Ultrastructure and Crystallographic Study of Enamel in Human Dental Fluorosis.

实验材料为人和猪氟斑牙的恒磨牙，氟斑牙患者的牙釉质表面一般呈浑浊或不透明状，并有不同大小和程度的凹陷或缺损。然而，患有氟斑牙的猪受试者没有看到凹陷或缺陷。在相对高度矿化的最外表面釉质层的正下方是广泛的低矿化区域。高矿化层由许多大的拉长的六方晶体和小的六方晶体组成。在大晶体的某些部分中，观察到在表面上的晶体生长或极小晶体附着到表面。大晶体和极小晶体的晶格条纹彼此精确地连接在一起。在沿着（100）面观察时，大的细长六方晶体的晶格间距为0.817 nm。小晶体的晶体结构为等边六方或不等边六方点阵 关于我们 间隔为0.812nm。这一结果表明，大的细长六方晶体是羟基磷灰石，小晶体是氟磷灰石。低矿化釉质区由相当稀疏排列的大晶体和少量小晶体组成。大的晶体通常小于在表面层中观察到的晶体。在这一地区的某些地方，要么是大晶体在其中心有穿孔，要么是在其表面形成不规则缺陷。然而，猪受试者没有看到这些晶体。在高矿化表层和次表层低矿化区之间的过渡区，既有大晶体，也有小晶体。大晶体内的中央穿孔经常包含明显新形成的晶体碎片。原始晶体和新形成的晶体材料之间的晶格条纹并不总是彼此对齐。波色散电子探针线分析表明，氟浓度是非常高的高度矿化的表面层和低矿化区。少

Materials used in this work were permanent molars of human and porcine dental fluorosis.Enamel surfaces from human subjects with dental fluorosis were generally cloudy to opaque, with several pits or defects of various size and degrees. Porcine subjects with dental fluorosis, however, were not seen pits or defects. Immediately below the relatively highly mineralized outermost surface enamel layer was an extensive hypomineralized area. The highly mineralized layer was composed of many large elongated hexagonal crystals and small hexagonal crystals. In some parts of the large crystals, crystal growth on the surface or attachment of extremely small crystals to the surface were observed. The lattice striations of the large and extremely small crystals were connected to each other in exact register. In views along the (100) plane, lattice intervals of large elongated hexagonal crystal were 0.817 nm. Shapes of small crystals were equilateral-hexagonal or nonequilateral-hexagonal and lattice … More intervals of it were 0.812 nm. This result showed that large elongated hexagonal crystals were hydroxyapatite and small crystals were fluorapatite. The hypomineralized enamel area was composed of fairly sparsely arranged, large crystals and a few small crystals. Large crystals were generally smaller than those observed in the surface layer. In some parts of this area, either the crystals large had perforations in their centers or irregular defects formed on their surfaces. Porcine subjects, however, were not seen those crystals. Both large and small crystal were observed in the transitional region between the highly mineralized surface layer and the subsurface hypomineralized area. Central perforations within the large crystals frequently contained apparently newly formed crystal fragments. Lattice striations between the original crystals and the newly formed crystalline material were not always in register with each other. Wave-dispersive electron-probe line analysis indicated that fluoride concentration was very high in the highly mineralized surface layer and low in the hypomineralized area. Less