Fatigue resistance of interim restorations: comparison of CAD/CAM and 3D-priting.

Aim: Additive manufacturing (AM) technologies can be used to fabricate 3D-printed interim restorations in dentistry. However, evidence of their performance is lacking. The purpose of this study was to compare the fatigue resistance of 3-teeth interim resin restorations made by 3D printing with those obtained from polymethylmethacrylate (PMMA) blocks using a CAD/CAM system. Methods: A titanium master model for 3-teeth fixed dental prostheses (FDPs) (abutment teeth 45 and 47) was manufactured. The master model was scanned and 14 FDPs were fabricated using respectively: group 1 (N=7): CAD/CAM + BreCAM HIPC-Bredent (BH); group 2 (N=7): 3D printing + Temporis-DWS (T). The FDPs were cemented on the titanium master model with a provisional cement (Temp Bond, Kerr) and submitted to a 5-step incremental cyclic isometric loading: step 1: 5.000 cycles at 10 Hz with 200 N compressive load; steps 2 to 5: 30.000 cycles at 3Hz with a compressive load respectively of 400 N, 600 N, 800 N and 950 N. The 2 groups were compared using the life table survival analysis and t-test. Results: Only 5 specimens of group 1 (BH) survived the entire fatigue process and two specimens failed during step 5 (i.e. 950 N). Four specimens of group 2 (T) failed during step 3 (600 N) and three specimens failed during step 4 (800 N). Conclusion: PMMA CAD/CAM fabricated interim restorations showed higher mechanical resistance if compared to the ones produced via 3D printing .