IN-VITRO BOND STRENGTHS AND SEM EVALUATION OF DENTIN BONDING SYSTEMS TO DIFFERENT DENTIN SUBSTRATES

In comparison to enamel, bonding to normal dentin is a greater challen ge because of its organic constituents, fluid-filled tubules, and vari ations in intrinsic composition. Bonding to sclerotic dentin is even m ore difficult. To evaluate the shear bond strengths of four adhesive s ystems to dentin substrates with different levels of mineralization, 1 20 extracted human teeth were randomly assigned to three groups (n = 4 0). After mid-coronal dentin was exposed, groups of specimens were art ificially hypermineralized by immersion in a remineralizing solution, demineralized by means of an acetic acid demineralizing solution, or s tored in distilled water to model sclerotic, carious, and normal denti n, respectively. Resin composite was bonded to dentin by use of commer cial adhesive systems. After the specimens were thermocycled, shear bo nd strengths were determined in an Instron universal testing machine. Dentin substrates and resin/dentin interfaces were examined by SEM. Fo r each adhesive system, the mean shear bond strength to normal dentin was significantly higher than that to either of the other substrates. Shear bond strengths to hypermineralized dentin were significantly hig her than those to demineralized dentin with all adhesives except Prism a Universal Bond 3.