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

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.