Comparison of fracture resistance of bonded glass fiber posts at different lengths.

PURPOSE To evaluate in vitro the fracture resistance of quartz fiber posts for three different dowel lengths. METHODS 30 single-rooted human premolars with similar root length and diameter were endodontically treated and randomly divided into three experimental groups (n = 10) according to the post space depth created: (1) 5 mm; (2) 7 mm; (3) 9 mm. Quartz fiber posts (Endo Light post) were cemented using a dual cured resin cement with its adhesive system (Prime & Bond NT + Fluorocore 2). After 24 hours, specimens were embedded in acrylic resin and loaded under continuous compressive force at the extruding coronal part of the post (45-degree angle) to the long tooth axis (crosshead speed: 0.75 mm/minute). Forces at fracture (Newtons) were recorded. One-way ANOVA and Tukey tests were used for the statistical analysis (P < 0.05). RESULTS Mean strength values (SD) were: (1) 40.52 (3.14); (2) 41.68 (5.31); (3) 44.88 (6.77), respectively. No statistically significant differences were found among the groups.