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

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ABSTRACT Basic ResearchJKACD Volume 36, Number 3, 2011 Apical preparation size and transportation Stainless steel hand file과Ni-Ti rotary file을이용한근관형성시근단부근관형태의순차적변화에대한평가 이우진 1 ∙이정호 1 ∙전경아 2 ∙서민석 3 ∙유연지 1 ∙백승호 1 * 1 서울대학교치과대학치과보존학교실, 2 고려대학교안암의료원치과보존과, 3 한양대학교서울병원 Evaluation of apical canal shapes produced sequentially during instrumentation with stainless steel hand and Ni-Ti rotary instruments using Micro-computed tomography Woo-Jin Lee 1 , Jeong-Ho Lee 1 , Kyung-A Chun 2 , Min-Seock Seo 3 , Yeon-Jee Yoo 1 , Seung-Ho Baek 1 * 1 Department of Conservative Dentistry and Dental Research Institute, College of Dentistry, Seoul National University, 2 Department of Conservative Dentistry, Korea University Anam Hospital, 3 Hanyang University Seoul Hospital, Seoul, Korea Objectives: The purpose of this study was to determine the optimal master a pical file size with minimaltransportation and optimal efficiency in removing infected dentin. We evaluated the transportation of thecanal center and the change in untouched areas after sequential preparation with a #25 to #40 file using 3different instruments: stainless steel K-type (SS K-file) hand file, ProFile and LightSpeed using micro-computed tomography (MCT). Materials and Methods: Thirty extracted human mandibular molars with separated orifices and apical fora-mens on mesial canals were used. Teeth were randomly divided in to three groups: SS K-file, Profile,LightSpeed and the root canals were instrumented using corresponding instruments from #20 to #40. Allteeth were scanned with MCT before and after instrumentation. Cross section images were used to evalu-ate canal transportation and untouched area at 1- , 2- , 3- , a nd 5- mm level from the apex. Data werestatistically analyzed according to ‘repeated nested design’and Mann-Whitney test (p= 0.05).Results: In SS K-file group, canal transportation was significantly increased over #30 instrument. In theProFile group, canal transportation was significantly increased after preparation with the #40 instrumentat the 1- and 2- mm levels. LightSpeed group showed better cent ering ability than ProFile group afterpreparation with the #40 instrument at the 1 and 2 mm levels. Conclusions: SS K-file, Profile, and LightSpeed showed differences in the degree of apical transportationdepending on the size of the master apical file.