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.%目的：：探讨不同浓度氟化物对氟牙症釉质硬度值及表面微观结构的影响。方法：收集临床拔除的中度氟斑恒牙56个,将每个牙冠部平均切割为3等份( n=56),分别列入A、B、C组。 A组样本置于蒸馏水中,B组置于60 mg/L 氟化钠液中, C组置于120 mg/L氟化钠液中。3组浸泡液均每天更换1次,并于37℃恒温箱放置10 d。用显微硬度计分别测定浸泡前后釉质表面硬度值,扫描电镜观察釉质表面微观及形态变化。结果：3组浸泡前釉质显微硬度均无显著差异(P>0.05)；浸泡后,釉质显微硬度 B组>A组>C组(P<0.05)。浸泡后釉质显微硬度与浸泡前相比：A组无明显变化(P>0.05),B组明显提高(P<0.05),C组明显降低(P<0.05)。除B组外,A、C组釉质表面未见反应物沉积。结论：高浓度氟化物可使氟斑牙硬度值降低,无釉质再矿化作用,氟牙症患者更适合用含有低浓度氟化物的牙膏。
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