The Research Of Amino Acid Induced Enamel-liked Hydroxyapatite Biomimetic Synthesis On Tooth Surface In Vitro

Enamel is a highly mineralized extracellular matrix and hardest tissue in thehuman body. The special features of enamel rely on its composite nature of organicmaterials and95–97%hydroxyapatite (Ca10(PO4)6(OH)2, HA) by weight. Thecomposition of human teeth is not pure hydroxyapatite, but more bicarbonatebiological apatite crystals. Some elements are contained inside to make the teeth moresensitive, such as carbonate. The initially formed armamentarium of enamel is crystalcarbon apatite, and the contents of the carbonate at the core of the enamel are muchhigher than the outer peripheral zone. The ordered structure plays an important role indetermining the remarkable mechanical strength and the protection of teeth. As theoutermost layer, enamel is susceptible to caries due to the products of bacteriametabolism or acidic foods. It is critically serious that the enamel damage ispermanent. Reconstructing enamel-like structures on teeth has been an importanttopic of study in the material sciences and dentistry.To restore the eroded enamel, a preferred and effective treatment is to synthesizethe enamel-like materials comprised of HA nanocrystals. Biomineralization is aprocess by which minerals are produced under the control of organic matrices thatregulate the crystal nucleation, morphology, and crystal structure of the mineral.Therefore, the study has important clinical significance, which the biomimeticself-healing repair of tooth structure use the method of biomineralization induced bythe organic macromolecules as template after dental tissue injuried. It must be highlighted that most non-collagenous proteins in the matrix ofbiological hard tissue-such as bone, dentin, and enamel are acidic proteins. Thepresent study sought to investigate apatite crystal growth in the presence/absence ofamino acids. For a better knowledge of the role of mineralization associated protein,Asp, glutamate and Ser were used as water-soluble additives, which were known tohave strong interactions with Ca2+, and these amino acids are all highly repetitivesequence elements in these mineralization associated proteins.Based on the principles of biomimetic synthesis, carbonized hydroxyapatitecrystals were prepared by vapor diffusion method in which L-Serine and acidic aminoacids acted as an organic substrate, and bio-inspired enamel repair viaL-Ser/Asp/Glu-directed assembly of hydroxyapatite nanoparticles at the same time.The products were characterized by means of field emission scanning electronmicroscope (FESEM), EDAX, X-ray powder diffraction (XRD) and FourierTransform Infrared Spectrometer (FTIR), and the effect of different concentrations ofserine on intermediates of calcium carbonate and final products of calciumhydroxyapatite limestone powder and dental film was studied. The results showed thatdifferent concentrations of serine significantly affected the morphology of the freecrystalline powder in solution, and the conversion of calcium carbonate tohydroxyapatite with morphological hereditary characteristic, as well as play animportant role for the continuation of the crystal arrangement on the surface ofenamel film.