Becoming Scientifically Objective About COVID-19 Preprocedural Rinsing

It's important to find objective, evidence-based science before determining whether to use preprocedural rinses in practice.

It was not until January 2021 that I finally got up the courage to make an appointment for 3-month periodontal maintenance. I was now almost a 2-hour drive away from my favorite hygienist, Lori, but it was worth the trip to receive excellent supportive therapy in a periodontal practice. It is also embarrassing to report that it had been about 12 months since I last saw Lori. Most of the procrastination was because of a trimalleolar ankle fracture that kept me preoccupied and in physical therapy. Lori offered me a 1% hydrogen peroxide preprocedural rinse before treatment and mentioned that it was being used in most dental practices during the coronavirus disease 2019 (COVID-19) pandemic. Being a scientific skeptic, which most of the time I am proud of, I knew right then that a column on the topic was forthcoming.

Let me also mention that I am a member of several dental hygiene chat groups on Facebook and am always curious to read questions/answers on various topics. Over the course of a year, I have read questions about COVID-19 oral prerinsing and they usually go something like this: “What is everyone using as a COVID-19 prerinse for hygiene appointments? Which one is your favorite and why?”

Preprocedural rinsing has been suggested by some sources (authors/speakers/dental practices, and other commercial interests) as a way to reduce the SARS-CoV-2 viral load, so I would like to explore the literature on the subject and ask the following question: Is there evidence to support the use of antimicrobial mouth rinses to reduce the viral load of SARS-CoV-2 and protect dental health care workers and patients?

Cochrane Oral Health

Cochrane is always my first go-to when looking for objective evidence; years ago, I visited their editorial-based team at the University of Manchester, Division of Dentistry, in Manchester, England. This large review group publishes summaries of quality research to assist practitioners in making informed decisions.

Cochrane reviewed the evidence on antimicrobial mouthwashes and nasal sprays for individuals with COVID-19 as a way to fight the transmission and prevent them from infecting health care workers who treat them.1 They also were interested in determining whether these measures would protect health care workers, especially before undertaking aerosol-generating procedures.1

The Cochrane team searched the medical literature for studies comparing effects of any antimicrobial mouth rinses or nasal sprays administered to patients or health care workers against no treatment or water or even a salt solution.1 The team investigated benefits and risks for patients and health care workers and effects of these medicaments on:

  1. Patient deaths and health care situations like the need for hospitalization, artificial breathing support, dialysis, or hemofiltration (treatment required when kidneys are not working properly)
  2. New COVID-19 infections and health care workers
  1. Adverse effects like loss of smell
  2. Change in patients’ COVID-19 viral load
  3. Viral load of patient droplets

Results were as follows: there were no completed studies to include in this review. Cochrane found 16 studies underway investigating mouthwashes and nasal sprays, but none had been completed or published.

When examining another aspect of antimicrobial mouthwashes and nasal sprays to protect health care workers when undertaking aerosol-generating procedures on patients without suspected or confirmed COVID-19 infection, Cochrane again found no completed or ongoing studies to include in this review.

A third aspect of the assignment was to review evidence pertaining to the use of antimicrobial mouthwashes and nasal sprays by health care workers to protect themselves while treating patients with suspected or confirmed COVID-19 infection. Again, Cochrane found no evidence concerning benefit or risk to health care workers who used antimicrobial mouthwashes or nasal sprays to protect themselves while treating these patients.

Where’s the Evidence?

The Cochrane review group did find 2 randomized controlled trials and 1 nonrandomized study that are underway. Until these clinical trials are analyzed, and reviews are updated based on available evidence, we do not know whether there are any benefits (or risks) of antimicrobial rinses and nasal sprays regarding risk mitigation.

In March 2020, the American Dental Association recommended having patients rinse with a 1% hydrogen peroxide solution before each appointment.2 No reference was given for this recommendation.

The Centers for Disease Control and Prevention reports no published evidence of antimicrobial mouth rinses regarding clinical effectiveness in reducing SARS-CoV-2 viral loads or in preventing transmission.3 Even so, they cite preprocedural mouth rinses with antimicrobial products like chlorhexidine gluconate, essential oils, povidone-iodine, or cetylpyridinium chloride as a possible means of reducing the level of oral microorganisms in aerosols and spatter generated during dental procedures.3

When there is no evidence, what do we do? We need to be aware and not dupe ourselves and patients into thinking there is. Therefore, until we have some evidence, whatever antimicrobial rinse we are administering during the pandemic might or might not be of benefit to ourselves or to our patients. Should you choose to use an OTC rinse like one of your favorites with licorice root extract or a more expensive antimicrobial rinse like chlorhexidine gluconate, do your homework and do not rely on a Facebook group to give you the answer you are looking for.

Without looking at the evidence from a reliable source like Cochrane, it is easy to be duped or “educated” by marketers to champion their products. Professional associations are not always a reliable source of evidence, either, even though we have come to expect a culture of integrity for every organization and business.

When there is no evidence, what do we do? In committing to a high standard of integrity in everything we do, always mitigate the risk of wrongdoing by following published research guidelines to the best of our ability. If I am offering a chlorhexidine prerinse, for example, I will tell the patient that chlorhexidine is the gold standard in plaque control. When there is no evidence to support a product, don’t cherry-pick it to support your or a particular group’s point of view.