Comparison of curved canals preparations using profile, GT and Hero 642 rotary files.

summary  This study compared preparations of curved canals, using Profile, GT file and Hero 642 rotary files. A total of 30 mesiobuccal canals of extracted first and second mandibular molars were used in this study. The teeth were embedded in resin and a pre-operative radiograph was taken. The specimens were then randomly divided into three instrument groups. Pre- and post-instrumentation radiographic images were scanned and superimposed using the visi cad/cam program. At nine horizontal sections at 1 mm increments from the apex, it calculated pre- and post-instrumentation cross sectional areas (mm2) and enlargements to the inner aspect and outer aspects (mm). A Kruskal–Wallis test found no statistical difference among the groups in terms of total areas removed by each instrument (P > 0·05). It also found no significant difference in any group between the total of the inner and outer enlargements (P > 0·05). However the GT file removed significantly more material from the outer side of the canal than the inside at sections 3–5, and the Hero removed significantly more material from the outer side at sections 7–9 (P < 0·05). All instruments produced preparations that maintained original canal curvatures.