Stability of chemically available fluoride in Chilean toothpastes

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. Aim To evaluate the stability of soluble F in Chilean toothpastes after 1 year of storage. Design 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.