Efficacy of Mouthwashes Delivered via Dental Unit Waterlines in Reducing Aerosolized Surrogate SARS-CoV-2

BACKGROUND Preoperative mouthwashes are recommended to reduce viral transmission during aerosol-generating procedures (AGP) in dental settings. However, their effectiveness may be compromised due to dilution by continuous water flow from dental unit waterlines (DUWL). This study evaluated the virucidal efficacy of various mouthwashes when delivered through DUWL using a novel 3D-printed dental aerosol model, with human coronavirus OC43 (hCoV-OC43) as a surrogate for SARS-CoV-2. MATERIAL AND METHODS Five mouthwashes - 0.12% chlorhexidine digluconate (CHX), 0.07% cetylpyridinium chloride (CPC), 1% hydrogen peroxide (HP), 0.2% povidone-iodine (PVP-I), and Oral7® - were assessed using suspension and carrier tests at 3 exposure times (30 s, 2 min, and 5 min). Viral infectivity was measured by median tissue culture infectious dose (TCID₅₀/mL), and log reduction values (LRVs) were calculated. The most effective mouthwashes were further evaluated in a novel 3D-printed aerosol model simulating mouthwash delivery through DUWL during AGP. RESULTS All tested mouthwashes significantly reduced viral infectivity within 30 s. CPC, PVP-I, and Oral7® achieved >4 log₁₀ reductions (>99.99%) in suspension and aerosol tests. However, only PVP-I and Oral7® appeared to be non-cytotoxic to the host cells. CONCLUSIONS PVP-I and Oral7® mouthwashes, when delivered via DUWL, rapidly and effectively reduced aerosolized surrogate SARS-CoV-2 within 30 s in this study, while remaining non-cytotoxic to the host cells. These findings support their potential integration into clinical infection control protocols during AGP.