Objectives: to evaluate marginal adaptability of root canal treated premolars restored with 3D printed and milled endo-crowns before and after thermo-mechanical aging, fracture resistance, and failure modes.
Materials and methods: Thirty-six mandibular first premolars were endodontically treated and prepared to receive endo-crowns that were divided according to CAD-CAM restorative material used into 3 groups (n=12): 3D printed (Varseo Smile) group, Brilliant Crios (BC) group and PEEK group. Marginal gap was measured before and after thermo-mechanical aging for 60000 loading cycles and 5000 thermocycles. Fracture loads were recorded, and failure modes were evaluated.
Results: Paired t-test revealed significant increase in overall marginal gap rates after thermo-mechanical aging of all tested groups with significant difference among them as verified by One Way ANOVA test. There was a significant difference between fracture resistance mean values of all tested groups (P<0.0001) where insignificant difference between Brilliant Crios (1879.45 ± 477.60 N) and PEEK groups (1730.5 ± 210.56 N) both revealed statistically significantly higher mean fracture resistance than 3D printed group (743.39 ± 68.71 N) as verified by Tukey's Post Hoc test.
Conclusions: Marginal adaptability of PEEK endo-crowns was better than those of Brilliant Crios and 3D printed (VarseoSmile) before and after thermo-mechanical aging which resulted in significant reduction of marginal adaptability of all tested endo-crowns. Fracture resistance of Brilliant Crios endo-crowns was higher than those of PEEK and 3D printed (VarseoSmile). Regarding failure mode, all tested endo-crowns showed repairable (favorable) fractures.