(PR153) The Impact of Anatomy on the Fracture Resistance of Contralateral Incisors Following Traditional and Ultra Conservative Endodontic Access

Objective: This ex vivo study compared the fracture resistance and effects of ultra-conservative and traditional endodontic access of contralateral maxillary central and lateral incisors.

Methods: Eighteen pairs of sound contralateral maxillary incisors were extracted for reasons unrelated to this study were obtained. The symmetry of contralateral maxillary incisors was confirmed using micro-CT scans to analyze anatomic parameters. For each contralateral pair, one tooth was assigned to traditional access cavity (TAC), and the other to ultra-conservative access cavity (UAC). Following access, endodontic treatment was performed using ProTaper Ultimate rotary files and hydraulic condensation obturation with calcium-silicate based sealer. Access cavities were restored with composite. The roots were covered with a silicone impression material and embedded in self-curing acrylic. All samples were loaded to fracture using a universal testing machine. Statistical analysis was performed with significance level set at 5%.

Results: Fracture resistance was significantly higher for maxillary central incisors compared to laterals (p < .05). There was no statistically significant difference in the fracture load between UAC and TAC, regardless of the type of tooth. There was a statistically significant difference when comparing the mean fracture resistance of teeth obtained from different patients (p < .05).

Conclusion: UAC did not improve the fracture resistance compared to TAC in contralateral maxillary incisors. The variations in fracture resistance of teeth from different patients highlights the impact of anatomical and structural parameters on the results of ex vivo studies.