Biomimetic Remineralization Of Demineralized Dentin By Phosphorylated Chitosan/Nano Amorphous Calcium Phosphate Compound And Tripolyphosphate

Objective To investigate the remineralizing therapy of deep caries and in vitro biomimetic remineralization of demineralized dentin by Phosphorylated Chitosan/Amorphous Calcium Phosphate Compound(P-chi/nano ACP) and Tripolyphosphate(TPP). Methods Thirty-two extracted human molars were cut into pieces that in same thickness, same size and same shape. The pieces were completely demineralized. Two groups were separated by different treating measures.P-chi/nano ACP+TPP group consist fifteen samples were treated by sodium tripolyphosphate and then put them on a phosphorylated chitosan/amorphous calcium phosphate treated in vitro bionic model. The P-chi/nano ACP group contains fifteen samples witch use almost the same treatment with the P-chi/nano ACP+TPP group but not treated by sodium tripolyphosphate. All the samples were distinguished into experimental side and control side by whether touch the phosphorylated chitosan/amorphous calcium phosphate treated side, nail polish were used to cover the control side to prevent the unnecessary touch with the phosphorylated chitosan/amorphous calcium phosphate treated in vitro bionic model. Then all samples were set on the in vitro model for 1 week. Micro-computed tomography(μCT)were used to assess the change of the density, transmission electron microscopy(TEM)and Field Emission Scanning Electron Microscope(FE-SEM) were used to assess the the micro change of the remineralization. Quantitative analysis of X-ray energy spectrometer were used to assess the amount and the ratio between phosphorus and calcium. Results Micro-computed tomography(μCT) detection revealed that the mineral density of the experimental sides(125.42±12.16 and119.39±8.64)were higher than that of the control sides(96.96±10.56 å'Œ105.27±9.42)(P<0.01)in both groups. TEM figures showed that hierarchical intrafibrillar remineralization was realized in the samples in P-chi/nano ACP+TPP group, while trace amounts of hierarchical remineralization was detected in P-chi/nano ACP group. Field Emission Scanning Electron Microscope(FE-SEM)shows the dentinal tubule in P-chi/nano ACP+TPP group are more complete and satiation compare with the ACP+TPP group. Quantitative analysis of X-ray energy spectrometer shows the suface part of the P-chi/nano ACP+TPP group have a higher phosphorus-calcium ratio and the ratio are more close to the natural normal dentin.Conclusions Fully demineralized dentin appears to have the potential to be remineralized with the application of P-chi/nano ACP. But P-chi/nano ACP combined with TPP provide a better option in micro dentin biomimetic remineralization. This study shows a promising model of in vitro biomimetic remineralization to make the experiment more close to the deep dentin caries and make P-chi/nano ACP combined with TPP more close to the clinical application.