Root canal preparation using micro-computed tomography analysis: a literature review

This literature review has critically analyzed the published research related to the biomechanical preparation of root canals with three-dimensional analysis using micro-computed tomography (micro-CT). In December 2017, six databases (PubMed, Cochrane, Web of Science, Embase, Scopus, and Science Direct) were accessed using keywords to find articles including the use of the micro-CT analysis in biomechanical root canal preparation. There were 60 full articles that were selected, which were screened and read by two authors. The research that was reviewed and analyzed included root canal anatomy and sample selection, changes in canal shape and untouched canal areas, canal transportation and centering ability, and kinematics (motion). Of the studies selected, 49.18% discussed anatomical characteristics, with 54.1% of these studies describing mesial roots of mandibular molars with moderate curvature. Only 35% used a stratified distribution based on root canal system morphology and quantitative data obtained by micro-CT. The analysis of canal transportation and centering ability showed that transport values in the apical third exceeded the critical limit of 0.3 mm in mesial roots of mandibular molars with moderate curvature, especially in the groups in which a reciprocating system was used. In relation to kinematics, 91.70% of the reviewed studies evaluated continuous rotating instruments, followed by reciprocating rotation (38.33%), vibratory (15%), and the adaptive kinematics, which was in only 8.33%. The reciprocating kinematics was associated with higher canal decentralization and transportation indexes, as well as a greater capacity for dentin removal and debris accumulation. This literature review showed that the anatomy, the type of design and kinematics of instruments, and the experimental design are factors that directly influence the quality of biomechanical preparation of root canals analyzed in a qualitative and quantitative manner by micro-CT.