Background
The World Health Organization (WHO) declared COVID-19 a pandemic on March 11, 2020.1 While this virus has affected all aspects of life and business in the US, its potential effect on the practice of dentistry may be the most dramatic. Transmission of this virus via an airborne route in the dental office has been proposed as routine dental procedures involve aerosol generation.2 Because severe acute respiratory syndrome (SARS)-CoV-2, the virus that causes COVID-19, can be aerosolized with a potential of airborne transmission, dentists and dental hygienists were listed as two occupations having the highest risk of contracting the virus.3 In a statement on interim guidance released on August 11, 2020, the World Health Organization (WHO) recommended that all routine dental procedures be delayed until COVID-19 transmission rates decrease from community transmission to cluster cases and the risk of transmission in the dental office can be studied and evaluated.4
We are currently witnessing multiple waves, viral variants, and resurgences of COVID-19–positive cases, with possible fourth- and fifth-wave peaks of infection. The potential for community transmission will continue to remain uncertain for an unknown amount of time. Continuing research demonstrating that safe dentistry can be delivered in this situation is important—particularly as the timeline for the change from pandemic to endemic status with this virus is not definitive.
The purpose of this article is to review a few seminal studies published over the past two years demonstrating that under strict infection control standards, dentistry can be delivered safely even with the potential of new variants of the SARS-CoV-2 virus emerging. We’ll also look at a multicenter retrospective study on the incidence of transmission of the SARS-CoV-2 virus. The difference between aerosol-generating medical procedures (AGMP) and aerosol-generating dental procedures (AGDP) once again needs to be emphasized. Finally, infection control protocols and specialized equipment that can be used for any potential airborne viral outbreak in the future, no matter the virulence and/or transmission potential, will be discussed.
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Studies
A group of patients (2,810) were treated by three dental offices with two periodontists and three hygienists during a six-month period from March 1, 2020, to September 15, 2020.5 Of those, 1,939 (69%) were recorded to be in the high-risk comorbidity (hypertension, diabetes, 65 years of age or older, immune dysregulation, and/or a history of immunosuppressive medication).
Various dental treatment was administered during this study that included AGDP. Control systems were put in place along with staff training, patient screening, strict adherence to standard operating infection control protocols, distancing appointments, mask use, air purification, air filtration, ventilation, operatory
All staff members were protected by N95 respirator masks, a full-face shield, surgical hair covering, a full-length gown, glasses with magnifying loupes, eye shields, and surgical gloves. Nose filters and glasses or nose shield masks with protective visors were given to patients along with single-use linen gowns and hair covers prior to dental treatment requiring aerosol generation. Throughout the length of this study, strict adherence to both standard and enhanced infection control precautions was given.6 These control systems resulted in a zero-transmission rate from patient to health-care worker or health-care worker to patient as signified by the absence of any COVID-19 symptoms from office staff and patients during the six-month period of this study.
In another study, US dentists were invited to participate in a monthly web-based survey from June 2020 through November 2020.7 785 dentists participated in all six surveys, and they were asked about COVID-19 testing diagnosis, symptoms experienced, and infection prevention procedures followed in their primary practice. Over a six-month period, the cumulative COVID-19 infection prevalence rate was 2.6%, and the incidence rates ranged from 0.2% through 1.1% each month. Because US dentists practiced enhanced infection control procedures in response to the ongoing pandemic, low rates of cumulative prevalence of COVID-19 were recorded. The study concluded that dentists are showing adherence to a strict protocol for enhanced infection control, which should help protect their patients, their dental team members, and themselves. COVID-19 infections among practicing dentists will likely remain low if dentists continue to adhere to infection control guidance.8
Finally, in a prospective cohort study just published, 644 dentists across Canada from July 29, 2020, through February 12, 2021, answered an online COVID-19 assessment questionnaire and self-reported SARS-CoV-2 infections every four weeks.9 Median follow-up time was 188 days. Six 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 per 100,000 person-days). The conclusion of this study was that the low infection rate observed among Canadian dentists from July 29, 2020, through February 12, 2021, should be reassuring to both the dental and general community that dentistry is safe if infection protocols are followed.
Discussion
The potential for viral transmission in a dental office continues to remain low, and the distinction between AGMP and AGDP must be reinforced. AGMP are those procedures that agitate the airway (e.g., tracheal or bronchial intubation) and may induce the patient to cough forcibly, thereby releasing aerosols filled with a high viral infectious dose.10 AGDP, on the other hand, are dental procedures that produce aerosols during instrument vibration, rotation, and air compression when contacting oral fluid. Oral secretions and nasal fluid have less viral concentrations than chest secretions. AGDP are often accompanied by high-volume evacuation and/or other filtration devices that may be absent during AGMP. These suction techniques lower an already low potential for transmission in the dental environment. Control systems using ventilation, intra-/extraoral suctions, and full PPE should still be employed, especially in times of high community infection rates, as dental health-care workers can encounter secretions with high viral load via a cough or sneeze.11
In conclusion, in the past two years since the pandemic began, studies and online surveys continue to demonstrate that incidence of SARS-CoV-2 transmission remains extremely low in the dental office setting with enhanced infection control measures in place. Oral health and dental care are a part of medical care and need to be deemed essential even in the event of a new viral variant or transmission event. Dental care can be administered safely under standard and heightened infection control measures even for patients at the highest risk of infection.12
Editor's note: This article appeared in the June 2022 print edition of Dental Economics magazine. Dentists in North America are eligible for a complimentary print subscription. Sign up here.
References
1. WHO director-general’s opening remarks at the media briefing on COVID-19 – March 2020. World Health Organization. March 11, 2020. https://www.who.int/director-general/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-on-covid-19---11-march-2020
2. Peng X, Xu X, Li Y, Cheng L, Zhou X, Ren B. Transmission routes of 2019-nCoV and controls in dental practice. Int J Oral Sci. 2020;12(1):9. doi:10.1038/s41368-020-0075-9
3. Lu M. The front line: visualizing the occupations with the highest COVID-19 risk. Visual Capitalist. April 15, 2020. https://www.visualcapitalist.com/the-front-line-visualizing-the-occupations-with-the-highest-COVID-19-risk/
4. Considerations for the provision of essential oral health services in the context of COVID-19. Interim guidance. World Health Organization. August 3, 2020. Accessed August 11, 2020. https://apps.who.int/iris/bitstream/handle/10665/333625/WHO-2019-nCoV-Oral_health-2020.1-eng.pdf
5. Froum SH, Froum SJ. Incidence of COVID-19 virus transmission in three dental offices: a 6-month retrospective study. Int J Periodontics Restorative Dent. 2020;40(6):853-859. doi:10.11607/prd.5455
6. Harte JA. Standard and transmission-based precautions: an update for dentistry. J Am Dent Assoc. 2010;141(5):572-581. doi:10.14219/jada.archive.2010.0232
7. Araujo MWB, Estrich CG, Mikkelsen M, et al. COVID-19 among dentists in the United States: a 6-month longitudinal report of accumulative prevalence and incidence. J Am Dent Assoc. 2021;152(6):425-433. doi:1016/j.adaj.2021.03.021
8. Estrich CG, Mikkelsen M, Morrissey R, et al. Estimating COVID-19 prevalence and infection control practices among US dentists. J Am Dent Assoc. 2020;151(11):815-824. doi:10.1016/j.adaj.2020.09.005
9. Madathil S, Siqueira WL, Marin LM, et al. The incidence of COVID-19 among dentists practicing in the community in Canada: a prospective cohort study over a 6-month period. J Am Dent Assoc. 2022;153(5):450-459.e1. doi:1016/j.adaj.2021.10.006
10. Wölfel R, Corman VM, Guggemos W, et al. Virological assessment of hospitalized patients with COVID-2019. Nature. 2020;581(7809):465-469. doi:10.1038/s41586-020-2196-x
11. Chanpong B, Tang M, Rosenczweig A, Lok P, Tang R. Aerosol-generating procedures and simulated cough in dental anesthesia. Anesth Prog. 2020;67(3):127-134. doi:10.2344/anpr-67-03-04
12. Richardson S, Hirsch JS, Narasimhan M, et al. Presenting characteristics, comorbidities, and outcomes among 5700 patients hospitalized with COVID-19 in the New York City area. JAMA. 2020;323(20):2052-2059. doi:10.1001/jama.2020.6775
