title: A qualitative and quantitative investigation into the effect of fluoride formulations on enamel erosion and erosion-abrasion in vitro.
abstract: OBJECTIVE
  To investigate the effect of a single application of highly concentrated SnF(2) and NaF solutions and a NaF/CaF(2) varnish on human enamel subjected to hydrochloric acid erosion and tooth brush abrasion.
  
  
  METHODS
  Forty enamel samples were prepared from human third molars and NaF (9500ppm, pH 8.0), SnF(2) (9500ppm, pH 2.6) solutions; Bifluorid10(®) varnish (42,500ppm, NaF 5%, CaF(2) 5%) and deionized water (control) was applied to the enamel. Following this three, six and nine cycles of erosion [1 cycle=erosion (0.01M HCl, pH 2.2, 2min)+artificial saliva (1h, pH 7.0)] and erosion-abrasion [1 cycle=erosion (0.01M HCl, pH 2.2, 2min)+artificial saliva (1h, pH 7.0)+abrasion (120 linear strokes in artificial saliva from Tepe medium soft brushes 200g loading)] were carried out. The fluoride treated enamel was analysed using Knoop microhardness, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS).
  
  
  RESULTS
  For erosion alone, there was significantly less microhardness reduction in the Bifluorid10(®) group after three and six cycles of erosion (P<0.05), however no other groups showed statistically different hardness (P>0.05). The EDS analysis showed that only the Bifluorid10(®) group had any detectable fluorine following erosion and erosion-abrasion (0.1wt.% and 0.2wt.% fluorine respectively). The surface fluorine was found to have been removed after erosion and erosion-abrasion for all other surface treatments. Although precipitates were observed after application of the surface treatments, following erosion-abrasion, no visible surface effects from any fluoride preparation remained.
  
  
  CONCLUSIONS
  Enamel surface precipitates from application NaF, SnF(2) solutions appear to not be able to provide protection against gastric erosion and tooth brush abrasion. The NaF/CaF(2) varnish provided limited protection against erosion but the role for such varnishes in gastric erosion and tooth brush abrasion remains uncertain.
authors.affiliation: Department of Primary Dental Care, King's College London Dental Institute, Caldecot Road, Denmark Hill, London SE5 9RW, UK. rupert.s.austin@kcl.ac.uk
authors.forename: R S
authors.initials: RS
authors.lastname: Austin
authors.forename: K S
authors.initials: KS
authors.lastname: Stenhagen
authors.forename: L H
authors.initials: LH
authors.lastname: Hove
authors.forename: S
authors.initials: S
authors.lastname: Dunne
authors.forename: R
authors.initials: R
authors.lastname: Moazzez
authors.forename: D W
authors.initials: DW
authors.lastname: Bartlett
authors.forename: A B
authors.initials: AB
authors.lastname: Tveit
mesh_terms: D000704:Analysis of Variance; D002124:Calcium Fluoride / Q000008:administration & dosage; D003799:Dental Stress Analysis; D005460:Fluorides, Topical / Q000008:administration & dosage*; D005461:Fluorine / Q000032:analysis; D005744:Gastric Acid; D006244:Hardness; D006801:Humans; D006851:Hydrochloric Acid / Q000009:adverse effects; D012969:Sodium Fluoride / Q000008:administration & dosage; D013052:Spectrometry, X-Ray Emission; D014002:Tin Fluorides / Q000008:administration & dosage; D014072:Tooth Abrasion / Q000209:etiology / Q000517:prevention & control*; D014077:Tooth Erosion / Q000139:chemically induced / Q000517:prevention & control*; D014099:Toothbrushing / Q000009:adverse effects
chemical_list: C094502:Bifluorid 12; D005460:Fluorides, Topical; D014002:Tin Fluorides; D005461:Fluorine; D012969:Sodium Fluoride; D002124:Calcium Fluoride; D006851:Hydrochloric Acid