Effects of fluoride on enamel hardness and microstructure of the teeth with dental fluorosis

YU Yong-na; ZHANG Dai-zun; XIAO Wen-lin; KANG Peng

doi:10.15956/j.cnki.chin.j.conserv.dent.2015.06.010

Abstract：AIM:To study the effect of different concentrations of fluoride on dental enamel hardness and surface microstructure of the teeth with dental fluorosis. METHODS:56 extracted teeth with moderate fluorosis were collected and each crown was divided into 3 equal parts and set in group A, B and C respectively. The crown samples of group A, B and C were placed in distilled water, 60 mg/L and 120 mg/L sodium fluoride solution respectively in a 37℃ oven for 10 d. The solutions of the 3 groups were changed once daily. The hardness, microstructure and change of enamel surface of the samples were detected before and after immersion using micro hardness tester and scanning electron microscopy (SEM) respectively. RESULTS:No statistically significant difference was found in the enamel microhardness among the 3 groups before immer-sion (P >0. 05). After soaking, the enamel microhardness of group B was higher than that of group A and group C (P<0. 05), and that of group A was higher than that of group C (P<0. 05). After sooking the enamel microhardness in group A was not changed(P>0. 05), in group B increased (P<0. 05), in group C reduced(P<0. 05). SEM observation showed that enamel surface in group B had reactive deposit, but in group A and group C had not. CONCLUSION:High concentration fluoride solution can decrease enamel hardness and remineralization of the teeth with dental fluorosis. Low con-centration fluoride toothpaste is more suitable for patients with dental fluorosis.