Abstract:

Objective To prepare the novel fluoride loaded poly （prolylene carbonate）（PPC）/sodium fluoride （NaF） dental patch based on PPC and explore its remineralization property and in vitro cytotoxicity， and to clarify its effect of fluorine-containing patches with different concentrations of fluoride in promoting the remineralization of demineralized enamel， and to provide the reference for its clinical application. Methods The PPC/NaF dental patch with different mass fractions of sodium fluoride （0， 0.5%， 2.5%，and 5.0%） were prepared by melt-blending method. The enamel blocks were prepared with extracorporeal tooth and randomly divided into PPC group， 0.5%PPC/NaF group， 2.5%PPC/NaF group， and 5.0%PPC/NaF group according to different contents of fluoride in the dental patches， and there were 10 samples in each group. The morphology of surface of enamel specimens was observed under scanning electron microscope（SEM），the microhardness of the enamel surface before and after demineralization and after remineralization was measured by microhardness tester， and the microhardness recovery percentage （SMHR） was calculated. The mouse fibroblast L929 cells were co-cultured with the PPC/NaF dental patch extract，and CCK-8 test was used to detect the relative proliferation rate （RGR） of the fibroblast L929 cells of the mice in various groups， and its cytotoxicity level was evaluated. Results The microhardness of the enamel specimens in various groups after demineralization was significantly lower than that before demineralization （P<0.05）. After being treated with PPC/NaF tooth patches with different contents of sodium fluoride， the microhardness of the enamel specimens in various groups was significantly higher than that before remineralization（P<0.05）， but still lower than that before demineralization （P<0.05）. The SMHR of enamel specimens in each group from high to low was 5.0% PPC/NaF group， 2.5% PPC/NaF group， 0.5% PPC/NaF group， and PPC group. The SEM results showed that the number of pores on the surface of the enamel specimens in PPC group was still large， and the irregular granular sediments were seen； in 0.5%PPC/NaF group， the number of pores on the enamel surface was decreased significantly，and the obvious enamel collapse was still seen on the surface and mineral crystal deposition was loose and uneven； in 2.5% PPC/NaF group， there were almost no pores on the enamel surface，and the enamel surface was regular and covered with a large number of needle-like crystals， which were densely arranged； in 5.0% PPC/NaF group， the enamel surface was covered with a large number of needle-like or irregular granular crystals and layered sediments were seen in some areas. Compared with PPC group， the RGR of the fibroblast L929 cells of the mice in 5.0% PPC/NaF group was decreased significantly （P<0.05）. The RGR of the fibroblast L929 cells after treated with PPC/NaF tooth patches with different contents of fluoride in various groups was greater than 75%， and the cytotoxicity grade was 0 or 1. Conclusion PPC/NaF dental patch can effectively promote the demineralization of the demineralized enamel without cytotoxicity；with the increasing of fluorine concentration， its remineralization is also enhanced.

Key words: Polypropylene carbonate, Fluoride, Dental patch, Remineralization, Cell proliferation rate