Elastic properties of resin-based filling materials

Some aspects of the viscoelastic behavior of resin-based filling materials have been studied by the use of a bending test. The specimens, designed as cantilever beams were loaded for 30 sec and then unloaded. The tests were performed at 1/2 h, 1 h, 3h, 24 h, and 1 week after mixing of the materials. The strains were measured by electric strain gauges cemented to the tensile side of the beam. Six products were tested, five of them composites. Different brands of materials showed considerable variation in degree of viscoelastic behavior. The value for elastic after-effect decreased markedly with time, reaching a fairly constant value at 24 h. Elastic moduli showed a similar increase and the stiffest materials exhibited the least elastic after-effect.