Is it possible to reduce file numbers of conventional rotary systems?

Abstract

Backround: frequent introduction of new dental instruments or devices into the market has been a concern for dentists worldwide, as the prices of such instruments are generally high, especially in developing countries. In addition, the use of these tools requires new skills and experience. For this reason, while innovations in dentistry are being pursued, it may be advantageous to update the dental instruments that we have been using for years. This study evaluated whether both ProFile and ProTaper files have the potential to reduce the number of files required for shaping curved root canals. Methods: A total of 45 simulated canals with 40o curvature in clear resin blocks were prepared with conventional rotary systems: ProFile orifice shaping (OS) #3 and final flaring #25/.06, Reciproc R25, and ProTaper shaping file SX and finishing file F2. Pre- and post-instrumentation views were analysed using digital images captured by a camera. Prepared inner and outer walls at 1–10 levels were measured using AutoCAD software. The time required for canal shaping and the frequency of broken instruments were recorded. Standardised pre- and post-instrumentation radiographs were taken to determine changes in working length (WL) and straightening of canal curvature. The presence of blockage or perforation was also evaluated. Data were analysed using the one-way multivariate analysis of variance (ANOVA) and least significant difference test. The level of significance was set at 0.05. The transportation, instrumentation time, change of WL, and instrumentation fractures were evaluated. Data were analysed by ANOVA, Kruskal–Wallis and independent t-test (p<0.05). Results: Reciproc removed more mass in total and caused less transportation in the middle and coronal third (p<0.001). The transportations performed in the apical third were opposite to the curve. There was no significant difference among the groups in terms of maintaining the original WL. Reciproc was significantly faster (p<0.001). Only one instrument fracture (25/0.06 ProFile) was noted. All groups showed one ledge each. Discussion: According to this study, both ProFile and ProTaper files have the potential to reduce the number of files required for shaping curved root canals. However, Reciproc, which was produced using a single-file concept, was determined to be more advantageous in terms of time. This study suggests that the conventional rotary technique system might have comparable efficacy to the single-file system for root canal shaping.