Influence of the Resin Cement Insertion Protocol on the bond Strength of Glass-Fiber Posts

Objective: Evaluate the effect of different techniques for insertion of the resin cement on the bond strength of glass-fiber posts cemented with RelyX U200. Methods: Thirty single-rooted premolars were sectioned at 14 mm from the apex, prepared with ProTaper Universal system and filled by single-cone technique with AH Plus sealer. Root canal filling was partially removed, maintaining 4 mm of gutta-percha at the apical third. Specimens were randomly divided into 3 experimental groups (n=10), according to the strategy used to fiber post cementation, as described: CENTRIX, POST/CEMENT, LENTULO. Exacto N1 glass fiber posts were placed into root canal and cemented with RelyX U200. A cutting machine was used for root’s sectioning providing 3 slices, one for each root third (cervical, medium and apical). Push-out test was performed using a universal testing machine and stereomicroscope was used to analyze the failure mode. Results: CENTRIX (10,05 ± 3,25 Mpa) and LENTULO (9,80 ± 3,21 Mpa) showed higher means of bond strength values, superior to POST/CEMENT (6,47 ± 3,85 Mpa). Regarding to root third, the cervical third presented the higher bond strength mean (10,62 ± 3,66 Mpa) and the apical root third presented the lowest bond strength values (6,58 ± 3,28 Mpa). Conclusion: Bond strength values of glass fiber posts are influenced by the method of insertion of the resin cement RelyX U200. On this sense Centrix and Lentulo systems are recommended.