Purpose: The purpose of this study was to compare canal transportation, centering ability, and removed dentin thickness (RDT) using hand nickel-titanium (NiTi) K-flex files and rotary systems in primary molars and using cone beam computed tomography (CBCT).
Methods: This study was conducted on 20 primary maxillary and 20 primary mandibular molars, which were randomly divided into two groups to be instrumented with hand NiTi K-flex files and a rotary system. Pre- and post-instrumentation slices were taken at three predetermined levels using CBCT to evaluate all the parameters by using Digital Imaging Communications in Medicine (DICOM) software. The results were statistically evaluated.
Results: Rotary instruments caused significantly less canal transportation and showed more centering ability than hand NiTi instruments at all levels and in all directions, except at the cervical level in the mesiodistal direction, where the hand group showed significantly superior results. The hand NiTi K-flex files removed significantly more dentin than rotary instrumentation at all levels and in all directions, except at the apical level in the buccodistal direction, where no significant difference between the two groups was observed.
Conclusion: Rotary files showed less canal transportation, more conservation of tooth structure, and superior centering ability compared to hand nickel-titanium K-flex files.