(PO120) Comparison of Fracture Resistance Between Traditional Endodontic Access and Minimal Endodontic Access in 3D-Printed Mandibular First Molars

Abstract: Many clinicians have employed the traditional endodontic access (TEA), which involves straight-line access to the canals and complete removal of the roof of the pulp chamber, whereas others advocate minimal endodontic access (MEA) to decrease the removal of tooth structure. Many have evaluated and compared the fracture resistance of TEA to MEA using human-extracted teeth, but variability in size, morphology, and strength resistance has remained uncontrolled variables. The aim of this study was to compare the fracture resistance of TEA and MEA, using identical 3D-printed mandibular lower first molars to eliminate such variabilities of natural human molars. Forty-five identical 3D-printed mandibular first molars were randomly assigned to three groups (n=15): TEA, MEA, and control/intact teeth. For the TEA group, the roof of the pulp chamber was completely removed and straight-line access was made to all three canals (4 mm by 4 mm). For the MEA group, access was made at the central fossa without complete roof removal (2 mm in diameter). Each tooth was instrumented, obturated, and restored with composite. All three groups were tested for their fracture resistance using the Instron Universal Testing Machine (Instron, Norwood, MA), and the maximum load at fracture was recorded. When analyzed with the ANOVA test and Tukey’s honestly significant difference test, the TEA groups showed significantly lower maximum load at fracture compared to the control and the MEA groups (p < .05).