ABSTRACT
Introduction:One of the most common dental procedures associated to vertical root fractures is the endodontic treatment with excessive dentin wall wear and another increasing risk factor is the use of intraradicular post. Objective: This study evaluated the resistance to fracture of the buccal and palatal roots of maxillary first premolars with endodontically treated canals and spaces for posts. Material and methods: Twenty two first permanent premolar roots (11 buccal and 11 palatal) composed the experimental sample. The canals were prepared with Protaper Universal® system until file F3 and then filled with gutta-percha cone F3 and endodontic sealer and received spaces for posts keeping 4 mm of filling at the apical third. The roots were subjected to compression test in a universal testing machine (Kratus). The roots were subjected to a progressive compression stress at a speed of 0.5 mm / min. A load cell of 200 kg was used. Results: Statistical analysis revealed significant differences between the strength values and resistance limit between groups (P<0.05), as analyzed by t Student test. The values of resistance to fracture of 0.44 kgf/mm2 for group 1 (buccal roots) and 0.31 kgf/mm2 for group 2 (palatal roots) were found. Conclusion: The resistance to fracture of the buccal roots was higher than that of palatal roots of first premolars submitted to biomechanical preparation and root preparation for intraradicular post.