Abstract
The durability of six commercially available composite resins for inlays was examined by storage for various periods in boiling water and by thermal cycling between 4 and 60℃.Bending strength and elastic modulus of these materials decreased by storage of the specimens in boiling water, and did not greatly change with the increase in storage period between 5 and 30 days in boiling water.On the other hand, Knoop hardness also decreased by storage in boiling water and Knoop hardness of the specimens stored in boiling water for 30 days was about 20 and the values were equal to that of unfilled resins.The variation in Knoop hardness on depth from the surface of these specimens stored in boiling water for 30 days was determined.The specimens were affected up to 0.4-0.8mm in depth from the surface by storage in boiling water.Bending strength and elastic modulus decreased after 10, 000 thermal cycles, but did not change with increasing number of thermal cycles.In conclusion, the durability of composite resins for inlays could be evaluated by the bending test of specimens stored in boiling water for a short period such as 5 days and the degradation of composite resins for inlays could be evaluated by the determination of the variation in Knoop hardness on depth from the surface.
