Oral Hygiene Jan/Feb 2023

4 BRIEFS

The new Cervitec Gel is recommended especially for the care of at-risk areas. The oral care gel with optimized care formula contains chlorhexidine, fluoride, xylitol and provitamin D-panthenol.

12

PREPROCEDURAL MOUTH

RINSES: A 2023 UPDATE

Prof. Laurie Walsh looks at the benefits of the consistent recommendation during the COVID pandemic to have dental patients use mouth rinses at the start of the dental visit

22 AN UPDATE ON COVID-19 FOR 2023

As we enter the 4th year of the pandemic, it’s fitting to reflect on the successes of 2022 and to ponder the challenges of 2023 reports Prof. Laurie Walsh

28

TAKING A PRACTICAL APPROACH TO AEROSOL MANAGEMENT IN DENTAL PRACTICE

During the pandemic, there has been an explosion of interest from manufacturers who have seen a more receptive market for devices and technologies that aim to improve air quality in dental practice explains Prof. Laurie Walsh

34 6 MYTHS ABOUT INSTRUMENT MANAGEMENT SYSTEMS

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Publisher & Editor: Joseph Allbeury

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Oral Hygiene (formerly Auxiliary) ISSN 1323-4919 is printed in Australia and published six times per year by Main Street Publishing P/L ABN 74 065 490 655 • PO Box 586, Cammeray 2062

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© 2023. All rights reserved. The contents of this magazine are copyright and must not be reproduced without the written permission of the publisher. Permission to reprint may be obtained upon application. Correspondence and manuscripts for publication are welcome. Although all care is taken, the editor and publisher will not accept responsibility for the opinions expressed by contributors to this magazine, or for loss or damage to material submitted for publication.

New Cervitec Gel with optimized care formula

The new Cervitec Gel is recommended especially for the care of at-risk areas. The oral care gel with optimized care formula contains chlorhexidine, fluoride, xylitol and provitamin D-panthenol. With the new formula, Cervitec Gel protects the teeth, gums, peri-implant tissue and mucuous membrane with even more efficiency. Cervitec Gel supports the treatment of gingivitis, mucositis, denture stomatitis, periodontitis and peri-implantitis and helps combat elevated bacterial counts. It prevents inflammation and freshens breadth. Provitamin D-panthenol and xylitol moisturize and protect the gums and mucous membrane. Depending on the situation, the gel is applied either directly on the oral mucous membrane or removable restoration and distributed with an interdental brush or used to brush teeth. Given its smooth consistency, the clear gel can be optimally distributed on complex surfaces, e.g. implant restorations. Cervitec Gel can be applied in the dental office or at home. Cervitec Gel is widely accepted due to its mild taste. The soothing ingredients leave a pleasant feeling in the mouth. Available from Ivoclar on 1300-486-252 or visit www.ivoclar.com

3 ways to get the most out of

When people want to find a dentist, they mostly use the internet and Google “Dentist in...”. That’s what the research shows. Word of mouth is no longer king! Google only shows 3 or 4 individual dental practices on the first page of its search results. The other results returned are for, among other things, the website www.dentist.com.au. This directory lists all practices and practitioners and is searched a million times a year.

Get Listed! If you’re listed on dentist.com.au, your phone will ring! So just do it!

Upgrade your listing: Just like in Google, where your practice sits in the dentist.com.au search results list determines how often your phone rings. If you’re at the top of the list, then your phone will ring more often and if there is more detailed information listed about your practice, then this helps too. Unlike Google, you can increase your priority in searches for an annual fee. This increases your prominence in searches for your home suburb and often also in the surrounding suburbs. Plus you can add heaps of detailed information about your practice and practitioners.

Add your link for online bookings. If you accept online bookings, then once you’ve upgraded your listing, you can add the link to accept online bookings through your preferred booking engine and this will appear directly in the search results list. For details on how to upgrade, visit: dentist.com.au/information-for-dentists

Dental treatments are inherently associated with potentially infective aerosols, as well as splashes of blood and saliva. This study measured the extent of contamination of protective eyewear during different dental treatments, and also the efficacy of the subsequent disinfection procedures for that eyewear. A range of different aerosol-producing dental treatment modalities were performed in clinic, using normal dental suction, namely supragingival cleaning, subgingival periodontal instrumentation, endodontic access and root canal treatment, and cavity preparation within carious teeth. The 53 face shields worn by the students, dentists and dental assistants who performed these procedures were analysed, using forensic techniques. To detect blood contamination, luminol solution was applied onto the surface of the face shields. A special forensic test paper was used to visualize saliva contamination. The face shields were decontaminated and then the same analyses were conducted. Macroscopically detectable contamination was found on 60.4% of face shields. Contamination with blood was detected on all shields after dental treatment. The area covered by blood was measured (median 330 pixels), and was equivalent to 0.3% of the total surface. The extent of blood contamination differed between treatments, with the most found after professional tooth cleaning (median 1,087 pixels). There were also significant differences in the extent of saliva contamination between the different measurements. Decontamination procedures for the face shields removed all saliva but left traces of blood (covering 0.02% of the total surface area). Decontamination procedures for face shields are effective against saliva contamination. However, after decontamination, macroscopically clean face shields may have up to 12% surface contamination with blood. Based on the results, it may be concluded that protective eyewear is essential for each dental practitioner. Decontamination of face shields after each patient is essential.

Bergmann N, et al. Blood and saliva contamination on protective eyewear during dental treatment. Clin Oral Investig. 2022; 26(5): 4147-4159.

For long-term quality assurance of implant-supported restorations

For long-term quality assurance of implant-supported restorations

In my surgery...

“One of the products I was most excited about was the Synapse Dental Pain Eraser. It’s a needle-free and pain-free way to provide numbing for patients! It works on alteration of nerve activity, also known as neuromodulation. Crossing my fingers we get this in Australia soon!”

By Tabitha Acret

Late last year, I was lucky enough to attend the Greater New York Dental Meeting at the Javits Center in New York City and it was really exciting to see some of the new products available that will hopefully make it to Australia soon!

Synapse Dental Pain Eraser

One of the products I was most excited about was the Synapse Dental Pain Eraser. It’s a needle-free and pain-free way to provide numbing for patients! It works on alteration of nerve activity, also known as neuromodulation. It’s a large pen-like device that has a flashing blue light at the end and it’s applied directly onto soft or hard tissues to prevent or alleviate dental pain. It can be used at home for patients with orthodontic pain or in surgery for debridement or shallow fillings. Unfortunately, its not currently TGA listed for Australia so the sample I was given I could only use on myself but it was AMAZING! I really feel this is going to change dentistry dramatically for sensitive and needle phobic patients. Crossing my fingers we get this in Australia soon!

Biogaia Oral Probiotics

This is an area in dentistry I am watching closely, BioGaia has launched a probiotic lozenge in the USA that contains lactic acid bacterium and prodentis which both help good microorganisms keep a natural balance in the mouth. It will be interesting to see the research that comes out of the use of oral probiotics – at the moment this is still a watch this space for me, but I am watching closely.

Designs for Vision

Fluorescence headlights for loupes is something new. Designs for Vision’s new REVEALTM FGS system uses fluorescence to show where bacteria is in the mouth. We played with them at the booth, it makes biofilm in cracks and microscopic areas glow orange which really helps when looking at margins and for post debridement that everything was removed.

There is some really great stuff happening in the space of dentistry and I’m excited to see when it will make it to Australia.

About the author

Tabitha Acret graduated from Newcastle University with a Bachelor of Oral Health and is currently studying her Masters in Public Health. She was previously the National VicePresident for the DHAA. Tabitha currently works as a clinical educator for implant maintenance and non-surgical periodontal therapy and lectures nationally and internationally on motivating patients, implant maintenance, disease prevention and periodontal therapy. Outside of her busy work life of lecturing and working clinically in private practice, Tabitha enjoys volunteering both locally and internationally to raise awareness and education of the benefits of good oral health. She was the winner of the 2018 leadership award in dental hygiene and 2019 award for clinical excellence.

Lunos® for premium prophylaxis

Safe and effective powder jet treatment with a feel-good factor

The Lunos prophylaxis system from Dürr Dental offers a range of products to help with all aspects of the prophylaxis session. The Lunos Prophy Powders Gentle Clean and Perio Combi, as well as the MyLunos powder jet handpiece, ensure that patients receive an air-polishing treatment that is both effective and comfortable.

The MyLunos handpiece is ideal for reprocessing manually and automatically and can be disassembled into its component pieces for placement into an ultrasonic bath and sterilisation unit. The handpiece’s precise balance allows for ergonomic, fatigue-free working, while the convenient exchangeable chamber approach gives much flexibility while

saving a tonne of time. The powder container may be easily changed on the handpiece, preventing the inconvenience of having to stop treating the patient to complete a time-consuming refilling operation. Powder containers are available in four colours: blue, orange, mint green and purple. These different colours can be used to help with the organisation and planning of prophylaxis treatments. For example, the container colours can be assigned to certain treatment rooms or specific powder variants.

Lunos Prophy Powders Gentle Clean and Perio Combi are the latest-generation of low-abrasive prophy powders made mostly of the water-soluble disaccharide trehalose. As an abrasive material,

Trehalose is gentle on surfaces while still providing effective cleaning and this leads to more comfort for patients and minimal invasiveness during treatment. Additionally, Trehalose’s excellent solubility protects suction systems and preserves their value. It is ideal to offer different flavours or a neutral option during prophylaxis treatments for patient comfort, accommodating different tastes and preferences while considering those who have allergies.

Lunos Prophy Powder Gentle Clean is available in the flavours Neutral (for patients at risk of allergies), as well as Orange and Spearmint. It is suitable for supragingival cleaning and removing extrinsic discolouration for general

hygiene appointments, around orthodontic brackets or before fissure sealants. The 30 μm particle size of Lunos Prophy Powder Perio Combi makes it perfect for recall appointments. It effectively removes biofilm subgingivally, makes it easy to clean around implants and removes slight discolouration supragingivally. This neutral-tasting powder is ideal for patients who are sensitive to flavours.

For more information on how MyLunos can improve your practice, contact Dürr Dental’s Product & Hygiene Specialist, Mina Farag, on 0437-799-323 or email mina.farag@duerrdental.com. Alternatively, you can contact your local Henry Schein Relationship Manager today.

Piksters win a Canstar Blue Award! Best-Rated Dental Floss & Picks 2023

Piksters has won a Canstar Blue Award for “Most Satisfied Customers” for the “Dental Floss & Picks” category, coming in above big name multi-national players such as Oral-B, Colgate and Sensodyne.

“Piksters was the favourite pick of shoppers in Canstar Blue’s dental floss and pick ratings, winning 5-star reviews for ease of use, effectiveness, packaging convenience, taste and overall satisfaction,” read the Canstar Blue citation.

Earning a Canstar Blue Award is a tribute to Piksters’ commitment to their customers which echoes Megan Doyle’s (Canstar Blue CEO) statement - “When you see the Canstar Blue Award logo, know that you’ve got a dedicated team and brand behind you every step of the way.”

“The gap between your teeth is where most big dental problems start. We have been working on easier and better ways

Erskine Oral Care (parent company of Piksters).

The Piksters “Dental Floss & Picks” range includes:

• Piksters Interdental Brushes

• Piksters Interpik

• Piksters Pikstix

• Piksters HydroPik Water Flosser

• Piksters Eco Charcoal Floss Picks

• Piksters SupaGRIP Floss Picks

• Piksters Gorilla Floss

Piksters is known for their leading interdental brush widely distributed throughout dental, grocery and pharmacy channels.

Oral care is their specialty. Piksters’ products span across categories such as floss, toothbrushes, toothpaste and teeth whitening. The company strives to bring innovative, new and improved products to the market that represent high quality and value to dental professionals and consumers.

to clean that gap for 30 years and it’s nice to see we’re having some success,” said Dr Craig Erskine-Smith BDS, CEO of

Learn more at the consumer website www.piksters.com and for dental professionals www.pikstersdental.com

Preprocedural mouth rinses: A 2023 update

By Emeritus Professor Laurence J. Walsh AO

In Australia during the COVID-19 pandemic, there has been a consistent recommendation to have dental patients use mouth rinses at the start of the dental visit as one of the layers of risk reduction, in combination with other measures such as high-volume evacuation.

This article summarises the key findings published in the last 18 months of work in this field, developing further the literature around how preprocedural mouth rinses can be used effectively as a risk reduction measure in dental practices. My previous articles on this topic reviewed laboratory microbiological studies of viral inactivation by mouth rinses and their components (such as

excipients). Now, during the pandemic, several research groups have undertaken clinical studies using commercial products and hence one can now move beyond laboratory studies to discuss how various mouth rinses have performed in the setting of the pandemic, where issues such as acceptability and feasibility may be quite different from studies undertaken at times outside a pandemic.

The 2022 Cochrane review

ACochrane review that appeared in August 20221 used standard, extensive Cochrane search methods, and included literature published up to February 2022, focusing only on randomised controlled trials. The Cochrane review was designed to assess the effects of preprocedural mouth rinses used in dental clinics to minimise incidence of infection in dental healthcare

providers and reduce or neutralise contamination in aerosols. A total of 17 studies were included in this Cochrane review and all of the participants in the included studies were adults (830 participants aged 18 to 70 years).

None of the 17 studies actually measured the incidence of COVID-19 infection in dental staff. Instead, they measured the extent of reduction in the level of bacterial contamination, at distances of less than 2 metres from the patient’s mouth (larger droplets) and more than 2 metres (aerosols). There are some obvious limitations to following such an approach and the studies were measuring bacteria rather than viruses.

In that regard, it is unclear what size of reduction in bacterial levels represents a clinically useful reduction in levels of virus.

Compared with no rinsing or rinsing with water, reductions were found for chlorhexidine, essential oils (Listerine™) and quaternary ammonium compounds such as benzalkonium chloride. The evidence from head-to-head comparisons was limited and inconsistent.

Several important limitations were noted. The studies did not provide any information on costs, change in microorganisms in the patient’s mouth or adverse events such as temporary discolouration, altered taste, allergic reactions or hypersensitivity. The studies did not assess acceptability of the intervention to patients or feasibility of implementation for dentists.

Not surprisingly, the authors of the Cochrane review pointed out that further studies are needed that measure the effect of rinses on infectious disease risk among dental healthcare providers and on the infectivity of contaminated aerosols.

Other recent systematic reviews

Similar conclusions were reached in an October 2021 systematic review,2 which included 13 studies. That review also focused on whether using mouth rinse could influence the risk of infection or the rate of progression of infection. The commonly used antimicrobial mouth rinses were found to exert significant

virucidal activity against SARS-CoV-2 in saliva. They concluded that the effective mouth rinses were povidone iodine, chlorhexidine and essential oils, but again noted how the available studies did not assess actual COVID-19 infection outcomes. Overall, these and other systematic reviews undertaken over the past 2 years have reinforced recommendations regarding the use of mouth rinses, albeit with the caveats already mentioned.

One must remember that the formulations used in different clinical studies around the world are not directly comparable, because even the same product type may have different excipients when manufactured by another company. These excipients, such as ethanol, surfactants and flavours, can in themselves exert potent antiviral actions, which can amplify the effect of the named active ingredients. This is also why there is not always a direct correlation between testing a single pure active ingredient in the laboratory and testing a commercial preparation with the same active ingredient in the laboratory, or in clinical practice.

From lab bench to clinic

Anarrative review published in July 20223 included a useful summary of 13 laboratory studies which tested, in the laboratory, the antiviral efficacy of povidone iodine, chlorhexidine, essential oils, hydrogen peroxide and benzalkonium chloride. All these active ingredients inactivated different clinical strains of SARS-CoV-2 after 15 or 30 seconds of contact. The authors of this review concluded that, based on these laboratory studies, rinses with these active ingredients could reduce the viral load in the oral cavity and, thereby, the likelihood of transmission of SARS-CoV-2 during dental procedures.

This same narrative review also included nine controlled clinical trials, which showed reductions in SARS-CoV-2 viral load in patients who were infected, with somewhat lower efficacy for hydrogen peroxide and a slightly lower duration of effect, which may be due to its inactivation by salivary enzymes. They commented on the high acceptability of mouth rinses with concentrations of hydrogen peroxide below 1.5%, but cautioned that going below 1% appeared to considerably reduce the therapeutic action on the virus.

The authors also noted that 1% povidone iodine seemed to work faster than other mouth rinse types in terms of the rate of reduction in viral load. A 1% concentration of povidone iodine is below the levels that are considered irritant or toxic to the oral mucosa.

The review also pointed out the useful features of quaternary ammonium compounds such as cetyl pyridinium chloride, which in most studies gave results comparable to those of chlorhexidine. They also included in their review studies which showed reductions in viral load after rinsing with Listerine.

Perhaps the most useful contribution of the narrative review, however, is its discussion of the various pathways and mechanisms that may be operating when mouth rinses are used. These include the mass dilution effect, which will be discussed later. While it is clear that the active ingredients and some of the excipients in mouth rinses can disrupt viral envelopes or act on viral proteins, it is important to discount the notion that the active mouth rinse components work by cytotoxic effects on virally infected cells. All oral antiseptics exhibit antiviral activity when used at levels that are not cytotoxic to human cells.

Air cleaner filter analysis

One of the most interesting studies published in early 2022 tested the presence of SARS-CoV-2 genetic material on HEPA filters from portable air cleaners that had been used in a dental facility in Spain for three months during one of the Covid-19 pandemic peaks.4

Based on the measured levels of carbon dioxide (around 900 ppm), the ventilation in the clinic where the study was done was rated as poor.

The researchers compared the filters in the waiting room where patients had not yet undergone mouth rinsing, with those in the treatment rooms where patients had undertaken mouth rinsing. The particular mouth rinse used in that study was 1% hydrogen peroxide used for 60 seconds.

Importantly, viral load was only found in filters that had come from the waiting room - but not in those from the treatment rooms.

As the study was conducted during a major pandemic peak (in this case, the third wave in Spain), it provides a useful real-world assessment of the efficacy of mouth rinses.

Gaps in the literature

One of the limitations in the available literature is that the molecular methods which are used to detect and quantify viral load will not be able to distinguish between viable versus non-infective viral particles. Studies do not culture samples to confirm the presence of viable infectious virus. This might seem like an unfair criticism, since laboratories that can do this are very few in number around the world and require special laboratory conditions such as biosafety level 4 precautions.

New formulations

There are always continual developments in formulations, with several new types of materials entering the mouth rinse category that may be of interest, including molecular iodine, beta-cyclodextrin + Citrox® (flavonoids), hypochlorous acid, octenidine, d-limonene and iota-carrageenan.5,6 Preliminary laboratory studies of antiviral actions of all of these have been undertaken over the past 18 months, but those results remain to be confirmed in other laboratories and documented in randomised controlled clinical trials.

Real world application

In patients with symptomatic infection, their very high viral loads and the rate of release of virus from infected cells in the oral tissues limits how much suppression can be achieved using mouth rinses. After all, the use of a preprocedural mouth rinse is not a panacea. Results from studies conducted in a general dental practice setting may well be different from those conducted in the COVID-19 ward of a local hospital, where patients will have been admitted because of serious illness. Those patients will have a very high viral load. Proper triage of dental patients will prevent those with serious acute COVID-19 illness from presenting to dental practice.

Indeed, there is good evidence from studies published in late 20227 that in patients with symptomatic COVID-19 infection, intact virus particles will be found not only in the saliva, but also in dental plaque and in crevicular fluid. This is because the oral cavity can be a niche for viral infection, with replication of the virus occurring in oral tissues, including the salivary glands. This is why such

studies have demonstrated the presence of oral epithelial cells that contain virus and have microscopic features of active viral infection, including vacuoles filled with particles ready to be released.

Waterline disinfectants are the silent partners

Finally, when considering the strategy of using mouth rinses, one should remember that part of their action is bulk dilution of the saliva and other oral fluids by the volume of the mouth rinse used and then by the water rinse which follows it. Given that the typical volume of saliva at rest in the mouth is in the order of 1.5 mL, this dilution effect can be greater than 50-fold. There is also further dilution of the saliva that occurs during a dental appointment because of the irrigants that flow through the dental unit waterlines, into the triple syringe and into various dental handpieces. In a paper which appeared in September 2022, the important finding was reported that commonly used dental unit waterlines disinfectants reduce the viability of viruses.8 This was demonstrated using the virus Bacteriophage MS2 as the target. This phage infects Escherichia coli and has structural similarity to several human viral pathogens (e.g., rhinoviruses, adenoviruses, coronaviruses). The water line treatment products that were tested comprised A-dec ICX™ (silver nitrate and hydrogen peroxide) and Alpro Apron™ which contains chloramine-T and polyhexanide biguanide. Both agents reduced the viability of this phage and when present in waterlines, reduced dispersion of viable virus into the simulated dental clinical setting.

The authors of that study commented that water line disinfectants have been

working silently to reduce the viability of viruses and the dispersion of pathogens from the mouth within aerosols and droplets. One could consider them having an action somewhat like a mouth rinse, but one that is present at all times. One could also conclude that such waterline disinfectants work in partnership with mouth rinses as a mitigation factor during infectious disease outbreaks/pandemics.

Conclusions

Looking to the future, there is likely to be ongoing interest in the antiviral actions of mouth rinses. One can expect greater recognition of the ways that residues of mouth rinse ingredients that are substantive and can be released over time (such as chlorhexidine) may work in partnerships with waterline disinfectants to keep levels of virus in the saliva low.

References

1. Nagraj SK et al. Preprocedural mouth rinses for preventing transmission of infectious diseases through aerosols in dental healthcare providers. Cochrane Database Syst Rev 2022; 8(8): CD013826.

2. Verma SK et al. Effectiveness of mouthwash against viruses: 2020 perspective. A systematic review. Minerva Dent Oral Sci. 2021;70(5):206-213.

3. Bernal CGG et al. Oral antiseptics against SARSCoV-2: a literature review. Int. J. Environ. Res. Public Health 2022; 19: 8768.

4. Burgos-Ramos E at al. Is hydrogen peroxide an effective mouthwash for reducing the viral load of SARS-CoV-2 in dental clinics? Saudi Dent J. 2022; 34(3): 237-242.

5. Garcia-Sanchez A et al. Virucidal activity of different mouthwashes against the salivary load of SARS-CoV-2: a narrative review. Healthcare 2022; 10: 469.

6. Garcia-Sanchez A et al. Efficacy of pre-procedural mouthwashes against SARS-CoV-2: a systematic review of randomized controlled trials. J. Clin. Med. 2022; 11: 1692.

7. Belhaouari DB et al. Microscopic observations of SARS-CoV-2 like particles in different oral samples. Eur J Oral Sci. 2022; 130: e12903.

8. Allison JR et al. Waterline disinfectants reduce dental bioaerosols: a multitracer validation. J Dent Res. 2022; 101(10): 1198–1204.

About the author

Emeritus Professor Laurence J. Walsh AO is a specialist in special needs dentistry who is based in Brisbane, where he served for 36 years on the academic staff of the University of Queensland School of Dentistry, including 21 years as Professor of Dental Science and 10 years as the Head of School. Since retiring in December 2020, Laurie has remained active in hands-on bench research work, as well as in supervising over 15 research students at UQ who work in advanced technologies and biomaterials and in clinical microbiology. Laurie has served as Chief Examiner in Microbiology for the RACDS for 21 years and as the Editor of the ADA Infection Control Guidelines for 12 years. His published research work includes over 390 journal papers, with a citation count of over 18,300 citations in the literature. Laurie holds patents in 8 families of dental technologies. He is currently ranked in the top 0.25% of world scientists. Laurie was made an Officer of the Order of Australia in January 2018 and a life member of ADAQ in 2020 in recognition of his contributions to dentistry.

Preprocedural mouth rinses: A 2023 update

IQuestion 1. What has been working silently to reduce the viability of viruses and the dispersion of pathogens from the mouth?

a. Rinses containing chlorhexidine

b. Listerine

c. Waterline disinfectants

d. Quaternary ammonium compounds

e. All of the above

Question 2. Ingredients that inactivate SARS-CoV-2 include:

a. Povidone iodine

b. Chlorhexidine

c. Essential oils

d. Hydrogen peroxide

e. All of the above

Question 3. Excipients used for the long-term stabilisation of mouth rinses that also exert potent antiviral actions include:

a. Surfactants

b. Flavours

c. Ethanol

d. All of the above

Question 4. Intact virus particles can be found in symptomatic COVID-19 infected patients in their:

a. Saliva

b. Dental plaque

c. Crevicular fluid

d. All of the above

Question 5. The mouth rinse active ingredient that worked fastest in terms of the rate of reduction in viral load is:

a. Chlorhexidine

b. Povidone iodine

c. Essential oils

d. Hydrogen peroxide

An update on COVID-19 for 2023

AQuestion 6. Total confirmed cases of COVID-19 globally exceed:

a. 550 million

b. 660 million

c. 770 million

d. 1 billion

Question 7. Australian data grossly under represent the true number of current COVID cases because...

a. Up to 40% of cases are asymptomatic.

b. Only GP doctors can order PCR tests.

c. Positive RAT test results are often not reported.

d. All of the above.

Question 8. Symptoms of LONG COVID are found in what percentage of the population:

a. 1.5-2%

b. 2-3%

c. 3-5%

d. 6-7%

Question 9. An antiviral drug used to treat COVID-19 is...

a. Penciclovir

b. Paxlovid

c. Promethazine

d. Peramivir

Question 10. An Omicron sub-variants in circulation during late 2022 is known as:

a. BA.1

b. BA.2

c. BA.3

d. XBB

e. All of the above

myths about Instrument Management Systems

Question 11. How many litres of air does HVE remove?

a. 100 litres per minute

b. 150 litres per minute

c. 200 litres per minute

d. 250 litres per minute

e. 300 litres per minute

Question 12. An alternative to HEPA air filtration is...

a. An open window

b. UVC light treatment

c. Reverse osmosis

d. All of the above

Question 13. Air quality can be improved by using a preprocedural antimicrobial mouthwash on every patient...

a. True

b. False

Question 14. Activated carbon filters absorb...

a. Aerosol particles

b. Volatile gases

c. Carbon dioxide

d. All of the above

Question 15. Aerosol particles settle onto surfaces in...

a. 1 to 2 hours

b. 2 to 3 hours

c. 3 to 4 hours

Question 16. IMS Cassettes take up too much space...

a. True

b. False

Question 17. Packing IMS Cassettes takes too long...

a. True

b. False

Question 18. IMS Cassettes make it more difficult for team members...

a. True

b. False

Question 19. IMS Cassettes take up too much space in autoclave...

a. True

b. False

Question 20. IMS Cassettes make staff turnover more difficult...

a. True

b. False

d. 4 to 5 hours POWERED

Infection Control BOOT CAMP

ON DEMAND ONLINE LEARNING PROGRAMME

29 VIDEOS - 8+ HOURS OF EDUCATION

Presented by Emeritus Professor Laurence Walsh AO

BDSc, PhD, DDSc, GCEd, FRACDS, FFOP (RCPA), FFDT (RCS Edin)

Learn from Australia’s leading authority on infection prevention and control in dentistry about recent changes in infection control including from the Dental Board of Australia (July 2022), the ADA (4th edition guidelines August 2021 and the ADA Risk management principles for dentistry during the COVID-19 pandemic (October 2021)), the new guidelines from NHMRC (May 2019), Hand Hygiene Australia (Sept 2019) and the CDNA (Dec 2018) as well as recent changes in Australian Standards and TGA regulations that are relevant to infection control. The course provides a summary of how those changes interlink with one another and also covers practical implementation of the new requirements and what it means for everyday dental practice. Hear about the why and the how and keep up-to-date with the changes that are happening.

COURSE TOPICS

This one day course will cover changes in regulations and guidelines from 2018 to 2022 including:

n Risk-based precautions.

n Hand hygiene and hand care practices.

n Addressing common errors in personal protective equipment.

n Biofilm reduction strategies.

n Efficiency-based measures to improve workflow in instrument reprocessing and patient changeover.

n Correct operation of mechanical cleaners and steam sterilisers.

n Wrapping and batch control identification.

n Requirements for record keeping for instrument reprocessing.

n Correct use of chemical and biological indicators.

8 HOURS CPD

Laurie Walsh is a specialist in special needs dentistry who is based at the University of Queensland in Brisbane, where he is an emeritus professor. Laurie has been teaching and researching in the areas of infection control and clinical microbiology for over 25 years and was chief examiner in microbiology for the RACDS for 21 years. His recent research work includes multiple elements of infection control, such as mapping splatter and aerosols, COVID vaccines and novel antiviral and antibacterial agents. Laurie has been a member of the ADA Infection Control Committee since 1998 and has served as its chair for a total of 8 years, across 2 terms. He has contributed to various protocols, guidelines and checklists for infection control used in Australia and represented dentistry on 4 committees of Standards Australia and on panels of the Communicable Diseases Network of Australia and of the Australian Commission on Safety and Quality in Health Care.

Oral Hygiene Abstracts 2023

Contamination of surgical masks during dental treatment

By Emer. Prof. Laurence Walsh AO

Surgical masks are contaminated during dental treatments and can itself be a source of further contamination, posing a threat to dental staff and patients. The aim of the study was to investigate mask contamination during dental treatments, when wearing a face shield and having patients perform a pre-procedural mouth rinse with chlorhexidine (CHX). This was a prospective, randomised study. A total of 306 treatments were included: 141 single-tooth restorations and 165 treatments involving the total dentition (supra- and subgingival ultrasonic scaling for periodontal debridement). The treatment was delivered by second and third year dental students over an appointment of 60-90 mins. For all types of treatment, a lingual low speed saliva ejector was used with a 3.3 mm diameter tip (suction flow rate 1.1 litre/sec), as well as high-volume evacuation (8.0 mm tip, 6.0 litre/sec) held by an assistant near the aerosol source. The students wore tie-band medical surgical masks on top of FFP2/KN95 masks, with a face shield (Clever One) over the top. There were 3 intervention groups (each with n = 102). In group 1, participants rinsed for 60 sec with 0.1% CHX or with water before treatment. As a control, a non-rinsing group was included. A face shield was used above the surgical mask. After treatment, the front surface of the masks were imprinted onto agar plates which were incubated at 35°C for 48 hours. Colonies were counted. Bacteria were classified by phenotypic characteristics, biochemical assay methods and matrix-assisted laser desorption/ionisation time of flight mass spectrometry. The following results were obtained. Rinsing with water before treatment reduced CFU significantly in comparison with not rinsing group (mean 47 CFU versus 80 CFU for non-rinsing), while CHX was even better again (24 CFU), giving a further statistically significant reduction of bacterial contamination of the surgical mask. Mask contamination with bacteria was found routinely, with no significant differences between single tooth restorations or total dentition periodontal treatments. The most common bacteria recovered were Streptococcus spp., Staphylococcus spp., Micrococcus spp., and Bacillus spp., which represent both the oral flora and the skin flora. We conclude that a pre-procedural mouth rinse is useful and it will reduce the bacterial load on the surface of the surgical mask. However, contamination of the mask’s outer surface cannot be prevented completely by rinsing, nor even by applying a face shield.

Gund MP et al. CHX and a face shield cannot prevent contamination of surgical masks. Front Med (Lausanne). 2022; 9: 896308

Low rates of COVID-19 infections in dentists before vaccines became available

Oral health care settings carry a potentially higher risk of causing cross-infection between dentists and patients and among dental staff members due to close contact and use of aerosol-generating procedures. Past studies of COVID-19 infections in dentists and dental care professionals have come from studies in the United States, UK, France and China, with the largest study (from the US) reporting a prevalence of 0.9% for confirmed or probable cases of COVID-19 infection among 2,195 dentists. The present prospective study estimated COVID-19 incidence rates among a cohort of 644 Canadian dentists over a 6-month period from July 29, 2020 through February 12, 2021. This was after a lockdown and restrictions on dental care to only emergencies during March 2020. Early in the reopening phase during May, 2020, Canadian dental regulatory authorities published detailed infection control and prevention protocols for providing oral health care. Most of the sample had their primary practices in Quebec and Ontario and were serving a metropolitan or urban community An online questionnaire, adapted from the WHO’s Unity Studies protocols for assessment of COVID-19 risk among health care workers, was used to collect data on self-reported COVID infections every 4 weeks. 226 participants were also randomly invited from this group to provide saliva samples every 4 weeks to test for asymptomatic cases of infection. No SARS-CoV-2 was detected in any of the saliva samples from 224 participants during the study period. The median age of the dentists was 47 years; most were women (56.4%) and were general dental practitioners (90.8%). Only 6 of the 644 participants reported COVID-19 infections during the study period, giving an incidence rate of 5.10 per 100,000 person days (95% CI, 1.86 to 9.91). The incidence proportion was estimated to be 1,084 per 100,000 dentists (95% CI, 438 to 2,011) which was lower than the rate in the Canadian population during the same period (1,864 per 100,000 people (95% CI, 1,859 to 1,868). During the period of the study, the use of N95 respirators or higher-specification respirators was low - because of shortages - but it increased over time, as more of this PPE became available. Uptake of vaccinations is not a possible explanation for the observed low infection rates, as the study was beyond more than 4 months of the 6 month duration follow-up at the time the COVID-19 vaccination campaigns began in Canada. At the time of data analysis, the proportion of participants who had received at least 1 dose of the COVID-19 vaccine was low (only 5%), so this cannot explain the lower infection rates seen in dentists versus the general community during the study period. Overall, the low infection rate observed among dentists should be reassuring to the dental and general community. This lower rate may have been a reflection of an array of interacting factors, including but not limited to pre-procedure screening of patients and adherence to rigorous infection prevention and control protocols used during these procedures..

Madathil S et al. The incidence of COVID-19 among dentists practising in the community in Canada: A prospective cohort study over a 6-month period. J Am Dent Assoc. 2022; 153(5): 450-459.

An update on COVID-19 for 2023

By Emeritus Professor Laurence J. Walsh AO

As we enter the 4th year of the pandemic, it’s fitting to reflect on the successes of 2022 and to ponder the challenges of 2023, knowing that there is a larger “toolbox” of interventions and a growing evidence base to support recommendations that are aimed at reducing risks of acquiring infection in the workplace.

The big picture

As of January 2023, total confirmed cases of COVID worldwide exceed 660 million and the number of deaths surpassed 6.6 million. A simplistic assessment of the ratio of deaths to cases gives approximately 1% as an overall mean fatality rate,

but that grossly underestimates the dramatic impact of COVID in certain subpopulations (such as the elderly and the medically frail). In data published by the Australian government’s Department of Health, in a typical week across the summer of 2022-2023, there were around 230 deaths, bringing the tally for Australia to over 16,500 by the end of 2022.

A plot of the cumulative number of deaths in Australia shows sudden increases in the gradient when a wave occurs, as in July 2022 and again in December 2022. Driving these waves in 2022 was the enormous infectivity of the Omicron variants and sub-variants (such as BA.4 and BA.5), which have been the dominant circulating strains in Australia during 2022 (Figure 1A). These are far more infectious than the previous Alpha and Delta strains that circulated during 2020 and 2021. Omicron transmission by the aerosol route explains transmission through aerosol-generating behaviours, pathways and contamination of air when people are present in very dense or crowded environments.

The total prevalence of COVID infection in Australia has now surpassed the 50% mark. In other words, more people have had Covid in Australia than people who have not. Beyond this glaring statistic, current published Australian data grossly under represent the true number of current cases, since (1) up to 40% of cases are asymptomatic; (2) only GP doctors can now order PCR tests; and (3) people using RAT tests often will not go online to report their RAT test results. Long gone are the days of people lining up in large numbers to get PCR tests. Hence, the true numbers of people who are infected at any one time is now becoming rather “fuzzy”.

One place where data are more complete is for residential aged care facilities. These have shown waves of infections in both staff and in patients in July 2022 and December 2022. Those align with peaks of infection in waves that occurred in the community. An ongoing concern is that workers may bring the infection into their aged care workplace, giving it to residents. As well, between the various waves, there has been persistence of cases in aged care, even when there were few or no cases in the community (Figure 2B). One implication of this is that nursing homes could be a reservoir for outbreaks in the general community.

Why COVID was different in 2022

Unlike the previous 2 years, COVID in 2022 was different because rates of people being admitted to intensive care units and placed on ventilators were both very low, despite spikes in the rate of hospitalisations when waves of infection occurred (Figure 1B, Figure 2A). Even during the July 2022 and December 2022 waves, COVID was not a major reason for ICU admission or going onto a ventilator. This is a very different situation from what was occurring in 2020 and 2021, where COVID cases overwhelmed hospital ICU facilities and created shortages in available ventilators.

There are likely several reasons why this occurred.

1. Some level of herd immunity is now emerging, since large proportions of the population have had at least one bout of infection;

2. Extremely high vaccination rates, particularly for third and fourth vaccine doses; and

3. The availability of several highly effective antiviral drugs in early 2022 and an important change in Australian government policy in early July 2022, which made these drugs widely available to those in the community by prescription from a general medical practitioner. Since all three of these factors lower the severity of disease, there is also a growing time period between the onset of infection and death. The pattern in 2020 and 2021 was that when people had severe infections, they would take between 7 and 10 days to succumb. This time period is now stretching out. This is not only because of better antiviral therapy, but also because of a greatly enhanced evidence base on how to better manage more severe COVID cases once they are admitted to hospital.

More than 4 jabs?

Uptake of 4 doses of a vaccine has been strong in Australians who are 60 years of age and above (Figure 3A), as one would expect, because these individuals are well aware that their age is a risk factor for severe infection. Unvaccinated individuals tend to be younger. Vaccination rates for people who have had all 4 doses are lower in the Northern Territory and in Western Australia than in other parts of the country. This low uptake is even more problematic because of the very dispersed population in both of those jurisdictions.

An interesting development of recent times is the bivalent COVID vaccine from Moderna for use in people who are 18 years of age or older.

Figure 1. Panel A shows a 3-year cumulative view of COVID-19 deaths in Australia. Dots show the January dates. The first restrictions period in March 2020 is shown in red. Note the steep gradient of increase during 2022 due to Omicron. Panel B shows the 2022 calendar year data in terms of case notifications (blue line and right hand scale in thousands), hospitalisations (orange bars) and ICU admissions (pink bars). The arrows show the 2 major waves of infection - July (orange) and December (red).

This targets the original strain and also the Omicron strains and like other vaccines, provides protection from severe disease. There are also clinical trials underway in Australia of vaccines that cover not only COVID, but also influenza and respiratory syncytial virus (RSV) with the concept being to have a “universal annual booster” to cover several respiratory viral infections in the one injection. Bundling all the components into one injection may reduce vaccine fatigue and hesitancy.

Antiviral medicinesthe game changer

The Australian government’s decision to expand the use of antiviral medicines (Molnupravir, Paxlovid, etc) in the community by prescription in early July 2022 has likely been a major factor in “sparing the ventilators” throughout 2022. Despite large numbers of cases in the community and hence considerable numbers of hospitalisations, a lower proportion of cases ended up in ICU on a ventilator than in past years. This point has not been widely discussed in the mass media, despite it being one of the success stories of 2022.

The eligibility criteria that are used for prescriptions for oral antiviral agents are:

1. Being over 70 years of age, regardless of whether there are symptoms or additional risk factors. A positive PCR test result is sufficient justification;

2. Being 50 years of age or older, with two additional risk factors (e.g. moderate or severe asthma, disability, medical frailty, heart failure, etc); or

3. Those of Aboriginal or Torres Strait Islander background aged over 30 with one additional risk factor.

This approach is a good way to target these expensive but highly effective medicines to those who are most likely to experience the most severe disease. PBS usage data from July to December 2022 show a massive uptake of prescriptions on the PBS as those two waves occurred (Figure 3B).

Patients using these medicines were mostly adults aged 70+ and 50+ as one would expect. This targeted program using antiviral drugs is certainly being taken up well and has been effective at keeping down demand for ICU beds and for ventilators.

Back to the future?

There are concerns relating to the 2023 lunar New Year in late January and what that might lead to in a world that is “living with COVID”. This applies all around the world due to people travelling at pre-pandemic levels.

Omicron has been generating subvariants with BA.4, BA.5 and XBB being in circulation during late 2022. These accounted for most of the cases during the second half of 2022. With some Omicron sub-variants (such as BA.2), transmissibility is greatly increased. Given the known history of COVID and of coronaviruses in general, it is highly likely that further variants and sub-variants will emerge. How transmissible they will be and whether these will become “variants of concern” or just “variants of interest” remains to be seen.

The gift that keeps on giving?

COVID-19 is vastly different from other respiratory viral infection pandemics in the past, where people who were infected either recovered or died and there were no long-term after-effects. With COVID, while most people will get a mild to moderate illness and recover without long-term side effects, others will experience severe disease and ongoing health problems, caused by the virus being present in multiple organs outside the respiratory tract. The reason for long term disease is persisting virus and as a result, ongoing inflammation. COVID is more than just an “ordinary” respiratory viral infection and SARS-CoV-2 is different from circulating endemic corona viruses because it is neurotrophic. Persisting inflammation in the brain explains why people with long COVID notice issues with attention, sleep, memory, smell and taste.

Figure 2. Panel A shows ventilator usage for COVID-19 cases as a proportion of all ventilator cases in Australia across 2022. The arrows show the 2 major waves of infection - July (orange) and December (red). Panel B shows outbreaks in residential aged care facilities in Australia during 2022. Note that this number has never fallen below 250 at any time across the year.

There is an emerging public health problem of long COVID in those who experience more severe infections. In many parts of the world, more than half the population has had at least one bout of infection and while only 3-5% of people will get long COVID, that can mean 1.52.5% of the entire population will have it. Long COVID can cause over 100 different symptoms and clinical presentations.

An important point is that the single biggest risk factor for getting long COVID is having a severe case and being hospitalised and ventilated. With fewer people with severe infection dying, more are at risk of going on to get long COVID. Early use of antiviral medicines limits disease severity so it should reduce the chance of long COVID developing.

Implications for infection prevention and control

All current strategies for infection prevention and control are based on attacking one of the links in the chain of transmission. The ADA recommendations for risk management during the COVID pandemic were updated in October 2021 and are based on the hierarchy of risk controls, moving from actions that are extremely effective down to those that are less effective and/or less predictable.

In the operatory, aerosol generating procedures can be altered (reduced coolant water with scalers or air turbines) and various measures can be applied to reduce risks from aerosols. Turning down water flow rates costs nothing and can be done quickly. Many clinicians perform restorative procedures with excessively high water flow rates. They probably do this because of what they learnt at dental school in the sim lab as students. Perhaps they do not know that dental school simulation labs tend to use unusually high water flow rates for handpieces because dental students burn plastic teeth and natural teeth because of poor technique and blunt burs!

In the waiting room, the challenge is from aerosol generating behaviours (breathing, speaking, etc). Studies of air filters from waiting rooms during waves of infection have recovered viral particles from these waiting room air filters - but not from the same type of filters used in the operatory. This reflects how well the multiple (layered) containment measures used in the operatory work. Said another

Figure 3. Panel A shows the age distribution of vaccine uptake, by the number of vaccine doses. The blue arrow shows that the older cohorts are more likely to have had 4 vaccine doses. Panel B shows PBS data for March 2022 to December 2022 for COVID-19 antiviral medicines prescribed for use in the community. The arrows show the 2 major waves of infection - July (orange) and December (red). Note how each wave has triggered intense usage of these medicines.

way, it could be more likely that people will get a COVID infection from being in a waiting room than the operatory. Hence, we need to keep people who are actively infected (and who thus have high viral loads in their secretions) out of the practice by triage before the appointment.

There is now good data from multiple studies showing that the protection afforded by layered measures is extremely high. Going forward into the future, we can have confidence that these measures are able to keep us safe at work while also reducing risks to our patients.

About the author

Emeritus Professor Laurence J. Walsh AO is a specialist in special needs dentistry who is based in Brisbane, where he served for 36 years on the academic staff of the University of Queensland School of Dentistry, including 21 years as Professor of Dental Science and 10 years as the Head of School. Since retiring in December 2020, Laurie has remained active in hands-on bench research work, as well as in supervising over 15 research students at UQ who work in advanced technologies and biomaterials and in clinical microbiology. Laurie has served as Chief Examiner in Microbiology for the RACDS for 21 years and as the Editor of the ADA Infection Control Guidelines for 12 years. His published research work includes over 390 journal papers, with a citation count of over 18,300 citations in the literature. Laurie holds patents in 8 families of dental technologies. He is currently ranked in the top 0.25% of world scientists. Laurie was made an Officer of the Order of Australia in January 2018 and a life member of ADAQ in 2020 in recognition of his contributions to dentistry.

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Taking a practical approach to aerosol management in dental practice

By Emeritus Professor Laurence J. Walsh AO

Prior to the COVID-19 pandemic and the recognition in early 2020 that airborne transmission of the virus was highly likely in certain situations, limited attention had been paid to the issues of aerobiology that are unique to a dental practice setting. During the pandemic, there has been an explosion of interest from manufacturers who have seen a more receptive market for devices and technologies that aim to improve air quality in dental practice. While there is clearly commercial opportunism at play here, one needs to recognise that there were devices already on the market prior to the pandemic that were very useful for addressing specific issues around air quality.

The tech from the past

The first notable example was the introduction of medical HEPA filter systems with a snorkel or elephant trunk design over 25 years ago, as part of the rollout of air abrasion in dentistry. These devices, which still exist today and still function extremely well, were intended to remove nuisance particles of alumina from the air, recognising that the spread of such particles was highly likely to occur despite the use of high-volume evacuation. Those who have used alumina particles for air abrasion dentistry will recognise the problems of the fine layer of dust.

The second notable pre-pandemic example was the inclusion in some dental practices of devices with medical HEPA air filters that were designed to reduce environmental allergens such as pollens, because the staff of the practice or their patient pool was particularly prone to asthma or atopic disease caused by such common allergens.

The physical removal of these submicron sized particles by such systems is highly effective. As with the previous example, both types of system were designed to be of high quality, have easily replaceable filters and have a low total cost of ownership, because the filters would often have a service life of

The more recent tech

uring the pandemic, a plethora of air filter devices hit the market, many of which lacked the medical HEPA air filter performance characteristics of the pre-pandemic technology. Some marketed systems lacked HEPA filters and instead had activated carbon (which will absorb volatile gases but not aerosol particles). Many of these recently marketed systems have a high total cost of ownership, with a short stated filter life. Hence, the question must be asked, why has quality suddenly gone backwards in this specific field?

And even more importantly, are such devices even necessary in the first place? Advertisements and social media advertising for such devices routinely lumped dental practice in the same situation as hospitals and medical centres, but is that actually correct?

Back to the basics

hen faced with any new challenge, be that in the realm of infection prevention and control, or in the realm of work health and safety, there is a basic algorithm that can be followed to guide one’s thinking. The process begins with a formal assessment of risk. This includes assessing the nature of the hazard, how frequently it is present and what existing risk control measures are in place and how well these are working. This is designed to address the question, is something more needed than what we are already doing? (Question one). There are a range of professional tools such as nomograms which can be used to calculate risk score precision to guide purchasing discussions.

Figure 1. Panel A shows the author’s design example of ducted central air conditioning for improved aerosol management. The ceiling features have been superimposed on the floor plan. Each room has delivery air (pink) being provided by a ceiling outlet positioned directly above the clinician’s head, as well as its own return air inlet (blue) positioned on the ceiling directly above the patient’s feet, to remove aerosols. This particular example is the LJ Walsh Clinic at the UQ Oral Health Centre in Brisbane (room 6129 in Clinic 6.1). Panel B shows the concept of air movement away from the breathing zones of the clinical staff that is achieved with this design, when the room is in use with the door closed.

If that assessment of risk results in a finding that an additional control measure is necessary to manage the hazard (in this case, infectious aerosols being present and posing a risk to staff and patients), then one moves on to explore issues of the effectiveness of the new control measure. In essence, one is asking, does this work? (Question 2). Under the situations encountered in the workplace, which are quite different between the waiting room, the dental operatory and the sterilising room, will the device work to reduce risk?

One then moves on to consider the issues of practicability and implementation. This is designed to answer the question, how do we make this work at its best? (Question 3). In the case of air filtration devices, where do we put them, how long do we leave them running, how do we know that they are working properly and how do we know that the filter needs to be replaced?

Answering the questions

For question 1, the answer will depend on the unique situation of the dental practice. For all the scenarios considered below, it is assumed that the standard management methods described in the ADA Risk Management Principles for COVID-19 are being followed (such as preappointment triage and the routine use of a preprocedural antimicrobial mouthwash).

Example 1

Consider the situation of a mobile dental van or dental caravan. There is no waiting room to consider and there may be no sterilising room because a back to base approach is being used for instrument management or disposable instruments are being used. In this case, the dental van or caravan is the operatory. It has a relatively small total air volume, with less height from the floor to the ceiling than one would find in a typical building. On the other hand, the van or caravan has operable windows, which can be opened to bring in fresh air. This is unlike the situation of a typical fixed building where the windows are not operable but remain closed.

The van or caravan will typically have a small air-conditioning system, which depending on its design, may or may not be able to bring in outside air.

Knowing if the air-conditioning only recirculates air is important since this will influence the risk assessment for aerosolrelated tasks.

If the patients being seen are only undergoing examinations, the generation of aerosol from the triple syringe being used will be relatively limited. Whether the clinician is working with an assistant who can provide high-volume evacuation during patient appointments is also an essential consideration.

This example highlights the importance of not only the physical dimensions of the working space and its ability to exchange air with the outside world, but also the nature of the procedures being undertaken.

Example 2

Consider the situation of a sole clinician dental clinic with a single operatory, a small sterilising room and a small combined waiting room and reception area. For such a small footprint, if the clinic is located within a shopping centre or mall, there may be three outlets for ducted central air-conditioning, but only one return air inlet. This is typically the case because such an approach reduces construction costs for the air-conditioning components, with the assumption that the tenants would be small businesses - rather than dental clinics where aerosols are being generated. In this situation with a single point for return air, aerosols floating within the environment of the practice only have four possible fates. The first is that they will move slowly through the air current created by the air-conditioning system to eventually reach the return air inlet. Often this inlet is located in a corridor, rather than in one of the individual spaces mentioned above. The inlet can readily be determined by the fact that air movement will draw in a sheet of paper held over the inlet. Inlets are also typically covered by a simple square grill. The second fate is that the aerosol will be inhaled by staff or patients. Because of their small diameter, being less than 5 µm, these particles will settle in the air sacs in the deeper areas of the lungs, where they can cause respiratory infections. The third fate is that the aerosol particles settle out onto surfaces. This normally takes 3 to 4 hours, so is relevant for the end of the day. The fourth fate is that some aerosol particles exit via the single front door of the practice.

This example highlights the importance of understanding where the inlets for ducted air-conditioning systems are located within the dental practice. Outlets which provide the delivered conditioned air are typically located on the ceiling with a diffuser that distributes the air. This makes them easy to locate and identify. Tracking down the return air is, however, much more important when considering risks of aerosol transmission.

Example 3

Consider the situation of a multi-chair dental practice that has areas that have an open plan design, with dividers or joinery between the chairs. Here the issue was that aerosol that is generated on one dental chair can pass into the environment of other dental chairs. A further consideration is that in a multi-chair dental practice, the throughput of patients will be higher because of the larger number of available chairs. The nature of the clinical work being undertaken is also important. If all of the patients are orthodontic cases having adjustments, there will be a large number of individual patients, but the time that each is within the dental chair will be short and the nature of the procedures being done are less likely to generate aerosol. On the other hand, if a patient is having a deband of their fixed appliances, this will be a long appointment and will generate a large amount of aerosol because of the powered devices that are being used. The same would be true if a dental chair was being used for ultrasonic scaling, especially if the operator did not have their own dental assistant and was only able to use low-volume evacuation.

This example highlights the importance of considering the type of aerosol generating procedures that will be done and the physical pathways through which aerosols may move. Particles which are coolant water have a much lower density than particles of human saliva, hence any spray that is dispersed into the air a long way from a dental chair is likely to be just water and contain no patient material.

Question 2

To address the question, do air filtration devices work, one needs to consider that some of the studies of such devices use situations that are completely unrealistic.

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For example, they are done in rooms with the air-conditioning (of whatever type) turned off, or they are tested clinically in procedures without the use of either low volume suction (saliva ejector), or even more importantly, high-volume evacuation. One needs to remember that HVE will remove 250 litres of air per minute, so when this is placed within the mouth close to the aerosol generating device, it gives a massive reduction of aerosols that leave the confines of the mouth. Any study of an air filtration device that does not also have the simultaneous use of normal high-volume evacuation is fundamentally flawed and appears to have been set up to make the air filtration system perform better than it would in real life.

An approach that is based on prevention and reduction (patient triage, pre-procedural rinses, HVE) will always be more effective than one which starts off with a large aerosol cloud and hopes to somehow capture that.

Question 3

Now moving on to discuss the issues of practicability, if a risk assessment reveals that one particular area of the practice has an unacceptable level of risk, then it would be appropriate to consider improving the air handling in that area. In many dental clinics, it is far more likely that the area of greatest risk is the reception area and waiting room, not the dental operatory. This is because the waiting room of a dental practice generally gets the least attention when dental practices are being designed and it is often undersized.

As an example of contemporary and award-winning design, when we designed the reception and waiting areas of the UQ Oral Health Centre in Brisbane, these all have both internal and outside waiting areas for patients to sit, with the appropriate environmental controls for the outside areas to be pleasant at most times of the year and patients sitting in the outside areas are still also easily within the eye line of the receptionist. There is also sufficient spacing that patients can achieve social distancing in the inside and the outside areas.

Staying with the same design example, having delivery air and return air in the same room creates air circuits that prevent aerosols leaving the room (Figure 1).

Likewise there are rooms designed deliberately with negative pressure. Given that this design work was undertaken in 2009, more than a decade before the pandemic, it has stood up well under the challenges of recent times. A lesson from this particular design is the importance of considering the distribution of return air inlets. This means considering the reflected ceiling plan and designing the ceiling with the same level of attention that one would normally give to the floor plan.

If a decision is made that air quality should be improved in the reception area, there are a range of different systems which are available to improve air quality using filtration. Remember that any system which has moving air will by definition generate noise because of that air movement. Considering the decibel rating of the device and its location is therefore very important. A range of mobile and wall mounted HEPA air filter units are available which could be suitable in such situations.

If the risk assessment process reveals that there are still risks in the dental operatory, then consideration needs to be given to simple measures such as reducing the coolant flow level on air turbine drills and ultrasonic scalers. This dramatically reduces the amount of aerosol that is generated, without causing problems of overheating. Some dental handpieces now come with specific valves for closing off some of the coolant spray outlets.

The next consideration is to use a high volume suction tip that has a large diameter (8 or 10 mm) and a conical or flared tip, which alters the air movement pattern to enhance aerosol removal.

The next step would be to ensure that low volume suction is used routinely with all patients. In the case of clinicians who are working alone without dental assistant support (as may be the case with some dental hygiene appointments), then the use of fixed suction systems, including those combined with lighting, such as IsoLight™ becomes more important, as does having patients clean their teeth thoroughly before attending for supragingival scaling.

One should also consider the benefits of alternatives to HEPA air filtration such as UVC light treatment. Several systems are available that can incorporate UVC treatment within existing airconditioning equipment.

If a snorkel or trunk design of air filtration devices is used, some practical considerations include: trip hazards from the power cables, noise, visual hindrance from the collector and steric hindrance from the system. This latter problem will be worse if the dental chair has a sidemounted element supporting the operating light, spittoon, monitors, etc, since this already influences the seated position of the dental assistant. Having an air filter device also present could make it difficult for the dental assistant to fulfil their tasks properly.

Summary

When considering the various physical facilities within which dentistry is undertaken, there is “no one size fits all”. This is why it is so important to consider the elements that alter risk and some of the simple measures discussed above they can reduce the risk of aerosols, before jumping over the steps and proceeding to try to implement a solution that may not be ideal for that particular work environment. In a way, it’s very much like prescribing antimicrobials: as much as necessary, but as little as possible.

About the authors

Emeritus Professor Laurence J. Walsh AO is a specialist in special needs dentistry who is based in Brisbane, where he served for 36 years on the academic staff of the University of Queensland School of Dentistry, including 21 years as Professor of Dental Science and 10 years as the Head of School. Since retiring in December 2020, Laurie has remained active in hands-on bench research work, as well as in supervising over 15 research students at UQ who work in advanced technologies and biomaterials and in clinical microbiology. Laurie has served as Chief Examiner in Microbiology for the RACDS for 21 years and as the Editor of the ADA Infection Control Guidelines for 12 years. His published research work includes over 390 journal papers, with a citation count of over 18,300 citations in the literature. Laurie holds patents in 8 families of dental technologies. He is currently ranked in the top 0.25% of world scientists. Laurie was made an Officer of the Order of Australia in January 2018 and a life member of ADAQ in 2020 in recognition of his contributions to dentistry.

6 myths about Instrument Management Systems

Myth 1: IMS Cassettes take up too much space

IMS™ Cassettes may be physically bigger than pouches, but that doesn’t necessarily mean that they take up more space. IMS

Cassettes help facilities better organise their reprocessing flow, freeing over two linear metres of counter space. They are also easily stacked, sterilised and stored in a more organised fashion than pouches. One cassette can do the job of multiple pouches during a single procedure - saving you extra space. Plus, they are made of durable, lightweight stainless steel.

Myth 2: Packing IMS Cassettes takes too long

IMS Cassettes eliminate time-consuming steps to streamline reprocessing, which can save facilities an hour or more each day. IMS

Cassettes systematically organise instruments according to procedure type, allowing for more focus on patients and less time spent looking for missing instruments. Instruments don’t need to be scrubbed by hand and they don’t need to be sorted and pouched. That time saved adds up quickly. On average, practices that use IMS Cassettes see a time savings of 5 to 10 minutes per procedure.1 Over the course of a day, that saves an hour or more.

Myth 3: IMS Cassettes make it more difficult for team members

With IMS Cassettes, team members are left with less sorting, less guess work, less forgotten instruments and less chance of mislabeling or mispacking instruments. Dental assistants and hygienists can feel confident walking into every operatory knowing they have the correct instruments and leaving more time to spend with the patient.

Myth 4: IMS Cassettes take up too much space in autoclave

Keeping procedures in a cassette helps to prevent overloading of the steriliser. Without the use of cassettes, pouches are frequently overstuffed. This leads to overloading the steriliser and the risk of not achieving full sterilisation. HuFriedyGroup IMS Cassettes have a patented design that permits optimal penetration of steam to instruments during sterilisation. Revolutionary hole pattern design provides more access to instruments during cleaning and sterilisation.

Myth 5: IMS Cassettes make staff turnover more difficult.

IMS Cassettes help facilities create a system for managing their procedural setups. Each setup includes all of the instruments that are needed to help with onboarding and standardising care throughout a single facility and even across multiple locations. Training new hires or temporary staff on patient prep, reprocessing and operatory breakdown is simpler with IMS Cassettes.

Myth 6: IMS Cassettes are not worth the investment

IMS Cassettes can make an immediate impact on a facility’s bottom line, with the time saved allowing them to see new patients and bring in tens of thousands of dollars in new revenue. IMS Cassettes also protect instruments and reduce costs of purchasing new instruments. Dental instruments are kept together throughout the cleaning process, reducing the potential for instrument breakage or loss. It’s no wonder IMS Cassettes have a 95% satisfaction rating.2

1. Based on Hu-Friedy market survey results when compared to single instrument reprocessing.

2. Based on IMS™ Cassettes user survey. Data on file.

INFINITY SERIES™ CASSETTES

INFINITY SERIES™ CASSETTES

INFINITY SERIES™ CASSETTES

The most sophisticated solution for instrument management

The most sophisticated solution for instrument management

Learn How to Scale

The

The most sophisticated solution for instrument management

Ensure predictable outcomes for your littlest patients with Hu-Friedy Stainless Steel Pedo Crowns. You’ll quickly discover why dentists favor our impeccable fit. Perfect for your patients. Easy for you. Because when it comes to the perfect fit, Hu-Friedy is just right.

Ensure predictable outcomes for your littlest patients with Hu-Friedy Stainless Steel Pedo Crowns. You’ll quickly discover why dentists favor our impeccable fit. Perfect for your patients. Easy for you. Because when it comes to the perfect fit, Hu-Friedy is just right.

That’s right, you deserve it. You deserve the peace of mind and confidence of knowing that you are employing the most contemporary method of processing instruments. As dentistry’s innovator of the cassette-based instrument management system, Hu-Friedy is proud to bring you the modern design and functionality of the Infinity Series Cassettes which include:

That’s right, you deserve it. You deserve the peace of mind and confidence of knowing that you are employing the most contemporary method of processing instruments. As dentistry’s innovator of the cassette-based instrument management system, Hu-Friedy is proud to bring you the modern design and functionality of the Infinity Series Cassettes which include:

The

That’s right, you deserve it. You deserve the peace of mind and confidence of knowing that you are employing the most contemporary method of processing instruments. As dentistry’s innovator of the cassette-based instrument management system, Hu-Friedy is proud to bring you the modern design and functionality of the Infinity Series Cassettes which include:

That’s right, you deserve it. You deserve the peace of mind and confidence that you are employing the most contemporary method of processing instruments. innovator of the cassette-based instrument management system, Hu-Friedy

• An open hole pattern that promotes water flow throughout the cassette

• An open hole pattern that promotes water flow throughout the cassette

Ensure predictable outcomes for your littlest patients with Hu-Friedy Stainless Steel Pedo Crowns. You’ll quickly discover why dentists favor our impeccable fit. Perfect for your patients. Easy for you. Because when it comes to the perfect fit, Hu-Friedy is just right.

• An open hole pattern that promotes water flow throughout the cassette

Ensure predictable outcomes for your littlest patients with Hu-Friedy Stainless Steel Pedo Crowns. You’ll quickly discover why dentists favor our impeccable fit. Perfect for your patients. Easy for you. Because when it comes to the perfect fit, Hu-Friedy is just right.

WHY DENTISTS LOVE OUR STAINLESS STEEL PEDO CROWNS:

• Color-coded silicone rail system that significantly reduces instrument contact and allows for more water flow while protecting the instruments during reprocessing

WHY DENTISTS LOVE OUR STAINLESS STEEL PEDO CROWNS:

• Color-coded silicone rail system that significantly reduces instrument contact and allows for more water flow while protecting the instruments during reprocessing

• Ideal height and mesio-distal width

• Easy-to-use, ergonomic latch that allows for one-handed opening

WHY DENTISTS LOVE OUR STAINLESS STEEL PEDO CROWNS:

• Color-coded silicone rail system that significantly reduces instrument contact and allows for more water flow while protecting the instruments during reprocessing

WHY DENTISTS LOVE OUR STAINLESS STEEL PEDO CROWNS:

• Ideal height and mesio-distal width

•

• Ideal height and mesio-distal width

• Easy-to-use, ergonomic latch that allows for one-handed opening

• Pre-trimmed and pre-crimped for simple placement

• Ideal height and mesio-distal width

• Accurate occlusal anatomy that matches the natural tooth

• Pre-trimmed and pre-crimped for simple placement

Performing at your best means having confidence in what you do. Experience Infinity Series™ Cassettes, and improve the efficiency of your practice, while helping protect your patients, your staff and your instrument investment.

• Pre-trimmed and pre-crimped for simple placement

• Accurate occlusal anatomy that matches the natural tooth

• Accurate occlusal anatomy that matches the natural tooth

• Pre-trimmed and pre-crimped for simple placement

Performing at your best means having confidence in what you do. Experience Infinity Series™ Cassettes, and improve the efficiency of your practice, while helping protect your patients, your staff and your instrument investment.

• Easy-to-use, ergonomic latch that allows for one-handed opening Performing at your best means having confidence in what you do. Experience Infinity Series™ Cassettes, and improve the efficiency of your practice, while helping protect your patients, your staff and your instrument investment.

VISIT US ONLINE AT HU-FRIEDY.COM/PerfectFit

©2016 Hu-Fried y Mfg. Co., LLC. All rights reserved.

©2016 Hu-Fried y Mfg. Co., LLC. All rights reserved.

©2016 Hu-Fried y Mfg. Co., LLC. All rights reserved.

• Accurate occlusal anatomy that matches the natural tooth

» Pola Light is super safe, doesn’t burn the gums, and produces the whitest natural shade over time B est of all, patients can w hiten from the comfor t of their own homes. «

Miles Cone, DMD, MS, CDT, FACP - USA

www.polawhite.com.au