Purpose: This research compared the fracture resistance of endodontically treated premolars with traditional and conservative access cavity designs and different root canal tapers (0.04 and 0.07).
Materials and methods: In the current study, ninety extracted human mature intact maxillary first premolars with comparable sizes were chosen. The teeth were randomly assigned into seven groups, one control group (n =30) and six test groups (n=10 each) according to the access cavity design and instrumentation system, Group 1 (control group): Intact teeth with no treatment, Group 2: Teeth with prepared TAC with no instrumentation, Group 3: Teeth with prepared CAC with no instrumentation, Group 4: Traditional access cavity/ Primary WaveOne gold, Group 5: Traditional access cavity/ XP‑Endo Shaper Group 6: Conservative access cavity/ Primary WaveOne gold, and Group 7: Conservative access cavity/ XP‑Endo Shaper. Filling of the root canals was done using gutta-percha/Endosequence BC sealer in lateral condensation technique.
The force required to fracture each tooth was measured and recorded in Newtons by loading it in the universal testing machine until fracture occurred.
Analysis of fracture resistance data was done using Two-Way ANOVA test, followed by Tukey test for multiple pairwise comparisons. Differences among groups were considered significant if p-value ≤0.05.
Results: The control group had the highest fracture resistance while group 4 (TAC/WaveOne gold) recorded the lowest value. The difference among the groups was statistically significant (P < .05).
Conclusions: Canal taper has more impact on the fracture resistance of endodontically treated maxillary first premolars compared with the access cavity designs.