An in vitro Comparative Evaluation of Fluoride Uptake by Demineralized Enamel Exposed to Four Different Low Fluoride Dentifrices

Background: Topical fluoride application has an important role in caries prevention. The aim of the present study was to evaluate and compare fluoride uptake of tooth enamel after exposure to four commercially available low fluoridated toothpastes. Methods: The present in vitro study was conducted on 60 sound extracted premolar teeth. The teeth were covered with acid-resistance nail polish except at a 5×5 mm area on the buccal and lingual surface of each tooth (for experimental and control group respectively). After demineralization of the window area for 2 days, the teeth were immersed in toothpaste slurry containing: Sodium Fluoride 1000ppm (Group A), Soduim monofluorophosphate 1000ppm (Group B), Soduim monofluorophosphate 500ppm (Group C) and Sodium fluoride 500ppm (Group D). The pH of the dentifrices was measured. The acid biopsy technique and fluoride ion-specific electrode was used for fluoride ion estimation. Results: All of the applied toothpastes significantly increased fluoride content of the enamel compared with the control group (P <0.001). There was a significant difference among the four groups of toothpastes in the mean fluoride uptake and group A showed maximum uptake of fluoride (5.5920 ppm), followed by group B, C and D respectively. According to Pearson correlation analysis, there was not any significant relationship between the pH of the dentifrices and uptake of fluoride. Conclusion: There was a positive correlation between the fluoride concentration of dentifrices and the fluoride uptake on demineralized enamel. The toothpastes containing NaF are more effective than toothpastes containing NaMFP. Moreover, dentifrice pH had no influence on fluoride uptake by enamel.