Evaluation of apical canal shapes produced sequentially during instrumentation with stainless steel hand and Ni-Ti rotary instruments using micro-computed tomography

I. Objectives Endodontic success depends on thoroughly cleaned and completely obturated root canal system. Effective cleaning and obturation will be achieved by well shaped canal. Numerous methodologies evaluating the efficacy and safety of canal preparation has been developed and the use of micro-computed tomography(MCT) in endodontic research is one of the latest innovations. This scientific tools could overcome the inherent limitations of other methodologies, and possesses the ability to visualize morphological characteristics in a detailed and accurate manner without destruction of the tooth and offers reproducible data in all three dimensions. The purpose of this study was to determine the optimal master apical file size with less transportation and more efficiency in removing the infected dentin. For this purpose we evaluated the transportation of canal center and change of untouched area after preparation sequentially from ＃25 file through ＃40 file with 3 different instruments：Stainless steel(SS) K-type hand instruments(MANI, Japan), ProFile.04 instruments (Dentply Tulsa Dental, USA) and Lightspeed instruments(Lightspeed Technology, San Antonio, USA) using micro-computed tomography.(omitted)