five minutes, comparable to the quality time received at Albertson’s checkout line.

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Is there a practitioner among us who doesn’t believe 28 teeth would have been plenty?

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There is an opinion shared by many patients that if a dentist is to be considered an authority on any given procedure, he should have undergone that procedure himself. A reasonable expectation, I suppose, but one that brain surgeons and I do not share.

2007 In less time than it took to build a single mile of the Great Wall of China, I had the amalgam mixed, packed, carved and ball-burnished, much to the interest of my assistant who clucked dutifully at each procedure.

---

Their [dentists’] work has been compared to that of repairing a fine watch while somebody spits on their hands, painting the Sistine Chapel wearing boxing gloves or solving Rubik’s Cube blindfolded in a fetal position in less than 45 seconds.

Dentists aren’t really all that fond of treating one another, as a matter of fact.

To be known as a “dentist’s dentist” might privately bolster your self-esteem, but at what price? The stress is maximized, the fee minimized.

---

Having been an old person myself for more than 25 years, I feel obliged to point out that, in spite of impaired body parts and integument the texture of Egyptian papyrus, most of us retain an enduring sense of wonder.

2009 The following is an attempt to increase your understanding and vocabulary to the point where you can hold your head high and proclaim to the world that you’re not as dumb as you look: Resicrud (RESI-crud) Little bits of cured resin fused to the end of your curing light, which you are afraid to scrape off for fear of altering the optical properties of the light.

Hideybur (HIDEE-bur) n. One of several locations in the innards of your chair where a fortune in lost diamonds lies at this moment. There is another in the Utrap under your sink.

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I did actually retire once. Grudgingly, it became clear at the end of my first summer as a busboy at Knott’s Berry Farm that, career-wise, I had probably peaked. My

C D A J O U R N A L , V O L 4 8 , Nº 12

white uniform was lavishly decorated with boysenberry stains; my every pore redolent with the cloying scent of fried chicken fat. Reluctantly, I tendered my resignation. It was obvious that several years of obsequious toadying would be required before rising above my 40-centsper-hour position to be CEO of the place.

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A press release at the conclusion of the meeting revealed to the world that the one inescapable fact on which all attendees agreed: Water is wet.

2010

2011

The only remnant of my dental education that remains valid today is the application of the patient’s bib to avoid ponytail or beard entanglements, and I don’t even get to do that myself.

Ostensibly to further education and promote camaraderie amongst dentists, the real reason that dental societies continue to flourish is that they provide a forum to exchange mutual fears. There is nothing that allays the worries of a fellow practitioner as much as discovering he is not alone.

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To those who demand even more from their water, please note it is “thermal friendly,” i.e., can be made either hot or cold and comes already wet.

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Citizens of my age (Pleistocene) regret not saving any energy while they still had some, having squandered it recklessly on making a living.

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Dentists, for the most part, have found muzzling facial hair behind a facemask to be not time effective and with a comfort level on a par with wearing socks made of steel wool.

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Certainly, there are secrets I don’t want my patients to know. My stash of Pepperidge Farm Milano cookies in the bottom of my desk drawer with 26 grams of sugar in each morsel, for example, or that the toothpaste we really, really like is whatever the company rep leaves us as samples.

---

Gum surgery appeals only to masochists.

Salesmen for cemetery plots have an easier pitch.

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We have never seen a picture of President Washington with his mouth open, a presidential condition not noted since the departure of Calvin Coolidge in 1929.

2012

A popular shortened version of the nap is the “doze.” A doze may be voluntary wherein you try to grab the traditional 40 winks while pretending to be awake, leaving your eyes narrowed to slits and rolling your eyeballs back up in their sockets. This generally fools no one. If caught, it will be necessary to vigorously deny you were dozing, but that you

were deeply pondering the Afghanistan problem and you resent having your train of thought interrupted by some smirking busybody. Again, nobody buys this.

---

From now on, when I prescribe the use of dental floss, the patient is going to have to sign an affidavit stating he will not use it for busting out of the slammer or any other illegal purposes.

He’s also going to sign a waiver holding me personally blameless for having suggested its use. I have no idea what we’ll do about the toothbrushes.

2013 Dental historians delight in pointing out that there is nothing new under the sun.

They may be right, but when future researchers dig up one of my patients who may be wearing one of my own oral masterpieces, I hope the descendants of this cadaver will be unable to trace it back to me, even with the help of French researchers. I’ve left instructions in my will for my own descendants, when pressed, to deny everything. Tell ‘em the blacksmith did it.

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The point is nobody wants to acknowledge the fact that we cannot kill bacteria — maybe stun them momentarily, but that just makes them furious. They are worse than ants. Ants at least travel for the most part in a straight line as if they had some important place to go, making them easier to whack.

But bacteria, knowing they can’t be seen by the naked eye, just hang around like juvenile delinquents on a Saturday night.

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Paradoxically, just 20 years ago, the two dental societies representing the northern and southern dental communities decided that individually they had more foibles than Aesop. So, for their mutual benefit, they would join and form the California Dental

Association. Actually, there had always been a CDA, this being the name the northern contingent had always had. The Southerners whacked the “S” off their name to make it unanimous.

---

Like water seeking its highest level, pants on a geezer seek their lowest within 15 minutes of donning them.

roll. I look across to her every morning.

She sleeps, mouth slightly open, her silver hair fanned out on her pillow and I reach over to softly touch the back of her hand where the ring I gave her 66 years ago still shines. That fall, that November when I was 27, it was a very good year. n Read Dr. Bob’s full columns in the CDA Journal archives at cda.org/journal.

2014 Now at 93, my wife and I are in the autumn — or arguably — the winter of our years. Like vintage wine from fine oaken casks, I offer poetically. Her eyes

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Essay

C D A J O U R N A L , V O L 4 8 , Nº 12

A Dental Visit Better Than Disneyland Dan Jenkins, DDS, CDE

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t was a 45-minute drive, according to the “lady in the box” giving me directions to meet the dentist who wrote the words of wisdom many of us were privileged to read. As the “lady” was telling me to get off the freeway and then turn right at the next nonlabeled road, I was reminiscing about so many of this dentist’s sayings that helped so many other dentists just get through a day with a smile on their faces while they repaired the smiles of their patients. This dentist was not a clinician teaching dentists how to do the ultimate MOD amalgam or the best way to remove a deciduous central incisor from a 5-year-old. However, I did learn later that he once taught at a dental school in Australia.

I finally arrived at the compound of this famously reclusive dentist and sneaked through the gate after a car went through.

When the door opened, a young lady about my age escorted me to the chamber where I met, for my first time, none other than Dr. Robert E. Horseman (also known as Dr. Bob), who wrote an opinion column for the Journal for more than 30 years. In 1999 the Journal celebrated Dr. Bob’s 20th year as a writer of the back-page humor we all grew to love. The June 1999 issue was dedicated to Dr. Bob and many kind words were written about him. Dr. Bob “retired” from contributing to the Journal in 2014, completing 35 years of writing entertaining articles full of wisdom. (The Journal continued for several years to publish “reruns” of his columns.) All of Dr. Bob’s work for the Journal was voluntary; he received no residuals.

Once when CDA Editor-in-Chief Kerry Carney and I did a skit about Dr. Bob, I was privileged to actually talk to him on the phone, as I was filling in for him in an outstanding presentation of wit and wisdom that Dr. Bob had written himself. But what many of us did not realize is that Dr. Bob is shy and shuns the spotlight. So my in-person visit with him was rare and exciting.

You may wonder why I am writing about Dr. Bob now — he’s already retired from dentistry and dental journalism. Well, 2020 has been a historic year for all of us in dentistry, and it is a very historic year for Dr. Bob as well. He was born in 1920 and is now 100 years old! It is only fitting that the Journal and its readers remember or become aware of Dr. Bob’s contributions to dental journalism — especially in the entertainment department. There is no substitute for his style and wit.

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essay C D A J O U R N A L , V O L 4 8 , Nº 12

I had a long list of questions for my interview with Dr. Bob. When anyone found out I was going to interview him, they would suggest questions. I had a pot full of questions.

I was curious if he had done any writing for other publications after retiring from his CDA column. He admitted he did write some short articles for a local senior newsletter but admitted he “somehow still referenced dentistry” in them.

Every dentist has a story to tell about how or why they became a dentist — and so does Dr. Bob. His father wanted to be a dentist but was not financially able. Dr. Bob wanted to be an engineer. His father had their family dentist talk to Dr. Bob and told him “all the benefits of being a dentist, including having Wednesdays off for golf.” Dr. Bob was convinced and graduated from dental school in 1943. He signed up with the Naval Reserves when in dental school, and after graduation, he worked as an associate dentist in Whittier while awaiting his orders.

He received his orders and while waiting assignment, he struck up a friendship with another officer who was a U.S. Marine fighter pilot. Dr. Bob had taken flying lessons while in dental school and was easily convinced to go to flight school instead of filling or extracting recruits’ teeth in San Diego. He said he went with the Marines instead of the Navy because he didn’t like the idea of flying off and landing on an aircraft carrier. He didn’t know that the Marines also took off and landed on aircraft carriers.

Eventually, he was aboard an aircraft carrier headed to the Western Pacific to fight in the war. Before he made it to Hawaii, the war ended. Dr. Bob decided not to make a career of the 704 D ECEMBER

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service and returned to his hometown of Whittier. He found a small space and opened his practice furnished with one chair, an X-ray machine with a “BIG” head and a white ivory cabinet.

He remembers, though not too fondly, of taking compound impressions.

I asked Dr. Bob what was his favorite year in his 100 years. He, without hesitation, said, “1947.”

“Why?” I asked. (I was born that year and was on the edge of my seat to find out why it was his favorite.)

During the summer of that year, he

It is only fitting that the Journal and its readers remember Dr. Bob’s contributions to dental journalism — especially in the entertainment department. met his wife and fell “madly in love,” he said, and she made his life the best it could be from that moment on. He and Claire married that November.

Australia was calling to Dr. Bob, so he sold his practice and moved there — although I did not detect an Aussie accent. He practiced in Australia and was soon asked to become an instructor at a dental school. His son Jeffrey completed dental school and married in Australia by the time Dr. Bob and Claire decided to return to the states. To Dr. Bob’s surprise, the dentist who purchased his practice in Whittier had left town.

Dr. Bob saw the opportunity and started his practice back up, and it did very well in a very short time. He eventually found a larger space in a “nicer” neighborhood and relocated again.

I wondered what historic events Dr. Bob might have considered of significance to him during his lifetime. He said that “the theory of worms in decay” was significant — though incorrect. I asked him if he remembered any family members or friends talking about the Spanish Flu pandemic of 1918, and he did not recall anyone mentioning it.

We agreed people will probably talk about the COVID-19 pandemic for many years to come. He remembered his father working very hard during the depression, and their family managed to get through it alright.

I had a wonderful, privileged time with Dr. Bob that I will never forget. We bonded over not only being dentists but being veterans who served during war. I think that helped Dr. Bob get over his shyness, and we shared many stories together during my three-hour visit. This interview “job” was not work at all, it was like going to Disneyland — only better and cheaper! n Dan Jenkins, DDS, CDE, is the editor for the Tri-County Dental Society

RM Matters

C D A J O U R N A L , V O L 4 8 , Nº 12

Hostility in the Workplace Escalates if Left Unchecked TDIC Risk Management Staff

D

uring this challenging year, stress levels have often been high and patience very low.

Regardless of these external stressors or how different individuals manage their frustrations, dental professionals deserve a working environment that is free from hostile interactions. Practice leaders, therefore, have an obligation to foster a culture of respect and clear communication.

The Dentists Insurance Company’s Risk Management Advice Line receives a substantial number of calls every month regarding confrontational patients or employees.

A call received by the Advice Line earlier this year illustrates how negative experiences in the practice can escalate into serious issues and even hostile workplace claims.

The caller said her practice’s situation began when the receptionist called the mother of a new pediatric patient to schedule a first appointment.

The receptionist felt the parent was acting quite unpleasant, as she was demanding a specific appointment time and pushing back on nearly every available date and time offered to her.

The parent and child presented to the first appointment and the same receptionist greeted them in a friendly and welcoming manner. When asked to complete new patient forms, the parent complained about the amount of paperwork needing completion and having to provide a copy of her identification. She expressed that she was in a rush and wanted to be out of the office within 45 minutes.

The receptionist informed the parent that an assistant would call her child

back as soon as the check-in process was complete. The parent rolled her eyes and said, “This is ridiculous.” However, the receptionist remained polite.

Instead of completing the child’s medical history, the parent made a call from her mobile phone and spoke in a way the receptionist described as loud and obnoxious. Seeing that the parent had stopped filling out the forms and was focusing her attention on her phone call, the receptionist reiterated that once the health history

was complete, she could call the patient to the back. The parent angrily replied, “What does it look like I am doing?”

The receptionist, feeling frustrated, sought out the office manager, explained the way the parent was speaking to her and asked for some assistance with the front desk. The office manager advised her to just ignore the parent’s attitude and remain professional. The receptionist was still upset and felt humiliated by the way the parent spoke to her.

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RM MAT TERS C D A J O U R N A L , V O L 4 8 , Nº 12

Once the dental assistant was able to call the patient back, the appointment seemed to go well. The dentist diagnosed treatment and the receptionist scheduled the next visit. The patient presented at the next visit and the parent was in a hurry again, demanding the receptionist “hurry up” and get her child to the back.

The dentist completed treatment and the patient was dismissed. After the dental benefits plan was billed, a balance from the deductible was due. At the following visit, when the receptionist informed the parent of the balance due, the parent yelled, “Do you people know how to bill insurance?”

Thereafter, every appointment and interaction with this parent was unpleasant and difficult for the receptionist, who seemed to be a target of the parent’s hostility. Other patients in the lobby observed how this parent treated the receptionist and expressed their disapproval of the parent’s behavior. Some even remarked, “You shouldn’t have to deal with that.” The office manager witnessed it as well but did not intervene to stop the parent’s behavior or defend the receptionist.

The parent became even more abusive over time and the receptionist expressed that she was feeling bullied.

The receptionist eventually made a formal complaint to the dentist, saying she was not only experiencing extreme anxiety, but also felt fearful and depressed at work and needed to go home. The receptionist asked the dentist to file a workers’ compensation claim for her distress.

Taking steps to prevent a ‘hostile work environment’

After hearing the details of this specific situation, TDIC’s Risk Management analyst determined that the office manager and the dentist failed to take action and protect the employee from a hostile work environment.

The analyst stated that the dentist has a responsibility to provide a safe environment 706 D ECEMBER

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free from hostility and that the proper way to handle the situation would have been to stop the parent’s behavior from the very first appointment. Because that did not happen, the analyst recommended that the caller formally dismiss the patient and comply with the receptionist’s request to open a workers’ compensation claim.

The analyst also discussed the importance of office culture with the caller. Some personalities may not be a good fit for the practice, and sometimes a relationship cannot be established.

In these instances, the practice owner

Every patient will require a different level of care and attention, but it is never acceptable for the patient to be abusive to any member of the dental team. must take action and dismiss the patient from the practice as long as the reasons for doing so are nondiscriminatory.

The staff needs to respect patients, but patients must also respect them.

One of the most important steps a practice owner can take is to document that the issue was discussed and any steps taken to solve the problem.

Documentation should be retained in the employee file in the event there is a complaint to the U.S. Department of Labor for a hostile work environment.

In this situation, one option would have been for the office manager to discuss the matter with the parent in private, informing the parent that communicating with staff in this manner was not acceptable. The parent should have been advised that if she presented with hostility again, the practice

would be forced to dismiss the patient.

The office manager should always lead by example and be trusted as a safe resource to whom employees can turn. If there is not an on-site office manager, the dentist should take on the role and offer a resolution. If the patient is not midtreatment, withdraw from further services by notifying the parent first and then by sending a dismissal letter to the patient’s home address. It is important to have objective notes regarding any interactions, using quotation marks to document specific relevant statements made by the patient and, as in this instance, the parent or, in some cases, another staff member who is behaving in a hostile manner.

Set clear expectations for professionalism, communication and interpersonal interaction among staff members and between staff and patients. When communication breakdowns happen, the environment can quickly become toxic. However, it’s the role of the practice owner to facilitate a safe environment free of fear of judgement or retaliation so staff members feel comfortable voicing their concerns.

Every patient will require a different level of care and attention, but it is never acceptable for the patient to be abusive to any member of the dental team. Taking action in a prompt manner is important, as it prevents the issue from potentially escalating or becoming a chronic problem.

CDA members can call TDIC’s Risk Management Advice Line at no cost when they face concerns. Dedicated risk management analysts provide assistance navigating challenges and with finding solutions before potential risks escalate. n TDIC’s Risk Management Advice Line is a benefit to TDIC policyholders. To schedule a consultation with an experienced risk management analyst, visit tdicinsurance.com/ RMconsult or call 800.733.0633.

Regulatory Compliance

C D A J O U R N A L , V O L 4 8 , Nº 12

Employer Obligations To Provide Vaccinations CDA Practice Support

Discussions on a COVID-19 vaccination at the time of this writing have focused on who will be first to get the vaccine and whether vaccination will be mandatory. Federal officials have ruled out a nationwide mandate, but other organizations have pointed out that certain agencies, schools and employers could choose to make vaccination for COVID-19 mandatory for certain groups such as school-aged children and health care workers. Neither OSHA nor Cal/ OSHA have indicated whether they would require vaccination for health care workers or require employers to provide vaccination to employees. The agencies do not currently require employers to provide flu shots, but COVID-19 is a greater threat in the workplace than the flu.

This is a good time to review current employer obligations to provide vaccinations to employees.

Many employers encourage employees to get flu shots each year and the employers pay for them. In some communities, local health departments have included dental settings in mandatory orders for health care facilities to require staff who work in patient care areas to get flu shots or to wear masks while at work. A dental practice should check its local public health department at the start of flu season and periodically to learn of any such order. Without a public health order, it is optional for a dental practice to offer annual flu shots to its staff.

Dental practices are required by the Cal/OSHA bloodborne pathogens regulation to make available the hepatitis B vaccination series, postvaccination

follow-up and a second series if warranted to any employee who is potentially exposed to blood or saliva in the workplace. An employer may not require a potential employee to have the vaccination series as a condition of employment because the law requires an employer to provide it.

A new employee may refuse the vaccination series, and the refusal must be documented on a form using specific language. Document the reason for refusal if it is provided. Possible reasons can include: a) the employee has already had the series, b) antibody testing has revealed the employee is immune or c) vaccination is medically contraindicated for the employee.

If an employee changes their mind and wants the vaccination series, an employer must provide for the series at that time as well as the required postvaccination follow-up. Postvaccination follow-up includes serologic testing (done one to two months after the last dose in the series), a second series of shots if test results are negative and another serologic test. If the final test results are negative, a dentist employer should refer the employee to a health care provider for further testing and counseling. More information about the vaccination can be found in the “Hepatitis B and Healthcare Personnel Q&A” issued by the Immunization Action Coalition, www.immunize.org/catg.d/p2109.pdf.

A dental practice should be aware of active communicable diseases in its community, especially aerosol transmissible diseases such as whooping cough and measles. The state and local

public health departments will have advisories for health care providers.

The Centers for Disease Control and Prevention recommends the following vaccinations for health care workers:1 MMR (measles, mumps, rubella) for workers born in 1957 or later who have no serologic evidence of immunity or prior vaccination.

Varicella (chickenpox) for workers who have no serologic proof of immunity, prior vaccination or diagnosis or verification of a history of varicella or herpes zoster (shingles).

Tetanus, diphtheria, pertussis (Tdap) for workers who have not received Tdap previously. Schedule Td boosters every 10 years thereafter. n REFERENCE 1. Centers for Disease Control and Prevention. Recommended vaccines for health care workers. www.cdc.gov/vaccines/ adults/rec-vac/hcw.html. Accessed Oct. 5, 2020.

Regulatory Compliance appears monthly and features resources about laws that impact dental practices.

Visit cda.org/practicesupport for more than 600 practice support resources, including practice management, employment practices, dental benefit plans and regulatory compliance.

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This season, give health and hope.

CDA Foundation volunteers and donors truly change the lives of others. Through your generosity, Californians in underserved communities gain access to dental treatment that relieves pain, restores dignity, creates smiles and opens more opportunities.

Make your year-end gift today or donate in the memory or honor of someone who made you smile.

Visit cdafoundation.org.

Ethics

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He Wants You To Do What? Ethical Issues of Providing Second Opinions Gary Herman, DDS

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r. Jones, a 52-year-old new patient, presented for a “second opinion.”

The last dentist he visited recommended six crowns to deal with “cracks and wear,” two possible root canals and clear retainer orthodontics. My examination revealed only two existing small composite fillings that appeared sound.

His mouth had minimal, asymptomatic wear. The patient had slight mandibular crowding, which did not bother him, but he did need periodontal therapy.

I did not know how to proceed.

First of all, the “second opinion” in dentistry is generally not the same as in medicine. If a significant treatment is recommended, an additional consultation is encouraged to assure that all options and possibilities are discussed and an informed consent for the procedure has occurred. Generally in dentistry a second opinion is initiated by a patient when they do not like or understand what they heard the first time.

If a patient truly is receiving a second opinion from you, it is implied that you are providing a service to the patient by confirming that the procedure is appropriate or that a different treatment option could be considered. It is clearly not designed to convince the patient to see you for treatment rather than the first dentist.

It is proper for you to be compensated

for your expertise and for you to inform the patient of the need to continue care with the first dentist, unless the patient expressly reveals a different preference (CDA Code of Ethics, Section 9).

The more common scenario in dentistry is a patient requesting another diagnosis and treatment plan with the hope that the second plan is less invasive, less time-consuming and, most frequently, less costly. Realistically, if the first treatment plan and presentation were thorough, the patient would have received all reasonable options of care with the associated risks and benefits of each. The patient should then have had enough information to make a free and fully informed decision. Your obligation to the patient the second time around is to do what the first dentist may not have done.

By calmly and thoroughly presenting all of the information to the patient, including alternative treatment options, you will be following the ethical principles of autonomy and nonmaleficence, providing a free and fully informed consent and practicing to the standard of care. By focusing on your comprehensive exam and findings, rather than bad-mouthing the original dentist, you will be honoring the principle of beneficence: doing good for the profession. Additionally, your truthful portrayal of the patient’s oral condition will satisfy the principle of

veracity. And finally, by providing this level of treatment planning for both your first and second opinions, you will be fair to all of your patients, thus including the principle of justice in your practice.1 By making sure that all of your patients always receive a full, appropriate diagnosis and treatment plan, you will be hitting the ethical grand slam and practicing dentistry to a high ethical standard. n REFERENCE 1. Autonomy, nonmaleficence, veracity and justice are ethical principles found in the CDA Code of Ethics.

Gary Herman, DDS, teaches at the University of California, Los Angeles, School of Dentistry and lectures on ethics, dental law and patient management.

He is past chair of the ADA Council on Ethics, Bylaws and Judicial Affairs and served on the CDA Judicial Council.

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Tech Trends

C D A J O U R N A L , V O L 4 8 , Nº 12

A look into the latest dental and general technology on the market

Dentalk (Free, Dental App Lab) Patient education continues to play an important role in providing patients with optimal comprehensive care treatment plans. In-office brochures, models and other materials have served this purpose effectively for many years. Digital chairside resources have been increasingly prevalent as the patient population shifts toward using more technology in their daily lives. Dentalk is an app that helps providers deliver patient education during appointments on their mobile devices with videos, animations, images, 3D models and caries prediction using artificial intelligence (AI).

Dentalk provides digital chairside patient education resources in four simple categories: hygiene, anatomy, treatment and AI prediction. Each category contains specific content to help patients better understand various instructions, diagnoses and treatment options given to them by their provider. Most categories contain free trial content, but a premium subscription is required to unlock all features. The hygiene category contains videos and GIF images of toothbrushing and flossing techniques using a wide variety of consumer products. The anatomy category contains images, crosssectional models and rotation-capable 3D models of teeth that can be annotated to point out exact areas for patients to focus on during a consultation with the provider. The treatment category contains brief slide presentations of common dental procedures in several disciplines that explain the steps involved in specific treatments.

The AI prediction category, which requires a premium subscription and could not be evaluated for this review, is advertised to utilize machine learning and epidemiological survey data with a providercompleted questionnaire prior to examination to predict the possible caries status and number of lesions in a patient case as a reference.

The app and sample of features in the free version were quickly accessible, easy to use and show their ability to provide basic patient education. A preview of its entire feature set for premium subscribers, however, highlights its limited scope of content currently available, which may be balanced by the potential usefulness of the AI caries predictor. A critical feature that is lacking in this patient education tool is the ability to send any presented content directly to the patient for viewing at their own convenience.

Digital patient chairside education is evolving to become the standard of practice as part of treatment planning in the delivery of modern comprehensive patient care. Dentalk helps providers educate patients with a limited set of features at a relatively affordable subscription price.

— Hubert Chan, DDS

27-inch iMac

($1,799, $3,179 (reviewed model), Apple) In August 2020, the 27-inch iMac received upgrades to its processors, graphics cards and, most importantly, solid-state drive (SSD) options. “Same package, better parts” summarizes this new generation of devices. Currently, those parts are indeed much better, though they unfortunately retain many of its longstanding design deficiencies. This review evaluated the 27-inch iMac with a 3.8GHz i7 processor, 64GB of RAM, 1TB SSD and the Radeon Pro 5500XT. Apple prides itself on giving users a streamlined experience, and the iMac continues that tradition. Simply plug the device into a power outlet and turn it on; no other assembly required. The 27-inch screen immediately makes its presence felt as it is sharp, responsive and does not strain the eyes. The rechargeable Magic Keyboard and Magic Mouse 2 are useable, but unpleasant: The keyboard is too small, and the mouse can’t find a spot between not responsive enough and too sensitive. Given the amount of screen real estate that needs to be covered, third-party peripherals are highly recommended. The processing prowess for all but the most intense tasks is impressive; however, those who use the iMac as an audio recording device need to be aware that its fans kick on at the drop of a hat, potentially introducing fan noise into recordings. The solidstate drives are fast and serve as a marked reliability upgrade from the maligned, but less expensive Fusion drives. Overall, the latest iMac serves as an iterative improvement in speed and durability over its predecessors, but those looking for a significant experience change would be better served looking toward the iMac Pro and Mac Pro product lines.

— Alexander Lee, DMD

710 D ECEMBER

2020

®

Simply brilliant.

Save the dates for CDA Presents.

Keep connected to CDA for news on upcoming conventions, including schedules, new courses, amazing speakers and special events planned for next year. Visit cda.org/cdapresents.

Earn C.E. online at any time.

Take part in your choice of innovative webinars, web-based courses and audio learning options. Explore courses and learn at your convenience. Get started at cda.org/brightbox.

MARK YOUR CALENDAR

Anaheim, California May 13–15, 2021 May 12–14, 2022

San Francisco, California September 9–11, 2021 September 8–10, 2022

Like us @cdadentists Follow us @cdadentists Connect with us California Dental Association Follow us @cdadentists

C D A J O U R N A L , V O L 4 8 , Nº 12

Journa C A L I F O R N I A

712 D ECEMBER

2020

D E N TA L

A S S O C I AT I O N