Remineralization of Early Caries by a Nano-hydroxyapatite Dentifrice

Objective: The purpose of this randomized, double-blind, crossover, in situ study was to evaluate the efficacy of nano-hydroxyapatite (nHAP) dentifrices on caries remineralization and demineralization inhibition.

Methods: Three demineralized enamel blocks (A,B,C) and one healthy block (D), cut from each of 30 molars, were exposed respectively to dentifrices of A) 5% nHAP, B) 10% nHAP, C) 1100 ppm fluoride, and D) 10% nHAP via an intra-oral appliance worn by 30 adults in this four-phase study lasting 28 days per phase. Baseline and post-test mineral loss (delta Z) and lesion depth (LD) were quantified using microradiography.

Results: Pair-wise comparison (baseline versus test) demonstrated significant (p < 0.001) reductions in delta Z and LD in A, B, and C. ANOVA showed no significant differences among the three products in percent mineral gain. No demineralization occurred in the sound enamel specimens exposed intra-orally while using 10% nHAP.

Conclusion: nHAP dentifrice caused remineralization comparable to a fluoride dentifrice, and inhibited caries development, thus suggesting that an nHAP dentifrice can be an effective alternative to fluoride toothpaste.