The effect of fabrication methods (conventional, computer‑aided design/computer‑aided manufacturing milling, three‑dimensional printing) and material type on the fracture strength of provisional restorations

Abstract

ABSTRACT Background: Fracture is the most common reason for the failure of provisional restorations. This study aimed to assess the effects of the fabrication method (conventional, computer‑aided design/ computer‑aided manufacturing [CAD/CAM] milling, three‑dimensional [3D] printing) and material type on the fracture strength of provisional restorations. Materials and Methods: In this in vitro study, 60 provisional restorations were made through the conventional (Tempron and Master Dent), CAD/CAM milling (Ceramill and breCAM.HIPC) and 3D Printing (3D Max Temp) methods based on a scanned master model. The provisional restorations were designed by the CAD unit and fabricated with milling or 3D printing. Then, an index was made based on the CAD/CAM milling specimen and used for fabricating manual provisional restorations. To assess the fracture resistance, a standard force was applied by a universal testing machine until the fracture occurred. One‑way ANOVA and Tukey’s test were used to compare the groups (α = 0.05). Results: The mean fracture strength was significantly different among the five groups (P < 0.001), being significantly higher in the breCAM.HIPC group (P < 0.001), followed by the Tempron group (P < 0.05). However, the three other groups were not significantly different (P < 0.05). Conclusion: Despite the statistical superiority of some bis‑acrylics over methacrylate resins, the results are material specific rather than category specific. Besides, the material type and properties might be more determined than the manufacturing method. Key Words: Computer‑aided design/computer‑aided manufacturing, fracture strength, provisional restoration, three‑dimensional printer