Observations on structural features and characteristics of biological apatite crystals. 6. Observation on lattice imperfection of human tooth and bone crystals. I.

In a series of studies to investigate the basic structural features and characteristics of the biological apatite crystals, using an 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 enamel, dentin, and bone crystals, such as the point defect structures and dislocations in the crystals. In this report, we describe the image of the point defect structures and line defect structures obtained, using the same approach from the sections of the human enamel, dentin, and bone crystals. The materials used for this study were the noncarious enamel and dentin from the freshly extracted human erupted lower first molars, and bone tissue obtained from the alveolar compact bone. 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 types of transmission electron microscopes operated at 200 kV and 300 kV. Each crystal was observed at the initial magnification of 300,000-500,000 times and at the final magnification of 10,000,000 times and over. We sincerely believe that the electron micrographs shown in this report are the first to show the images of the lattice imperfections in the human enamel, dentin, and bone crystals, such as the point defect and line defect structures, at near atomic resolution.