Why does fluorosed dentine show a higher susceptibility for caries: an ultra-morphological explanation.
BACKGROUND
Chronic endemic dental fluorosis is a malformation of teeth caused by excessive ingestion of fluoride during period of tooth development. Apatite crystallites and collagen fibrils determine the caries susceptibility related properties of dentine. Information relating the effect of dental fluorosis with dentine crystallite and collagen structure is currently unavailable. This study examined structural aberrations of apatite crystallites and collagen fibrils in human fluorosed dentine.


METHODS
Superficial dentine of thirty six normal (Thylstrup-Fejerskov index - 0) and thirty six severely fluorosed (Thylstrup-Fejerskov index - 7 to 9) extracted human molars from individuals living in an area which is endemic for dental fluorosis were morphologically analyzed using transmission electron microscopy with selected area electron diffraction and dynamic force microscopy.


RESULTS
A statistically significant enlargement in the size of crystallites was found in fluorosed dentine (p<0.05). These crystallites were not homogenously arranged. Selected area electron diffraction revealed a lower density of crystallites in fluorosed dentine. Randomly distributed collagen fibrils showed a less complex lay out in contrast to normal dentine tissue.


CONCLUSIONS
Ultrastructure aberrations of the dentine explain the caries susceptibility of the tissue and suggest the necessity of special approach in dental caries treatment for patients with chronic severe endemic dental fluorosis.
Waidyasekera
Kanchana
K
Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate school, Tokyo Medical and Dental University, Tokyo, Japan. kanchanapgkw@yahoo.com
Nikaido
Toru
T
Weerasinghe
Dinesh
D
Watanabe
Akihiko
A
Ichinose
Shizuko
S
Tay
Franklin
F
Tagami
Junji
J
D000328:Adult; D001031:Apatites / Q000737:chemistry; D024042:Collagen Type I / Q000737:chemistry; D003460:Crystallization; D003731:Dental Caries / Q000209:etiology*; D003733:Dental Caries Susceptibility; D003804:Dentin / Q000737:chemistry / Q000473:pathology / Q000648:ultrastructure*; D009050:Fluorosis, Dental / Q000150:complications*; D006801:Humans; D046529:Microscopy, Electron, Transmission; D013188:Sri Lanka
D001031:Apatites; D024042:Collagen Type I