Evaluation of antimicrobial effectiveness and dentine mechanical properties after use of chemical and natural auxiliary irrigants

Objective: To evaluate the effect of GSE, NaOCl, CHX and QMix as an antimicrobial agents against Enterococcus faecalis and their influence on flexural and ultimate tensile strength of root canal dentine. Methods: Root canals were divided into five groups (n = 10) according to the substances used: 2.5% NaOCl, 2% CHX, 6.5% GSE, Qmix and control group (distilled water) (DW). Final irrigation was done with 17% EDTA in all groups, except when DW was used. The number of colony-forming units was used to evaluate the antimicrobial activity. Dentine beams were used to assess the flexural strength after treatment with substances as described before (n = 10). The UTS was evaluated after the treatment of root dentine hourglass shape sections with the same substances (n = 30). Results: The lowest bacteria contamination was observed for CHX and GSE, while NaOCl and QMix showed an intermediate antimicrobial activity (p > 0.05). NaOCl and QMix significantly reduced the mechanical properties of dentine (flexural strength and UTS) (p < 0.05) and no statistical difference was found among CHX, GSE and DW (p > 0.05). Conclusion: CHX and GSE were more effective than NaOCl and QMix against Enterococcus faecalis. Furthermore, they did not harm dentine mechanical properties as observed for NaOCl and QMix. Clinical significance: The use of GSE can be recommended for endodontic procedures since it has good antimicrobial activity and does not interfere in the mechanical properties of dentine; similarly to CHX. (C) 2015 Elsevier Ltd. All rights reserved.