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Review 1: "Efficacy of commercial mouth-rinses on SARS-CoV-2 viral load in saliva: Randomized Control Trial in Singapore"

This potentially informative randomized control trial suggests that specific mouth rinses could prevent SARS-CoV-2 transmission. Reviewers suggested that additional analyses are necessary to generalize and test the secondary hypotheses made by the study.

Published onOct 23, 2020
Review 1: "Efficacy of commercial mouth-rinses on SARS-CoV-2 viral load in saliva: Randomized Control Trial in Singapore"
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key-enterThis Pub is a Review of
Efficacy of commercial mouth-rinses on SARS-CoV-2 viral load in saliva: Randomized Control Trial in Singapore

The presence of high SARS-coronavirus 2 (SARS-CoV-2) titres in saliva may result in transmission of the virus and increase the risk of COVID-19 infection. This is particularly important as significant amounts of aerosols are generated during dental procedures, posing risk to dental care personnel and patients. Thus, reducing the titres of SARS-CoV-2 in the saliva of infected patients could be one of the key approaches to reduce the risk of COVID-19 transmission during dental procedures. In this randomised control trial, the efficacy of three commercial mouth-rinse viz. povidone-iodine (PI), chlorhexidine gluconate (CHX) and cetylpyridinium chloride (CPC), in reducing the salivary SARS-CoV-2 viral load in COVID-19 positive patients were compared with water. A total of 36 COVID-19 positive patients were recruited, of which 16 patients were randomly assigned to four groups: PI group (n=4), CHX group (n=6), CPC group (n=4) and water as control group (n=2). Saliva samples were collected from all patients at baseline and at 5 min, 3 h and 6 h post-application of mouth-rinses/water. The samples were subjected to SARS-CoV-2 RT-PCR analysis. The fold change of Ct values were significantly increased in CPC group at 5 minutes and 6 h time points (p<0.05), while it showed significant increase at 6 h timepoint for PI group (p<0.01). Considering Ct values as an indirect method of arbitrarily quantifying the viral load, it can be postulated that CPC mouth-rinse can decrease the salivary SARS-CoV-2 levels within 5 minutes of use, compared to water rinsing. The effect of decreasing salivary load with CPC and PI mouth-rinsing was observed to be sustained at 6 h time point. Within the limitation of the current study, it can be concluded that use of CPC and PI formulated commercial mouth-rinses, with its sustained effect on reducing salivary SARS-CoV-2 level, may be useful as a pre-procedural rinse to help reduce the transmission of COVID-19.

RR:C19 Evidence Scale rating by reviewer:

  • Reliable. The main study claims are generally justified by its methods and data. The results and conclusions are likely to be similar to the hypothetical ideal study. There are some minor caveats or limitations, but they would/do not change the major claims of the study. The study provides sufficient strength of evidence on its own that its main claims should be considered actionable, with some room for future revision.



Need: The presence of high SARS-CoV-2 titers in saliva and nasopharyngeal region has had significant implications for oral health providers worldwide. The U.S. Department of Labor’s Occupational Safety and Health Administration (OSHA) categorizes dentists performing aerosol generating procedures (AGPs) on known or suspected COVID-19 positive patients as very high risk.1 In addition to implementing enhanced PPE and engineering controls, simple and cost-effective solutions such as pre-procedural mouth rinse, if proven effective, can be recommended as an integral part of the safe in-office practices protocol.

Strengths: The authors have used a high-quality randomized control research design to study effectiveness of three commonly used mouthwashes as compared to water (control) in decreasing the salivary viral load of SARS-CoV-2. In addition, the RT-PCR method used to detect SARS-CoV-2 constitutes a reliable approach. The study results confirm previous work2,3 published on effectiveness of mouth rinses and adds to the quality of the available evidence.

The results of this study confirm reduction in salivary viral load evaluated at 5 minutes to 6 hours post 30-seconds mouth rinse using CPC and PI. Considering the potential benefit of diminished salivary viral load in reducing the risk of transmission during dental treatment coupled with limited or no known adverse events/risk associated with the studied mouthwash, the findings support recommending the use of pre-procedural mouth rinses in dental offices especially before high-risk procedures.  

Limitations: As noted by the authors, the study has some limitations related to its rather small sample size and the used testing method (RT-PCR), which warrants the need for more studies with a larger sample size to arrive at a strong recommendation. In addition, the level of the baseline viral load as determined by Ct value showed high variability among the subjects between groups, which may have masked the true efficacy of the studied mouth rinses.  Interestingly, out of the 36 COVID-19 positive recruits selected, 19 (>50%) patients had undetectable SARS-CoV2 RNA at baseline and were excluded from the study. In our opinion, the authors could have further investigated for any association between undetectable SARS-CoV-2 titers levels and the demographic characteristics studied and deliberated on the potential implications of this finding in clinical practice.

Recommended Decision Term: Accept


1.     United States Department of Labor. Occupational Safety and Health Administration. COVID-19-Control and Prevention/Dentistry Workers and Employers. Available at: “

2.     Yoon JG, Yoon J, Song S-Y et al. Clinical Significance of a High SARS-CoV-2 Viral Load in the Saliva. J Korean Med Sci. 2020;35(20): e195

3.     Vergara-Buenaventura A, Castro-Ruiz C. Use of mouthwashes against COVID-19 in dentistry. British Journal of Oral and Maxillofacial Surgery 2020; 58: 924–927

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