Enamel and dentine remineralization by nano-hydroxyapatite toothpastes

Objectives: This in vitro study evaluated the effects of nano-hydroxyapatite (n-HAp) toothpastes on remineralization of bovine enamel and dentine subsurface lesions. Methods: Specimens were demineralized, randomly divided into five groups, and exposed to an aqueous remineralizing solution for two and five weeks (37 degrees C). Brushing procedures were performed with the respective toothpaste/storage solution slurry twice daily (2 x 5 s; total contact time of the slurries 2 x 120 s/d): storage in remineralizing solution only (0); additional brushing with B (20 wt% zinc carbonate nano-hydroxyapatite, ZnCO3/n-HAp); BS (24 wt% ZnCO3/n-HAp); E (0.14 wt% amine fluoride); or A (7 wt% pure n-HAp). Differences in mineral loss (Delta Delta Z) before and after storage/treatment were microradiographically evaluated. Results: Dentine groups 0, B, BS, and A showed significantly higher DDZ values compared to E (p < 0.05; ANOVA). Enamel DDZ values of group A were significantly higher compared to group E (p < 0.05), whilst no significant differences of these groups could be observed compared to 0, B, and BS (p > 0.05). Conclusions: With the in vitro conditions chosen, toothpastes containing n-HAp revealed higher remineralizing effects compared to amine fluoride toothpastes with bovine dentine, and comparable trends were obtained for enamel. (C) 2011 Elsevier Ltd. All rights reserved.