title: Caries susceptibility of human fluorosed enamel and dentine.
abstract: OBJECTIVE
  Objective of our laboratory study was to determine the impact of dental fluorosis severity on the formation of caries in the human enamel and dentine.
  
  
  METHODS
  Thirty-three human molars were grouped according to modified Thylstrup-Fejerskov index (TFI) into normal (N, TFI 0), mild fluorosis (ML, TFI 1-3) and moderate fluorosis (MD, TFI 4-6). Three mesio-distal sections were made in corono-apical axis of the tooth, giving enamel and dentine samples. They were embedded in an epoxy resin, and polished. Half of the polished surface was covered with an acid resistant varnish and immersed in standard acidified buffer solution (pH 4.5) for 48 h to create artificial caries lesions. They were treated with 5% NaOCl for 45 min and sectioned longitudinally along the center into two halves. Cut surfaces were polished and observed under a confocal laser scanning microscope for depth of demineralization. Morphology of the demineralized zones was observed under a field emission scanning electron microscope (FE-SEM). Data were analyzed using one-way ANOVA and Sheffe test (p=0.05).
  
  
  RESULTS
  Statistically significant difference in depth of demineralization was found between N and MD groups (p=0.046) in the enamel, and between N and ML (p=0.002), N and MD (p<0.001), ML and MD (p=0.029) in dentine. FE-SEM observation of the normal enamel showed direct dissolution with large fissures. Spongy appearance of intertubular dentine gradually disappeared from N to MD.
  
  
  CONCLUSIONS
  Moderately fluorosed enamel showed a significant caries resistance. In contrast, mild and moderately fluorosed dentine was significantly caries susceptible in vitro.
authors.affiliation: Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. kanchanapgkw@yahoo.com
authors.forename: P G K
authors.initials: PG
authors.lastname: Waidyasekera
authors.forename: T
authors.initials: T
authors.lastname: Nikaido
authors.forename: D D S
authors.initials: DD
authors.lastname: Weerasinghe
authors.forename: K A
authors.initials: KA
authors.lastname: Wettasinghe
authors.forename: J
authors.initials: J
authors.lastname: Tagami
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D003733:Dental Caries Susceptibility; D003743:Dental Enamel / Q000737:chemistry* / Q000473:pathology / Q000648:ultrastructure; D003804:Dentin / Q000737:chemistry* / Q000473:pathology / Q000648:ultrastructure; D009050:Fluorosis, Dental / Q000503:physiopathology; D006801:Humans; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D008963:Molar; D017001:Tooth Demineralization / Q000473:pathology / Q000517:prevention & control*