Effect of the length of glass fiber posts on the fracture resistance of restored maxillary central incisors.

Purpose: To evaluate the influence of post length insertion on the fracture resistance of directly restored endodontically treated teeth. Methods: 30 maxillary central incisors were restored with glass fiber posts and composite cores to produce groups with post lengths of (1) 5 mm, (2) 7 mm, and (3) 9 m. Specimens were loaded at 130 degrees (Instron). Fracture strengths were analyzed with the Kolmogorov-Smirnov Test to verify the normality of the data distribution and with ANOVA and Tukey's post hoc test at P < 0.05. Fracture patterns (restorable or unrestorable) were analyzed (Pearson's Chi-square test). Results: The average fracture resistance was: Group 1 = 366.4 N, Group 2 = 507.4 N and Group 3 = 509.9 N. No significant difference was found among the three groups for fracture resistance or for failure mode. The insertion length did not influence the fracture pattern; more restorable fractures were detected.