Tensile fatigue of resin cements to etched metal and enamel

The purpose of this study was to compare the tensile adhesive fatigue behavior of 2 composite adhesives used in the resin-bonded bridge technique to both enamel and a base metal alloy. Samples were tested to failure or to a maximum of 10⁶ cycles. The practical endurance limit for both was determined and the fracture surfaces were evaluated using SEM. The nature of the fatigue failure of the 2 cements varied. The higher viscosity cement exhibited failure primarily due to tag pull out from the etched enamel. This occurred at significantly lower load levels as compared to the lower viscosity cement. The lower viscosity cement exhibited both adhesive and cohesive failure at higher load levels. The majority of fatigue failures in the lower viscosity material occurred at the composite/bonding agent interface or through the material itself.