Data sources: Cochrane Central Register of Controlled Trials (CENTRAL), Medline through PubMed, Scopus, Science Direct, ISI Web of Science, Evidence-Based Dentistry, ClinicalTrials.gov, the European Union Clinical Trials Register, the Spanish General University Board database of doctoral theses in Spain (TESEO), the Spanish National Research Council (CSIC) bibliographic databases, and the Spanish Medical Index (IME).
Study selection: Randomised controlled trials (RCTs) (with or without placebo) of patients of any age or gender who underwent maxillary or mandibular third molar extractions. Studies were required to have analysed the efficacy of only chlorhexidine in any concentration, formulation or treatment regimen for preventing alveolar osteitis (AO). There was no language restriction.
Data extraction and synthesis: Data extraction was carried out independently by two researchers, and a third researcher was consulted in case of disagreements. When explicit data were not stated in the text, they were calculated using data from the tables where possible. In addition, authors were contacted to obtain any necessary missing information. Datasets were assessed for heterogeneity, and meta-analysis was conducted on homogenous datasets. Publication bias was assessed through funnel plots. The research was conducted and is reported in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.
Results: Twenty-three studies published from 1979 to 2015, corresponding to 18 trials (16 parallel-group and two split-mouth RCTs), that reported on 2,824 third molar extractions (1,458 in experimental group and 1,366 in control group) were included. The overall relative risk (RR) was 0.53 (95% CI, 0.45-0.62; P<.0001). There was evidence of low heterogeneity (I2= 9.3%; P = 0.336 by X2test). The number needed to treat was eight (95% CI, 7-11). There were no differences between chlorhexidine rinse (RR = 0.58; 95% CI, 0.47-0.71) and gel (RR = 0.47; 95% CI, 0.37-0.60) for the prevention of AO after third molar extractions. Chlorhexidine did not cause more adverse reactions than placebo.
Conclusions: The use of chlorhexidine, in any formulation (rinse or gel), concentration (0.12% or 0.20%), or regimen (before, during and/or after surgery), is efficacious and effective in preventing AO in patients who have undergone third molar extraction. The findings showed that in order to prevent one case of AO, eight patients would have to be treated with chlorhexidine. Chlorhexidine gel was found to be moderately more efficacious than the rinse formulation.