Effect of an Experimental Paste with Hydroxyapatite Nanoparticles and Fluoride on Dental Demineralisation and Remineralisation in situ.

This study evaluated the effect of an experimental paste containing hydroxyapatite in nanoparticles (nano-HA)/fluoride on dental de-remineralisation in situ. Thirteen subjects took part in this crossover/randomised/double-blind study performed in 4 phases (14 days each). Four sound and 4 pre-demineralised specimens were worn intraorally at each phase corresponding to the following treatments: Nanop Plus (10% HA, 0.2% NaF, nano-HA/fluoride), MI Paste Plus (casein phosphopeptide-amorphous calcium phosphate, 0.2% NaF), F (0.2% NaF) and placebo. Two-hundred and forty enamel and 240 dentine specimens were selected by using surface microhardness; half of them were subjected to pre-demineralisation and the other half remained sound. Sound specimens were further exposed to severe cariogenic challenge (20% sucrose in biofilm) in situ, while pre-demineralised specimens were not. All specimens were exposed to fluoride dentifrice slurry 2×1 min/day. Thereafter, the treatments were done for 4 min. The de-remineralisation was quantified by transversal microradiography. The data were statistically analysed by repeated-measures ANOVA/Tukey's tests (p<0.05). Generally, no huge differences were found among the treatments. However, Nanop Plus was the only treatment able to significantly reduce dentine demineralisation (x0394;Z, integrated mineral loss) and to improve enamel remineralisation (x0394;x0394;Z, integrated mineral uptake) compared to placebo. No treatments were able to reduce enamel demineralisation, while for dentine remineralisation all treatments were similarly effective in improving x0394;x0394;Z compared to placebo. Nanop Plus seems to have a positive influence on dental de-remineralisation, which should be further confirmed.