In vivo evaluation of the virucidal efficacy of chlorhexidine and povidone-iodine mouthwashes against salivary SARS-CoV-2. A randomized-controlled clinical trial

Objectives: The oral cavity is potentially high-risk transmitter of COVID-19. Antimicrobial mouthrinses are used in many clinical preprocedural situations for decreasing the risk of cross-contamination in the dental setting. It is important to investigate the efficacy of mouthwash solutions against salivary SARS-CoV-2 in order to reduce the exposure of the dental team during dental procedures.

Aims: The aim of this in vivo study was to evaluate the efficacy of 2 preprocedural mouthrinses in the reduction of salivary SARS-CoV-2 viral load and to compare the results of the mouthwashes to a control group.

Materials and methods: In this randomized-controlled clinical trial, studied group comprised laboratory-confirmed COVID-19 positive patients through nasopharyngeal swabs. Participants were divided into 3 groups. For 30 s, the control group mouthrinsed with distilled water, the Chlorhexidine group mouthrinsed with 0.2% Chlorhexidine and the Povidone-iodine group gargled with 1% Povidone-iodine. Saliva samples were collected before and 5 min after mouthwash. SARS-CoV-2 rRT-PCR was then performed for each sample. Evaluation of the efficacy was based on difference in cycle threshold (Ct) value. The analysis of data was carried out using GraphPad Prism version 5 for Windows. Kristal wullis and Paired t-test were used. A probability value of less than 0.05 was regarded as statistically significant.

Results: Sixty-one compliant participants (36 female and 25 male) with a mean age 45.3 ± 16.7 years-old were enrolled. A significant difference was noted between the delta Ct of distilled water wash and each of the 2 solutions Chlorhexidine 0.2% (P = .0024) and 1% Povidone-iodine (P = .012). No significant difference was found between the delta Ct of patients using Chlorhexidine 0.2% and 1% Povidone-iodine solutions (P = .24). A significant mean Ct value difference (P < .0001) between the paired samples in Chlorhexidine group (n = 27) and also in Povidone-iodine group (n = 25) (P < .0001) was found. In contrast, no significant difference (P = .566) existed before and after the experiment in the control group (n = 9).

Conclusion: Chlorhexidine 0.2% and 1% Povidone-iodine oral solutions are effective preprocedural mouthwashes against salivary SARS-CoV-2 in dental treatments. Their use as a preventive strategy to reduce the spread of COVID-19 during dental practice should be considered.