Antibacterial effect of calcium hydroxide combined with chlorhexidine on Enterococcus faecalis: a systematic review and meta-analysis

Objective

Enterococcus faecalis (E. faecalis) is the mostfrequently isolated strain in failed endodontic therapy cases since it isresistant to calcium hydroxide (CH). Whether a combination of CH and chlorhexidine(CHX) is more effective than CH alone against E. faecalis is a matter ofcontroversy. Thus, the aim of this study was to conduct a systematic review andmeta-analysis of the literature.

Material and Methods

A comprehensive search in PubMed, EMbase, EBSCOhost, The Cochrane Library, SciELO,and BBO databases, Clinical trials registers, Open Grey, and conferenceproceedings from the earliest available date to February 1, 2013 was carried outand the relevant articles were identified by two independent reviewers. Backwardand forward search was performed and then inclusion and exclusion criteria wereapplied. The included studies were divided into "comparisons" according to thedepth of sampling and dressing period of each medicament. Meta-analysis wasperformed using Stata software 10.0. The level of significance was set at0.05.

Results

Eighty-five studies were retrieved from databases and backward/forward searches.Fortyfive studies were considered as relevant (5 in vivo, 18in vitro, 18 ex vivo, and 4 review articles).Nine studies were included for meta-analysis. Inter-observer agreement (Cohenkappa) was 0.93. The included studies were divided into 21 comparisons formeta-analysis. Chi-square test showed the comparisons were heterogeneous(p<0.001). Random effect model demonstrated no significant difference betweenCH/CHX mixture and CH alone in their effect on E. faecalis(p=0.115).

Conclusions

According to the evidence available now, mixing CH with CHX does not significantlyincrease the antimicrobial activity of CH against E. faecalis. Itappears that mixing CH with CHX does not improve its ex vivoantibacterial property as an intracanal medicament against E.faecalis. Further in vivo studies are necessary toconfirm and correlate the findings of this study with the clinical outcomes.