[Effect of topical fluoride application on young permanent teeth enamel demineralized by juice drinks].

PURPOSE: To observe the capability of enamel surface resisting juice drinks erosion and the remineralization process of etched enamel after topical fluoride application on young permanent teeth enamel. METHODS: The change of surface microhardness(SMH) of young permanent teeth enamel fluoride which was immersed in orange juice in advance and then applied on its etched part was evaluated.The change of SMH of young permanent teeth enamel treated by 0.1%NaF solution and fluoride toothpaste in advance and then immersed by juice drinks was observed. The change of enamel SMH was measured by a Leitzs microhardness tester. The morphological change of enamel surface was observed under scanning electron microscope (SEM). The change of calcium and phosphate contents in juice drinks before and after enamel immersion was analyzed by Roche biochemical analyzer. One-way ANOVA was performed using SPSS 15.0 software package. RESULTS: Juice drinks led to the dissolution of calcium and phosphate in young permanent teeth enamel while the SMH of enamel decreased. The SMH of young permanent teeth enamels immersed in orange juice and then topical application of fluoride increased significantly (Plt;0.05). But for those young permanent teeth enamels treated with fluoride or fluorin enhanced toothpaste, the dissolution of calcium and phosphate and the SMH decreased significantly after juice drinks immersion(P<0.05). The variable degree of etching and remineralization of the enamel either treated by juice drinks or by fluoride in each experimental group was found by SEM. CONCLUSIONS: Enamel demineralization can be caused by juices drinks. Topical fluoride treatment on enamel can not only enhance enamel's resistance to the acid etch caused by soft drinks but also promote the remineralization of enamel immersed by beverages. Supported by Excellent Middle-Aged Science Foundation of Shanghai Jiao Tong University School of Medicine(Grant No.040407).