title: Protection of short-time enamel erosion by different tetrafluoride compounds.
abstract: OBJECTIVE
  This in vitro study aimed to analyse the protective effect of differently concentrated titanium (TiF(4)), zirconium (ZrF(4)) and hafnium (HfF(4)) tetrafluoride on enamel erosion.
  
  
  METHODS
  Polished enamel surfaces of 36 bovine crowns were covered with tape leaving 4 enamel windows each 3mm in diameter exposed. The crowns were randomly assigned to six groups (each n=6) and pretreated with 4% TiF(4), 10% TiF(4), 4% ZrF(4), 10% ZrF(4), 4% HfF(4) or 10% HfF(4) for 4 min (first window), 10 min (second window) or 15 min (third window). The fourth window of each crown was not pretreated and served as control. Erosion was performed stepwise with 1% HCl (pH 2) in five consecutive intervals of each 15 s (total 75 s). Enamel dissolution was quantified by colorimetric determination of phosphate release into the acid. For each tooth, cumulative phosphate loss of enamel pretreated with one of the tetrafluoride compounds was calculated as percentage of the respective control and statistically analysed using two-way ANOVA.
  
  
  RESULTS
  Enamel erosion was significantly reduced by TiF(4), ZrF(4) and HfF(4) application. Cumulative phosphate loss (mean % of control, 75s erosion) after 4-15 min application was significantly lower for 4% ZrF(4) (7-11%), 10% ZrF(4) (2-6%), 4% HfF(4) (11-9%) and 10% HfF(4) (12-16%) compared to 4% TiF(4) (42-27%) and 10% TiF(4) (54-33%). Only for 4% and 10% TiF(4), phosphate loss decreased with increasing duration of application, but also increased with increasing acid intervals.
  
  
  CONCLUSIONS
  TiF(4), ZrF(4) and HfF(4) might protect enamel against short-time erosion, but protection was more enhanced by ZrF(4) and HfF(4) compared to TiF(4) application overtime.
authors.affiliation: Clinic for Preventive Dentistry, Periodontology and Cariology, University of Zürich, Plattenstrasse 11, 8032 Zürich, Switzerland. annette.wiegand@zzmk.uzh.ch
authors.forename: Annette
authors.initials: A
authors.lastname: Wiegand
authors.forename: Kolja Alexander
authors.initials: KA
authors.lastname: Laabs
authors.forename: Grit
authors.initials: G
authors.lastname: Gressmann
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Roos
authors.forename: Ana Carolina
authors.initials: AC
authors.lastname: Magalhães
authors.forename: Thomas
authors.initials: T
authors.lastname: Attin
mesh_terms: D000818:Animals; D002327:Cariostatic Agents / Q000627:therapeutic use*; D002417:Cattle; D003743:Dental Enamel / Q000187:drug effects*; D003747:Dental Enamel Solubility / Q000187:drug effects*; D005459:Fluorides / Q000008:administration & dosage*; D006851:Hydrochloric Acid; D010865:Pilot Projects; D019228:Tooth Crown; D014077:Tooth Erosion / Q000139:chemically induced / Q000517:prevention & control*; D016896:Treatment Outcome
chemical_list: D002327:Cariostatic Agents; D005459:Fluorides; D006851:Hydrochloric Acid