Fracture resistance of weakened human premolar roots after use of a glass fiber post together with accessory posts

OBJECTIVE: To evaluate the fracture strength of human premolar teeth with wide root canals, restored with glass fiber posts and resin cement, together with different numbers of accessory posts.MATERIAL AND METHOD: Thirty-six premolars received standardized preparations that simulated weakened roots, and were divided into three groups (n=12): G0 - glass fiber post (Reforpost/Angelus) cementation with dual cure resin cement (Rely X ARC/3M ESPE); G1 - glass fiber post cementation and one accessory post (Reforpin/Angelus), with dual cure resin cement; G2 - glass fiber post cementation and two accessory posts, with dual cure resin cement. Resin composite cores were placed in each tooth. A metal coping was placed in a standardized position on the cores to perform the compressive tests using a test machine. Testing was performed applying a force parallel to the long axis of the teeth at a speed of 0.5 mm/min. Fracture mode was analyzed under a stereoscopic loupe, classified by scores.RESULT: the Analysis of Variance (ANOVA) was applied, and there was no statistical difference in the mean values of fracture strength among the groups (in kgf): G0 = 91.1 ± 56.9; G1 = 104.7 ± 66.6; G2 = 106.1 ± 51.9. Greater frequency of fracture or cracks was observed in the cervical one-third of the root in the teeth without cemented accessory posts, but no statistical difference was observed among the fracture modes.CONCLUSION: The number of accessory posts cemented into debilitated roots had no influence on either fracture strength or type of fracture of pre-molar roots