title: Fluoride-induced precipitates on enamel surface and subsurface areas visualised by electron microscopy and confocal laser scanning microscopy.
abstract: The present study examined the enamel surface after in vitro topical treatments with a neutral 2% NaF solution. For minimising the risk of artefacts, samples were inspected without pre-treatment as fresh, naturally wet specimens by complementary techniques: variable pressure electron microscopy (VP-SEM) and confocal laser scanning microscopy (CLSM). VP-SEM provided information on the surface morphology, whereas CLSM allowed non-destructive visualisation of subsurface areas. Neutral NaF solutions induced globular precipitates on the enamel surfaces. If the globules formed may be described as "calcium fluoride like material", the additional information of this experiment is that, after interaction with neutral solutions, they also contain considerable amounts of NaF. When the NaF solutions were soaked on pellets and then were brought into contact with the enamel surfaces, NaF crystallites of cubic shape are formed. Confocal optical tomographies of subsurface enamel after treatments with neutral NaF solutions revealed partly coroded enamel structures, whereas VP-SEM showed intact surfaces. In between the coroded areas, a fine granulate precipitate could be observed. This is evidence that fluoride induces the formation of sub-surface precipitates only when applied during demineralisation. The precipitate could be readily removed by 24-h contact with a KOH solution.
authors.affiliation: Johannes Gutenberg-University, Medical Faculty, Department for Applied Structure- and Microanalysis, Mainz, Germany. DUSCHNER@MZDMZA.ZDV.UNI-MAINZ.DE
authors.forename: H
authors.initials: H
authors.lastname: Duschner
authors.forename: H
authors.initials: H
authors.lastname: Götz
authors.forename: B
authors.initials: B
authors.lastname: Ogaard
mesh_terms: D000293:Adolescent; D016477:Artifacts; D002118:Calcium / Q000032:analysis; D002124:Calcium Fluoride / Q000737:chemistry; D002327:Cariostatic Agents / Q000737:chemistry* / Q000378:metabolism; D002424:Caustics / Q000737:chemistry; D011232:Chemical Precipitation; D002648:Child; D003460:Crystallization; D003743:Dental Enamel / Q000378:metabolism / Q000648:ultrastructure*; D004577:Electron Probe Microanalysis; D005460:Fluorides, Topical / Q000737:chemistry* / Q000378:metabolism; D005461:Fluorine / Q000032:analysis; D006801:Humans; D006878:Hydroxides / Q000737:chemistry; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D017680:Potassium Compounds / Q000737:chemistry; D012964:Sodium / Q000032:analysis; D012969:Sodium Fluoride / Q000737:chemistry* / Q000378:metabolism; D017001:Tooth Demineralization / Q000378:metabolism / Q000473:pathology
chemical_list: D002327:Cariostatic Agents; D002424:Caustics; D005460:Fluorides, Topical; D006878:Hydroxides; D017680:Potassium Compounds; D005461:Fluorine; D012969:Sodium Fluoride; D012964:Sodium; D002124:Calcium Fluoride; D002118:Calcium; C029943:potassium hydroxide