A range of dental procedures particularly those using high-speed hand pieces and ultrasonic scalers as well as coughing sneezing and breathing lead to the production of aerosols. As a large number of microbial species including SARS-CoV-2 are present these aerosols may be contaminated. With dental treatment involving close contact between dental professionals and the patients there is the potential for cross-infection. Studies have demonstrated that mouthwash may reduce bacterial contamination and viral load but the impact on infection in dental professionals is unclear.
The aim of this Cochrane review was to assess the effects of preprocedural mouthwash used in dental clinics to minimise incidence of infection in dental healthcare providers and reduce or neutralise contamination in aerosols.
Searches were conducted in the Cochrane Oral Health’s Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase, World Health Organization COVID-19 Global Literature on Coronavirus Disease Database (search.bvsalud.org/ global-literature-on-novel-coronavirus-2019-ncov) Cochrane COVID-19 Study Register (covid-19.cochrane.org/), ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry databases. The primary outcome was the incidence of infection of dental healthcare providers with reduction in the level of contamination, cost, change in patient’s oral microbiota and as adverse events secondary outcomes. Parallel arm or cluster randomised controlled trials (RCTs) were considered for the primary outcome with cross- over designs for secondary objectives with the intention of using first- period data from cross-over trials as parallel-arm studies. Quasi-RCTs, split-mouth studies, controlled clinical trials and experimental studies conducted in a laboratory environment were excluded. Standard Cochrane data extraction and analyses procedures were followed.
- 17 RCTs involving 830 participants were included
- 3 RCTs were at high risk of bias, 2 at low risk and 12 had an unclear risk of bias.
- 11 RCTs were from India, 3 from the USA, 2 from Brazil and one from Puerto Rico.
- Sample sizes ranged from 18 – 185.
- None of the studies measured the incidence of infection in dental healthcare providers.
- The studies measured reduction in the level of bacterial contamination measured in colony-forming units (CFUs) at different distances. It is unclear what size of CFU reduction represents a clinically significant amount.
- There is low- to very low-certainty evidence that chlorhexidine (CHX) may reduce bacterial contamination (CFUs), compared with no rinsing or rinsing with water.
- Similar results were seen comparing cetylpyridinium chloride (CPC) with no rinsing and when comparing CPC, essential oils/herbal mouthwashes or boric acid with water.
- There is very low-certainty evidence that tempered mouth rinses may provide a greater reduction in CFUs than cold mouth rinses.
- There is low-certainty evidence that CHX may reduce CFUs more than essential oils/herbal mouthwashes.
- The evidence for other head-to-head comparisons was limited and inconsistent.
- No information on costs, change in micro-organisms in the patient’s mouth or adverse events was provided in the studies.
- Patients’ acceptability or feasibility of implementation was not assessed.
The authors concluded: –
None of the included studies measured the incidence of infection among dental healthcare providers. The studies measured only reduction in level of bacterial contamination in aerosols. None of the studies evaluated viral or fungal contamination. We have only low to very low certainty for all findings. We are unable to draw conclusions regarding whether there is a role for preprocedural mouth rinses in reducing infection risk or the possible superiority of one preprocedural rinse over another. Studies are needed that measure the effect of rinses on infectious disease risk among dental healthcare providers and on contaminated aerosols at larger distances with standardised outcome measurement.
This Cochrane review is a companion review to an earlier review on other interventions to reduce aerosol generating procedures during dental procedures (Dental Elf 19th Oct 2020). The review found no studies addressing the reviewer’s primary objective of infection in dental personnel only changes in bacterial CFUs. While reductions in CFUs were shown this is a surrogate measure so the importance of these reductions in unclear as the review authors point out there is, no information on a minimally important clinical difference (MICD) for CFUs in order to determine the effectiveness of the mouthrinse. This review found no studies involving viruses and two other Cochrane reviews by Burton et al focusing specifically on SARS-CoV-2 (currently being updated) found also identified no trials. A more recent review by Silva et al that included mainly in-vitro studies suggested that povidone-iodine and CPC mouthwashes may be potentially effective in reducing SARS-CoV-2 oral load however, the studies only evaluated the presence of viral particles and not their viability or infectious capacity. Silva also noted that there are international standards for chemical and physical properties of mouthwashes and test methods there is a lack regarding virucidal properties. Additional high quality RCTs are needed with common reporting outcomes.
Kumbargere Nagraj S, Eachempati P, Paisi M, Nasser M, Sivaramakrishnan G, Francis T, Verbeek JH. Preprocedural mouth rinses for preventing transmission of infectious diseases through aerosols in dental healthcare providers. Cochrane Database Syst Rev. 2022 Aug 22;8(8):CD013826. doi: 10.1002/14651858.CD013826.pub2. PMID: 35994295; PMCID: PMC9394685.
Cochrane Oral Health Blog – Does using a mouth rinse before dental treatment reduce the spread of infection from the patient to the dental professional?
Dental Elf 19th Oct 2020
Burton MJ, Clarkson JE, Goulao B, Glenny AM, McBain AJ, Schilder AG, Webster KE, Worthington HV. Antimicrobial mouthwashes (gargling) and nasal sprays administered to patients with suspected or confirmed COVID-19 infection to improve patient outcomes and to protect healthcare workers treating them. Cochrane Database Syst Rev. 2020 Sep 16;9(9):CD013627. doi: 10.1002/14651858.CD013627.pub2. PMID: 32936948; PMCID: PMC8187985.
Burton MJ, Clarkson JE, Goulao B, Glenny AM, McBain AJ, Schilder AG, Webster KE, Worthington HV. Antimicrobial mouthwashes (gargling) and nasal sprays to protect healthcare workers when undertaking aerosol-generating procedures (AGPs) on patients without suspected or confirmed COVID-19 infection. Cochrane Database Syst Rev. 2020 Sep 16;9(9):CD013628. doi: 10.1002/14651858.CD013628.pub2. PMID: 32936947; PMCID: PMC8188293.
Silva A, Azevedo M, Sampaio-Maia B, Sousa-Pinto B. The effect of mouthrinses on severe acute respiratory syndrome coronavirus 2 viral load: A systematic review. J Am Dent Assoc. 2022 Jul;153(7):635-648.e16. doi: 10.1016/j.adaj.2021.12.007. Epub 2021 Dec 30. PMID: 35287944; PMCID: PMC8716175.