Antibacterial effect of a hyperosmotic solution containing sorbate and ethanol on Enterococcus faecalis in planktonic form and as biofilm: an in vitro study

Abstract

The antibacterial effect of a hyperosmotic solution containing sorbate and ethanol on E. faecalis in planktonic state and in biofilm was evaluated. Three hyperosmotic solutions (HS-A, HS-B y HS-C) were obtained from different formulations of potassium sorbate and sodium chloride, which were tested as antimicrobials against planktonic forms of E. faecalis, in McFarland standards from 0.5 to 7, using the sedimentation technique and colony forming units (CFU) count. Afterwards an E. faecalis biofilm was produced in the palatal roots of upper first molars, by a static method in 21 days; subsequently they were prepared biomechanically by the Universal Protaper system, using the hyperosmotic solution B as an irrigant to evaluate the bacterial load reduction. One pre-instrumentation sample and one post-instrumentation sample were taken, and then were processed and cultivated to count CFU. Consecutively, roots were observed by scanning electron microscopy. The hyperosmotic solution had an important antibacterial effect when used against E. faecalis in planktonic state; solutions HS-A and HS-B were effective in eliminating E. faecalis up to 7 McFarland, while a statistical difference (p˂0.001) was observed in reducing the bacterial load in the biofilm, based on the log10 CFU count. The final solution tested seemed not to harm the dentinal structure and was capable of causing morphological changes to the bacterial cell consistent with a hyperosmotic shock. Thus, the solutions tested could be an option to be considered as irrigating agents; nonetheless further research is required regarding its biocompatibility.