| The biological material is a multidisciplinary approach research field and is also a key technology among the national economic and social development,and has already become a hot topic of research at home and abroad. As a typical representative of the biological materials, dental implant materials have become the clinical and scientific research hotspot at present. Implant surface treatment methods plays a vital role in improving the success rate of implanting. At present, there are so many methods of the implant surface treatment among kinds of products in the market, different processing methods have their respective advantages and disadvantages, but their common goal is to form a rough surface, making it a better bone combination ability and biological activity.The implant surface feature is one of the main factors which can directly affect the rate of bone integration process, and plays a significance clinical value in improving the success rate of dental implanting.Scholars have been trying to find the best way of the implant surface treatment for many years in order to achieving the best implant-bone interface.In the early time, the mechanical surface treatment of titanium implants has many shortcomings, such as:hard to form the chemical combination with the tissue in the early time, slow to achieve the bone combination, long healing period and so on. The hotspot of dental implant surface treatment method is to use different process to change the physical and chemical properties of the implant surface, promoting the early implant-bone combination, so as to ensuring the long-term function of implants.Pure titanium implant surface composite sandblasting acid corrosion of micro-arc oxidation is to realizing the best biological effect of the coating surface by changing the process condition and the design, adjusting the structure of the oxide film, element composition and the biological characteristics. The technology also has the characteristics of simple process, ecologically,and is worth for further demonstration and usage in clinical.This paper intends to conduct the research in the following respects: Materials and methods:PART I:The preparation and characterization of MAO combined with sand-blasting acid-etching surface treatment pure Ti implant.Sand-blasting:The samples used a certain granularity Al2O3grinding grain and jet to the prepared TA2pure Ti specimen surface with a high speed. The main process parameters that can affect the sand-blasting pure Ti substrate surface property:Particle size is200microns, gas pressure is0.9bar, gas flow velocity of210m/min, jet angle is70°, nozzle distance of15cm.Acid-etching:With a mixture of HF and HCI hydrochloride acid solution to corrode TA2pure Ti substrate surface, the main process parameters that can affect the acid-etchingpure Ti substrate surface property:Hydrofluoric acid concentration is40%, hydrochloric acid concentration was38%, the mixture of HCl and HF ratio of6:4, corrosion solution volume of40ml, pickling temperature is25℃, acid etching time was100min.MAO:MAO is a method that changing the working area by introducing the ordinary Faraday area of anodic oxidation process into the high pressure discharge area and creating oxide ceramic membrane in aluminum,magnesium and titanium metal surface with the use of the high working voltage.The electrode voltage is500V, electrode frequency is550HZ, oxidation temperature is less than40℃, oxidation time is18min,(CH3COO)2Ca·H2O concentration is30mmol/L, C3H7Na2O6P·5H2O is10mmol/L, NaOH is8mmo/L.Due to the formation of MAO is a complex process, influenced by various factors and regulations,this early experiments have already optimized a set of process parameters, combined sand-blasting and acid-etching on the basis of this process parameters.Ⅱ. Samples were divided into4groups according to the surface treatment: group A:MAO treatment; group B:MAO sand-blasting treatment; group C:MAO acid-etching treatment; group D:MAO sand-blasting and acid-etching treatment, characterized and analized each group separately from the surface morphology, surface energy spectrum analysis, membrane thickness, surface roughness, film bonding strength and so on.PART II The effects of MAO sand-blasting acid-etching corrosion of pureTi surface treatment on osteoblast biology behaviorMachining the TA2pure Ti cylindrical specimens with CNC wire-cutting machine.Processing of height3.0mm, base diameter of8.0mm. Processing of height3.0mm, base diameter of8.0mm. Burnishing the sample step by step with200-1000#metallographic sand paper, and then placing it into the60～80℃oxide sodium solution to deal with the oil after polishing, the soak time is5min. Firstly we cleaning the sample with the deionized water and soaking it into hydrochloric acid and nitric acid solution for10-15s, adequately removed the old oxidation layer, and then dry it using deionized water at the room temperature. Samples were divided into4groups according to the surface treatment:group A:MAO treatment; group B:MAO sand-blasting treatment; group C:MAO acid-etching treatment; group D:MAO sand-blasting and acid-etching treatment.The four groups cultivated with ST2cell lined respectively, and then analysised the cell proliferation, adhesion, differentiation through SEM observation, cell toxicity detection, ALP activity, osteocalcin content detection,comparative analysis the biological compatibility of four groups of different surface treatment pure Ti implant.Part Ⅲ The rabbit femoral implant experiment of MAO sand-blasting acid-etching pureTiMachining the TA2pure Ti cylindrical specimens with CNC wire-cutting machine.Processing of height3.0mm, base diameter of8.0mm. Burnishing the sample step by with200～1000#metallographic sand paper, Burnishing the sample step by step with200～1000#metallographic sand paper, and then placing it in the60～80℃oxide sodium solution to deal with the oilthe samples after polishing, the soak time is5min.Firstly we cleaning the sample with the deionized water and soaking it into hydrochloric acid and nitric acid solution for1015s, adequately removed the old oxidation layer, and then dry it using deionized water at the room temperature.Samples were divided into4groups according to the surface treatment: group A:MAO treatment; group B:MAO sand-blasting treatment; group C:MAO acid-etching treatment; group D:MAO sand-blasting and acid-etching treatment.We implanted the pure Ti specimen into the rabbit femoral respectively, removed the specimens at the time of healing4w and8w.Then calculated the bone mass and quality around the implant and evaluated implant-bone bonding strength after MAO sand-blasting acid-etching treatment by push-out test, bone and implant contact rate, researched bone features from the organizations form metrology.Results:Part Ⅰ:The Surface Roughness:pure Ti substrate surface roughness Ra is0.2μm. And after the processing surface of MAO process, the Ra into0.8μm.The increase of surface roughness after MAO treatment is mainly for the appearance of the micro-arc oxide film holes.The roughness Ra of MAO sand-blasting pure Ti substrate micro-arc oxidation film is1.4μm, slightly larger than the sample MAO only. And the roughness Ra of MAOacid-etching pure Ti substrate micro-arc oxidation film is1.4μm, better than MAO sample.But it reached2.2μm after MAO treatment combined the sand-blasting and acid-etching.It shows that the MAO film roughness of sand-blasting and acid-ecthing has significantly increased, which are apparently manifested on the emergence of more uniform holes in oxide film.Membrane Layer Thickness:MAO film thickness is37.2μm;MAO sand-blasting film is28.3μm; MAO acid-ecthing film thickness can reach40.2μm; MAO sand-blasting acid-etching thickness is43.1μm,the thickest of all. It made difference of the thickness of the oxide film because of the different pretreatment.Bonding Strength:MAO film load is20.7N;MAO sand-blasting film is23.2N; MAO acid-ecthing film thickness can reach27.9N; MAO sand-blasting acid-etching thickness is31.2N. It made difference of the thickness of the oxide film because of the different pretreatment.Contact Angle:The test result is as follows:MAO contact angle is82.9°;MAO sand-blasting contact angle is76.7°; MAO acid-ecthing is69.3°; And MAO sand-blasting acid-etching is63.2°.Part II:Cytotoxicity test:According to the OD determined by MTT calculating the relative generation rate (RGR),RGR%=Dexperimental group/ODnegative control group X100%.We classificated the cytotoxicity according to the different period RGR of each group(CTS).The experiment result showed that the implant leaching solution of modified four groups have no significant difference when compared with negative control group(P>0.05).The CTS classification are level O.It is showed that the pure Ti implant of this experiment is non-toxic, and is conformed to the 《Requirements Of The Medical Equipment Biological Assement National Standard GB/T16886.1-2001》to the cytotoxicity of medical equipment.The results of cell adhesion:SEM (2500x):MAO group ST2cells are long fusiform or polygon, the pseudopodia spreaded to the porous titanium implant surface; Cells in MAO acid-etching group presented a long spindle appearence, the cyton lies in the primary hollow of acid corrosion,and the pseudopodia attached to the micro hole in planus; In MAO sand-blasting group,cells lied in the rough surface in irregular polygon shape, pseudopodia and antenna attached to the secondary micro hole. MAO sand-blasting acid-etching group:Cells showed irregular shape, the cyton embedded into the primary hollow with good extensibility.Multiple celluar processes swelled into the bone trabecular structure with strong adhesion.We can know the effects samples made to the cell proliferation function according to the cells quantity change at1,3,5, and7days which inoculation to the sample surface. Results:As time went by, OD increased in the whole four groups;At the same time, OD in the four groups MAO、MAO sand-blasting、MAO acid-etching and MAO sand-blasting acid-etching increased gradually.Except for Group B and C, there shows significant difference between groups(P<0.05).Cell differentiation results:After three days, the difference of ALP activity in Group A、B、C is not abviously(P>0.05),but it shows significant difference between groups(P<0.05) because the ALP activity in Group D increased than before.The tendency was same as before after five days and seven days. Part Ⅲ:Iconography examination:Imaging examination:X-ray examination results showed that the implantation direction was perpendicular to the surface of the femur, and the implant impaled both side of the bone wall.And there is no abnormal phenomenon such as fracture in the area.Put out test:In4weeks and8weeks,the bone-implant interface shear strengthen showed group D> group B> group C> group A, group D is the highest and otherwise group D is the lowest, both showed statistical significance than other groups(B and C)(P<0.05).Histological examination:The hard tissue biopsies found that the bone around the implant have the similar situation in group B and C, BIC were58.74±6.57%、51.09±6.39%.On the contrary, group A declined and group D increased obviously:30.13±6.14%and77.49±4.96%.Conclusion:l.The surface of MAO sand-blasting acid-etching pure Ti have the largest roughness, the highest film bond strength and the relatively best invasive than the other three groups, so we speculates that it has the highest biological activity.2.The biocompatibility of the surface of MAO sand-blasting acid-etching pure Ti is superior to the other three groups.3.The bone combineation speed and osteogenesis ability of MAO sand-blasting acid-etching pure Ti implant is better than the other three groups. |
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