Efeito do protocolo de fotoativação de cimentos resinosos nas propriedades mecânicas e resistência de união na cimentação de pino de fibra de vidro

Abstract

The aim of this study was to test the hypothesis that photo-activation protocol and resin cement affect the mechanical properties and bond strength of fiber glass posts to root dentin at different depths. Hundred fifty six bovine teeth were selected, sectioned to 15 mm long and instrumented with Kerr files and drills Gattes-Gliden. After endodontic instrumentation roots were prepared with a length of 10 mm to receive fiberglass post Exact no. 3(Angelus). RelyXU100 (3M-ESPE), BisCem (Bisco), Panavia F 2.0 (Kuraray) and RelyX ARC (3MESPE) resin cements were used to cement fiber glass posts in association with one of the three photo-activation protocols: light-curing immediate, 3 minutes and 5 minutes after to cement Exacto Fiber Post (Angelus). The root canal were stored at 37 ° C for 24 hours, after that time were carried tests push- out and hardness test In each group 10 posted root were used for push-out test obtaining 2 slices for each region for each root region cervical, middle and apical. For indentation test, the other 3 roots per group were sectioned longitudinally through the post included in cold resin inlay and polished. This samples were used by determinate modulus of elasticity (E) and Vicker s (VHN) hardness with load progressive of 0 to 500 mN in 20 seconds. E and VHN were determinate of the cement layer were assessed for each root depth. Resin cements RelyXU100 and BisCem showed significantly higher bond strengths than RelyX ARC and Panavia F. The delayed photo-activation protocol increased bond strengths for all resin cements evaluated. Bond strengths decreased significantly from coronal to apical root canal regions.Multiple linear regression determined that the bond streng this associated with the protocol photo activation (p <0.001) and root region (p <0.001) for all cements with R2 ranging between 0.594 and 0.643. The mean values for E and VHN increased significantly with the delayed photo-activation protocol for resin cements RelyX U100 and BisCem and decreased from coronal to apical root thirds for all resin cements. For the E and VHN, the multiple linear regression showed a direct relationship with the protocol of photo activation (p <0.001) and an indirect relationship with the depth to the cements tested (p <0.001) with high coefficients of determination (R2 from 0.721 to 0.908), but the time factor was more important for self-adhesive resin cements The delayed photo-activation protocol increased the bond strength and mechanical properties of self-adhesive resin cements used to lute fiber posts. The root canal region is a critical factor for the bond strength and mechanical properties of dual-cure resin cements photo-activated using different protocols.