Effect of photodynamic therapy and ErCrYSGG laser irradiation on the push-out bond strength between fiber post and root dentin.

Background: To evaluate the push out bond strength and modes of failure of fiber post by using photodynamic therapy (PDT), Er,Cr:YSGG laser and conventional cleaning and shaping (CCS).

Methods: Sixty maxillary anterior teeth were sectioned horizontaly 2 mm incisal to the cemento-enamel junction, and root canal were prepared for post space. Tapered fiber posts were placed inside the root canal after post space was made. The fiber posts were subjected to PDT, Er,Cr:YSGG laser and CSS with 20 specimens in each group. The specimens obtained were sectioned in cervical and apical sections. A universal testing machine was used to perform the push out test and the push out bond strength was formulated by σ = C/A, expressed in mega-pascals (MPa).

Results: The highest mean push out bond strength was achieved by PDT group (8.08 ± 2.73 MPa) and the lowest was shown by specimens in CCS group (7.45 ± 1.04 MPa). ANOVA showed no statistical difference among the experimental groups (p = 0.481). In the cervical segments, the mean push-out bond strength was found to be slightly higher for all three groups compared to apical segments (P < 0.05). The independent t-tests results showed that the mean push-out bond strength values of the cervical segments were slightly higher than the apical segments in PDT, Er,Cr:YSGG and CSS groups (P < 0.05). Significant differences were observed when mean push-out bond strengths were compared for both cervical (p = 0.037) and apical (p = 0.019) segments between all the groups. Twenty-one failures were found at the interface between the adhesive and the dentin surface, 6 failures were observed at the interface between the adhesive and post, whereas 5 failures were mixed.

Conclusion: Push-out bond strength to root canal dentin were not affected by Er,Cr:YSGG compared with conventional cleaning and shaping. However, PDT produced the smallest number of failure modes and slightly higher push-out bond strength to root dentin.