Ichijo T, Yamashita Y, Terashima T
Department of Oral Anatomy, Faculty of Dentistry, Tokyo Medical and Dental University, Tokyo Ika Shika Daigaku.
Bull Tokyo Med Dent Univ. 1993 Dec;40(4):207-16.
In a series of studies to investigate the basic structural features and characteristics of the biological apatite crystals, using a transmission electron microscope, we examined the ultrastructure of the human enamel, dentin, and bone crystals at near atomic resolution and showed the configuration of the hydroxyapatite structure through the cross and longitudinal sections of the crystals. Subsequently, based on the results of the observations by the authors of the ultrastructure of the tooth and bone, using the same approach, we have been able to directly examine the images of the lattice imperfections in the human tooth and bone crystals, such as the point defect structure, line defect, and face defect, in the crystals. In this report, we describe the images of the crystal fusion obtained by using the same approach from the sections of the human enamel crystals. The materials used for this study were the noncarious enamel from the freshly extracted human erupted lower first molars. The small cubes of the material were fixed in glutaraldehyde and osmium tetroxide and embedded in epoxy resin using the routine methods. The ultrathin sections were cut with a diamond knife without decalcification. The sections were examined with the HITACHI H-800 H and H-9000 type transmission electron microscopes operated at 200 kV and 300 kV. Each crystal was observed at an initial magnification of 300,000 times and at a final magnification of 10,000,000 times and over. We are, therefore, able to confirm that the fusion between the adjacent crystals can occur at some time during the life history of the human enamel. We sincerely believe that the electron micrographs shown in this report are the first to show the ultrastructures of the crystal fusion in the human enamel crystals at near atomic resolution.
在一系列旨在研究生物磷灰石晶体基本结构特征的研究中，我们使用透射电子显微镜，以近原子分辨率检查了人类牙釉质、牙本质和骨晶体的超微结构，并通过晶体的横截面和纵截面展示了羟基磷灰石结构的构型。随后，基于牙齿和骨骼超微结构作者的观察结果，采用相同方法，我们得以直接检查人类牙齿和骨晶体中的晶格缺陷图像，如晶体中的点缺陷结构、线缺陷和面缺陷。在本报告中，我们描述了通过相同方法从人类牙釉质晶体切片获得的晶体融合图像。本研究使用的材料是新鲜拔除的人类下颌第一恒磨牙的无龋牙釉质。将该材料切成小方块，用戊二醛和四氧化锇固定，按常规方法包埋在环氧树脂中。用金刚石刀切割超薄切片，无需脱钙。切片用日立H - 800H型和H - 9000型透射电子显微镜在200 kV和300 kV下进行检查。每个晶体最初以300,000倍的放大倍数观察，最终放大倍数达到10,000,000倍及以上。因此，我们能够证实相邻晶体之间的融合可能发生在人类牙釉质的生命历程中的某个阶段。我们由衷地相信，本报告中所示的电子显微照片首次以近原子分辨率展示了人类牙釉质晶体中晶体融合的超微结构。
