Weiner S, Veis A, Beniash E, Arad T, Dillon J W, Sabsay B, Siddiqui F
Department of Structural Biology, Weizmann Institute of Science, Rehovot, 76100, Israel.
J Struct Biol. 1999 Jun 1;126(1):27-41. doi: 10.1006/jsbi.1999.4096.
Peritubular dentin (PTD) is a relatively dense mineralized tissue that surrounds the tubules of coronal tooth dentin. It is composed mainly of crystals of carbonated apatite together with a small amount of collagen. Its mode of formation has been investigated by studying the relatively dense particles isolated from a powdered preparation. Electron microscopic examination of the PTD particles, including 3-dimensional image reconstruction and electron diffraction, shows that the organization of the crystals of PTD is very similar to that of the adjacent intertubular dentin (ITD). The latter contains relatively large amounts of collagen and the carbonated apatite crystals are closely associated with the collagen matrix. The proteins present in the PTD particles are soluble after decalcification and stain with Stains All. The principal protein has higher molecular weight and a quite different amino acid composition than the phosphophoryns of the intertubular dentin. The interface between the PTD and the ITD shows structural continuity. These data show how two distinct carbonated apatite-based mineralized tissues can be organized and formed contiguously within the same organ by utilizing different sets of matrix proteins.
管周牙本质（PTD）是一种相对致密的矿化组织，它围绕着冠部牙本质的小管。它主要由碳酸磷灰石晶体和少量胶原蛋白组成。通过研究从粉末制剂中分离出的相对致密颗粒，对其形成方式进行了研究。对PTD颗粒的电子显微镜检查，包括三维图像重建和电子衍射，表明PTD晶体的组织结构与相邻的管间牙本质（ITD）非常相似。后者含有相对大量的胶原蛋白，碳酸磷灰石晶体与胶原蛋白基质紧密相关。PTD颗粒中存在的蛋白质在脱钙后可溶，并能用氨基黑染色。主要蛋白质的分子量比管间牙本质的磷蛋白更高，且氨基酸组成有很大不同。PTD和ITD之间的界面显示出结构连续性。这些数据表明，如何通过利用不同的基质蛋白组，在同一器官内连续地组织和形成两种不同的基于碳酸磷灰石的矿化组织。
