RESUMO
AIM: To evaluate the shaping ability of the XP-endo shaper file system in maxillary molars, representing root canals with variation in morphology. MATERIALS AND METHODS: Twenty maxillary molars were instrumented according to recommended protocols. Pre- and postoperative microcomputed tomography (CT) scans were performed and the root canals classified according to canal type and curvature. The volume change, number of strokes needed to prepare the canals and the size of the 0.04-tapered gutta-percha cone that was adapted in the canal were recorded. RESULTS: XP-endo shaper created a significant change in volume after instrumentation in all the canals, with the biggest change found in the DB canals, followed by the MB1 and the P canals, both at full length and in the apical 4 mm. The number of strokes needed to achieve working length and final shape did not differ between the various root canals. Although not significant, the number of strokes needed to prepare the root canal increased with severity of the curvature, but the severity of the curvature did not result in increased removal of dentin in the apical 4 mm. It was possible to achieve a final root canal size where a 0.04-tapered gutta-percha cone could be adapted. CONCLUSION: The XP-endo shaper was a safe and effective instrument to achieve a root canal preparation of at least size 30 and a 0.04 taper. CLINICAL SIGNIFICANCE: The clinical performance of XP-endo shaper was to some extent dependent on preoperative volume and curvature of the root canal.