Bond strengths of FRC post according to cements and depths

Objectives: This in vitro study was undertaken to compare push-out bond strengths to tooth-fiber reinforced post according to various resin cements and the depths of roots.

Methods: Fifty, caries free human mandibular premolars were used and divided into five groups of 10 teeth each. Fiber posts were inserted using five resin cements: Panavia F 2.0(PA), Rely X Unicem(Uni), Contax with activator & Luxacore(LuA), Contax without activator & Luxacore(Lu) and SuperBond C&B(SB). Each root was sliced into three discs(thickness 1 mm) representing the coronal, middle and apical part. Push-out tests were performed with UTM at crosshead speed 0.5 mm/min. Maximum push-out strength was recorded, and the failure mode was evaluated with microscope. Cement space was calculated with Image-Pro Plus 4.5. Statistical analysis was conducted using analysis of One-way ANOVA, followed by the Duncan's test, to make comparisons among the groups(p=0.05). Failure mode was analyzed using chi-square test.

Results: The bond strengths were significantly affected by the resin cements, the depth of roots(p < 0.05). Uni group, LuA group and Lu group had significantly higher bond strengths. The coronal regions of the root canal had significantly higher bond strengths compared with the middle and coronal regions. Additionly, in Uni group, LuA group and Lu group, there were significantly higher percentages in cohesive failures at middle regions(p<0.05). In PA group, SB group, Lu group were significantly higher percentages in adhesive failures at apical regions(p<0.05).

Conclusion: Uni group, LuA group and Lu group had significantly higher bond strengths. There were no significant differences in bond strengths according to the depth of roots in Uni group and LuA group. Therefore, these two groups are considered to be clinically useful for bonding FRC post.