Abstract
Adhesion of MMA-TBB resins to ivory instead of to dentin was studied to identify the bonding mechanism of resins to dentin. Tensile bond strength of MMA-TBB resin to ground ivory was 14 MPa but that to ground dentin was lower than 5 MPa. The width of the hybrid layer created by diffusion of MMA into ground ivory and by the polymerization was 50 μm, but the methacrylate could not diffuse into dentin. These findings suggested thet the permeability of ivory was much higher than that of dentin. Therefore, 4-META which was effective in promoting the diffusion of MMA was not necessary for the adhesion to ivory. On the other hand, it was required for the bonding to dentin. It was concluded that diffusion of monomers into teeth, which is changed by either the permeability of substrates, diffusion capability of monomers or both, is essential to bond resins to teeth.
