Influence of Storage Time and Cementation Strategies on Push-Out Bond Strength of Fiber Posts to Root Dentin

Abstract

Introduction: The restoration of structurally compromised endodontically treated teeth pose most challenging adhesive restorative procedure and controversies still exist about which material or technique are best for their restoration. Aim: To evaluate the push-out bond strength of two fiber post systems luted with self-etch adhesive after phosphoric acid conditioning of the root dentin at two different storage periods. Materials and Methods: Eighty mandibular premolars with single straight canals, decoronated at cementoenamel junction were endodontically treated and post spaces of 8 mm were prepared. Root samples were randomly divided into two groups; Groups 1 and 2 (n=40 each) according to the storage period and four subgroups (n=10 each) depending on the type of fiber post (subgroups A and C: glass fiber posts, B and D: carbon fiber posts) cemented. In subgroups A and B, fiber posts were luted with self-adhesive (Rely X U200) cement. In C and D subgroups, 37% phosphoric acid etching of the root dentin was done prior to cementation of the posts. After one month and 12 months storage period, uniform root slices were obtained for all the specimens with the help of a diamond saw and the slices were subjected to push-out test. The results were analysed with twoway ANOVA and Tukey’s multiple post-hoc test. Results: The 37% phosphoric acid etching significantly improved the bond strength of fiber posts luted with self-adhesive resin (p<0.05) cement. Storage time significantly influenced the bond strength (p<0.05). The statistically significant difference was found between the type of posts tested, glass fiber posts exhibited better push-out bond strength compared to carbon fiber posts. Among the prepared post space regions lowest bond strength was observed in apical thirds. Conclusion: Post space conditioning with 37% phosphoric acid prior to cementation could improve the bond strength of fiber posts luted with self-adhesive cements. Both storage time and location within the post space significantly influenced the push-out bond strength.

Keywords

• endodontically treated teeth
• phosphoric acid
• self-etch adhesives
• universal testing machine