Data sources: Medline, Embase, LILACS and Scopus database.
Study selection: Studies were screened independently by three reviewers. Randomised controlled trials with a minimum of six months follow-up of daily use of essential oils-containing (EO) mouthwashes compared with placebo, flossing or cetylpyridinium chloride (CPC) as adjuncts to mechanical plaque control were considered.
Data extraction and synthesis: Data were abstracted by two reviewers and study quality assessed using the Cochrane risk of bias tool. Dental plaque was summarised using the Turesky modification of the Quigley-Hein Index (QHI), gingivitis using three indices; the Gingival Index (GI) by Loe and Silness, the Modified Gingival Index (MGI) and bleeding upon probing. Mean and standard deviations were reported and meta-analysis conducted. Sources of effect modification were investigated using meta-regression.
Results: Sixteen trials were included involving 4016 patients in total. Study quality was considered to be moderate to low. Compared with placebo meta-analysis of 14 studies showed statistically significant differences in favour of EO mouthwashes for plaque and gingival indices. Meta-analysis of four studies also demonstrated statistically lower levels of plaque and gingivitis for EO mouthwashes compared with cetylpyridium chloride (CPC). Meta-regression indicated that heterogeneity observed in plaque scores was mainly explained by the percentage of males in a trial and supervision of the mouthwash use.
Conclusions: In patients with gingivitis, EO-containing mouthwashes are more efficacious for the reduction of plaque and gingival inflammation than mechanical plaque control either alone (placebo) or in combination with mouthwashes with CPC. The expected benefits may be clinically relevant and may be also observed in the interproximal area.