The Applied Basic Research On Functionalization And Biomimetic Mineralization Of Enamel Surface

Enamel matrix proteins(EMPs) and different active groups were deposited on the enamel surface to study enamel matrix proteins and different active groups on the impact of the enamel surface's biomineralization by means of the mechanism of Control Biomineralization with protein and organic matrix,and it provided a theoretical foundation and experimental evidence for an in-depth study of the enamel remineralization in the treatment of dental caries.This research work is divided into two parts:Part 1.the impact of EMPs on enamel remineralizationThe EMPs of SD rats were extracted by Acetic Acid Process,separated and purified by SDS-PAGE electrophoresis.The technology of quartz crystal microbalance(QCM) was applied to research the adsorption behavior of EMPs,the formation and growth induction hydroxyapatite crystals on enamel surface in simulated body fluid(SBF) solutions at 37℃.The results showed that EMPs of rats were mainly amelogienin and aneloblastin. QCM image data showed that the frequency decreased with the increased concentration, but the adsorbed amount increased steeply with the increased concentration.It was also reflected in the D-f plot that adsorption at 20μg/mL exhibits a much more viscose outer-layer structure.Qualitative analysis and morphology characterization showed that the adsorbed EMPs biomimetic mineral layers on enamel surface contained hydroxyl, phosphate and carbonate groups.The nano-spheres on enamel surface grew with the mineralization time,and crystal showed a good degree of crystallinity and contained a small amount of Na⁺ and CO₃^2-substituted hydroxyapatite crystals.Part 2.the impact of enamel surface functionalization on enamel remineralization Various active groups HS(CH₂)_nX(-SO₃H,-PO₄H₂,-COOH,-OH,-CH₃) were deposited on enamel surface by hydrolysis method,which is based on the bonding effects of sulfhydryl and hydroxyl groups,to form self-assembled monolayers(SAMs).Then they were soaked in SBF at 37℃for biomimetic mineralization.The results indicated that thealkanethiols were firmly deposited on the enamel surface.The treated enamel surface showed a good hydrophilic except the one treated by methyl group.Morphology characterization showed that the surface functional groups dependence on apatite formation determined were as follows:The growth rates decrease in the order -PO₄H₂＞-SO₃H＞-COOH＞-OH＞-CH₃;based on the acidic and alkaline property of active groups on the SAMs,the porous crystals were emerged on enamel surface with -PO₄H₂,-SO₃H,-COOH active groups;due to the impact of ion species in SBF and external cause of mineralization,crystal surface appeared a number of box-shaped crystals of calcium carbonate.To sum up,the EMPs and various active groups were deposited on the enamel surface by the technology of QCM and SAMs.The results showed that either the EMPs or active groups can induce the hydroxyapatite crystal,nucleation growth and aggregation.Thus it firstly confirmed that the protein and organic matrix played a key role in the regulative process of enamel mineralization,and provided an experimental basis for the treatment of caries with the method of biological mineralization in the futher.