title: Impact of the acid flow rate on dentin erosion.
abstract: OBJECTIVE
  The study aimed to evaluate the erosive effects of acids flowing with different velocities and duration on dentin previously pre-treated with distilled water or human saliva.
  
  
  METHODS
  Bovine dentin surfaces were submitted to a 10 min demineralisation with hydrochloric or citric acid (pH 2.3, 37 degrees C) in an artificial mouth at flow rates of 3, 2.25, 1.5, 0.75 or 0.15 ml/min or in 30 ml of the respective acid without movement (each subgroup n=16 specimens). Prior to the demineralisation, half of the specimens of each group were either pre-treated with distilled water or human saliva for 120 min. After 2, 5 and 10 min demineralisation, profilometric traces of dentin loss were performed perpendicular to the direction of acid flow at three sites (A-C) with intervals of 500 microm. The first profile (A) was taken in a distance of 1.5 mm from the acid starting to flow over the sample. Thus, median dentin loss at each site was calculated and statistically analysed by five-way ANOVA.
  
  
  RESULTS
  Dentin loss increased with increasing acid flow rate and demineralisation time and was higher for demineralisation with citric acid compared to hydrochloric acid. For given flow rates of 0.15 to 3 ml/min, measurement of dentin loss yielded highest values for site A and decreasing values for sites B and C. For all groups, no significant differences of dentin loss were observed between specimens pre-treated with distilled water or human saliva.
  
  
  CONCLUSIONS
  Under the conditions of this study, both duration of demineralisation and acid flow rate but not pre-treatment with distilled water or saliva influence the extent of dentin erosion.
authors.affiliation: Department of Operative Dentistry, Preventive Dentistry and Periodontology, University of Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany. annette.wiegand@zzmk.unizh.ch
authors.forename: A
authors.initials: A
authors.lastname: Wiegand
authors.forename: A
authors.initials: A
authors.lastname: Stock
authors.forename: R
authors.initials: R
authors.lastname: Attin
authors.forename: C
authors.initials: C
authors.lastname: Werner
authors.forename: T
authors.initials: T
authors.lastname: Attin
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D000818:Animals; D002417:Cattle; D019343:Citric Acid / Q000009:adverse effects*; D003804:Dentin / Q000187:drug effects*; D005260:Female; D006801:Humans; D006851:Hydrochloric Acid / Q000009:adverse effects*; D008297:Male; D012463:Saliva; D012997:Solvents / Q000009:adverse effects*; D013997:Time Factors; D017001:Tooth Demineralization / Q000139:chemically induced; D014077:Tooth Erosion / Q000139:chemically induced*
chemical_list: D012997:Solvents; D019343:Citric Acid; D006851:Hydrochloric Acid