title: Evaluation of low fluoride toothpaste using primary enamel and a validated pH-cycling model.
abstract: OBJECTIVE
  To develop and validate pH-cycling model for primary enamel, which was then used to evaluate the anti-caries potential of fluoride toothpastes.
  
  
  METHODS
  Human primary enamel slabs were subjected to pH-cycling model for 10 days and maintained for 6 h in demineralizing solution and 18 h in remineralizing solution daily. Twice/day, the slabs were treated. To validate it, the treatments were water or solutions containing 62.5, 125, 250, and 375 μg F/mL. Commercial toothpastes containing no fluoride, 500, 1100, and 1450 μg F/g were evaluated. Demineralization was assessed by percentage of surface hardness loss (%SHL) and cross-sectional hardness (ΔS). Fluoride dose-response effect was analysed by quadratic regression and the effects of toothpastes by Tukey's test.
  
  
  RESULTS
  Dose-response effect was found between fluoride concentration and %SHL (R2= 0.7047; P < 0.01) or ΔS (R2= 0.4465; P < 0.01). %SHL and ΔS (mean ± SD) for the group treated with 500 μg F/g toothpaste was 36.6 ± 8.0 and 6298.5 ± 1221.3, respectively, which were significantly higher than those treated with 1100 (25.2 ± 8.7; 4565.7 ± 1122) and 1450 μg F/g (24.2 ± 5.2; 2339.1 ± 879.7) toothpastes.
  
  
  CONCLUSIONS
  The developed pH-cycling model may be used to evaluate and compare the anti-caries potential of toothpaste formulations with low fluoride concentration because it presents dose-response effects on the reduction of primary enamel demineralization.
authors.affiliation: Department of Physiological Sciences, Piracicaba Dental School, University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Marilia Mattar de Amoêdo Campos
authors.initials: MM
authors.lastname: Velo
authors.affiliation: Department of Physiological Sciences, Piracicaba Dental School, University of Campinas, Piracicaba, SP, Brazil. cinthia@fop.unicamp.br.
authors.forename: Cínthia Pereira Machado
authors.initials: CP
authors.lastname: Tabchoury
authors.affiliation: Department of Physiological Sciences, Piracicaba Dental School, University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Dayse Andrade
authors.initials: DA
authors.lastname: Romão
authors.affiliation: Department of Physiological Sciences, Piracicaba Dental School, University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Jaime Aparecido
authors.initials: JA
authors.lastname: Cury
mesh_terms: D002327:Cariostatic Agents / Q000737:chemistry*; D003743:Dental Enamel / Q000187:drug effects*; D005459:Fluorides / Q000737:chemistry*; D006244:Hardness; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D013499:Surface Properties; D014100:Toothpastes / Q000737:chemistry*
chemical_list: D002327:Cariostatic Agents; D014100:Toothpastes; D005459:Fluorides