Fatigue of packable dental composites

ObjectiveThe purpose of the study was to measure the fatigue properties of four dental resin composites using a dynamic mechanical analysis and to relate the results with viscoelastic properties.MethodsDynamic torsional loading was conducted at resonance at 30–50 Hz. Specimens were thoroughly cured and tested dry at 21 °C.ResultsAll of the specimens showed a loss of strength following repeated stress, due to material fatigue. The material with the highest shear modulus had the lowest damping and the highest fatigue strength.SignificanceDental composites exhibit a modest loss of strength due to fatigue. Since mastication involves many cycles of stress during the life of a restoration, fatigue properties should be taken into account in restoration design.