title: Stability of chemically available fluoride in Chilean toothpastes.
abstract: BACKGROUND
  Storage time may reduce the amount of soluble fluoride (F) in toothpastes. Although we previously studied the type and concentration of F in fresh samples of commercial Chilean toothpastes, their stability was not determined.
  
  
  OBJECTIVE
  To evaluate the stability of soluble F in Chilean toothpastes after 1 year of storage.
  
  
  METHODS
  All the toothpastes (n = 30) previously used were re-analyzed after 1 year of storage time at room temperature (±22°C). Total F (TF = soluble F + insoluble F) and total soluble F (TSF = F ion + MFP ion) were assessed using an ion-specific electrode, through a validated methodology. Data were expressed in ppm of F (mg F/kg).
  
  
  RESULTS
  Mean (±SD; n = 30) TF and TSF concentrations after storage were 1049 ± 427 and 987 ± 411 ppm F, respectively. Five toothpastes showed between 30% and 50% of insoluble F, four of them formulated with MFP/calcium-based abrasive. In two products, there was a reduction in TSF below the evidence-based anticaries effectiveness threshold of 1000 ppm F.
  
  
  CONCLUSIONS
  Although most of the toothpastes tested kept their original TSF content after 1 year of storage, some products evidenced an important reduction, which may compromise their anticaries efficacy. Reductions in TSF may be explained by an incorrect F salt-abrasive formulation.
authors.affiliation: Piracicaba Dental School, UNICAMP, Piracicaba, SP, Brazil.|Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Constanza E
authors.initials: CE
authors.lastname: Fernández
authors.affiliation: University of Minnesota, Minneapolis, MN, USA.
authors.forename: Carola A
authors.initials: CA
authors.lastname: Carrera
authors.affiliation: Cariology Unit, Department of Oral Rehabilitation, University of Talca, Talca, Chile.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Muñoz-Sandoval
authors.affiliation: Piracicaba Dental School, UNICAMP, Piracicaba, SP, Brazil.
authors.forename: Jaime A
authors.initials: JA
authors.lastname: Cury
authors.affiliation: Cariology Unit, Department of Oral Rehabilitation, University of Talca, Talca, Chile.|Interdisciplinary Excellence Research Program on Healthy Aging (PIEI-ES), University of Talca, Talca, Chile.
authors.forename: Rodrigo A
authors.initials: RA
authors.lastname: Giacaman
mesh_terms: D002677:Chile; D004356:Drug Storage; D005459:Fluorides / Q000032:analysis*; D012995:Solubility; D014100:Toothpastes / Q000737:chemistry*
chemical_list: D014100:Toothpastes; D005459:Fluorides