REMINERALIZATION OF TOOTH ENAMEL WITH HYDROXYAPATITE NANOPARTICLES: AN IN VITRO STUDY

The use of toothpastes is the best way to combat enamel loss and degradation. When they also contain hydroxyapatite nanoparticles, HAP NPs, the tooth enamel can be restored by remineralization. In this study, we developed two types of toothpastes, one with nano sized HAP, noted P1, and the other with nano multi-substituted hydroxyapatite (ms-HAP, HAP-Mg-Zn-Si), noted P2, which were used to treat the artificially demineralized teeth enamel surface. The remineralization efficacy of the two toothpastes was determined on artificially created enamel lesions by suspending healthy enamel slices in demineralizing solution, made of orthophosphoric acid of 37.5% for 90 s. For this purpose, six extracted third molars were collected and twenty-four enamel slices were cut and arbitrarily allocated to the four groups, namely n = 6 enamel slices for each group. One group served as untreated (natural) enamel control, and another group comprised demineralized enamel and two test groups, firstly demineralized, and then, they were treated with toothpastes P1 and P2, respectively, each of them for ten days, and finally were noted P1 and P2 enamel surfaces. The surface morphology and roughness of all enamel specimens were studied by atomic force microscopy (AFM) before and after applying the treatment with the toothpastes. The toothpastes effect was evidenced by the average diameter of ceramic nanoparticles deposited within the superficial smooth layer on enamel surface having, at the completion of 10 days treatment, a low surface roughness close to that of natural enamel. This in vitro comparative study demonstrated that both toothpastes P1 and P2 can promote surface enamel repair by remineralization and the formation of a protective hydroxyapatite coating layer on the enamel surface treated with these toothpastes.