In Vitro Study of the Effect of Conservative Endodontic Cavities on Fracture Strength in Mandibular Molars Using CBCT Analysis

Abstract

Background: Endodontically treated teeth with conservative cavity preparation show better fracture resistance than traditional designs. Objective: To compare the fracture strength of endodontically treated teeth using traditional endodontic cavity (TEC), conservative endodontic cavity (CEC), truss access cavity (DDC), and ninja endodontic cavity (NEC) access designs. Methods: In an in-vitro study, 50 freshly extracted human intact mandibular molars with two separate roots were selected. The anatomic crown height, buccolingual, and mesiodistal dimensions were measured and randomized to control (intact teeth), TEC, CEC, DDC, and NEC groups (n = 10). Using cone‑beam computed tomography, TEC, CEC, DDC, and NEC access cavity outlines were planned. Following endodontic treatment, the fracture strength of teeth was assessed using a universal testing machine and fracture type with a stereomicroscope. Results: The mean volume percentage of the coronal hard tissue removal was significantly lower in the NEC group than in the TEC, and CEC groups (P < 0.05), while the difference was comparable between the NEC and DDC groups (P > 0.05). The fracture strength of teeth prepared with the TEC design was significantly lower than teeth prepared by CEC, DDC, NEC, and control groups (P < 0.05). Conclusion: Teeth with traditional access preparation showed lower fracture strength than the conservative approaches.