title: On the chemical and physical nature of erosions and caries lesions in dental enamel.
abstract: The aim of the present paper was to study the relation between the development of enamel erosion and caries lesion. Intact teeth were exposed to a gently agitated 50 mM acetate buffer, with or without fluoride for various periods of time. Further, intact teeth were exposed to an agitated 0.2 M HCl solution. It was found that irrespective of experimental conditions the aqueous phase was initially unsaturated with respect to both hydroxyapatite and fluorapatite during which period fluorhydroxyapatite was dissolved. Histological examination showed that the dissolving apatite originated from the enamel surface and the resulting lesion exhibited the signs of a dental erosion. The depth of the erosive lesion was found to be a direct function of the amount of mineral dissolved before the aqueous phase became saturated with respect to fluorapatite. The calcium, phosphate and fluoride dissolved made the aqueous phase first saturated and later supersaturated with respect to fluorapatite and a reuptake of fluoride in the enamel began, now under development of a caries-like lesion with preservation of the surface layer over a subsurface demineralizing zone. The demineralization depended on the volume of the aqueous phase. In conclusion, in a closed system with a limited amount of unsaturated solution a double lesion, an erosion over a caries lesion, will develop according to the changing saturation with respect to fluorapatite.
authors.affiliation: Department of Oral Anatomy, Dental Pathology and Operative Dentistry, Royal Dental College, Aarhus, Denmark.
authors.forename: M J
authors.initials: MJ
authors.lastname: Larsen
mesh_terms: D001031:Apatites / Q000737:chemistry*; D002118:Calcium / Q000032:analysis; D003731:Dental Caries / Q000378:metabolism* / Q000473:pathology; D003743:Dental Enamel / Q000737:chemistry / Q000473:pathology; D017886:Durapatite; D005459:Fluorides / Q000032:analysis / Q000378:metabolism; D006801:Humans; D006882:Hydroxyapatites / Q000737:chemistry*; D012996:Solutions; D014077:Tooth Erosion / Q000378:metabolism* / Q000473:pathology
chemical_list: D001031:Apatites; D006882:Hydroxyapatites; D012996:Solutions; D017886:Durapatite; C025105:fluorapatite; D005459:Fluorides; D002118:Calcium