Drs. Stuart and Scott Froum present the results of a new multicenter study. It concludes that the potential for viral transmission in a dental office is low, and here’s why.
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 United States, 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 coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19, can be aerosolized with a potential for an airborne route of transmission, dentistry and dental hygiene were listed as two occupations with the most risk of contracting the SARS-CoV-2 virus.3 In a statement on interim guidance released on August 11, 2020, the 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 a dental office can be studied and evaluated.4
As we are currently witnessing a resurgence of COVID-19-positive cases with possible second and third wave peaks of infection, the potential for community transmission remains high for an uncertain period of time. The need for research to demonstrate that safe dentistry can be delivered while COVID-19 cases are high is important as the timeline for the development of an effective vaccine remains unknown.
The purpose of this article is to review a new multicenter retrospective study on the incidence of transmission of the SARS-CoV-2 virus during a six-month time period of the pandemic, which included assessing patient risk for COVID-19 disease severity as related to comorbidities in their medical history.5 The difference between aerosol-generating medical procedures (AGMP) and aerosol-generating dental procedures (AGDP) will be briefly addressed. Finally, infection control protocols and specialized equipment dedicated toward airborne precautions used during this study will be discussed.
Study
Three New York dental offices with two periodontists and three hygienists treated 2,810 patients during a six-month time period from March 1, 2020, to September 15, 2020. 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 period that included aerosol-generating procedures. Control systems were put in place that included staff training, patient screening, strict adherence to standard operating infection protocols, distancing appointments, mask use, air purification, air filtration, ventilation, operatory sanitization with hypochlorous acid and UVC light, and proper personal protective equipment (PPE) use as directed by the Centers for Disease Control and Prevention (CDC) and the Occupational Safety and Health Administration (OSHA). Refer to Table 1.
Table 1: Enhanced infection control precautions
1. Triage Screening questionnaire answered prior to, day of, and 2 weeks post appointment (Follow App digital screening questionnaire)
2. Handheld or infrared scanners used at the entrance to the waiting room for temperature screenings (Total Fire Protection Scanner)
3. Use of a 60 second rinse and gargle with .5% povidone iodine or 1.5% hydrogen peroxide by the patient prior to any dental examination or treatment
4. High volume evacuation (HVE) suction use with at least 8mm bore sizes and low speed saliva ejectors with back-flow valves were used when any aerosol generating dental treatment (Dentsply Purevac & Henry Schein back flow valve)
5. High efficiency particulate air (HEPA) filters placed in treatment and waiting room (Sentry Air Systems)
6. Extra oral vacuum suctions equipped with Ultra-low particulate air (ULPA) filters were used during aerosol generating procedures (Sentry Air Systems)
7. Ultra Violet-C (UV-C) germicidal lights used in treatment room post procedure
8. All central Heating Ventilation Air Conditioning (HVAC) units were modified with air ionization for air scrubbing (Active Air)
9. Fogging the treatment room for 2-3 minutes with hypochlorous acid (HOCL) at 200 ppm (Cloudburst Technology)
10. All patients approaching the front desk maintained 6 feet from any office staff member or other patients. Custom made sneeze guards separated the patient and the front desk staff.
All staff members were protected by N95 respirator masks, a full-face shield, surgical hair cover, 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 were followed.6
These control systems resulted in zero transmission 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. If the patient did not present to the dental office for a two-week posttreatment exam and to ascertain symptom status, the asymptomatic status was obtained by contact via a phone call, text, email, or dental follow-up application. Seventy-three patients called the office prior to their scheduled dental appointments upon receiving the office screening questionnaire to report they tested positive for COVID-19. None contracted the virus in any of the three dental offices followed in the study. Three staff members, each working at a different office, contracted COVID-19 during the time period of emergency treatment only and while they were furloughed and not working.
Discussion
Although there has been anecdotal social media sharing of dental offices that have had staff develop COVID-19, the etiology and tracing of those infections were not clear. In a recent survey of 2,195 dentists conducted by the American Dental Association, less than 1% (20) had suspected or probable COVID-19 infections.7 The potential for viral transmission in a dental office is low, and a distinction must be made from AGMP and AGDP. 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.8 On the other hand, AGDP are dental procedures that produce aerosols during instrument vibration, rotation, and air compression when contacting oral fluid.
Oral secretions and nasal fluid usually 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, intraoral or extraoral suctions, and full PPE still need to be employed as the dental health-care worker can encounter secretions with high viral load via a cough or sneeze. 9
In conclusion, during the six-month period of working in all of the three dental offices during the height of the COVID-19 pandemic in New York, no dentists, staff members, or patients treated during this time contracted SARS-CoV-2. Of the patients, 69% had high-risk comorbidities, showing that dental care can be administered safely even in high-risk patients.10
