Fatigue of packable dental composites

Objective The 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. Methods Dynamic torsional loading was conducted at resonance at 30–50 Hz. Specimens were thoroughly cured and tested dry at 21 °C. Results All 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. Significance Dental 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.