Nano area evaluation for adhesive mechanism of resin to dentin

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The purpose of this study was to solve the adhesive mechanism of resin to dentin. The mechanical property of resin-dentin interface was evaluated by nanohardhess mesurements, and microtensile bond strength test to human dentin and FE-SEM observations of resin-dentin interface with argon ion etch technique were also performed. The self-etch systems which available on the market were evaluated in this study.We measured adhesive layer of resin-dentin interface by self-etch systems using an ENT-1100a Nanoindentation tester (Elionix, Japan). From the nanohardness results, commercially available self-etch adhesives evaluated in this study showed no significant difference in, hardness of adhesive layer.The human dentin bond strength of an available self-etch systems were evaluated by microtensile bond strength tests. The microtensile bond strength of 2-step self-etch systems were higher than 1-step or one bottled self-etch systems. We were not able to find about the relationship between nanoh … More ardness and bond strength of self-etch systems.The ultra-morphological interaction to human dentin of self-etch adhesive was observed by field-emission SEM (FE-SEM) with argon-ion (Ar-ion) beam etch technique. Ar-ion beam etch technique have been widely employed as SEM observation of resin-dentin interface, describing hybrid layer as composed of a meshwork structure. We examine the meshwork structure after ar-ion etch by FE-SEM, and also observed resin-dentin interface of self-etch adhesives. Our data suggested the meshwork strucrure on resin-dentin interface by ar-ion etch is composed of porymerized primer and bonding resin, hybrid layer and partially exposed collagen fibers.Ar-ion etching of 30-sec's to 2 step self-etch adhesives demonstrated a wide hybrid layer meshwork width (2 to 5 μm) similar to that previously reported, while one-bottled self adhesives showed narrow or no meshwork width (0 tO 0.5 μm) between dentin and adhesive after 30-sec's Ar-ion etching, It was suggested that width of hybrid layer is not necessary for dentin adhesion, and dentin adhesion is not formed only mechanical interlocking to dentin. Less