Efficacy of essential oils mouthwashes with and without alcohol on the plaque formation: a randomized, crossover, double-blinded, clinical trial

Background: Essential oil (EO) mouthwash has been considered as one of the effective chemical agents as an adjunct to mechanical plaque control, without adverse effects compared with chlorhexidine (pigmentation, changes of taste, and formation of supragingival calculus), which limits its continuous use. New EO alcohol-based has emerged with questions regarding contraindications for its daily use. Objective: To compare the efficacy of EO mouthwashes with and without alcohol on the early supragingival and subgingival plaque formation using a plaque-free zone score system. Methods: This study was a crossover, randomized, double-blind clinical trial. Eleven participants, totaling 396 sites of evaluation, remained 4 days with no mechanical oral hygiene control and only used EO mouthwash with (control) and without alcohol (test) during this period. The presence of the plaque-free zone was recorded every 24 hours. Friedman and Wilcoxon tests were used with a 5% significance level. Results: The control group showed a more significant number of buccal surfaces free of plaque at 48, 72, and 96 hours compared with the test group. Both groups presented satisfactory efficacy up to 72 hours with a significant difference in favor of the control group. The presence of subgingival plaque on both the proximal and free surfaces was significantly higher in the test group. Conclusion: EO with alcohol presented better results in retarding the early supragingival and subgingival plaque formation compared with EO without alcohol.