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The effects of pretreatment of Co-Cr alloy, including two adhesive primers that contain either MDP or MAC-10, and silicoating on the bond. The results obtained as follows : Strength of 4-META/MMA-TBB resin were investigated using FT-IR SEM, and EDAX. In the SEM observation of surface morphologies, the sandblasted specimen exibited a very rough surface, whereas the surfaces of the two groups primed with either MDR or MAC-10 were covered with a layer of primer, and the surface morphology of the silicoated specimen remained almost the same after sandblasting. Before the thermocycling tests, the group treated with MDP demonstrated the highest mean tensile bond strength and the sandblasted group showed the lowest bond strength. After 20,000 themocyling, the mean tensile bond strength of the sandblasted group exhibited a 50% reduction in bond strength, while the other showed a 20~30% reduction. Observation of the metal-resin interface revealed that in all groups the resin permeated the rough surface formed by sandblasting thereby producing a mechnical bond between the metal and the resin, It was also found that thermocycling resulted in a gap formation at the metal-resin interface of the specimens, and the sandblasted group exhibited a larger gap width than the other groups. In fracture mode, all specimens indicated a cohesive fracture within the resin before thermocycling. However, thermocyling produced adhesive failure at the edge of the resin-metal interface in most specimens, The sandblasted group, which exhibited the lowest bond strength after thermocycling, also demonstrated the largest area of adhexive failure.
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