Effectiveness of photodynamic therapy on bonding strength and failure modes of fiber-posts in c-shaped treated root canals.

Abstract Aim The present study aimed to assess the push-out bond strength (PBS) and failure modes of fiber-posts after photodynamic therapy (PDT) and Erbium yttrium scandium gallium garnet (Er,Cr:YSGG) in c-shaped canals. Methods Sixty molars with c-shaped root configuration were studied. The endodontic prepared teeth specimen were equally randomized into four groups: i) photodynamic therapy (PDT); ii) Er,Cr:YSGG; iii) chlorhexidine and; iv) control group. Post root filling, 10 mm space was prepared for insertion of post in the root canals. The push-out bond strength was evaluated using Universal testing machine. Modes of failure were evaluated as adhesive, cohesive and admixed. Mean values were computed between groups using Kruskal-Wallis test followed by Bonferroni post hoc test. Comparison between two thirds of root sections were analyzed using Friedman test. P-value was set at 0.05 or less. Results Specimens treated with PDT reported the highest mean PBS (8.56 ± 2.12 MPa), while the lowest PBS was observed in NaOCl group (6.92 ± 2.21 MPa). Thirteen failures were observed at the adhesive post interface, whereas 22 failures were found at the interface forming between the dentin surface and adhesive. Similarly, 9 failures were categorized as mixed. For PDT group, a sum of 3 failures and 4 failures were noted at the apical and cervical points. Conclusion The specimens treated with PDT showed the highest push out bond strength with least number of failures.in c-shaped root canals.