Abstract:

Objective To study the effect of DNaseⅠ combined with Nd: YAP laser on the removal of enterococcus faecalis (E.f) biofilm in root canals. Methods The E.f infection model on dentin surface was established and observed by scanning electron microscope (SEM). E.f biofilm samples cultured for 48 h were divided into 5 groups by random number table method, with 5 samples in each group. The group A was treated with 0.5%NaOCl, the group B was treated with 0.5%NaOCl+Nd: YAP laser, the group C was treated with DNaseⅠ+ 0.5%NaOCl, the group D was treated with DNaseⅠ+ 0.5%NaOCl+Nd: YAP laser and the group E was treated with 0.9% normal saline. The adhesion of E.f on dentin surface was observed by laser confocal microscope (CLSM), and the amount of green fluorescence was counted, which was the amount of viable bacteria. Results SEM observation showed the dentin tubule opening on the dentin surface. E.f adhesion was observed on the dentin surface, and bacterial adhesion was observed in the deep layer of dentin tubule. CLSM observation showed that living bacteria with green fluorescence were scattered on the dentin surface in the group A, the group B and the group C. Less green fluorescence was observed in the group D. Green fluorescent live bacteria covered all the sample surface in the group E. The amount of bacteria in the group D was significantly less than that in the groups A and the groups E, and the amount of bacteria in the group C was significantly less than that in the group E (P<0.01). Conclusion Compared with 0.5% NaOCl alone, DNaseⅠ combined with Nd: YAP laser and 0.5% NaOCl can treat E.f biofilms more effectively.

Key words: Enterococcus faecalis, biofilms, deoxyribonuclease Ⅰ, Nd: YAP laser, root canal irrigation