slices) must be aligned for any adverse events to occur. Barriers in a system (the slices themselves) are intended to prevent errors that result in these adverse events.” 33 There are no reports of COVID-19 transmission ascribed to dental treatment. As of August 2020, there have been no reports of COVID-19 virus contracted during dental treatment. 6 While much is unknown of the novel COVID-19 virus, it has been shown that dental aerosol transmission has little to no history of infectivity based on previous heav-ily researched infectious diseases, such as tuberculosis. 6 When reviewing the World Health Organization’s current recommendations, it has been noted that trans-mission of SARS-CoV-2 by an aerosol route has not yet been demonstrated. 23 However, perhaps the risk of trans-mission is low given the employment of universal PPE and HVE. In a recent survey of 355 dentists, the preva-lence rate of COVID-19 infections was found to be 0.9%. 34 This indicates that the risk of infection may be low. Drs. Mair and Korne stated: “Dogged contact trac-ing has established that asymptomatic spreaders can cause cluster infections in various settings: places of worship, cruise ships, family gatherings, nursing homes, restaurants, business conferences, meat processing plants, choir rehearsals, etc. Unquestion-ably, asymptomatic spreaders have also visited dentists this year. Yet there remain no documented cluster events linked to a dental office setting. We submit that this is because both dose and time are mitigated during traditional dental visits due to PPE, HVE and the brevity of social interactions.” 6 A viricidal rinse that is effective against the COVID-19 virus could help greatly mitigate virus transmission in the dental practice. Studies have demonstrated the antimicrobial properties of mouth rinses such as chlorhexidine, essential oils, povidone-iodine and cetylpyridinium chloride. 36,37,38 Of these, there is recent evidence that povidone-iodine (PVP-I) may also have viricidal properties against COVID-19. A recent 2020 study that tested SARS-CoV-2 against various dilute concentrations of PVP-I found that even at the lowest concentration of 0.5%, the virus was completely inactivated within 15 seconds. 39 These findings suggest that pre-procedu-ral rinsing with PVP-I could be a viable adjunctive measure to mitigate risk of virus transmission. Iodine or silver in dental waterlines may inactivate COVID-19. Dental unit waterlines (DUWL’s) connected to dental instruments are a potential source of aerosols contami-nated with pathogenic agents. It is well established that DUWL’s are ideal environments for the growth of microorganisms, and that sources of contamination include both the public water supply and patients’ saliva. 40,41 Therefore, it is reasonable to assume that they could also be reservoirs for viral particles. While the dominant microorganisms isolated from waterlines are bacteria and fungi that persist mainly as biofilms, viral particles have been isolated as well. 42,41 Reducing the microbial load in DUWLs is part of comprehensive infection control proto-cols. It is reasonable that viricidal agents could be included as part of routine disinfection methods. PVP-I is commonly used for antimicrobial chemical treatment protocols for DUWL’s. 43 Given the recent research that suggests PVP-I can inactivate COVID-19, even in dilute concentrations, it is possible that PVP-I may be effective to treat DUWL’s for possible COVID-19 contamination from patients. 39 Existing automatic treat-ment devices could be utilized to simultaneously control biofilm growth and protect against contamination by COVID-19. For example, iodinated resin cartridges, which continuously release 2-6ppm free iodine into water to control biofilm, are available. 41 Further research is needed to investigate the presence of viral particles in treatment water and to establish the benefits of viricidal agents in improving the safety of water delivered by dental units. Although this has not been studied, waterline dilution of infected saliva may limit infectivity as well. Aerosol generated by dental treatment has been confused with aerosol generated during intubation of ill patients who may be shedding a higher viral load. In dentistry, the standard of care for routine restora-tive procedures, like crowns and fillings, employ the use of universal PPE, high vacuum evacuation of the imme-diate area and placement of an isolation device, such as a rubber dam. Aerosols generated by dental treatment are different than those aerosols generated via intuba-tion of COVID-19 ill patients, who are shedding a higher viral load. To, K et al reported that, “salivary viral load was highest during the first week after symp-tom onset and subsequently declined with time.” 8 Given the completion of a pre-screening and triage COVID questionnaire, as strongly encouraged by the American Dental Association, it is highly unlikely that a patient experiencing symptoms would be seen for dental care in the office, which thereby reduces the chances of aerosolizing the virus. 35,6 Conclusion It is difficult to truly assess the risk to dental personnel. Pan et al thoroughly detailed the difficulties of detecting airborne viruses. They stated, “At present, the lack of a standard sampler and standardized procedure for sampling virus aerosols has hindered progress towards a better understanding of the occurrence of airborne viruses, the persistence of viruses in the aerosols, movement of aerosol particles in air cur-rents, residence time of aerosolized particles and the bio-threats posed by the aerosols.” 19 Santarpia and Booth discussed the difficulty of assess-ing SARS-CoV-2 with air sampling. 22,31 Santarpia stated www.orthodontics.com Iodine pre-rinses may inactivate COVID-19. Preprocedural oral rinsing is an adjunctive protective measure that has been shown to effectively reduce the number of microorganisms in dental aerosols and spatter. 36,37 Spring 2021 35
Journal of the American Orthodontic Society Spring 2021: Page 35
