There is little truth to the notion that patients and providers are more at high risk of catching COVID-19 at the dentist’s office.
That’s according to a new study that dispels the misconception, according to a new release from Ohio State University.
The study was published May 12 in the Journal of Dental Research.
SARS-CoV-2, the virus behind the pandemic, spreads mainly through respiratory droplets. Dental procedures are known to produce aerosols.
This led to fears that saliva is spread during a cleaning or a restorative procedure, making the dentist’s chair a high-risk location.
Researchers at Ohio State University looked at whether saliva is the main source of the spray. They collected samples from personnel, equipment and other surfaces reached by aerosols during a range of dental procedures.
Then they analyzed the genetic makeup of the organisms detected in those samples. They were able to determine that the liquid spray from dental irrigation tools, not saliva, was the main source of the aerosols.
That is, the dental tools were the main source of bacteria or viruses present in the aerosols that come from the mouth of patients.
The aerosols that come from procedures conducted on asymptomatic patients had low levels of the SARS-CoV-2 virus.
In essence, from a microbial standpoint, the contents of the spray mirrored what was in the office environment, an Ohio State press statement said.
“Getting your teeth cleaned does not increase your risk for COVID-19 infection any more than drinking a glass of water from the dentist’s office does,” said study lead author Purnima Kumar, Professor of Periodontology at Ohio State.
“These findings should help us open up our practices, make ourselves feel safe about our environment and, for patients, get their oral and dental problems treated – there is so much evidence emerging that if you have poor oral health, you are more susceptible to COVID.”
Previous studies have shown that aerosols generated from dental procedures tend to land on the faces of dentists and the patient’s chest. Aerosols can travel as far as 11 feet.
The studies collected the aerosol spray in petri dishes placed on people, equipment and around the dental clinic. While the petri dishes collected bacteria, the microbes were rarely identified. The sources were never determined.
For a long time, it was presumed that saliva was the source.
Because saliva was considered potentially deadly early on during the pandemic, Dr. Kumar decided a long-term answer was long due.
She needed to know whether it was saliva indeed which is the main source of dental aerosols.
Between May 4 and July 10, 2020, researchers enrolled 28 patients receiving dental implants and restorations using high-speed drills or ultrasonic scaling procedures at Ohio State’s College of Dentistry.
The researchers included Archana Meethil, Shwetha Saraswat and Shareef Dabdoub of Ohio State and Prem Prashant Chaudhary of the National Institute of Allergy and Infectious Diseases.
Before each procedure, the researchers collected samples of saliva and irrigant, the water-based cleaning solutions used to flush out the mouth. Thirty minutes after the procedure, aerosol remnants – called condensate – were collected from the face shields of dentists, the patient’s bib and an area 6 feet away from the dental chair.
Dr. Kumar and the co-researchers then used genome sequencing technology to first characterize the microbial mix in pre-procedure saliva and irrigants. These were then compared to organisms in the aerosol samples collected later.
They looked for variations in sequences that provided information to identify the family of bacteria or viruses to which they belonged.
“Some species that live in your mouth can closely resemble those in water and the environment,” Dr. Kumar explained.
“Using this method, we don’t even have to know the names of these organisms – you can tell whether they are exactly genetically identical or genetically different,” she continued. “If you use this approach to see the differences in the genetic code, you can very accurately identify where they’re coming from.”
No matter the procedure or where the condensate had landed, microbes from irrigants contributed to about 78 percent of the organisms in aerosols. Saliva, if present, accounted for 0.1 percent to 1.2 percent of the microbes distributed around the room.
Salivary bacteria were detected in condensate from only eight cases. Of those, five patients had not used a pre-procedural mouth rinse.
The SARS-CoV-2 virus was identified in the saliva of 19 patients. However, the virus was not detected in the aerosols in any of the cases.
The research is validated by a 2020 study that reported a COVID-19 positive rate of less than 1 percent among dentists.
Dentistry has long been aware of the need to control infections. More so during the pandemic, and dental clinics worldwide instituted new protocols, including strengthened ventilation systems, extra aerosol suction equipment, N95 masks and face shields on top of goggles and PPEs, and extended intervals between attending to patients.
Dr. Kumar hopes the study’s findings will make practitioners and patients feel at ease about being in the dentist’s office – with continued strict protection in place.
“Dental surgeons and hygienists are always at the forefront of the war against bacteria in the mouth, and they of course did not feel safe because they are front-line workers surrounded by aerosol,” said Dr. Kumar, who was one of the dentists that made the dental procedures during the study.
“Hopefully this will set their mind at rest because when you do procedures, it is the water from the ultrasonic equipment that’s causing bacteria to be there. It’s not saliva.”
The risk of spreading infection “is not high,” she said. “However, we should not lose sight of the fact that this virus spreads through aerosol, and speaking, coughing or sneezing in the dental office can still carry a high risk of disease transmission.”
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Dr. Joseph D. Lim is the former Associate Dean of the UE College of Dentistry, former Dean of the College of Dentistry, National University, past president and honorary fellow of the Asian Oral Implant Academy, and honorary fellow of the Japan College of Oral Implantologists. Honorary Life Member of Thai Association of Dental Implantology. For questions on dental health, e-mail jdlim2008@gmail.com or text 0917-8591515./WDJ