Reducing aerosol viral load to minimise spread of SARS-CoV-2 in dental clinics

Jeremy Booth, DTI

Tue. 21. April 2020

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MUMBAI, India: Dentists and their patients are increasingly concerned about the elevated risk of infection with SARS-CoV-2 in dental clinics, owing to the generation of virus-containing aerosols through dental procedures. Mumbai-based periodontist and educator Dr Rajeev Chitguppi has proposed that adding povidone-iodine (PVP-I) to the water bottle that is attached to the dental unit for use as an irrigant with high-speed handpieces could minimise the spread of the virus in dental clinics.

Chitguppi says that such a safety protocol could represent a simple solution to overcoming the challenge of making dental clinics safer during the pandemic.

Chitguppi took three established pieces of evidence from the scientific literature as a starting point for what he has proposed as a hypothesis for further development by the international dental community: firstly, droplet and aerosol transmission of SARS-CoV-2 are the most critical concerns in dental clinics because it is difficult to avoid the generation of high quantities of aerosol and droplets mixed with the patient’s saliva and even blood during dental procedures; secondly, PVP-I formulations have demonstrated more than 99.99% activity against the Ebola virus, MERS coronavirus, SARS coronavirus, influenza virus and viruses that most commonly cause hand, foot and mouth disease; and, thirdly, the rapid bacterial and viricidal efficacy of povidone-iodine solutions (such as in mouthwashes) against pathogens that cause respiratory tract infections have been observed in in vitro and in vivo studies, and the antiseptic’s established safety profile provides a strong rationale for use in hygiene management in high-risk environments.

Furthermore, evidence has emerged that PVP-I solutions have a higher viricidal activity than other commonly used antiseptic agents, such as chlorhexidine and benzalkonium chloride. In one of the studies Chitguppi cites, the researchers thus proposed that a protocolised nasal inhalation and oropharyngeal wash of PVP-I should be used during the current COVID-19 pandemic to limit the spread of SARS-CoV-2 between patients and healthcare workers.

Considering that it is a recommended irrigant for use with an ultrasonic scaler at a specific dilution ratio, Chitguppi has proposed that dentists consider using a PVP-I solution as an irrigant with high-speed handpieces. He acknowledged that one concern would be how the devices cope with the addition and what the corresponding maintenance protocols would be.

Chitguppi’s hypothesis and supporting scientific evidence were published on ResearchGate at the beginning of April, and on Dental Tribune South Asia’s website, and his proposals have received a high volume of interest and comments from dentists and fellow researchers.

Working to make dental clinics safer during the COVID-19 outbreak

Dental Tribune International spoke with Chitguppi about the work he has been doing to reduce the risk of transmission of SARS-CoV-2 in dental settings.

He said that the work began after a 15 March New York Times article went viral in the dental community because it stated that dental professionals face a greater risk of becoming infected with the coronavirus. “The entire dental community got busy discussing and debating what needed to be done in order to reduce the risk of disease transmission in dental clinics. India announced a 21-day lockdown from 24 March, and the main concern among dentists in the country has been what they will need to do when they reopen their clinics after the lockdown ends,” he explained.

Further research confirmed that the most critical concern in dental clinics is the droplet and aerosol transmission of SARS-CoV-2 and that devices such as high-speed dental handpieces generate a large amount of aerosol and droplets that are small enough to remain airborne for extended periods before settling on environmental surfaces or entering the respiratory tract.

Reducing the aerosol-based risk is critical, and Chitguppi asserts that it is the viral load in the aerosols, and not the aerosols themselves, that carries the risk. The basis of his research was his question: “We cannot prevent aerosol generation in dental clinics, but can we minimise the viral load in the aerosols?”

“The risk of transmission from aerosols is real, so we need to look at ways to control the quality [viral load] as well as the quantity [volume] of aerosols generated” – Dr Rajeev Chitguppi, periodontist

Chitguppi said that dentists are looking for a solution that is practical and inexpensive. He emphasised that his hypothesis needs to be tested and has not been established, but added that the response from the dental community has been constructive.

“Within 24 hours of my publication, Dr Raghu Narayan, an endodontist from Bengaluru in India, created a prototype to test the idea: a simple experiment to check how well PVP-I mixes with the particles in aerosol generation. I am now trying to take it to different researchers and collaborate with them so that the hypothesis can be tested thoroughly in order for us to obtain concrete evidence about the modifications required to make it applicable in clinical practice.”

“The risk of transmission from aerosols is real, so we need to look at ways to control the quality [viral load] as well as the quantity [volume] of aerosols generated,” he continued. “As far as the quality of aerosols is concerned, I am not only looking at PVP-I. There are other agents, too, that have demonstrated viricidal activity, such as sodium hypochlorite, chlorine dioxide and hydrogen peroxide. We need to work on all options and test them before coming up with the best recommendations and guidelines. Also, there is an increasing interest in the development of devices such as filters and extra-oral aspirators that can reduce the volume of aerosols generated in dental clinics. Many dentists are sharing with me the latest developments and emerging evidence, which I am adding to the project in order to keep it up to date.”

Chitguppi is also executive editor of the publication Dental Tribune South Asia, which has called on dental professionals to think laterally and share their ideas about solutions for improving safety in the dental practice. He hopes that this initiative will serve as a point of connection between dentists and industry partners.

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