Cone-beam computed tomography analysis of centering ability and transportation of curved root canals prepared with three rotary nickel-titanium systems (In Vitro-Study)

Abstract

Objective: The aim of this study is to compare the degree of transportation, centering ability, and dentin thickness after mechanical preparation using three different nickel-titanium rotary instrumentation systems, ProTaper Next (PTN), twisted file (TF), and K3 Endo in curved root canals analyzed using cone-beam computed tomography (CBCT). Materials and Methods: Thirty moderately curved roots of extracted human maxillary and mandibular molars were divided into three groups with 10 root canals each. Group I, the root canals were prepared with PTN rotary system; Group II, the root canals were prepared with TF rotary system; and Group III, were prepared with K3 rotary file system. Preinstrumentation and postinstrumentation three-dimensional CBCT images were obtained from root cross sections in three levels; coronal, middle, and apical third. Results: It was observed that there were no significant differences in the degree of canal transportation at apical level and the remaining dentin thickness between the rotary instruments (P > 0.05). There were no statistical significant differences in centering ability between buccolingual centering ratio after using the three systems at coronal and middle levels (P > 0.05) except for apical level is significantly difference (P = 0.047). In addition, there were no statically significant differences between centering ratio after using the three systems at cervical, middle, and apical levels (P > 0.05). Conclusions: Under the conditions of this study, CBCT analysis showed that the TF has the ability to produce centered preparation maintaining the original root canal anatomy in the apical one-third of the root canal while PTN showed some degree of canal deviation and K3 showed the highest canal deviation.