The long-term effect of a mouthrinse containing essential oils on dental plaque and gingivitis: a systematic review.

BACKGROUND The purpose of this study was to review the literature on the effects of a mouthrinse containing essential oils (EO) on plaque and parameters of gingival inflammation. METHODS The MEDLINE and Cochrane Central Register of Controlled Trials were searched up to and including December 2006 to identify appropriate studies. The primary outcome measure was gingivitis. Secondary parameters were plaque and, when reported, staining. RESULTS Independent screening of titles and abstracts of 566 papers resulted in 11 publications that met the criteria of eligibility. In all studies, EO was used as an adjunct to regular daily toothbrushing. A statistically significant reduction in overall gingivitis was noted compared to the control (weighted mean difference [WMD]: -0.32, 95% confidence interval [CI]: -0.46 to -0.19, P <0.00001; test for heterogeneity: P <0.00001, I(2) = 96.7%). For interproximal sites the use of the test mouthrinse resulted in significantly more gingivitis reduction compared to control mouthrinse (WMD: -0.29, 95% CI: -0.48 to -0.11, P = 0.002; test for heterogeneity: P <0.00001, I(2) = 95.18%), whereas no differences were observed compared to dental floss. With respect to plaque scores, EO produced significant overall reductions in plaque (WMD: -0.83, 95% CI: -1.13 to -0.53, P <0.00001; test for heterogeneity: P <0.00001, I(2) = 96.1%). Separate analysis for interproximal areas revealed that EO resulted in more pronounced plaque drops compared to the control mouthrinse (WMD: -1.02, 95% CI: -1.44 to -0.60, P <0.00001; test for heterogeneity: P <0.00001, I(2) = 96.1%) or the use of floss (WMD: -0.75, 95% CI: -1.15 to -0.363, P <0.0002; test for heterogeneity: P <0.0002, I(2) = 93.0%). Most studies agreed that EO did not produce more staining than the control products. CONCLUSION When used as an adjunct to unsupervised oral hygiene, EO provides an additional benefit with regard to plaque and gingivitis reduction as compared to a placebo or control.