Effect of calcium salt of functional monomer on bonding performance.

To determine the amount of 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-calcium (MDP-Ca) salt produced through the demineralization of enamel or dentin by MDP, we designed experimental MDP-based one-step adhesives with different amounts of MDP. The null hypotheses were that (1) the amount of MDP-Ca salt produced through the demineralization of enamel was the same as that for dentin, and (2) the amounts of MDP-Ca salt have no effect on bonding performance. Increases in the amount of MDP resulted in increased amounts of MDP-Ca salt. The production amount of MDP-Ca salt of the dentin was 1.3 times higher than that of the enamel. The predominant species of the MDP and enamel reactants was a calcium hydrogen phosphate of MDP. In contrast, the dentin yielded both calcium phosphate and calcium hydrogen phosphate of MDP. Increases in the amount of MDP-Ca salt decreased both enamel and dentin bond strengths. An optimal concentration of MDP exists in one-step self-etch adhesives.