Essential oils mouthwash with or without alcohol in relation to effect on parameters of plaque and gingivitis: A systematic review and meta-analysis

Aim: The primary aim was to systematically assess the available literature on the effect of an essential oils mouthwash without alcohol (EOalc-) compared to an essential oils mouthwash with alcohol (EOalc+) on plaque scores and parameters of gingival health. The secondary aim was to evaluate user appreciation. Materials and Methods: The MEDLINE-PubMed and Cochrane-CENTRAL databases were searched to identify eligible studies published up to and including March 2024. Papers comparing the effectiveness of EOalc- and EOalc+ were included. The quality was assessed. A descriptive analysis and a meta-analysis were performed. Results: After screening, seven papers were found to be eligible. The descriptive analysis demonstrates a significant difference in plaque scores in favour of EOalc+. This is confirmed by the meta-analyses of plaque scores in non-brushing and brushing studies (DiffM = 0.40; 95% CI [0.27; 0.53], p < 0.00001 and DiffM = 0.05; 95% CI [0.01; 0.10], p = 0.01, respectively). This finding is also supported by the sub-analysis of brands. The meta-analyses of bleeding and gingival scores in brushing studies did not show significant differences between products. For user appreciation, the difference found was for taste perception in favour of EOalc- (DiffM = 1.63; 95% CI [0.72; 2.55], p = 0.0004). Conclusion: When an EO-mouthwash is used in non-brushing or brushing situations, with small to moderate certainty, EOalc- provided less effect regarding plaque control than EOalc+. For bleeding and gingival index there is weak certainty for no difference. In terms of the taste perception EOalc- seems more appreciated.