Effects of Simulated Salivary Hexametaphosphate on De-/Remineralization in vitro

Objective: An in vitro pH-cycling model was utilized to evaluate the impact of a new chewing gum additive (hexametaphosphate/polyphosphate) on fluoride activity in conjunction with a series of dose response dentifrice formulations containing NaF. Methods: Enamel crowns were used to study lesion initiation and progression. A series of fluoride dose response dentifrice formulations and a tartar control dentifrice, both with and without the gum additive, were compared. The pH cycling was carried out for 14 days, consisting of twice daily dentifrice treatments before and after a demineralization period, and simulated saliva soaking (with and without the additive). The regimen was modified for some treatment groups to permit simulation of chewing gum, with and with the additive. Crowns were assessed by cross-sectional microhardness; mineral loss (DZ, vol% mineral x mm) was calculated. Results: The model demonstrated a good fluoride dose response for the dentifrice formulations (1100ppm = 1677 ± 554, 250ppm = 2690 ± 989, and <1ppm = 3606 ± 812, differences were significant at p=0.05). The treatment groups modified to simulate additive-free chewing gum also demonstrated a good fluoride dose response (1100ppm = 1042 ± 231, 250ppm = 1227 ± 316, and <1ppm = 1932 ± 665, differences were significant at p=0.05). The treatment groups containing the additive exhibited less lesion severity at each fluoride level. These DZ values were nearly identical (1100ppm = 535 ± 571, 250ppm = 513 ± 281, and <1ppm = 656 ± 445, no significant differences, p>0.05). Conclusion: Based on these results, we conclude that the new chewing gum additive (hexametaphosphate/polyphosphate) does not negatively impact fluoride’s anticaries potential and shows no apparent detrimental affects.