Influence of ultrasonic activation of the photodynamic therapy photosensitizer on the bond strength of gutta-percha/bioceramic sealer and fiberglass posts/self-adhesive cement

Introduction the role of endodontic treatment is to eliminate microorganisms without compromising adjacent tissues and adhesion. The aim of present study was to evaluate the influence of ultrasonic activation (US) of the photodynamic therapy (PDT) photosensitizer on the bond strength of filling and restorative material. Methods sixty single-rooted teeth were used. After coronal sectioning, 30 roots were used to assess the bond strength of filling material and 30 to assess the bond strength of restorative material. After complete chemomechanical preparation, the roots were randomly divided into three groups in both evaluations (n = 10), according to PDT and US protocol: G1(negative control)–distilled water; G2–conventional PDT; G3–PDT + US. Then the roots were filled with gutta-percha/Bio-C bioceramic sealer in the first evaluation, and with fiber glass posts/Rely-X U200 self-adhesive cement in the second evaluation. In both evaluations, the roots were sectioned to obtain 1 mm thick dentin discs containing the filling/restorative material, and the push-out test was performed. Failure patterns were observed under optical microscope. Specific statistical analysis was performed in both evaluations (α 5%). Results in both evaluations, bond strength was significantly lower in groups 2(PDT) and 3(PDT + US) compared to control group (p < 0.05), with no statistically significant difference between them (p > 0.05). Regarding the failure patterns, no statistically significant difference was found between groups (p > 0.05), with a predominance of cohesive failure in all groups. Conclusion US of the PDT photosensitizer did not influence the bond strength of gutta-percha/bioceramic sealer and fiber glass posts/self-adhesive cement to root dentin when compared to conventional PDT.