| Pure titanium(Ti) or titanium alloy are widely used as the main materials in dental implant in clinical application due to their attractive features such as good biocompatibility and excellent biomechanical property. This metal, however, still have several limitations including low bone-bonding ability i.e. bioactivity, relatively high modulus of elasticity and and relatively low resistant to acid corrosion, thus makes a great impact on their clinical effectiveness and the long-term results. In recent years, with the rapid development of biomaterilals and dental implant techniques, much attentions have been paid on dental implant on alterations and enhancements of surface characteristic on titanium based biomaterials, and improvement their bioactive of bone-implant interface, mimicking the structure of osseous cancellous bone and enhancement of osseintegration, or osseoincorporation, and eventually, increase the success of dental implant for patients.Tantalum(Ta), with its excellent mechanical properties such as excellent biocompatibility,extreme resistant to acid corrosion and ideal mechanical properties and stable chemical property, is the most widely used implant material. Tantalum is highly unreactive in almost all acids, and is a member of the refractory metals group which are widely used as components in alloys in electronic, chemical engineering, atomic energy and aviation industry fields. The development of porous tantalum metal has allowed for stronger, more biocompatible orthopedic, artificial joint, spine cord, bone defect and craniofacial defect repair material, some products have already success in clinical applications.This porous tantalum material has high frictional characteristics that potentially facilitate initial implant stability agingst adjance bone has been used . On the other hand, Ta is a rare elemant, the main source of material for recycling, Ta is waster from capacitors. Thorefore, it is interesting to combine the advantages of this metal and develop a Ta enhanced titanium dental implant.Ta coating of dental Ti is thus a complementary advantage strategy not only for the biological aspects but also for cost reducing in clinical appliation of dental implant.Up to date, litter is known about Ta coating Ti dental implant. This study is designed to modify the surface of Ti dental implant with Ta coating by plasma spraying technique. The parameter and technical process of plasma spraying in produing Ti-Ta dental implant was determined, and the biocompatibility of this newly desiged implant was explored, and eventully, the osseointegration with plasma spraying technique was also observed though pathological analysis. The main results are showed as followings:Part ?. Preparation and characterization of tantalum coating/titanium materialsThis study is designed to determine the paramster and process of Ta coating by plasma spraying technique and three groups were divided including titanium coating,tantalum coating and sandblasting titanium scanning. After materials preparation, the surface properties of these material were performed by electron microscope (SEM)observation, scanning spectrum (EDX), then coating thickness and chemical composition and vickers hardness, the adhesion strength and contact angle Measurement were prformed.Results: Under the Scanning electron microscope, we see rough surface, uneven pore size, and under the 500 times SEM, the feather flake protrusions and porous structure,uneven crack size; the titanium material surface coating specimen groups SEM, the 300 times more dense, melting shaped, irregular surface circular protrusions lava samples, and 500 times SEM bumps range size and shape, and have different length fracture porosity;Under 300 times by the SEM,Tantalum surface coating specimen groups are dense fused,more close and uniform texture, 500 times the SEM, the surface layers are flake or globular swelling size at the surface of the micro hole or crack. Loss, falling off, and the fracture phenomenon of the coated specimen are not be seen. The thickness of the coating are between 80-100um, the purity of tantalum coating is 98.86%,and the purity of titanium coating is 95.83%; Scratch test of average terminal load is 40.75N/mPa, the average measurement results of micro vickers hardness tester is 335, the average of tensile strength reaches to 989.5mPa; tantalum coating group enjoys the best hydrophilic, and sandblasting titanium group have the best hydrophobic. Conclusion: The morphological and ultra-struction of these three group were quite different as seen in SEM, and no difference were found in these three group on the thickness of coating. The surface binding strength in Ta coating group was significant higher than that of in Ti coating group, while the hydrophilicity and contact angle in Ta coating group were lower those in Ti coating group. These results may provide important basis for further study.Part ?. Study on the compatibility of dental periodontal ligament stem cells(PDLSCs)on tantalum-coating modified material in vitroTo evaluate the ability of cell adhesion, proliferation and toxic effect on the surface of the titanium coating, tantalum coating and sandblasting titanium, human periodontal ligament stem cells(PDLSCs) were primary cultured, isolated and identifiedby flow cytometry instrument (FCM) for CD29?CD34?CD44?CD45?CD73?CD90?CD105?CD146 and CD166 detection, and CCK-8 kit detection, respectively, then these PDLSCs were cultured on the Ta-coating, Ti-coating and sand blasting of titanium material surface,next the SEM was performed and cells coating area ratio in the material surface were analysis by software. Results: We have successful cultured and isolated hPDLSCs, By flow cytometry instrument (FCM), these cells were found to positively express markers of MSC on STRO-1,CD29, CD44?CD73,CD90,CD105,CD146, and negatively expressd CD34, CD45. After co-cultured on Ta-coating, Ti-coating and sand blasting of titanium material surface for 12d, hPDLSCs in each group under SEM observation proliferated rapidly with the time duration. The results of semi-quatitative analysis by ImageJ showed that cell growth in Ta-coating group was significantly faster than that in other two groups,that means, Ta coating>Ti coating>sandblasting Ti. By comparion, cell number in Ta coating was obviousy much than that of in sandblasting Ti. The same effects were found in CCK-8 detection. Cells coating area ratio in the material surface of Ti-coating group significantly higer than other two groups (p<0.05), Ta-coating group > sandblasting Ti (p <0.01). Conclusion: HPDLSCs in each group were found to adhere and grow in all cells-material co-cultur groups and no poisonous was presented. The plasma spraying method for the material surface modification can promoted the bioactivity of the titanium based materials. In contrast, plasma spraying tantalum coating surface modification has the best cell compatibility when compared with titanium coating modification and sandblasting processing titanium.Part ?. Study on tissue biocompatible and ossteointegration of Tantalum coating dental implant in dogsAnimal model of tooth loss was established based on the molar tooth extracted operation in beagle dogs.The wound sites were sutured for closure and extraction site were allowed to heal for 3month, the model was determined by the clinical examine and radiological images. Then the plasma spraying technique was used to produce titanium coating, tantalum coating and titanium implant according to the parameter and process of above results. Here, we use dental implant of ITI as the positive control. Subsequently, the new dental implants were implanted into the alveolar bone of beagle dogs according to the divided groups. 1m?3m?6m postoperative, the implants were performed imaging and radiographic assessments including X-rays, CBCT and Micro-CT. Then animals were killed via intravenous injection of pentobarbital overdose. Each specimen was fixed for undecalcified section for histomorphology. Results: Results of radiographic assessments and histomorphology showed that the density of bone-impant interface of the specimen in 3m and 6m group were higher than those in 1m group. In contrast, The implant-bone tissue slice analysis shows that the early implanted into bone around implant with implant are all increased with the extension of time, the postoperative lm, 3m and 6m each implant surrounding bone volume fraction horizontal contrast has no obvious difference (P > 0.05), the same specimen groups of vertical between lm and 3m, 6m, there are differences between 1m and 3m, 6m groups (P < 0.05), relative low bone density was found in appearance of the periimplant in all groups in 1m. With the prolonging time, the density gradulally increased. Evidences were also found in the histomorphology. By comparison, ossteointegration in Ta coating group was significangly better than Ta-coating group and sandblasting Ti group at any time points. No different was found between Ta-coating group and ITI control group(P > 0.05). conclusion: Dental implants in the four groups were all stable and retained and have good tissue compatibility.The early stability were favorable, and there are no statistical difference between two groups (P >0.05); But The histology and radiological imaging examination showed that the tantalum coating and ITI implants exhibited an better ossteointegration effects compared with other group. And the implant-bone interface both in radiology and histology and long-term effect are still needs further study and assessment.Summary: Tantalum(Ta), with its excellent biocompatibility and mechanical properties and highly corrosion resistant, is used widely as orthopedic implant, while the application of dental implant remains limited until now. Hence, development a Ta-enhanced dental implants combined conventional titanium implant design and instrumentation has attacted much attention in both the field of biomaterial field and dental impant. This study is designed as Ta coating on the surface of Ti impant through plasma spraying technique, and then the biocompatible of hDPSCs and tissue were explored both in vitro and in vivo. The results showed that hDPSCs performance was significant improved in Ta coating group than those in Ti coating group and sandblasting Ti group which is used as the control group.Furthermore, the histological and radiographic results demonstrated that Ta coating group promte bone formation and osseointegration at bone-implant interface when compared with clinical used ITI impant and sandblasting Ti imlant.Further research is still needed to focus on Ti implant surface techniques of Ta and biological performance of biomaterials and modulate the neighboring cell/tissue reactions. |
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