Hand file and manual rotary file behavior in curved canals: an ex vivo micro-CT study

Abstract

Several instrumentations systems are available in the market and it is necessary to assess their behavior in curved root canals. Aim: To analyze the ability of two manual instrumentation techniques to center mesial root canals of mandibular molars, studied by computed microtomography (micro-CT). Materials and Method: Twenty mesial root canals of mandibular molars were matched based on similar morphological dimensions using micro-CT evaluation and divided in 2 groups (n=10): (1) Crown-down technique with Gates-Glidden drills and K-Flexofiles and (2) M manual NiTi rotary system. Changes in volume, surface area and canal transportation were compared using an unpaired t-test with a 5% significance level. Results: No significant differences were observed between groups regarding volume surface area after root canal preparation (p>0.05). Variation in the centroid differed between groups in the total canal length, and in the cervical and middle thirds, with better centralization for the M files (p<0.05). Conclusions: Both manual instrumentation techniques had similar volume and surface area variation. Both techniques left unprepared canal areas with similar values. M manual NiTi files caused minor canal transportation.