Antibacterial efficacy of different irrigation methods on Enterococcus faecalis infected root canals in vitro

Abstract

Objective To compare the ultrasonic, Er, Cr: YSGG laser and Er: YAG laser-assisted 1% sodium hypochlorite (NaOCl) solution on the bactericidal effect of Enterococcus faecalis (E.faecalis) biofilm on the root canal surface and E.faecalis in different depth from dentinal tubules in the apical region. Methods Forty-two single mandibular premolars were used to establish a root canal model of E.faecalis biofilm infection. Two teeth were determined by digital randomization method to establish the model of infection of E.faecalis. The remaining 40 teeth were divided into 5 groups according to the principle of random comparison by digital random method as well as 8 in each group. The groups were: Positive Control: group A: 5.25% NaOCl + 17% EDTA springed, Negative Control: group B: physiologic saline springed, group C: ultrasound + 1% NaOCl, group D: Er: YAG laser + 1% NaOCl, group E: Er, Cr: YSGG + 1% NaOCl. The data from each group were compared using the SPSS 17.0 statistical software for the homogeneity of the experimental data and the normality test to compare the relative sterilization rates between groups and groups. Results (1) Comparison between groups: The sterilization rate of each group was compared. Group B (5.74%) <C group (69.70%) <D group (90.14%) <E group (99.25%) , All of which were lower than group A (99.95% of the positive control group) , and the differences between the groups were statistically significant (P<0.05) . (2) Comparison within the group: Compared with the relative sterilization rate of dentin at different depths of 4 mm, the difference of antibacterial rate in different depths of group A and group C was statistically significant (P<0.05) . Conclusions Ultrasound, Er: YAG laser, Er, Cr: YSGG laser can enhance the root canal disinfection effect, and the difference between the two laser root canal disinfection effects is not statistically significant, both of which are better than 1% NaOCl ultrasonic washing. Key words: Root canal irrigants; Laser therapy; Ultrasonic therapy; Laser-activated irrigation; Passive ultrasonic irrigation