Effectiveness of Preprocedural Mouthwashes: A Triple-Blind Randomised Controlled Clinical Trial.

Objectives: Bioaerosols generated during dental treatment are considered to be potentially carriers of infectious respiratory pathogens. The use of preprocedural mouthwashes has been suggested to reduce microbial load prior to dental surgery procedures. However, limited evidence on the effectiveness of preprocedural mouthwashes regarding mitigating respiratory pathogens exists. The aim of this clinical trial is to determine and compare the effectiveness of 3 preprocedural mouthwashes recommended by the Department of Health of the Hong Kong Special Administrative Region in the mitigation of respiratory pathogens during dental care in pandemic times.

Methods: In all, 228 participants were block-randomised to three groups based on preprocedural mouthwash used: povidone-iodine, hydrogen peroxide, and chlorhexidine digluconate. Participants, operators, and assessors were blinded to the assigned mouthwashes (triple-blind). Saliva was assessed for the presence of a number of respiratory pathogens (19 viruses including SARS-CoV-2). Changes in the prevalence and mean number of "any" pathogen present following mouthwash use were determined.

Results: Overall, the prevalence of any detected respiratory viral pathogens in the preprocedural saliva was 3.5% as compared to the postprocedural saliva: 1.3% (P = .034). The mean (SD) number of viruses was significantly lower following preprocedural mouthwash use, from 0.04 (0.18) to 0.01 (0.11) (P = .025). No significant differences were observed in the downward change (∆) of any detected virus (prevalence) (P = .155) or in the reduction of the mean number (∆) of any detected virus in the postprocedural saliva compared to preprocedural saliva of participants with respect to mouthwash used (P = .375).

Conclusions: The practice of using preprocedural mouthwash, as recommended by the government of Hong Kong, was effective in reducing the number of respiratory pathogens present during dental aerosol-generating treatment. This study lends support for official policy on use of preprocedural mouthwashes, which has significant implications for practice and policy during pandemics.