BACKGROUND: The existing difficulty during the preparation chemistry-mechanic is to make the instrument to extend the canal and if to adapt to its form without causing deformations. PURPOSE: evaluate the alteration of the curved in root canals, 25° at beyond, for hand file and rotary canal preparation. MATERIAL AND METHOD: Twenty‑seven maxillarys and mandibulars molars permanent teeth had used, preparation hand file K 15 the apex, radiographed and divided in three experimental groups: G1 (control) - preparation technique crown-apex used Gates-Glidden drills 3, 2 and 1, preparation in the apical and mid-root areas used shape 20, 25 and 30 hand file flex; G2 (Pro taper) - preparation technique rotary Pro taperÒ System and preparation in the apical-root shaping 30 and G3 (ProFile) - preparation technique rotary system ProFileÒ and preparation in the apical-root shaping 30.06. The angle of the curved canals were determined by digital radiography (Image Tool software, version 3.0) using the Schneider method. The data had been submitted to the Kruskal-Wallis tests with significance of 1%. RESULT: It did not have difference statistics, when of the variation of the angle of the canals prepared for the hand file and the technique rotary. It had significant difference of the angle between first and the last instrument of each rotary system. CONCLUSION: The alteration of root canal curvature for the manual method and the method of rotation continues (Pro taper and ProFile system) had been similar.
Endodontics; root canal therapy; molar