Mode of Bond Failure Between 3D-Printed Denture Teeth and Printed Resin Base Material: Effect of Fabrication Technique and Dynamic Loading. An In Vitro Study

Purpose: To evaluate the failure load of 3D-printed denture resin material and teeth before and after dynamic loading. Materials and Methods: A total of 40 specimens were fabricated following ISO/TS 19736 and were divided into two equal groups. In the test group, the cylindrical base and denture teeth were 3D printed separately and then luted together. In the control group, the specimens were fabricated from conventional heat-cured polymethyl methacrylate (PMMA) and commercially available denture teeth using the compression-molding technique. Ten specimens from each group were subjected to a dynamic load of 50 N for 250,000 cycles in a chewing simulator. All specimens were subjected to a static load of 50 N using an Instron machine with a crosshead speed of 1 mm/minute until fracture. The fractured surfaces were analyzed using field emission scanning electron microscopy. The failure loads were calculated and compared using analysis of variance (P < .05). Results: All specimens survived the loading, undergoing 250,000 cycles without fracture. The mean failure load was influenced by fabrication technique and was significantly higher for the 3D-printed test group (P = .028). 3D-printed teeth showed a mixed mode of fracture, whereas in the control group, the specimens showed cohesive fracture within the teeth. Conclusion: The fabrication technique has an influence on the mode of failure between the acrylic teeth and resin base material. Cohesive failure in teeth was predominant in the conventional group, suggesting possibly higher bond strength between the teeth and resin base in this group. The observed failure modes revealed that both fabrication techniques exhibit satisfactory bond strength. Chewing simulation did not significantly influence the bond strength of any of the tested groups.