Antimicrobial effects of aqueous and gel chlorhexidine

Antimicrobial dressings have been used as intracanal medicaments for many years although the ideal formula has not been established besides some microorganisms are more resistant than others to root canal therapy. Objectives: the aim of this study was to evaluate the antimicrobial effect in vitro of 2% aqueous chlorhexidine or 2% chlorhexidine in gel as vehicle. Methods: cylindrical, standardized dentin specimens of bovine incisors were sterilized. Afterwards they were infected with Enterococcus faecalis ATCC 29212 and incubated for 24 h. at 37ºC. They were divided into 2 groups of 3 discs: GROUP I – 2% aqueous chlorhexidine; GROUP II – 2% chlorhexidine with natrosol as vehicle. Two specimens were used as control (GROUP III). Then they were incubated for 48 h. at 37ºC. The bacteriological samples were taken by shaving the dentin inside the lumen with round burs ISO 25, 27 and 29. The dentin powder was collected in test tubes containing trypticase soy broth and incubated. After 24 h. 200 mL were transferred for another two tubes and incubated again. When growth occurred, it was checked in every instance for purity of E. faecalis. All proceedings were repeated six times. Results: the data were analysed using the chi-square test and no statistical differences were observed between the experimental groups. Conclusion: both medications were equally effective against E. faecalis. .