Comparison of fracture strength after thermo-mechanical aging between provisional crowns made with CAD/CAM and conventional method

PURPOSE: The objectives of this study were to evaluate the fracture strength and fracture patterns of provisional crowns fabricated from different materials and techniques after receiving stress from a simulated oral condition. MATERIALS AND METHODS: A monomethacrylate-based resin (Unifast Trad) and a bis-acryl-based (Protemp 4) resin were used to fabricate provisional crowns using conventional direct technique. A milled monomethacrylate resin (Brylic Solid) and a 3D-printed bis-acrylate resin (Freeprint Temp) were chosen to fabricate provisional crowns using the CAD/CAM process. All cemented provisional crowns (n=10/group) were subjected to thermal cycling (5,000 cycles at 5°-55℃) and cyclic occlusal load (100 N at 4 Hz for 100,000 cycles). Maximum force at fracture was tested using a universal testing machine. No statistically significant difference was noted among other groups. For failure pattern analysis, Unifast Trad and Brylic Solid showed less damage than Protemp 4 and Freeprint Temp groups. CONCLUSION: Provisional crowns fabricated using the CAD/CAM process and the conventionally fabricated bis-acryl resins exhibited significant higher fracture strength compared to conventionally fabricated monomethacrylate resins after the aging regimen. Therefore, CAD/CAM milling and 3D printing of provisional restorations may be good alternatives for long term provisionalization.