Data sources: Medline/PubMed, Cochrane central, Scopus and Google scholar.
Study selection: Randomised controlled trials (RCTs) published in English between January 2010 and December 2015 were identified by two reviewers. Unpublished studies were not considered.
Data extraction and synthesis: Standard Cochrane Collaboration assessment tools were used to carry out a risk of bias assessment. The following data were collected from the articles; sample size, country, mean age of participants, diagnosis of alveolar osteitis (AO), type of intervention and outcomes. Heterogeneity (I2) was calculated to determine the statistical model to be used for meta-analysis.
Results: Ten randomised control trials (RCTs) were included, with 862 participants. Eight studies used 0.2% chlorhexidine (CHX) gel in the experimental group, 1% CHX gel in one study, and in one study the concentration was not specified. Two studies used adjunctive antibiotics, and one study gave 400mg Ibuprofen to all participants.Six of the RCTs were at low risk of bias, three studies showed possible selection and/or performance bias, and one study gave no information on bias. Heterogeneity was low level (I2= 40%) and a funnel plot presented a low level of publication bias.The included RCTs used Blum's criteria for diagnosis of AO. Six of the RCTs were conducted double-blinded. The risk ratio (RR) was calculated for each RCT and also for the pooled effect. The overall pooled effect of CHX gel placed in the extraction socket following mandibular 3rd molar removal was calculated to have prevented 57% of AO instances (RR = 0.43, 95% CI: 0.32, 0.58; p<0.00001). Subgroup analysis of the effect of CHX gel in participants who smoked/used the oral contraceptive pill (OCP) was calculated to have prevented 40% of AO (RR = 0.60, 95% CI: 0.41, 0.87; p = 0.007). In the studies that used a split-mouth design, CHX gel prevented 71% of AO incidence (RR = 0.29, 95% CI: 0.16, 0.50; p <0.0001).
Conclusions: This meta-analysis and systematic review concluded 'clinically significant evidence that CHX gel application in the extraction socket of mandibular 3rd molar has reduced the incidence of alveolar osteitis'.