Study On The Effect Of DS-QE On The Durability Of Resin-dentin Bonds

Objective:The exposure of the collagen fibers at the bottom of the hybrid layer and the degradation of the exposed collagen fibers are the important causes for the poor durability of the resin-dentin bond.In order to prevent the exposure and degradation of collagen fibers at the bottom of hybrid layer,it is necessary to construct a bionic remineralization system to protect the exposed collagen fibers at the bottom of hybrid layer and induce the mineralization of collagen fibers inside and outside.The purpose of this study was to explore the specific adsorption capacity of the peptide DSESSEEDR-QESQSEQDS(DS-QE)on collagen fibers and dentin,and its biomimetic remineralization effect on dentin collagen fibers,so as to provide new ideas and methods for improving the bond durability of resin-dentin.Methods:The peptide DS-QE was synthesized by solid-phase synthesis and characterized by high-performance liquid chromatography(HPLC),high-resolution electrospray ionization mass spectrometry(ESI-MS),hydrogen nuclear magnetic resonance(~1HNMR)and fourier transform infrared spectroscopy(FTIR).The cytotoxicity of DS-QE was evaluated by the Cell Counting Kit-8(CCK-8)assay.The immediate microtensile bonding strength(MTBS)of the bonding interface was used to evaluate whether DS-QE had an adverse effect on resin-dentin bonding.The hydroxyproline(HYP)content determination experiment,circular dichroism(CD)and fluorescein isothiocyanate staining experiment were conducted to detect the protective effect of DS-QE on collagen fibers and its adsorption capacity on demineralized dentin.Type I collagen fibers and demineralized dentin adsorbed by DS-QE were soaked in artificial saliva.At different time points,the morphology of type I collagen fibers were observed and analyzed by transmission electron microscopy(TEM)and selected area electron diffraction spectrum(SAED),and the morphology of demineralized dentin was observed and analyzed by scanning electron microscopy(SEM),energy dispersion spectroscopy(EDS),x-ray diffraction(XRD)and fourier transform infrared spectroscopy(FTIR),and the ability of DS-QE to induce the external mineralization of collagen fibers at the bottom of hybrid layer was evaluated.Results:The results of HPLC,ESI-MS,~1HNMR and FTIR showed that DS-QE was successfully synthesized.The CCK-8 assay showed that DS-QE had low cytotoxicity on human dental pulp cells(HDPCs)and fibroblasts(L929).The micro-tensile test showed that DS-QE had no adverse effect on resin-dentin bonding.The HYP,CD,and FITC results indicated that DS-QE could protect collagen fibers and had a good adsorption effect on demineralized dentin.The TEM and SAED results showed that regenerated mineral crystals were deposited in collagen fibers,which realized the mineralization in collagen fibers.The EDS,XRD and FTIR results indicated that the regenerated mineral composition structure and calcium-phosphate ratio were similar to those of hydroxyapatite.The SEM results indicated that a large number of regenerated mineral crystals were deposited in the dentinal tubules in the DS-QE group,which realized the external mineralization of collagen fibers.Conclusions:In this study,a biomimetic remineralization system based on DS-QE was successfully constructed.DS-QE can stabilize the collagen structure,firmly adsorb on the surface of demineralized dentin,and induce the internal and external mineralization of collagen fibers,effectively reduce the exposure and degradation damage of collagen fibers at the bottom of the hybrid layer,and has significant significance in improving the durability of resin-dentin bonding.