Kodaka T, Kuroiwa M, Abe M
Second Department of Oral Anatomy, School of Dentistry, Showa University, Tokyo, Japan.
Scanning Microsc. 1990 Dec;4(4):975-85.
Using SEM after EDTA etching, the mid-coronal inner enamel of human permanent teeth was classified into three regions of the 1st, 2nd, and 3rd zones. The 1st zone showing a highly negative birefringence was the innermost 10 - 15 microns enamel. This zone consisted of arcade and circular initial prisms, and the succeeding arcade prisms only. These initial prisms arising perpendicularly to the dentine surface resembled pseudoprisms because these prisms showed a somewhat centripetal arrangement of crystallites and indistinct prism boundaries. The succeeding prisms were frequently bent following a faint slit within the prism. The 2nd zone adjacent to the 1st zone measured 20 - 40 microns in thickness. This zone was mainly composed of horseshoe-shaped prisms with EDTA-insoluble prism sheaths in the deep-etched prism boundaries, but the inner-half layer had dotted irregular prisms including circular, double marginal, and spiral shapes with the prism sheaths. Prismless structures were rarely seen in the 2nd zone. The 3rd zone was mainly occupied by horseshoe-shaped prisms without EDTA-insoluble prism sheaths in the deep-etched prism boundaries, although tuft prisms in the 3rd zone contained a large amount of EDTA-insoluble substances in the prisms, interprismatic regions, and the boundaries.
在乙二胺四乙酸（EDTA）蚀刻后使用扫描电子显微镜（SEM），人类恒牙的冠中内部釉质被分为第1区、第2区和第3区三个区域。显示高度负双折射的第1区是最内层10 - 15微米的釉质。该区域由拱形和圆形初始棱柱以及后续的拱形棱柱组成。这些垂直于牙本质表面产生的初始棱柱类似于假棱柱，因为这些棱柱显示出微晶的某种向心排列且棱柱边界不清晰。后续的棱柱经常沿着棱柱内的一条微弱缝隙弯曲。与第1区相邻的第2区厚度为20 - 40微米。该区域主要由马蹄形棱柱组成，在深度蚀刻的棱柱边界处有乙二胺四乙酸不溶性棱柱鞘，但内层有包括圆形、双边缘和螺旋形等点状不规则棱柱以及棱柱鞘。在第2区很少见到无棱柱结构。第3区主要由马蹄形棱柱占据，在深度蚀刻的棱柱边界处没有乙二胺四乙酸不溶性棱柱鞘，尽管第3区的束状棱柱在棱柱、棱柱间区域和边界中含有大量乙二胺四乙酸不溶性物质。
