Evaluation of Iranian toothpaste containing different concentrations of nano-hydroxyapatite on the remineralization of incipient carious lesions: in vitro

Dental caries is one of the most common infectious diseases which could be prevented in various ways. The aim of the present study was to evaluate the effect of a toothpaste containing different concentrations of nano-hydroxyapatite on the remineralization of incipient caries. 9 sound first premolar teeth of maxilla and mandible were sectioned to four pieces. 6 specimens were stored in distilled water as control group. The remaining 30 specimens were demineralized for 72 hours and then their microhardness was measured. 0, 0.5, 1, 2 and 5% wt nano-hydroxyapatite were added to the solution of distilled water and toothpaste. Specimens were divided into 5 groups (N=6) and after demineralization, each group were randomly immersed in the above-mentioned solutions for 15 minutes. Next, specimens were kept in artificial saliva for 1 hour followed by immersion in the related remineralizing solution for another 15 minutes. This procedure was repeated for 5 days. Finally, the microhardness of the teeth was measured. Data were analyzed using repeated measures analysis of variance (ANOVA). The microhardness of demineralized teeth was increased following exposure to different concentrations of nano-hydroxyapatite, but this increase was not statistically significant (P=0.62). Nano-hydroxy apatite can enhance remineralization and increase the tooth microhardness although this increase was not significant.