Investigation on Effective Education Methods for Preparing Curved Root Canals with FKG RaCe

Abstract

 Purpose: Nickel-titanium (NiTi) files are becoming more popular for root canal treatments, since they have the clear advantage of maintaining the original shape of curved root canals because of their low elastic modulus and flexibility. The present study assessed the educational effectiveness of preparing curved root canals with FKG RaCe in dental students' hands-on practical classes.

 Methods: A total of 49 third-year students in the School of Dentistry, Osaka University performed root canal preparation of J-shaped canals in transparent epoxy resin blocks with FKG RaCe twice. After measuring the length of root canals with a #15 K file, cervical preflaring was performed with a preRaCe and glide path preparation was performed with a #15 K file. Working length was determined by subtracting 1 mm from the root canal length and root canal preparation was performed with RaCe (#30/6%, #30/4%, #25/4%, and #20/4%). For evaluating the quality of root canal preparation, digital images of the epoxy resin blocks before and after the instrumentation were captured by micro-computed tomography. Using image analysis software, the images of pre- and post-instrumentation were superimposed and the distances between pre- and post-instrumentation were measured on both the inner and outer sides. Measuring levels were set at 1, 2, 3, 5, 7 and 10 mm from the root apex and the distances were compared between the outcomes by the students and by specialists accredited by the Japanese Society of Conservative Dentistry.

 Results: In 49 root canals instrumented by the students for the first time, 28 apical perforations, one separated file, and one apical blockage were observed. In 49 root canals instrumented by the students for the second time, five apical perforations and one apical blockage were observed. The distances between pre- and post-instrumentation at the different levels and working time showed no significant differences among the first and second trials by the students and specialists.

 Conclusion: In hands-on training of root canal preparation for dental students, successful root canal preparation was achieved by instructing students to pay attention especially when preparing a root apex.