Influence of light transmission through fiber posts: Quantitative analysis, microhardness, and on bond strength of a resin cement.

CONTEXT: Light transmission (LT) into deeper areas of the dentin root is limited. AIM: The aim of this study is to perform a quantitative investigation of the radial transmission of light (LT) through different fiber posts and its influence on the Knoop hardness number (KHN) and bond strength (BS) of a dual-cure self-adhesive resin cement at 3 different depths. MATERIALS AND METHODS: Four types of fiber posts (2 translucent and 2 conventional) were used. LT and KHN analyses were performed in a specially designed matrix, which allowed measurements at 3 different depths. LT was measured using a volt-ampere meter while KHN tests were performed in a microhardness tester. For BS analysis, endodontically treated bovine roots were divided into 4 groups, each group receiving one type of post. After cementation, cross sections of the root were tested for resistance to displacement using a universal testing machine. STATISTICAL ANALYSIS USED:: Statistical analysis was performed by using this ANOVA and Tukey's test. RESULTS: For LT, translucent posts showed significantly higher values at all depths compared to the conventional ones. For all posts, LT decreased at the deeper depths. The KHN results showed no statistical differences among the different posts, regardless of depth. For BS, a translucent post showed the highest values, and comparative analyses between the different depths of posts also showed statistically significant differences while comparisons among the different depths of the same post showed no differences. CONCLUSIONS: LT depended on the type of post and on depth. The type of post did not significantly influence the cement KHN. A translucent post showed higher BS in pooled data.

Effects of immediate and delayed intraradicular preparation on bond strength of fiber posts.

BACKGROUND: To assist the retention of restorations prepared in endodontically treated teeth, fiber posts are widely used in dental practice. The ideal time to prepare space for the post is still controversial. AIM: The purpose of this study was to evaluate the effects of immediate and delayed postspace preparation on the retention of the self-adhesive resin cement. MATERIALS AND METHODS: Twelve bovine teeth were used with sectioned roots standardized to 19 mm. The teeth were properly instrumented and filled with gutta-percha and eugenol-free cement AH Plus. Two experimental groups (n = 6) were created based on the different times of post preparation (immediate and delayed). Using cemented cylindrical fiber posts, the teeth were put in acrylic resin and polyvinyl chloride tubes, where the cuts were made. Two slices were obtained from the cervical third, two from the medium third and two from the apical third. Subsequently, the samples were subjected into push-out tests. Statistical analysis were performed using ANOVA and Tukey's test (P = 5%). RESULTS: The results indicated that, for all of the evaluated thirds, delayed preparation showed greater bond strength than immediate preparation. CONCLUSION: A delayed post preparation of the root space, following the root canal filling, is recommended.