Total, soluble, and ionized fluoride concentration in cavity protection dentifrices marketed in Iran by two analytical methods

Abstract Background and Objectives : Given the proven role of fluoride-containing toothpastes in preventing and controlling dental caries, the present study aimed to determine the concentration of total, soluble, and ionized fluoride in children's and adult toothpastes available in the Iranian market using two measurement methods, including spectrophotometry and potentiometry. Materials and Methods In this experimental-laboratory study, the concentration of total, soluble, and ionized fluoride was measured at the beginning and end of two toothpaste tubes from 28 different brands of children's and adult toothpastes available in the Iranian market. The selected products had a production date difference of less than six months and had at least one year until the expiration date. Fluoride measurement was performed using two analytical methods, including spectrophotometry and potentiometry. In addition, parametric and nonparametric statistical tests were used to analyze the data. Results The average total fluoride concentration of toothpastes ranged from 552.39 to 3749.41 ppm, and the soluble fluoride concentration ranged from 220.38 to 3436.79 ppm. In all cases, there was no significant difference between the total and soluble fluoride values, or between the soluble and ionized fluoride values (P > 0.05), but in 75% of the toothpastes, a significant difference was observed between the total and ionized fluoride values (P < 0.05). No significant difference was observed between the ratio of soluble to total fluoride in national and licensed toothpastes (P = 0.98). In examining the uniformity of fluoride distribution, fluoride concentrations were significantly lower at the end of the tube (P < 0.05). The fluoride concentration values in toothpastes with NaF composition were lower but more homogeneous compared to MFP (P < 0.05). The absolute values of the spectrophotometric and potentiometric data differed, but they ranked similarly. In five brands, the fluoride levels measured were close to those claimed by the manufacturers. Conclusion Fluoride levels were evaluated ≥ 1000 ppm in 78% of toothpastes. There was no difference in fluoride levels or in the ratio of soluble to total fluoride between domestic and internationally licensed toothpastes. Toothpastes containing MFP exhibited higher fluoride concentrations than those containing NaF. Fluoride distribution was not uniform throughout the tube, and differences between total and ionized fluoride levels were observed in many brands. The spectrophotometric method can be useful as an accessible, cost-effective approach.