The Necessary Reassessment of Mask Use in Dentistry

-John Hardie BDS, MSc, PhD, FRCDC -George Freedman BSc, DDS, DiplABAD, FIADFE, FAACD Introduction For at least three decades masks have been compulsory requirements of the uniform worn by dentists and their clinical staff. The impetus for this behavior might well have been the belief that masks would prevent contamination from the blood and saliva of HIV infected patients. Although such a source of infection has never been documented, masked dentists have become the rule rather than the exception. Simultaneously with this development, numerous clinical and laboratory studies led to a better understanding of how respiratory pathogens, and particularly viruses are transmitted. These studies raised serious doubts concerning the ability of traditional masks to stop the transmission of respiratory infections such as influenza. These concerns were ignored during the COVID -19 pandemic when mask wearing became obligatory within all levels of society. Fortunately, the earlier studies on mask efficacy have continued culminating in the release of a recent major study which proves - with as much certainty as is possible - that masks do not stop the spread of respiratory diseases such as COVID-19. Based on this understanding, mask use in dentistry should be a personal decision irrespective of the opinions of peers and regulatory authorities. This article will provide the evidence to substantiate such a reassessment. Airborne Transmission The purported reason for a mask is to prevent the airborne transmission of respiratory pathogens expelled as a moisture-laden suspension of droplet, and considerably smaller aerosol particles, during coughing, sneezing, and talking. The suspension experiences rapid dehydration which results in desiccation of the particles. This induces conformational changes in the lipid envelopes surrounding influenza, respiratory syncytial and coronaviruses such that they lose their ability to attach to and infect new host cells, effectively becoming non-infectious.

reason why the role of airborne transmissions in hospital infections and from dental and orthopedic aerosols remains debatable, it serves to question the necessity of masks. (3,4) Size Matters A nanometer is one billionth of a meter. A strand of human hair is approximately 80,000 to 100,000 nanometers wide. The influenza and coronaviruses range from 80-120 nanometers (approximately 0.1 microns) in diameter. This means that approximately 1,000 of these viruses would fit across the width of a human hair. (5,6) The best fitting mask will not prevent a single human hair from passing between it and the face. N95 mask fabrics are designed to filter out 95% of airborne particles provided they are larger than 0.3 microns in diameter and most surgical mask materials filter out particles 2.5 microns or larger. (7) Therefore, their effectiveness in filtering out viruses of 0.1 microns in diameter is highly questionable. Even if such devices did impede the flow of influenza and coronaviruses, millions of stray viruses would continue to pass through the gaps occurring around the periphery of masks. In practical terms this means that a mask is no more effective at stopping viruses than a strainer is at collecting sand. (Fig 2) Historical Perspective Beginning with studies from 1946, a metaanalysis of masks efficacy published in February 2020 concluded that surgical-type face masks were not effective in reducing influenza transmissions. (8) In 2013 Ontario nurses filed a grievance against the use of masks in lieu of receiving a flu vaccination. Independent arbitrators in 2015 and 2018 reviewed hundreds of relevant documents and found that hospitals could not force mask mandates because supporting evidence was insufficient, inadequate, and completely unpersuasive. (9,10) In 2017 the CDC compiled a report based on a sixteen-year study of almost two hundred articles concerning non-pharmaceutical methods of mitigating the effects of influenza pandemics. Masks were not mentioned - attesting to the CDC’s recognition of their ineffectiveness. (11) The WHO in 2019, while commenting on the use of non-pharmaceutical measures to avoid respiratory transmissions, noted that, “There is also a lack of evidence for the effectiveness of improved respiratory etiquette and the use of face masks in community settings during influenza epidemics and pandemics.” (12) Dr. Fauci in a March 2020 60 Minutes interview stated categorically that “There’s no reason to be walking around wearing a mask.” (13) The large randomized DANMASK-19 study released in 2021 concluded that surgical masks did not reduce SARS-CoV-2 infection rates among wearers in a community setting. (14) This is but a small sample of the decades of studies refuting mask efficacy. For more extensive reviews readers are referred to: The Mask Studies You Should Know (15) and, More than 170 Comparative Studies and Articles on Mask Ineffectiveness and Harms (16). Real World Data In his 2022 book, UNMASKED The Global Failure of COVID Mask Mandates, Ian Millar provides numerous graphs from around the world comparing unmasked and masked populations. (Fig 3) These many real-world experiences show no appreciable differences in COVID infection rates among the two groups. (17) Harms A fundamental tenet of health care is: First, Do No Harm. This applies not only to the delivery of health care but to measures taken to mitigate disease transmission, including the use of masks. The harmful effects of masks include increased irritability and headaches (18), face mask dermatitis (19), increased rates of caries and gingivitis (20), and bacterial and fungal Fig. 2 Masks stop viruses much this strainer collects sand contamination. (21) Alterations in oxygen and INFECTION CONTROL & SAFETY 32 , January – February – March 2025 carbon dioxide blood levels and changes in respiratory physiology and function among other harmful effects of masks including their ineffectiveness are comprehensively discussed by Dr. J Meehan in, An Evidence Based Scientific Analysis of Why masks are Ineffective, Unnecessary, and Harmful. (22) It has been reported that each surgical and N95 face mask releases more than a billion nanoplastics and microplastics. (23) Although their pathological effects are unknown these miniscule particles have been detected in the nasal mucosa and blood of mask wearers. (23,24) The possibility exists of titanium dioxide, a potential carcinogen, being inhaled from the synthetic fibers of face masks. (25) By 2021, surgical and N95 masks were major components of 8 million tons of COVID related plastic waste. (26) In landfills these plastics leach toxic chemicals and their disposal in the oceans leads to their ingestion by seabirds and marine animals. The environmental and ecological degradation from this humongous mass of mask induced pollution is unfathomable. If masks were a drug or new surgical treatment, they would not be approved as their identified harms outweigh any tangible benefits. Cochrane Review The Cochrane Collaboration, based in London, England, is an independent not -for-profit international network of researchers. By adopting meta-analytical methods which limit biases, random errors and increase the statistical power of its conclusions, the Collaboration has earned a global reputation for providing the highest standard in evidencebased health care. (27) Randomized trials, the gold standard for medical research, are a major focus of the Collaboration. Such a trial for masks would consist of the subjects being divided at random into two groups, one with masks, one without masks, balanced by age, sex, and other pertinent characteristics. The Collaboration has been conducting meta-analysis reviews on physical interventions (including masks) to reduce respiratory viral transmissions since 2006. The latest review of 11 new and 67 previous randomized trials involving a total of 610,872 participants was released in January 2023. (28) It is a comprehensive, detailed 324-page report including results pertinent to the H1N1 pandemic, SARS and COVID-19. Significant findings are as follows. Moderate degree of certainty that wearing masks compared to not wearing masks in the community makes little to no difference to the outcome of influenza-like and COVID-19-like illness. Moderate degree of certainty that wearing masks compared to not wearing masks in the community makes little or no difference to the outcome of laboratory confirmed influenza/SARS-CoV-2. Moderate degree of certainty that the use of N95/P2 respirators compared to surgical masks probably makes little to no difference for the objective and more precise outcome of laboratory-confirmed influenza infection. There were no clear differences between the use of medical/surgical masks compared with N95/P2 respirators in healthcare workers when used in routine care to reduce respiratory tract infection. Moderate level of confidence in the accuracy of the above findings. Potential harms of wearing masks were rarely reported and poorly measured. Accepting that the Cochrane Reviews are based on sophisticated statistical analyses of human behavior, the latest review supports the results of previous ones that - with as much certainty as it is possible to have, masks and respirators provide neither meaningful nor observable benefits regarding the prevention of respiratory infections. In Support of the Cochrane Review On the 7th of April 2023, St. George’s Hospital London, released the results of a study which showed that surgical mask use made no appreciable difference in reducing hospital acquired COVID-19 infections. The results of this investigation will be presented at the April 2023 meeting of the European Congress of Clinical Microbiological and Infectious Diseases. (29) Conclusion The enthusiastic intuitive adoption of mask mandates because they must do some good ignored the effects of viral desiccation and size, dismissed the absence of any historical and scientific support, and disregarded their obvious harms. Mandating mask use must be supported by the highest level of evidence. This requires clinically derived substantiation that masks and respirators categorically prevent the transmission of respiratory viral infections. The recent Cochrane Review