In vitro antimicrobial activity of calcium hydroxide pastes and their vehicles against selected microorganisms.

The aim of this study was to investigate in vitro the antimicrobial activity of calcium hydroxide in combination with several vehicles against some microorganisms commonly isolated from root canals. Antimicrobial activity was determined by the agar diffusion method. Stainless-steel cylinders were placed on each inoculated agar medium. The test medicaments and their controls were placed inside the cylinders. The zones of growth inhibition were measured and recorded after incubation for each plate and the results were analyzed statistically (ANOVA). The in vitro antimicrobial effects of the medications were ranked from strongest to weakest as follows: Ca(OH)2 + CMCP + glycerine, Ca(OH)2 + CMCP, Ca(OH)2 + glycerine, Ca(OH)2 + anesthetic, Ca(OH)2 + saline, Ca(OH)2 + H2O, Ca(OH)2 + polyethyleneglycol. The pastes with oily vehicles showed significantly larger mean zones of inhibition compared to those with aqueous or viscous vehicles. It was concluded that diffusion and antimicrobial activity of calcium hydroxide were affected by the type of vehicle used.