RESUMEN
OBJECTIVES: The aim of this study was to determine the apical surface characteristics and presence of dental cracks in single-rooted premolars, resected 3.0 mm from the root apex, using the Er: YAG laser, tungsten carbide bur, and diamond-coated tip, by scanning electron microscopy (SEM). EXPERIMENTAL DESIGN: Thirty single-rooted premolar teeth were collected. The instrumented and obturated teeth were divided into three groups according to the root resection method (2.94 µm, 100 mj, 20-Hz Er: YAG laser, plain tapered fissure tungsten carbide bur at a low speed of 40,000 rpm, or a diamond-coated SG6D tip coupled to the handpiece of a conventional ultrasound device). The specimens were prepared for SEM and analyzed by the Kruskal-Wallis and Mann-Whitney statistical tests. RESULTS: The SEM images showed that tungsten carbide burs produced significantly smoother resected root surfaces than the diamond-coated tip. There was no statistically significant difference between the Er: YAG and tungsten carbide bur groups. The analysis of scores obtained for the cut quality by the Kruskal-Wallis test revealed no significant differences among the groups. In our study, five teeth had no cracks after the apical resection. The mean number of cracks per tooth was 3.5 ± 1.780 (Er: YAG laser group), 2.5 ± 1.716 (tungsten carbide bur group), and 4.5 ± 2.593 (diamond-coated tip group). CONCLUSIONS: Under the tested conditions smoother surfaces were observed in the groups treated with the tungsten carbide bur and Er: YAG laser when compared with the diamond-coated tips.