title: STEM and HRTEM studies of accumulated deposits on human tooth surface.
abstract: The aim of this study was to clarify the fine structure of accumulated deposits on the surface of teeth that are considered to affect the gloss of teeth. The study was carried out using, as specimens, human incisor teeth having gloss, which were extracted from teenage donors and those incapable of showing gloss even by brushing which were extracted from donors in their 50s. Thin longitudinal sections of tooth enamel with accumulated deposits on the surface were prepared by focused ion beam (FIB) milling, and the fine structure was analyzed using a scanning transmission electron microscope (STEM) and a high resolution transmission electron microscope (HRTEM). By FIB, thin longitudinal sections could be prepared from tooth enamel together with organic and inorganic substances accumulated on the surface without artifacts. The accumulated deposits on the surface of teeth having gloss were composed of organic substances. However, it was first revealed by STEM observation that the accumulated solid deposits on the surface of teeth having no gloss had a complicated structure wherein inorganic and organic substances coexisted. It is suggested that the organic substances contain proteins derived from saliva. The inorganic substances were spherical and needle-like hydroxyapatites (HAs). It is considered that amino acids constituting the proteins affected the nucleus formation and the crystal formation of HA. It is considered that the unevenness of the accumulated deposits existing on the surface of tooth enamel having no gloss causes the decrease in gloss of teeth due to diffuse reflection of light.
authors.affiliation: Analytical Science Research, Kao Corporation, Wakayama, Wakayama Prefecture, 640-8580, Japan.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Wakasa
authors.affiliation: Personal Health Care Products Research, Kao Corporation, Sumida-ku, Tokyo, 131-8501, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Eshita
authors.affiliation: Analytical Science Research, Kao Corporation, Wakayama, Wakayama Prefecture, 640-8580, Japan.
authors.forename: Kuniyuki
authors.initials: K
authors.lastname: Nakanishi
authors.affiliation: Personal Health Care Products Research, Kao Corporation, Sumida-ku, Tokyo, 131-8501, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Isobe
authors.affiliation: Analytical Science Research, Kao Corporation, Wakayama, Wakayama Prefecture, 640-8580, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Manago
authors.affiliation: Analytical Science Research, Kao Corporation, Wakayama, Wakayama Prefecture, 640-8580, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Okamoto
authors.affiliation: Department of Electrical Engineering and Electronics, Kyoto Institute of Technology, Sakyo-ku, Kyoto, 606-8580, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Isshiki
mesh_terms: D000293:Adolescent; D000367:Age Factors; D003741:Dental Deposits / Q000737:chemistry* / Q000648:ultrastructure*; D003743:Dental Enamel / Q000737:chemistry / Q000648:ultrastructure*; D005459:Fluorides; D005583:Fourier Analysis; D006801:Humans; D006882:Hydroxyapatites / Q000737:chemistry; D007180:Incisor / Q000737:chemistry / Q000648:ultrastructure; D017348:Microscopy, Electron, Scanning Transmission / Q000379:methods; D046529:Microscopy, Electron, Transmission / Q000379:methods; D008875:Middle Aged; D013499:Surface Properties; D014070:Tooth / Q000737:chemistry / Q000648:ultrastructure*; D014099:Toothbrushing
chemical_list: D006882:Hydroxyapatites; D005459:Fluorides
keywords: crystal growth; focused ion beam; hydroxyapatite; morphology; tooth gloss