Marshall A F, Lawless K R
J Dent Res. 1981 Oct;60(10):1773-82. doi: 10.1177/00220345810600100801.
The dark line which is observed in enamel crystallites represents a planar defect involving a single 100 plane of the hydroxyapatite structure. It may occur in the majority of crystals throughout the enamel, although it is only observed in specific diffraction conditions. Its presence may be related both to the formation and growth of crystallites in the developing tooth and to the manner in which the crystallites dissolve during caries. TEM studies show clearly that the central defect is not a dislocation, stacking fault or lattice twin boundary. They further indicate that it cannot represent a structural twin boundary. The remaining possibilities are that it represents a substitution in the HAP lattice, most likely involving carbonate ion, or a separate compatible calcium phosphate phase.
在牙釉质微晶中观察到的暗线代表一种平面缺陷，涉及羟基磷灰石结构的单一100面。它可能出现在整个牙釉质的大多数晶体中，尽管只有在特定的衍射条件下才能观察到。它的存在可能与发育中牙齿的微晶形成和生长有关，也与龋齿过程中微晶的溶解方式有关。透射电子显微镜研究清楚地表明，中心缺陷不是位错、堆垛层错或晶格孪晶界。它们进一步表明，它不可能代表结构孪晶界。其余的可能性是，它代表HAP晶格中的一种替代，最有可能涉及碳酸根离子，或者是一种单独的相容磷酸钙相。
