The Study On The Surface Modification Of Titanium And The Effects On Its Bioactivity

Titanium has become the main material of dental implant,many technologies of surface modification have been proposed in order to obtain ideal tissue interface of implant.However,the surface modification of the abutment and collar of dental implant which requireing smoothing treatment is always the blind spot of dental material research,so finding a simple method to acquire optimal tissue interface of dental implant is the key point of current development of dental material and clinical dental implant.This study contains two parts,chemical modification and biomimetic extracellular matrix(ECM) treatment of titanium surface, and to evaluate their bioactivity.The first part:chemical modification of titanium surface and its effect on cytobiological behaviorThis study is to treat smooth titanium sheet with the mixture of hydrogen peroxide and chlorhydric acid,and followed with the heat treatment of 400℃,titania gel layer on the surface was produced. Then the titanium sheet surface was examined by scanning electron microscopy(SEM) and atomic force microscope(AFM).Osteoblast and fibroblast cells were seeded on the titanium sheet surface,observing the changes of cytoskeleton and cell morphology,and calculating the cell shape factor to evaluate the effect of surface modification on cell spreading.Meanwhile,the effect of modified surface on cell attachment and cell proliferation was determined by MTT method.Results showed that there was not much change on surface topography after modification,just the colour of titanium sheet surface changed from argentite to aureate.The 30,000 magnification of SEM figure illustrated that compared with untreated titanium,there existed an integrite and dense film in treated titanium,and the AFM examination showed the film was composed of multiple uniform microspike,which was in nanometer dimension,while the surface of smooth sheet titanium was even.The result of cell experimemt indicated the titania gel layer produced from surface modification could enhance the cell initial attachment and spreading on titanium material.So we thought it was a promising modification method of implant surface, for its simple manipulation,impact binding between gel layer and basement,it has some clinical application perspective.The second part:Biomimetic extracellular matrix modification of titanium surface based on static electricity layer by layer assembling technologyCompared with chemical modification of surface,the result of biomimetric modification through biochemical method might be more direct and effective.To find a simple method,which can be immobilized to implant surface that has complicated topography and keep the activity of biomolecules,is the key to apply the theory of biochemical modification of implant surface into clinical practice.In this study, collagen and hyaluronic acid,which are two main ingredients of ECM and possess negative charge and positive charge,were assembled on titanium surface and then the biomimetic modification was achieved.We first examined the assembling behavior on treated quartz surface by means of ultraviolet absorption spectrometry and contact angle experiment,meanwhile we used AFM to assess the modified titanium surface and analysed the element on surface by photoelectron spectrum analysis.Then we evaluated its bioactivity by measuring the effects of modified surface on fibroblast attachment and proliferation.The results showed collagen and hyaluronic acid were alternatively assembled on the charged surface.The AFM figure and the nitrogen peak shown in photoelectron spectrum analysis figure after modification both proved that collagen and hyaluronic acid could be immobilized on titanium surface for biomimetic ECM modification by static electricity assembling method.On the other hand,the results of cell experiment indicate that it has good bioactivity and promote cell attachment and proliferation.Any big biomolecules with opposite charges can be assembled into film in theory,so to immobilize biomimetic ECM on dental implant surface and any functional biomolecules for cells in interface between hard tissue and soft tissue.And it is a direction to enhance implant survival rate by optimizing the modification method of implant surface. This study is innovative and unique,having some application perspective,and an invention patent" A method of biomimetic ECM modification for dental implant surface" has been applied.