1988 Volume 7 Issue 1 Pages 44-61
Mechanical properties of seven kinds of light cured composite resins were measured to evaluate the environmental durability in water after storage in distilled water at 37℃ for 2 months. Water sorption of all composite resins increased rapidly within 1 week and then increased gradually for 2 months. This water uptake was thought to be involved in the physical or chemical deterioration of composite resin material. The tensile strength of all composite resins measured by the direct tensile test reached the maximum value after 24 hours but decreased significantly after 2 months and became the 55〜75% of their maximum values. However, the rate of decrease differed with the commerical resin. The diametral strength and the compressive strength of most composite resins reached equilibrium after 1 week with no further decrease. The direct tensile test was found to be useful to evaluate the environmental durability in water in a relatively short period.
