Evaluation of Root Dentin Removal and Apical Debris Extrusion during Root Canal Preparation Related to the Different Endodontic Access Cavities: An In-vitro Study

Introduction: The restricted access cavity and the remaining roof of the pulp chamber may change the angle at which the instrument enters the root canal, which could have an impact on the effectiveness of chemo-mechanical canal preparation, potentially leading to endodontic mishaps. Aim: To evaluate the effect of the Traditional Endodontic Cavity (TEC) and Conservative Endodontic Cavity (CEC) on the amount of Root Dentin Removal (RDR) and the related Apical Debris Extrusion (ADE) in the curved root canals prepared with ProTaper Next (PTN) and TruNatomy (TN). Materials and Methods: The in-vitro study included a total of 120 extracted human mandibular molars, separated into four groups (n=30) based on the type of endodontic cavity and file used: TEC-TN, CEC-TN, TEC-PTN, and CEC-PTN. Before biomechanical preparation, Cone Beam Computed Tomography (CBCT) scans were taken. During the preparation, apically extruded debris was collected in Eppendorf tubes. After canal preparation, a post-CBCT scan was performed, and the RDR was evaluated by comparing the pre-and post-CBCT scans. To determine the amount of ADE, the weight of the clear tubes was subtracted from the weight of the tubes containing the debris. The data were analysed using one-way analysis of variance and post-hoc Tukey test. The significance level was set at p<0.05. Results: Analysis and comparison of four groups each with n=-30 extracted mandibular molars was done in the present study. The CEC-PTN group showed the highest total RDR of 0.32. Additionally, the CEC-PTN group produced the highest ADE with statistically significant differences between the TEC-TN, CEC-TN, and TEC-PTN groups (p<0.05). Conclusion: The CEC causes engagement of the rotary instrument with the dentinal wall, leading to RDR, debris production, and ultimately more ADE compared to TEC. The TN file caused less RDR and ADE in both endodontic access cavities compared to the PTN file.