Abstract: Objective: To investigate the effects of amorphous calcium phosphate on microhardness and polishing performance of resin infiltrant. Methods: Artificial model of dentin caries lesion was established by demineralization fluid treating on the enamel. The specimens were infiltrated by resin infiltrant or resin infiltration mixed with amorphous calcium phosphate agent. Microhardness was investigated by the microhardness tester and the polishing performance was investigated by scanning electron microscopy. Results: The microhardness of resin infiltration group was higher than that of demineralized group (P<0.05), but lower than that of normal enamel group (P<0.05). There were no statistical differences between the nano amorphous calcium phosphate group and the normal enamel group. In the resin infiltration group, the enamel was smoother with smaller amount of slide mark and smaller pores on the surface in resin infiltration group observed by scanning electron microscope. The surface was rougher with big pores in the nano amorphous calcium phosphate group. Conclusion: Resin infiltration can improve the microhardness of demineralized enamel surface. The nano amorphous calcium phosphate mixed with the resin infiltration can improve the microhardness but decrease the polishing performance.

Key words: Amorphous calcium phosphate , Resin infiltration, Microhardness, Polishing performance