Effect of Specimen Design on Bond Strength Values to Dentin

Objectives: To evaluate the design of specimens for a push out test, which was used to obtain information about the bond strenghts between coronal/root dentin and a self-etching adhesive system. Methods: Ten teeth, extracted for periodontal reasons, were cut 4mm coronal to the CEJ, endodontically instrumented and divided into two groups (n=5), according to the post space created: G1- prepared with a parallel burs system; G2- prepared with a tappered burs system. Parallel (Æstheti Plus^TM, Bisco) and Tappered (D.T. Light-Post®, Bisco) posts were molded, duplicated in resin cement (Duo-link, Bisco) and cemented with Tyrian SPE (Bisco) and Duo-link (Bisco). The push-out test was performed on different sections of the root and the data was subjected to a two way repeated measures ANOVA and Tukey's test (a=0.05). Results: There were no significant differences between the two designs tested. The middle part of the root canal preparation (1.59±2.06) had the lowest bond strength values and differed statistically from the coronal region (5.39±3.76). Conclusions: The design of specimens did not affect the push out test results. There was a decrease on push out bond strengths in the middle part of the canal preparation with the self-etching adhesive employed.