engleski

Simulated fatigue of porcelain/composite resin CAD/CAM overlays on endodontically-treated molars.

Background. Adhesive coverage restorations (overlays) are indicated to reduce the risk of fracture of endodontically-treated (RCT) molars. Purpose: This study assessed the influence of material selection (porcelain vs. composite resin) for overlay-type restorations on RCT molars and its effect on the fatigue resistance. Materials and methods. standardized tooth preparations were applied to 30 RCT extracted molars: 2mm coverage of all cusps, mesial box below the CEJ, GI base and immediately sealed dentin. All teeth were restored with standardized overlays using the CEREC machine. Fifteen restorations were milled in ceramic (Vita MKII, group CER) and the other fifteen in composite resin (Paradigm MZ100, group CPR). Fitting surfaces were etched and silanated (CER) or sandblasted and silanated (CPR). Preparations were sandblasted and etched. All restorations were adhesively luted (Optibond FL adhesive and Z100 composite resin). Simulated chewing was applied, starting with a load of 200 N, followed by stages of 400, 600, 800, 1000, 1200 and 1, 400 N at a maximum of 30, 000 cycles each (load unit Mini Bionix II MTS). Samples were loaded until fracture (or maximum 185, 000 cycles). Results. Restored molars in CER fractured at an average load of 1, 147N and none withstood all 185, 000 load cycles (survival 0%) ; in CPR, the survival rate was 73%. In CER, 40% of the fractures ended below the CEJ ; in CPR, only 7% did. Conclusions. Composite resin MZ100 increased the fatigue resistance of overlays in RCT molars when compared to porcelain MKII. Fractures of porcelain restorations led to dramatic failures difficult to restore.

fatigue resistance; overlay

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