Ichijo T, Yamashita Y, Terashima T
Department of Oral Anatomy, Faculty of Dentistry, Tokyo Medical and Dental University.
Bull Tokyo Med Dent Univ. 1993 Mar;40(1):29-44.
In a series of studies to investigate the structural features of the biological crystals, using electron microscope, we examined the ultrastructure of the human dentin crystals at near atomic resolution through the cross and longitudinal sections of the crystals. The materials used for this study were the deep layer of the non-carious coronal dentin from freshly extracted human erupted permanent molars. The small cubes of the dentin 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 HITACH H-700 type of transmission electron microscope operated at 200kV. Each crystal was observed at the initial magnification of 300,000 times and at the final magnification of 10,000,000 times and over. Using this approach, the authors have been able to show the configuration of the hydroxyapatite structure in the cross and longitudinal sections of the dentin crystals deposited within and between the collagen fibrils (intrafibrillar and interfibrillar crystal) in the intertubular dentin and observe the basic hexagonal pattern of the unit cell viewed down the c-axis. The authors sincerely believe that the electron micrograph shown in this report is the first atomic image to be obtained from a hydroxyapatite crystal from the human dentin, using the sections.
在一系列旨在研究生物晶体结构特征的研究中，我们使用电子显微镜，通过牙本质晶体的横断面和纵断面，以近原子分辨率研究了人类牙本质晶体的超微结构。本研究使用的材料是从新鲜拔除的人类萌出恒牙的非龋坏冠部牙本质深层获取的。将牙本质小块用戊二醛和四氧化锇固定，并采用常规方法包埋于环氧树脂中。用金刚石刀切割超薄切片，无需脱钙。切片用工作电压为200kV的日立H-700型透射电子显微镜进行观察。每个晶体最初以300,000倍的放大倍数观察，最终以10,000,000倍及以上的放大倍数观察。通过这种方法，作者得以展示管间牙本质中沉积在胶原纤维内部和之间（纤维内和纤维间晶体）的牙本质晶体横断面和纵断面中羟基磷灰石结构的形态，并观察沿c轴向下观察时单位晶胞的基本六边形图案。作者坚信本报告中所示的电子显微照片是首次使用这些切片从人类牙本质的羟基磷灰石晶体获得的原子图像。
