title: A novel approach to study in situ enamel erosion and abrasion lesions.
abstract: OBJECTIVE
  This study investigated previous hypotheses that the tongue can abrade acid softened/eroded enamel surfaces.
  
  
  METHODS
  Twelve upper removable appliances each retaining 2 anterior and 2 posterior human enamel specimens were constructed. Each specimen was exposed to acid on both surfaces, but only one surface was allowed contact with the tongue. Therefore, 96 surfaces were assessed. Appliances were worn from 9.30 to 17.00 Monday to Friday for 22days. Acid eroded lesions were created by immersing the specimens for 5min in 50ml orange juice three times daily. Enamel loss was measured using Quantitative light- induced fluorescence (QLF) and Non- contact profilometry (NCLP) and the differences (D) between tongue (Dt) and palate facing (DP) surfaces determined.
  
  
  RESULTS
  %ΔFD(t-p)from the two anterior specimens were greater than from those placed posteriorly with mean values of 15.9% (±9.1) and 14.4% (±8.4), 5.6% (±8.7) and 4.5% (±6.6) respectively. Similarly, NCLP data showed anterior specimens had greater differences for mean step height (MSH) between tongue- facing and the palate- facing (control) surfaces than posterior specimens. MSHD(t-p)values were 59.4μm (±30.3) for anterior tongue facing surfaces and 55.5μm (±29.4) for posterior palate facing surfaces. For the posterior specimens MSH was 48.1μm (±26.1) and 51.7μm (±30.4) respectively (p<0.05).
  
  
  CONCLUSIONS
  The greater enamel surface loss of the anterior specimens demonstrates that abrasion by the tongue on acid softened/eroded enamel in situ is likely.
authors.affiliation: Department of Restorative Dentistry, Liverpool University Dental Hospital, UK. Electronic address: m.ablal@liverpool.ac.uk.
authors.forename: M A
authors.initials: MA
authors.lastname: Ablal
authors.affiliation: Department of Restorative Dentistry, Liverpool University Dental Hospital, UK.
authors.forename: A
authors.initials: A
authors.lastname: Milosevic
authors.affiliation: Department of Restorative Dentistry, Liverpool University Dental Hospital, UK.
authors.forename: A J
authors.initials: AJ
authors.lastname: Preston
authors.affiliation: Department of Health Services Research/School of Dentistry, Institute of Psychology, Health and Society, University of Liverpool, UK.
authors.forename: S M
authors.initials: SM
authors.lastname: Higham
mesh_terms: D000328:Adult; D001628:Beverages / Q000009:adverse effects; D032084:Citrus sinensis / Q000009:adverse effects; D003743:Dental Enamel / Q000187:drug effects* / Q000473:pathology; D019587:Dietary Supplements; D005260:Female; D000067030:Fruit and Vegetable Juices / Q000009:adverse effects; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007180:Incisor; D008297:Male; D008437:Maxilla; D008875:Middle Aged; D009968:Orthodontic Appliances, Removable; D012463:Saliva / Q000737:chemistry; D013499:Surface Properties; D013997:Time Factors; D014059:Tongue / Q000503:physiopathology*; D014072:Tooth Abrasion / Q000139:chemically induced / Q000209:etiology* / Q000473:pathology; D014077:Tooth Erosion / Q000139:chemically induced / Q000150:complications* / Q000473:pathology; D006113:United Kingdom; D055815:Young Adult
keywords: Enamel erosion; Profilometry; QLF; Tongue abrasion