Evaluation of canal transportation and centering ability of two nickel-titanium rotary instruments

Abstract

Introduction: Rotary nickel-titanium (NiTi) instruments have become very popular in recent years mainly because they allow an effi cient preparation of the root canal system. New rotary endodontic instruments resulted from the development of new features, such as variable taper, non-cutting safety tip and variable length of cutting blades. The purpose of this study was to evaluate the degree of canal transportation observed with two nickel-titanium rotary systems, K3 (SybronEndo, Orange, CA, USA) and Mtwo (VDW, Munich, Germany), as well as their centering ability, by measuring dentin wall thickness before and after instrumentation. Methods: Thirty extracted mandibular molars were embedded in resin blocks and sectioned 3.5 and 5.0 mm short of the anatomical apex. The mesiobuccal canals were prepared with the K3 system, using instruments 0.12/25, 0.08/25, 0.06/25, 0.04/25, and 0.02/30 progressively until reaching the working length; and the mesiolingual canals were prepared with the Mtwo system, using instruments 0.04/10, 0.05/15, 0.06/20, and 0.06/25 to full working length. Pre- and postoperative sections were photographed and all data were recorded and analyzed statistically using the Mann-Whitney test. Results: Canal transportation and centering ability results were similar for both instruments (p > 0.05). Relevance: The K3 and Mtwo systems allowed the preparation of curved root canals with minimal transportation, 3.5 or 5.0 mm short of the anatomical apex.