Abstract
Effect of the thickness of the adhesive layer between two Co-Cr alloy plates on mode I fracture toughness of dental adhesive resin was investigated varying the type of adhesive resin using a double cantilever beam(DCB)test.As adhesive resins typical of the soft and hard types, Super-Bond C&B(SB)and Panavia 21(PV)with filler were used respectively.The respective adhesive layers of the DCB test specimens were of 20, 100 and 200μm thick.The major findings were as follows.In case of SB, crack propagating areas in all test specimens were observed as cohesive failure, and those surfaces became remarkably rougher as the thickness of the adhesive layer increased.Fracture toughness also had a tendency to increase as the adhesive layer became thicker.Next, in case of PV, the fracture modes of the crack propagating area differed with the thickness of the adhesive layer, such as interface failure at 20μm thickness, and cohesive fracture at 100 and 200μm thickness.The cohesive fractures were observed as similar flat surfaces.Therefore, regarding fracture toughnesses, there was no difference due to the thickness of the adhesive layer between 100 and 200μm thickness, however, at 20μm thickness, it was found that the fracture toughness decreased somewhat.
