[Stable adhesion to dentin. Combination of EDTA 3-2 (NH4/Fe) pretreatment and 2% 4-META/MMA-TBB resin].

An excellent durability of adhesion was obtained in the adhesion of 2% 4-META/MMA-TBB resin to dentin pretreated with EDTA 3-2 (NH4/Fe). Such high bond strength as 15 MPa did not change for up to one year even when they were immersed in water at 37 degrees C. The resin reinforced dentin, a hybrid, was identified between dentin and the cured resin by TEM. The collagen and hydroxyapatite were encapsulated with the copolymer and the crystals were not removed by the demineralization with either HCl or electronic staining. Tensile fracture between the hybrid and dentin like the adhered samples to 10-3 treated dentin did not occur and the cohesive failure in the resin was observed here after the storage in water for a year. EDTA 3-2 (NH4/Fe) could not completely demineralize the hydroxyapatite especially at the deeper portion and the width of the demineralized dentin became thinner than 1 micron. The encapsulated crystals with the resin could improve the resistance of collagen against deterioration in water and such good bonding durability could be obtained.