Effect of Conservative Access Cavity Preparation on the Fracture Resistance of Endodontically Treated Molars

Introduction: This study aimed to evaluate the influence of different access cavity designs (conservative versus traditional) and the impact of thermocycling and load cycling on the fracture resistance of endodontically treated molars. Materials and Methods: In this in vitro investigation, sixty extracted human molars were selected and allocated into six groups based on access cavity design and subsequent thermocycling (1000 cycles between 5 °C and 55 °C) and load cycling (200,000 axial cycles at 80 N) protocols. Root canal treatment was performed on all specimens using standardized endodontic procedures. Fracture resistance was subsequently assessed using a universal testing machine. Results: The mean fracture resistance of the teeth with conservative access cavity preparation was significantly higher than that of traditional preparation (P = 0.044). Furthermore, the application of thermocycling and load cycling significantly reduced fracture resistance across all tested groups (P < 0.05). Conclusion: These findings underscore the critical roles of access cavity design and simulated functional aging conditions in determining the long-term structural durability of endodontically treated teeth.