A study on enamel demineralization produced by citric acid

Objective To observe the effect of different etching time of citric acid on enamel blocks to acquire a reliable in vitro model for early enamel caries, and explore more effective experiment method for enamel demineralization.Methods Human premolars were selected and made into enamel blocks. The morphologies of enamel blocks surfaces etched by 10% citric acid for different time periods( 90 s, 120 s, 150 s) and partially saturated acid buffer demineralization system for a week were observed by scanning electron microscope. And the surface micro hardness of these specimen before and after demineralization were tested by the micro hardness tester. Results After demineralization, enamel surface had an obvious acid etching appearance. In the 90 s etching time group, only a small part of enamel prism lattice was demineralized and dissolved, and the ability of demineralization was limited. In 120 s etching time group, the morphology of enamel blocks surface was similar to natural early enamel lesions, like the honeycomb. In the 150 s etching time group, the enamel surface had an acid corrosion damage morphology, and it was excessive etched. However, the demineralization effect of partially saturated acid buffer demineralization system was relatively low. Conclusion Citric acid has a strong etching effect, and its ability of demineralization is enhanced with the extension of time. The model of early enamel lesions can be obtained by 10% citric acid for 120 s.