[Studies on the dynamic durability of dental restorative materials. (Part 2) Properties for the repeated impact compressive load ot composite resins (author's transl)].

Based on the fracture energy form the compression test of composite resins under the repeated impact loads in compression after stored for a period in water at 37 degrees C, the dynamic durability of commercially used composite resins was evaluated. The results obtained were summarized as follows. (1) The fracture energy of composite resins under the repeated impact compressive loads after stored in water at 37 degrees C is clearly lower than the initial fracture energy. Particularly the decrement of the initial fracture energy for Concise, Epolite 100 and Superlux after stored for 30 days in water at 37 degrees C is influenced considerably both by the physicochemical degradation caused by water and the mechanical deterioration caused by the repeated impact compressive loads, but Clearfil is superior to the mechanical deterioration. (2) In each composite resins, there is a close correlation between fracture energy and compressive strain. In composite resins without Superlux, also a correlation is in fracture energy and compressive strength. (3) In clearfil, concise and Epolite 100, the morphology of fracture in compression test of composite resins which are subjected to and are subjected to the repeated impact loads in compression is classified in a mode of shear fracture, but in Superlux, a mode of crack fracture.