Using Amorphous Calcium Phosphate Repair Demineralization Of Dentin

Bone and teeth are both biomineral hard tissues playing functions as supporting the fresh-body and masticating food, respectively. For a long time, Chemical scientists have been launching efforts in synthesizing composite materials with mechanical properties and biological functions close to that of natural bone and dentin to repair or substitute hard tissues in human body. Nevertheless, it has still been an unsolved problem due to the structural complexity of bone and teeth as well as the limited understanding on the process of biomineral formation in organism. Very recently, discovery of ACP in the formation of bone and teeth opened a window for overcome of the issue.In the first chapter, we have a brief review on three subjects:biomineralization, calcium phosphate mineral in organism, structure of dentin and the process of dentin formation. At the end of the chapter, the research contents of the dissertation are introduced.In chapter Ⅱ, we investigate the stabilize effect of PAA on ACP and the diameter control of PAA on ACP particles. The exact time that PAA can stabilize ACP is examined by collecting FT-IR spectra of solids extracted in the precipitate solution. We calculate the ratio between A1(area enclosed by the spectrum and the straight line through two maxima at600and560cm-1) and A2(area enclosed by the spectrum and baseline in the range of450-750cm-1) to define the crystallization degree during calcium phosphate evolutions in the present study. Diameters of the ACP particles in the solutions are tested with DLS (Dynamic Light Scattering) and SEM (Scanning electron microscopy) and TEM (Transmitting electron microscopy). These studies show that the higher concentration of PAA is, the longer calcium phosphate can stay in amorphous phase, and the smaller ACP particle’s diameter would be.In chapter Ⅲ, partially demineralized dentins are remineralized in mineralization solutions with different concentrations of PAA basing on results in the last chapter. SEM、TEM and Nano Indentation are used to examine the remineralized dentin slides. Different results of remineralization could be obtained when the concentrations of PAA were changed, and only in the presence of proper concentration of PAA, the structure of remineralized dentin zone is restored close to that of natural dentin.Chapter IV, summary...