title: Space-group determination of human tooth-enamel crystals.
abstract: In the present work, we have determined the space group of human tooth-enamel crystals using--for the first time for a biological crystal--convergent beam electron diffraction (CBED). The symmetries observed in the different patterns we have obtained lead us to the P6(3)/m hydroxyapatite space group. Disorder, most likely situated in the columns formed by the hydroxyl ions of the crystals, is suggested as a cause of weak intensity in the otherwise forbidden 000l (l odd) reflections and low visibility of first-order Laue zone (FOLZ) reflections in the CBED pattern from crystals oriented along the [0001] zone axis. A monoclinic phase was not observed.
authors.affiliation: Max-Planck-Institut für Metallforschung, Institut für Werkstoffwissenschaft, Stuttgart, Germany.
authors.forename: E F
authors.initials: EF
authors.lastname: Brès
authors.forename: D
authors.initials: D
authors.lastname: Cherns
authors.forename: R
authors.initials: R
authors.lastname: Vincent
authors.forename: J P
authors.initials: JP
authors.lastname: Morniroli
mesh_terms: D000328:Adult; D003460:Crystallization; D003743:Dental Enamel / Q000737:chemistry*; D006801:Humans; D008875:Middle Aged; D014961:X-Ray Diffraction