Effect of Benzydamine Hydrochloride on Dental Plaque Accumulation During Short-Term Restricted Oral Hygiene: A Randomized, Placebo-Controlled Trial

Background/Objectives: Benzydamine hydrochloride (B-HCl) is a non-steroidal anti-inflammatory agent with antimicrobial properties that may be beneficial in oral biofilm control. The aim of this study was to evaluate the effect of a 0.15% B-HCl mouthrinse on dental plaque accumulation and gingival inflammation under short-term conditions of restricted mechanical oral hygiene. Methods: Fifty periodontally healthy female subjects (aged 16–27 years) were randomly assigned (1:1) to receive either a 0.15% B-HCl mouthrinse or a placebo. Following professional prophylaxis, subjects rinsed with 15 mL twice daily for 30 s and refrained from all other oral hygiene procedures for 3 days. Full-Mouth Plaque Score (FMPS) was the primary outcome, and Full-Mouth Bleeding Score (FMBS) was the secondary outcome, recorded at baseline (Day 0) and Day 3. This study was conducted in accordance with CONSORT guidelines. Results: All subjects (n = 50) completed the study. FMPS increased significantly in both groups (p < 0.001). However, plaque accumulation at Day 3 was significantly lower in the B-HCl group compared with placebo (47.9% vs. 73.8%, p < 0.001), representing an absolute reduction of 25.9% and a relative reduction of 35.1%. No statistically significant differences were observed between groups in FMBS at Day 3 (p = 0.180). Conclusions: A 0.15% B-HCl mouthrinse reduced dental plaque accumulation compared with placebo during a 3-day period of restricted mechanical oral hygiene (mean difference: 25.9%; 95% CI: 16.1% to 35.7%). Given the short study duration, the anti-inflammatory properties of B-HCl could not be adequately evaluated. Longer-term studies are needed to determine whether B-HCl provides clinically meaningful benefits as an adjunct to mechanical oral hygiene. Trial registration: ClinicalTrials.gov (Identifier: NCT07565766).