Residual root dentin thickness for three different rotary systems: A comparative cone beam computed tomography in vitro study

Residual root dentin thickness (RDT) in endodontically treated teeth is a major factor that is responsible for longevity of treated tooth. Aims and Objectives: To evaluate and compare the amount of RDT during endodontic treatment using manual K-files and rotary Mtwo, ProTaper Next, and Hero shaper instruments. Settings and Design: Anin vitro study was carried out on a sample of 100 freshly extracted human single straight rooted mandibular first premolar teeth. Methodology: The teeth were divided into five groups of twenty each and mounted on wax rims for a preoperative cone beam computed tomography scan to calculate the dentin thickness 3 and 6 mm from the apex. All the teeth were treated according to their groups. Statistical Analysis: The observations were then statistically analyzed using one-way ANOVA to evaluate the difference among four groups followed by post hoc test for pairwise comparison. Results: Maximum preservation of dentin was seen in Group V (cleaning and shaping done with rotary Hero shaper files) at 3 and 6 mm from the apex, whereas minimum preservation of dentin was seen in Group IV at 3 mm (cleaning and shaping done with rotary ProTaper Next files) and Group II at 6 mm (cleaning and shaping done with hand K-stainless steel files) from the apex. Overall there was a statistically significant difference in RDT values between Group V and Groups I, II, III, IV both at 3 and 6 mm from the apex. Conclusion: Cleaning and shaping with rotary Hero shaper files preserved more amount of dentin when compared to hand K-files, rotary Mtwo, ProTaper Next.