The Influence of Time and Cement Type on Push-Out Bond Strength of Fiber Posts to Root Dentin

The bond strength of fiber posts luted with resin cements was evaluated after two storage times in different regions of a post space. A total of 40 single-rooted human teeth were endodontically treated and prepared for cementation of fiber posts (White Post DC). In groups 1 and 3 (G1 and G3, respectively), posts were luted with RelyX ARC, whereas the posts in groups 2 and 4 (G2 and G4, respectively) were luted with RelyX Unicem. After one month of storage at 100% humidity, G1 and G2 were transversally sectioned in 1.7-mm slices of the cervical (C), middle (M), and apical (A) thirds of the post space and submitted to push-out testing at 1 mm/min. After nine months of storage, the roots of G3 and G4 underwent the same process. Mean values were analyzed using the Mann-Whitney and Kruskal-Wallis tests (alpha=0.05). The bond strengths in G2 (C=4.26 +/- 2.29; M=4.67 +/- 3.54; A=7.27 +/- 4.30) were statistically higher than in G1 (C=3.81 +/- 1.07; M=1.57 +/- 1.62; A=1.99 +/- 1.60) in the middle and apical thirds (p=0.001). Bond strengths in G4 (C=3.36 +/- 1.39; M=4.49 +/- 2.17; A=3.83 +/- 1.92) were higher than in G3 (C=2.13 +/- 0.47; M=0.94 +/- 1.05; A=0.95 +/- 1.02) in all evaluated regions (p=0.02, p<0.001, and p<0.001, respectively). When comparing the root regions for each group, G1 had higher values in the cervical third than the middle third (p=0.02). The self-adhesive resin cement showed better results than the conventional resin cement at both storage times. For both materials a similar performance among the three root regions was found. Storage time did not influence the shear bond strength.366643648FUNDECT [23/200.084/2007]FUNDECT [23/200.084/2007