Pf11cap03

Practice-Based Research on the Effectiveness of Ceramics

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Van P. Thompson, dds, phd Kenneth A. Malament, dds, mscd

There continues to be a translational gap, that is, a lag (averaging 15 to 20 years) between pivotal technologic discovery or clinical trial and general clinical application and adoption.1 Both medicine and dentistry are struggling to accelerate the incorporation of advances or best practices into clinical patient care. Practice-based research is centered on determining the comparative effectiveness of different procedures, treatments, or materials in use. The intention is to find out what works best in the real world clinical situations of practitioners with diverse talent levels treating broad populations of patients. Practice-based research can be considered translational research when it compares emerging technologies or materials to those in common usage, for example, all-ceramic posterior crowns to metal-ceramic crowns. In US Food and Drug Administration (FDA) terms, these are deemed phase V studies.2 Currently in the United States about 150 US medical practice-based research networks (PBRNs) are listed by the Agency for Healthcare Research and Quality of the US Department of Health and Human Services; however, only three PBRNs represent dentistry.3 PBRNs provide an infrastructure in which practitioners can participate in clinical studies, assessing conventional and new technologies, to answer questions generated by the clinical community. These practitioners and their findings are likely to be better accepted by the clinical community at large and reduce the translational gap for best practices.

This chapter describes the organization and activities of PBRNs, in particular as a feasible means to broadly compare the effectiveness of all-ceramic crowns and fixed prostheses to that of traditional metal-ceramic restorations.

History of PBRNs While no agreed-on definition of a PBRN presently exists, the Practitioners Engaged in Applied Research and Learning (PEARL) Network defines a PBRN as follows: “a collaboration between an academic health science center and community practitioners for conducting primarily clinical studies of mutual

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Practice-Based Research on the Effectiveness of Ceramics interest to benefit and enhance patient care and delivery, systems assessment, quality assurance, and other factors affecting health care outcomes and policy.”4,5 First conceived more than 100 years ago in England, medical PBRNs took root in the United States in the 1970s.6,7 PBRNs are an important instrument of change, driven primarily by the recent health care reform legislation highlighting patient-centered outcomes research in the form of the Patient-centered Outcomes Research Institute8–11 and the Health Care and Education Reconciliation Act of 2010.12–14 Medical PBRNs were designed to bring together community physicians to conduct studies of interest and relevance to everyday clinical practice,7 and many conduct surveys to assess practitioner practice patterns. Comparative effectiveness studies are directed at comparing treatment outcomes and are the clinical focus of PBRNs. Health improvement network has been suggested as a new title for PBRNs.15 In 2005, the US National Institute of Dental and Craniofacial Research (NIDCR) funded three dental PBRNs as an experiment to initiate change in dentistry: the PEARL Network at New York University (NYU); the Dental PracticeBased Research Network at the University of Alabama; and the Northwest Practice-Based Research Collabora­ tive in Evidence-Based Dentistry, a collaboration between the University of Washington and Oregon Health Sciences School of Dentistry. The NIDCR-funded PBRNs were designed to implement change in the way dentistry is practiced. Basic research that remains in the laboratory, not translated to clinical practice, does not contribute to improved patient care. The infrastructure design of the dental PBRNs allowed practicing dentists to be part of dental research, which was historically limited to a small percentage of academic dentists and scientists. The three NIDCR-funded dental PBRNs were replaced in 2012 by the National Dental PBRN, which is coordinated from the University of Alabama. The PEARL Network continues as an independent organization.

Role of the Practitioner Dentists are highly educated but underutilized health care professionals. They take medical histories, spending more time with a patient than do their physician counterparts; yet there is no forum for collaboration and transformation of this information. The advent of electronic health records means that dental practitioners will inevitably be part of a larger system of health care, inclusive of patients’ health histories, through the “electronic medical home.”16 PBRNs foster familiarity for such data exchange. Overall the intention is to provide clinical solutions to optimize oral health treatment and foster prevention paradigms.17 34

Dentists are generally relatively isolated in their practices (70% solo).18 The initial objective of the dental PBRNs was to build a network of dental practitioners, utilize them in surveys and standard-of-care studies, and keep them engaged through annual meetings, newsletters, study-related meetings, monthly teleconference calls, and, when possible, monitoring visits to assess study progress. Participation in PBRNs is a venue for dentists to learn newer and advanced treatments and techniques in a guided, university-based environment that allows peer education, participation in study protocols, and an information dissemination process that ensures some quality control and practitioner feedback; all these components work to establish best practice outcomes.19 Transformation theory suggests that practitioners’ willingness to change depends on the ability of the network to establish credibility and trust,20 objectives requiring a long-term commitment typical of PBRN experience.

Funding may allow reimbursement of dentists for a portion of their time spent participating in clinical studies; it generally does not subsidize patient care. Patients routinely visit the dental office, and any patient presenting with a clinical situation that fits a study’s clinical criteria is eligible for recruitment into that study. Funding is intended to cover the time the practitioner and staff spend on informed consent, data recording and transmission, and follow-up visits.

Structure and Function of PBRNs This chapter will describe the activities of the PEARL Network as a successful example of PBRN organization and function across a range of comparative effectiveness research studies. A PBRN requires an executive committee comprising practitioner-investigators (PIs), academics, a data coordinating center (usually academic based), and staff (some of whom are clinical research coordinators) to provide study support and logistics. In addition, the network must work closely with one (ideally) or more institutional review boards (IRBs).

The executive committee is critical because it represents the interests of the PIs and, working with the academics and data coordination center, formulates the research questions and designs the comparative effectiveness research studies that can be realistically conducted in the offices of the PIs. A data-coordinating center is pivotal to design of questionnaires and data collection instruments, electronic collection and collation of data, and statistical analysis. The clinical research coordinators play a critical role in implementation, conduct, and closeout of the studies.

They are the primary interface with the individual dental practices and their staff, responsible for educating the staff

Structure and Function of PBRNs TABLE 3-1 Research capabilities of PBRN investigators, based on training Investigator designation Nature of the study

Tier 1

Tier 2

Randomized clinical trial

X

Phase III trial development

X

Standard-of-care randomized clinical study*

X

Comparative effectiveness research (prospective)

X

X

Comparative effectiveness research (retrospective)

X

X

Standard-of-care phase IV trial (randomized clinical trial)

X

X

Patient surveys

X

X

Tier 3

X

*Products cleared by the FDA and approved by the American Dental Association.

about the study and participant recruitment and concerns.

In addition, they troubleshoot any problems encountered in patient recruitment, training, data entry, data integrity, data anomalies, or study closeout.

PEARL evolved over 7 years to include a registry of more than 519 dentists designated as PIs. Of these, 364 are credentialed for enrolling patients, and 311 are trained to participate in the network (Table 3-1). PEARL also includes 30 community centers. Credentialing is based on a number of parameters for IRB risk mitigation and regulatory compliance, which will be discussed later.

PEARL has also created a schema for determining a practitioner’s appropriate participation level (see Table 3-1). This model is intended to capture the input of as many practitioners as possible and include a range of clinicians, from those who want to participate only in surveys to those who are interested in joining randomized comparative effectiveness research studies. PEARL’s surveys assess practitioner interest in a given study and/or the feasibility of a study in terms of patients, logistics, and dental practice ergonomics; the surveys are usually, but not always, followed by a study.

Recruitment strategies are designed to attract practitioners who understand the long-term benefits of a PBRN, because it costs time and money to replace and train PIs. High practitioner turnover can stall clinical study progress. Motivated practitioners are screened by PEARL, based on criteria from various agencies (FDA, Office of the Inspector General of US Department of Health and Human Services, and state boards of dentistry), to help ensure data integrity (Box 3-1).

The size of any network is limited by the cost of support.

As noted, 311 of PEARL’s 364 credentialed practitioners are trained PIs, having fulfilled the requirements of tier 2 partici-

pation (see Box 3-1). A relatively large number of trained PIs is necessary, and only a limited number will be interested in participation in a given study.21 A rule of thumb is that a network must have three times more trained PIs than are required for any individual study in order to achieve sufficient PI participation for each study. In other words, it is best to recruit to the study and not assume that all trained PIs will consider recruitment of participants.

PEARL was designed to support the generalizability of the obtained data. The term generalizability suggests some level of confidence to ensure robustness of the findings to the community at large. How can a clinical network take clinicians with no training in clinical research, have them conduct a study, and expect that the data will be generalizable to the profession? To address generalizability, PEARL follows the principles of good clinical practice (GCP) for investigator training and clinical operations. GCP creates an audit trail of the data to ensure a level of confidence in clinical study findings.22 The entire clinical process is supported with standard operating procedures and oversight from certified clinical research coordinators. The GCP process extends to the official closeout of a study, including final monitoring visit, queries resolution, and database lock that ensures the completeness of the archived study.

PEARL developed an organizational structure at each dental practitioner’s site. In addition to the practitionerinvestigator, an essential member of the study team is the practice research coordinator, the key person through whom PEARL clinical research coordinators maintain liaison via monthly teleconference calls and whenever there is a study-related issue. The dental practice unit also must include a dental hygienist, a dental assistant, and an office 35

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Practice-Based Research on the Effectiveness of Ceramics Box 3-1

Credentialing and training requirements for PBRN clinical investigators

Tier 1: Experienced and capable of randomized controlled trials • Participation in previous studies and demonstrated capabilities at the tier 2 level • Awareness of need for continuous safety monitoring Tier 2: Trained for standard-of-care studies (tier 3 requirements plus) • Signed curriculum vitae or résumé • Current certification in cardiopulmonary resuscitation • Financial disclosure and conflict of interest statements • Evidence of decision-making authority at practice site • IRB–approved human subjects training* plus: – Informed consent – Good clinical practice • Study-specific training: – Study manual review and test – Manual of operations review – Electronic data capture training – Data closeout requirements • Screened as qualified, without any censure from governmental bodies or professional societies Tier 3: Credentialed for surveys • Registered as a research practitioner • Active dental license • Trained in informed consent • Abbreviated human subjects training • Data capture training *May require official affiliation with an institution or a hospital.

manager—a configuration PEARL has found to be optimal for the conduct of office-based studies but one that understandably limits practitioner recruitment.

A close working relationship with an IRB helps the PBRN reduce the burden of training and compliance placed on the PI and his or her staff. The official IRB of record for the PEARL Network is the NYU School of Medicine. PEARL is structurally obligated to advise its IRB of the risk potential of its studies, to ensure patient safety, and to maintain a level of quality assurance for the practitioners and their staff through education and training, thereby maintaining compliance with protocol and adherence to GCP. Each PEARL practitioner engaged in a study is appointed as an NYU College of Dentistry Research Associate, to come under the IRB’s umbrella. PEARL terms its undertakings as clinical studies, not clinical trials, a term reserved for the drug development pipeline (see Table 3-1). This mitigates the risk potential for the IRB, so network studies are mainly deemed low risk and standard of care.

The PEARL Network views its educational component as paramount in sustaining the PBRN concept of foster-

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ing change in dentistry. Study information is disseminated through annual meetings, publications, newsletters, social media, and online learning. Practitioners have been encouraged to learn the process of presenting clinical results.

One motivational component for PIs to participate in the PBRN is benchmarking: Practitioners participating in a study receive from PEARL a report measuring their performance anonymously against that of their study peers. This feedback is unique for each dental practitioner and informs the participant about how he or she may improve delivery of care and/or treatment outcomes.

The PEARL Network envisions educating dentists in clinical research as a means of generating potential clinical faculty to fill the vacancies in US dental schools. The education obtained from a PBRN is a real-time dental curriculum, revised as clinical study results become available, closing the gap between academics and practitioners.23 The clinical philosophy of the PEARL Network is to design studies that are of interest to the practitioners, are clinically relevant, and have the potential to change practice patterns and improve patient care. Studies are also designed to

Potential PBRN Study Designs for All-Ceramic Restorations

Endodontic treatment 3 to 5 years previously: Tooth identified Tooth present Clinical assessment

Radiograph

Tooth missing

10% of preoperative periapical radiographs evaluated through random selection

Pain and quality of life questionnaire History data entered

Database

History data entered

Analysis

Fig 3-1  Algorithm of study design to determine endodontic treatment and restoration outcomes.

evaluate the capability and robustness of the network, and to balance science with clinical relevance and the logistics of conducting the study in the practice. The studies also adhere to the recent guidelines proposed by the PatientCentered Outcomes Research Institute.24,25 Additionally, the broader perspective of professional research organizations is reflected in PEARL studies, which include findings on oral health–related quality of life outcomes of specific protocols.26,27

Potential PBRN Study Designs for All-Ceramic Restorations The PEARL clinical portfolio comprises a variety of studies that demonstrate the capability of PIs to collect detailed and in-depth information over the duration of the study.

PBRN studies balance control and risk with office logistics.

As study risk increases, so does the control of the study for patient safety and IRB compliance. A strength of PBRN stud-

ies is their participant recall rates, which can be as high as 99% over a 6-month period,28 indicating the commitment of PIs and their participating patients to these studies.

PBRN methods could be applied to evaluate the effectiveness of all-ceramic restorations. Such a study was planned for the PEARL Network, but funding limitations prevented its full development. Retrospective studies that involve patient visits to verify outcomes are ideal for PBRNs and could be applied to all-ceramic restoration outcomes.

Review of recent PEARL studies suggests how this could be accomplished. For example, PEARL PIs wanted to compare the outcomes of implant restoration and endodontic treatment of compromised posterior teeth. To support the decision-making process in treatment planning, PEARL conducted two overlapping retrospective studies, one to assess endodontic outcomes and one to assess implant outcomes.

The findings from the endodontic outcome study have been published.29,30 The study design is shown as a flow­chart in Fig 3-1. PI staff identified from their records patients in whom endodontic therapy and restoration were complet37

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Practice-Based Research on the Effectiveness of Ceramics ed 3 to 5 years previously. At the recall appointment the patient was approached to be enrolled as a study participant.

Following enrollment, the participant was evaluated by the dentist. If the study tooth was not present, the history of the loss was recorded. When the tooth was present, the PI performed a clinical evaluation of the tooth and restoration and reviewed a recent or immediate radiograph. Evaluation included, among other items, evaluation of the restoration for replacement or repair, pain in the general area, and pain on percussion. The patient completed questionnaires related to pain and quality of life. Data were collected from 64 PI offices and 1,312 participants.

The data can be interpreted as endodontic failure (19.1%)29 or restorative failure (13.9%).30 Based on these patient-centered outcomes, the total failure rate (with all reasons mutually exclusive) across the practices was 33% at 3.9 Âą 0.6 years in function. The study data for implant outcomes are still undergoing analysis; however, thus far the retention rate for the implants is very high, but bone loss is a concern.

This type of retrospective study across a number of practices could provide outcomes data on a large number of restorations. Key to the validity of the findings is the clinical evaluation of the restorations, which is missing from sources such as insurance claims databases. Clinical evaluation would require agreement on what constitutes clinical success and failure for all-ceramic restorations, as discussed in a recent review.31 A prospective study design applicable to evaluation of all-ceramic crowns is a randomized clinical effectiveness study conducted by PEARL on treatment outcomes for hypersensitive noncarious cervical lesions28 (Fig 3-2). For this study, 17 PIs were trained in identification of, evaluation of, and three treatments for these lesions. The treatments were use of a dentifrice containing potassium nitrate, application of a dentin bonding agent covered with a sealant layer, or use of the same bonding agent and a flowable resin-based composite restoration.

On enrollment, participants were randomly assigned by the coordinating center to one of the treatments. Participants were recalled at three time points to report their hypersensitivity and undergo clinical evaluation for hypersensitivity. At the 6-month recall the sealant and restoration were equally effective, while the dentifrice had positive effects but fell short of the other treatments at all recalls.

This type of study design could be considered to compare short-term and even long-term results between adhesive cementation and luting of all-ceramic posterior resto-

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rations. Such PRBN studies could provide meaningful data and avoid the expense associated with large randomized controlled trials that have recently been recommended.32 Meaningful clinical outcomes data can be gleaned from individual or group dental practices. The generalizability of the data becomes more acceptable if the results of several practices can be combined or if the practices have similar results. Both of these instances depend critically on agreement as to the data to be collected and on data definitions (curation) as well as rankings and scoring methods. Deidentification of the data for patient safety and compliance with privacy regulations is also of importance.

Provided that a clinician pays careful attention to detail and maintains GCP, practice findings are a helpful source of information on treatment outcomes. However, most studies of all-ceramic crowns from individual practices or dental schools include a limited number of restorations or have a mean duration of less than 5 years.33–36 The German Society for Ceramic Dentistry sponsors a registry for single-tooth all-ceramic restorations and has collected data from more than 200 dental practices over almost 12 years. There is one publication to date on outcomes.37 Placement data have been collected for more than 5,000 ceramic restorations, predominately inlays and onlays and only about 15% complete crowns. The registry has collected recall data on 3,096 of these restorations, with times in service of up to 11.8 years. Reports from individual practices have contributed at least 50 restorations to the database. The report allows comparison of the placement techniques of individuals with the average across the group.

Overall the German findings indicate that the all-ceramic restorations in the study are performing reasonably.37 The Kaplan-Meier probability of survival at 12 years was 81.6% for all teeth but only 60% for nonvital teeth. The registry recorded 2% of the restorations as failures; of the failures, 50% were fractures and 20% endodontic failures. Failure rates were reported to be higher for crowns than for inlays and onlays, but the values were not provided, nor were differences in ceramic systems discussed. Unfortunately to date there have been no subsequent publications regarding this German PBRN study.

The dental profession should seize the opportunity to fully utilize the patient information that practitioners gather and to have a PBRN to help capture and relate that information to best practices. PBRNs offer the chance to expand the domain of interests and responsibilities for dentists at a time when they may be challenged by midlevel providers.

Potential PBRN Study Designs for All-Ceramic Restorations

• Establish subject eligibility • Obtain subject’s informed consent

• Hypersensitivity (HS) measure • Randomize to treatment arm • Impression • Sleep bruxism evaluation • HS survey • Quality of Life (QoL) survey

Treatment 1: Dentifrice dispensed, reviewed

Treatment 2: Self-etch DBA and sealant applied

Study baseline

Treatment 3: Self-etch DBA and flowable composite resin applied

Treatment

• HS measure • HS survey • Impression

Treatment baseline

• Pain medication usage • HS measure • HS survey • QoL

1-month recall

• Pain medication usage • HS measure • Impression • HS survey • QoL

3-month recall

• Pain medication usage • HS measure • Impression • HS survey • QoL

6-month recall

Fig 3-2 Flowchart of study design to compare the effectiveness of three different treatments for hypersensitive noncarious cervical lesions. DBA, dentin bonding agent.

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Practice-Based Research on the Effectiveness of Ceramics

Example of Individual Practice Data Collection One instance in which individual practice results have provided broadly applicable data should be noted. Glassceramics in a cast or pressable form (Dicor, Corning and later Dentsply) were advocated for complete-crown restorations based on their physical properties, which were reportedly similar or superior to tooth enamel.38 A data collection instrument was developed to document the performance of all-ceramic crowns; the original instrument comprised a 27-field data set for each restoration placed.39 This data set has now been reduced to 23 fields (Box 3-2). In addition to information on patient demographics, the instrument records the ceramic material, the margin design, and material thickness in six locations. Details of the supporting structure, cements employed, and opposing dentition are also recorded. This documentation is continued at each recall or when an adverse event occurs.

Resulting from this dedicated individual clinical effort is a highly informative series of articles elucidating the factors leading to failure or survival of these glass-ceramic restorations over time39–41 and defining risk factors associated with failure.42 These results provided clinical verification of predictions from studies on layered ceramic models of crowns.43–45 Surprisingly, crown thickness and two different margin designs (shoulder or chamfer) did not play a significant role in outcomes.

The culmination of this work is a 20-year report of outcomes of different combinations of variables and the risk factors associated with those combinations, derived from data on more than 1,400 restorations in 417 patients.46 The elastic modulus of the supporting structure (gold versus dentin), molar versus premolar, and gender are all compounding risk factors. Even comprehensive meta-analyses of clinical reports on all-ceramic crowns cannot provide such detail, because most studies do not have such comprehensive databases and do not include a sufficient number of restorations to allow survival analysis with appropriate statistics or to investigate compounding variables.32,47 The long-term clinical data46 cast doubt on extrapolation from short-term data, because the predicted survival from the short-term data and the actual survival rates of Dicor restorations in the long-term study differed considerably.

The data strongly suggest that the only reliable method to evaluate the survival of prosthetic materials is long-term clinical testing in human subjects. Future studies of allceramic restorations should:

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• Include a baseline of at least 500 restorations, the majority of which are posterior crowns.

• Have a study duration of at least 5 years for all restorations.

• Require data to be updated at each recall examination.

• Include survival analysis with confidence intervals.

• Account for all participants entered into the study.

During the time of data analysis and calculation of survival statistics for the 20-year report, Malament expanded the materials in his practice in 2006 to include lithium disilicate glass-ceramic restorations (e.max Press, Ivoclar Vivadent).

Table 3-2 contains the latest summary of all-ceramic crown performance data from May 2006 and includes more than 1,700 patients and more than 5,550 restorations. Covered is the entire suite of all-ceramic materials employed for restoration in this practice, including partial-coverage restorations and veneers.

Failures in Tables 3-2 and 3-3 are defined as ceramic fracture requiring replacement. In Box 3-2, the category “Reason for replacement” includes 18 different codes. This is the basis for the listings “Failures,” ”Chipping,” and “Replaced” in Tables 3-2 and 3-3. Not all failed restorations were replaced. In this summary, the failure rates are generally low, given the extended period in service for most of the materials, less than 1% per year for all except Dicor. Most of the failures for Dicor occurred in the first 5 years in service, as has been pointed out previously.46 While e.max restorations have been in service for a limited time in Malament’s practice (now more than 6 years for the earliest restorations), only one failure has occurred to date; this was a full crown on an implant abutment. This is the lowest failure rate of all the materials investigated in this practice. Unfortunately, there are no zirconia-based restorations in the database for comparison.

The outcomes for all-ceramic crowns from March 1993 to date (June 30, 2013) are summarized in Table 3-3. Almost three-quarters of the lithium disilicate crowns (884 of 1,158) are located in the posterior region, and there have been no failures to date (service duration of up to 74 months).

If highly motivated individual dentists were to employ the data set developed by Malament (or a modification thereof ) in their practices, important information about the outcomes of all-ceramic restorations could be gained more rapidly. Alternatively, individual dentists can develop their own database to answer a clinical question; guidance in this regard can be provided by most dental colleges. What is required are individual and group initiatives to gather and interpret clinical data.

Example of Individual Practice Data Collection

Box 3-2

All-ceramic restoration database fields and codes used by Malament

1 Subject identifier 2 All-ceramic material 1 Dicor 2 Inceram 3 Empress 4 Empress 2 5 Procera 6 Eris 7 e.max: Pressed and fluorapatite 8 e.max: Pressed 9 e.max: Pressed and Creation feldspathic 10 e.max: CAD/CAM and fluorapatite 11 e.max: CAD/CAM 12 Feldspathic porcelain 3 Gender (male = 1; female = 2) 4 Patient date of birth 5 Date completed 6 Last recall date 7 Tooth (number 1 to 32) 8 Procedure 1 Posterior complete coverage 2 Anterior complete coverage 3 Posterior partial-coverage inlay 4 Anterior partial-coverage inlay 5 Core 6 Posterior partial-coverage onlay 7 Veneer 8 Dowel core 9 Fixed partial denture (FPD) 10 Dicor luted to metal FPD 11 Zirconia post fused to Empress (dowel core) 12 Zirconia implant abutment 13 Crown and cantilever 14 Splinted crowns 15 e.max Pressed to gold dowel core 16 e.max Pressed to gold implant abutment 17 e.max endodontic core inlay 18 e.max luted to titanium implant abutment 9 Failure (yes = 1; no = 0) 10 Failure or replaced date 11 Replaced but no failure (yes = 1; no = 0) 12 Reason for replacement 1 Caries 2 Periodontics 3 Endodontics 4 Sensitivity 5 Esthetics 6 Loosening 7 New treatment plan 8 Fractured root 9 Dowel and/or core failure 10 Increasing mobility needing splinting 11 Open contacts 12 Poor fit 13 Restoration lost 14 Root resorption 15 Fractured cusp (tooth) 16 Internal cracking (ceramic) 17 Large ceramic chip 18 Fractured implant abutment 13 Chipping (yes = 1; no = 0) 14 Laboratory (create own code) 15 Preparation structure 0 None 1 Dentin

2 Gold and dentin 3 Empress and dentin 4 Dicor and dentin 5 Feldspathic porcelain and dentin 6 Composite resin and dentin 7 Enamel 8 Enamel and dentin 9 Alumina Ceradapt implant abutment 10 Porcelain-fused-to-gold implant abutment 11 Zirconia abutment 12 Silver amalgam and dentin 13 Gold abutment 14 e.max and dentin 15 Gold implant abutment 16 e.max implant abutment 17 Titanium implant abutment 18 e.max implant abutment 16 Margin design (shoulder = 1; chamfer = 2) 17 Luting agent 1 Zinc phosphate 2 Glass ionomer 3 Dicor light-activated resin 4 G Cera bis-GMA resin 5 Enforce UDMA resin 6 Dual resin 7 Sono Cem resin 8 Helio Link resin 9 Compspan resin 10 Calibra UDMA resin 11 Variolink 12 Appeal 13 Multilink 14 Resin-reinforced glass ionomer (RMGI) 15 Polycarboxylate (Duralon) with silicone 16 Zinc oxide and eugenol (Temp Bond) 18 Ceramic etch on internal (yes = 1; no = 0) 19 Restoration thickness (to 0.01 mm) 1 Mesial occlusal 2 Middle occlusal 3 Distal occlusal 4 Labial 5 Lingual 6 Mesial 7 Distal 20 Opposing dentition material 1 Natural tooth enamel 2 Silver amalgam 3 Edentulous 4 Gold 5 Composite resin 6 Feldspathic ceramic 7 Glass-ceramic 21 Dentin surface preparation 1 Dentin bonding agent 2 Varnish 3 Polyacrylic acid cleaning 4 None 22 Number of teeth in mouth 23 Biologic failures 1 Tooth requires endodontic therapy 2 Fractured tooth 3 Advancing periodontal disease 4 Increased mobility 5 Tooth sensitivity without endodontic 6 Psychosomatic pain

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Practice-Based Research on the Effectiveness of Ceramics TABLE 3-2 All-ceramic restoration data from the Malament prosthodontic practice Ceramic Parameter Start date

Dicor

In-Ceram

Empress

e.max Press*

Totals

March 1993

February 1990

June 1992

May 2006

June 2013

Maximum service (mo) Patients (No.) Restorations (No.)

364

281

253

74

364

415

137

692

491

1,736

1,504

331

2,130

1,586

5,556

240

49

100

1

390

Failures (No.) †

Failures (%)

19.8

Chipping (No.) Replaced‡ (No.)

15.7

7.5

<0.1

9.7

4

13

31

4

52

227

48

145

41

457

*Veneered with fluorapatite-containing feldspathic ceramic. † Material fracture requiring replacement. ‡ Replaced for all reasons.

Table 3-3 All-ceramic crown data from the Malament prosthodontic practice Ceramic Parameter Start date

Dicor

In-Ceram

Empress

e.max Press*

Totals

March 1983

February 1990

June 1992

May 2006

June 2013

Maximum service (mo)

373

290

262

83

364

Patients (No.)

415

137

692

526

1,770

1,504

331

2,131

1,816§

5,782

Failures† (No.)

240

50

100

Failures (%)

15.96

Restorations (No.)

Chipping (No.) Replaced‡ (No.)

1

391

15.11

4.69

0.0

6.76

4

13

31

4

52

227

49

146

51

472

*Majority monolithic crowns. † Material fracture requiring replacement. ‡ Replaced for all reasons. § Includes 884 posterior complete-coverage restorations, of which 182 were veneered with fluorapatite-containing feldspathic ceramic.

Conclusion The strength of the practice-based research approach to assessing outcomes for all-ceramic restorations will derive from both the number of practices involved and the number of restorations evaluated. The collection data is of particular importance because, in the last decade, numerous new restorative ceramic and composite resin materials have been introduced and strongly marketed to the dental community, and a stream of new materials is anticipated. The clinical testing of such materials often falls short because many studies employ too few observations to achieve statistical significance, and the duration of the studies is too 42

short to provide a meaningful assessment. Furthermore, investigators rarely examine potential confounding variables that may elucidate important factors that govern appropriate utilization of the restorative material.

There has been a tendency in recent articles to provide survival curves showing seeming differences without providing statistical analysis to evaluate differences between or among groups. Likewise, the increased willingness of researchers to publish in nonrefereed journals is a disturbing trend, and often the “data” presented appear to be more of a marketing effort than a scientific investigation. There is no substitute for a carefully performed clinical evaluation of large numbers of units and subjects who are followed over a prolonged period of time and the use of appropriate sta-

References tistical analysis to report results. If high standards of clinical investigation are not adhered to, patient care will ultimately be compromised.

Practice-based research, particularly in a network, is now recognized as an emerging and important method to answer the need for large-scale high-quality studies of the effectiveness of new materials, techniques, and changes in restoration design on outcomes for patients. Only in this manner can the profession provide reliable guidance to its clinicians about what works best in practice. With the significant decline in funded research in this area, it is obvious that this type of practice-based research will become an increasingly important source of information.

This chapter has described a formal PBRN structure and presented some study design examples to illustrate how the PBRN system could be applied to the analysis of outcomes for all-ceramic restorations. Practitioners working together are likely to play an important role in studying and reporting on the performance of many of the newer ceramic materials, with varying preparation design, methods of fabrication, and cementation methods. These practicebased research groups have the potential to study large numbers of patients over an extended period of time, filling the void created by the decline in funded research support.

References 1. Hart TC, Pihlstrom BL, Tabak LA. Oral health research at the crossroads: Translate we must! J Endod 2004;30:684–688.

2. Rogers MA. What are the phases of intervention research? American Speech-Language-Hearing Association. http://www.asha.org/ academic/questions/PhasesClinicalResearch/. Accessed 17 January 2014.

3. Agency for Health Care Research and Quality, US Department of Health and Human Services. Practice-Based Research Networks 2011. http://pbrn.ahrq.gov/pbrn-registry. Accessed 17 January 2014.

4. Curro F, Craig R, Thompson VP. Practice-based research networks and their impact on dentistry: Creating a pathway for change in the profession. Compend Contin Dent Educ 2009;30:184–187.

5. Curro FA, Vena D, Naftolin F, Terracio L, Thompson VP. The PBRN initiative: Transforming new technologies to improve patient care. J Dent Res 2012;91(7 suppl):12S–20S. 6. Green LA, Hickner J. A short history of primary care practice-based research networks: From concept to essential research laboratories.

J Am Board Fam Med 2006;19:1–10.

7. Lanier D. Primary care practice-based research comes of age in the United States. Ann Fam Med 2005;3(suppl 1):S2–S4.

8. The American Recovery and Reinvestment Act of 2009. Pub L No. 111-5, 123 Stat 15.

9. Clancy C, Collins FS. Patient-Centered Outcomes Research Institute: The intersection of science and health care. Sci Transl Med 2010;2(37):37cm18.

10. Kamerow D. PCORI: Odd name, important job, potential trouble. Br Med J 2011;342:d2635.

11. Slutsky JR, Clancy CM. Patient-centered comparative effectiveness research: Essential for high-quality care. Arch Intern Med 2010; 170:403–404.

12. Health Care and Education Reconciliation Act of 2010. Pub L No. 111–152, 124 Stat 1029.

13. Manchikanti L, Caraway DL, Parr AT, Fellows B, Hirsch JA. Patient Protection and Affordable Care Act of 2010: Reforming the health care reform for the new decade. Pain Physician 2011;14:E35–E67.

14. Manchikanti L, Falco FJ, Benyamin RM, Helm S 2nd, Parr AT, Hirsch JA. The impact of comparative effectiveness research on interventional pain management: Evolution from Medicare Modernization Act to Patient Protection and Affordable Care Act and the PatientCentered Outcomes Research Institute. Pain Physician 2011;14: E249–E282.

15. Williams RL, Rhyne RL. No longer simply a practice-based research network (PBRN): Health improvement networks. J Am Board Fam Med 2011;24:485–488.

16. Advisory Committee on Trainng in Primary Care Medicine and Dentistry, Seventh Annual Report to the Secretary of the US Department of Health and Human Services and to Congress. Coming Home: The Patient-Centered Medical-Dental Home in Primary Care Training, December 2008. http://www.hrsa.gov/advisorycommittees/ bhpradvisory/actpcmd/Reports/seventhreport.pdf. Accessed 17 January 2014.

17. Hujoel PP, Powell LV, Kiyak HA. The effects of simple interventions on tooth mortality: Findings in one trial and implications for future studies. J Dent Res 1997;76:867–874.

18. American Dental Association. ADA explores growth of large group practices. 9 April 2012. http://www.ada.org/news/6947.aspx. Accessed 17 January 2014.

19. Stephens MB, McKenna M, Carrington K. Adult learning models for large-group continuing medical education activities. Fam Med 2011;43:334–337.

20. Matthew-Maich N, Ploeg J, Jack S, Dobbins M. Transformative learning and research utilization in nursing practice: A missing link?

Worldviews Evid Based Nurs 2010;7:25–35.

21. Gilbert GH, Richman JS, Gordan VV, et al. Lessons learned during the conduct of clinical studies in the dental PBRN. J Dent Educ 2011;75:453–465.

22. International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH). ICH Harmonised Tripartate Guideline. Guideline for Good Clinical Practice. E6(R1). 10 Jun 1996. http://www.ich.org/fileadmin/Public_ Web_Site/ICH_Products/Guidelines/Efficacy/E6_R1/Step4/E6_ R1__Guideline.pdf. Accessed 3 January 2014.

23. Curro FA, Grill AC, Thompson VP, et al. Advantages of the dental practice-based research network initiative and its role in dental education. J Dent Educ 2011;75:1053–1060.

24. Patient-Centered Outcomes Research Institute 2012. PatientCentered Outcomes Research. http://www.pcori.org/research-wesupport/pcor/. Accessed 17 January 2014.

25. Patient-Centered Outcomes Research Institute 2012. Research Methodology. http://www.pcori.org/research-we-support/researchmethodology-standards/. Accessed 17 January 2014.

26. Botello-Harbaum MT, Matthews AG, Collie D, et al. Level of oral health impacts among patients participating in PEARL: A dental practice-based research network. Commun Dent Oral Epidemiol 2012;40:332–342.

27. Sischo L, Broder HL. Oral health-related quality of life: What, why, how, and future implications. J Dent Res 2011;90:1264–1270.

28. Veitz-Keenan A, Barna JA, Strober B, et al. Treatments for hypersensitive noncarious cervical lesions: A Practitioners Engaged in Applied Research and Learning (PEARL) Network randomized clinical effectiveness study. J Am Dent Assoc 2013;144:495–506.

29. Bernstein SD, Horowitz AJ, Man M, et al. Outcomes of endodontic therapy in general practice: A study by the Practitioners Engaged in Applied Research and Learning Network. J Am Dent Assoc 2012; 143:478–487.

30. Spielman H, Schaffer SB, Cohen MG, et al. Restorative outcomes for endodontically treated teeth in the Practitioners Engaged in Applied Research and Learning network. J Am Dent Assoc 2012; 143:746–755.

31. Anusavice KJ. Standardizing failure, success, and survival decisions in clinical studies of ceramic and metal-ceramic fixed dental prostheses. Dent Mater 2012;28:102–111.

43

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Practice-Based Research on the Effectiveness of Ceramics 32. Wang X, Fan D, Swain MV, Zhao K. A systematic review of allceramic crowns: Clinical fracture rates in relation to restored tooth type. Int J Prosthodont 2012;25:441–450.

33. Beier US, Kapferer I, Dumfahrt H. Clinical long-term evaluation and failure characteristics of 1,335 all-ceramic restorations. Int J Prosthodont 2012;25:70–78.

34. Rinke S, Schäfer S, Roediger M. Complication rate of molar crowns: A practice-based clinical evaluation. Int J Comput Dent 2011;14: 203–218.

35. Sorrentino R, Galasso L, Tete S, De Simone G, Zarone F. Clinical evaluation of 209 all-ceramic single crowns cemented on natural and implant-supported abutments with different luting agents: A 6-year retrospective study. Clin Implant Dent Relat Res 2012;14:184– 197.

36. Zembic A, Bosch A, Jung RE, Hämmerle CH, Sailer I. Five-year results of a randomized controlled clinical trial comparing zirconia and titanium abutments supporting single-implant crowns in canine and posterior regions. Clin Oral Implants Res 2012;24:384–390.

37. Reiss B. CSA: The online portal for determining the clinical standing of ceramic restorations in practice. Int J Comput Dent 2011;14:243– 253.

38. Malament KA, Grossman DG. The cast glass-ceramic restoration. J Prosthet Dent 1987;57:674–683.

39. Malament KA, Socransky SS. Survival of Dicor glass-ceramic dental restorations over 14 years. 1. Survival of Dicor complete coverage restorations and effect of internal surface acid etching, tooth position, gender, and age. J Prosthet Dent 1999;81:23–32.

44

40. Malament KA, Socransky SS. Survival of Dicor glass-ceramic dental restorations over 14 years. 2. Effect of thickness of Dicor material and design of tooth preparation. J Prosthet Dent 1999;81:662–667.

41. Malament KA, Socransky SS. Survival of Dicor glass-ceramic dental restorations over 16 years. 3. Effect of luting agent and tooth or tooth-substitute core structure. J Prosthet Dent 2001;86:511–519.

42. Malament KA, Socransky SS, Thompson V, Rekow D. Survival of glass-ceramic materials and involved clinical risk: Variables affecting long-term survival. Pract Proced Aesthet Dent 2003;suppl:5–11.

43. Lawn B, Pajares A, Zhang Y, et al. Materials design in the performance of all-ceramic crowns. Biomaterials 2004;25:2885–2892.

44. Rekow ED, Zhang G, Thompson V, Kim JW, Coehlo P, Zhang Y. Effects of geometry on fracture initiation and propagation in allceramic crowns. J Biomed Mater Res B Appl Biomater 2009;88:436– 446.

45. Zhang Y, Lawn BR, Malament KA, Van Thompson P, Rekow ED. Damage accumulation and fatigue life of particle-abraded ceramics.

Int J Prosthodont 2006;19:442–448.

46. Malament KA, Socransky SS. Survival of Dicor glass-ceramic dental restorations over 20 years. 4. The effects of combinations of variables. Int J Prosthodont 2010;23:134–140.

47. Pjetursson BE, Sailer I, Zwahlen M, Hämmerle CH. A systematic review of the survival and complication rates of all-ceramic and metal-ceramic reconstructions after an observation period of at least 3 years. 1. Single crowns. Clin Oral Implants Res 2007;18(suppl 3):73–85 [erratum 2008;19:326–328].