Impacts of conservative endodontic cavities on root canal therapy compare to traditional endodontic cavities in premolars

Abstract Background: This study aims to compare the percentage of dentin removed, instrumentation efficacy, root canal filling and load at fracture between contracted endodontic cavities and traditional endodontic cavities in premolars. Methods: Forty extracted intact human first premolars were imaged with micro-CT and randomly assigned to CEC or TEC groups. Minimal CECs were prepared with the aid of 3D-printed guide template, canals were prepared with a 0.04 taper M-Two rotary instrument and cavities were restored with resin. The specimens were loaded to fracture in an Instron Universal Testing Machine after a fatigue phase. The data were analyzed by the independent samples T test and Mann-Whitney U test, appropriate post hoc tests. Results: In the premolars tested in vitro, CECs conserved coronal dentin in premolars with two dental roots but no impact on the instrument efficacy, the root canal filling or the biomechanical responses compared with TECs. Conclusion: The results of this study did not suggest that CEC could improve the fracture resistance of the endodontically treated premolars. The instrumentation efficacy and the percentage of filling material did not significantly differ between CECs and TECs in the premolars.