Abstract
Comparison of Shear Strength, Fatigue-Limit, and Fatigue-Life in Metal/Enamel Bonds. *PADIPATVUTHIKUL P, MAIR LH. (University of Liverpool, School of Dental Studies, UK)
Objectives: To compare the Shear Bond Srength (SBS) of resin-bonded metal/enamel bonds with the Fatigue-Limit and Fatigue-Life of identical joints.
Materials and Methods: 285 discs of Ni/Cr-alloy(dia 5mm*4mm) were cast and treated by either (1)Sandblasting with aluminium oxide or (2)Sandblast + 15 min electrolytic-etch in HCl. The discs were bonded to etched enamel (37% HPO4/30 sec) using 3 bonding systems. Ten discs of each group were subjected to Shear test in a Universal Testing Machine5 (CHS= 50mm/min). Fifteen discs of each group were subjected to a Staircase Fatigue-Test using 5000 cycles, load increment = 4 kg. Another 10 discs were subjected to cyclic loads of 20, 10, and 5 kg to determine Fatigue-Life of the bonds. Load data was compared by correlation analysis and cycle data by Weibull statistic to determine the beta and alpha coefficients for the 3 loads.
Results and Conclusions: The Fatigue-Limit of the bonds was much lower than the Shear strength and there was no correlation between the two values. Fatigue-Limit was not a good predictor of the Fatigue-Life in this study.
