【作者】 公柏娟；

【导师】 孙宏晨； 孙新华；

【作者基本信息】 吉林大学 ， 口腔临床医学， 2007， 博士

【摘要】 本研究通过动物实验,结果表明,微种植体位于骨皮质厚的部位,其支抗稳定性明显高于其他部位的微种植体,微种植体的稳定与种植体和骨的结合率有关。为提高微种植体与骨结合率,开发新微种植体材料,本研究采用粉末冶金法制备Ti-In系合金,并检测其组织结构、机械性能,进行腐蚀实验。通过毒性实验、溶血实验、MTT实验等评价其生物安全性。结果表明,采用粉末冶金方法并加入适量In元素制备的钛合金,其弹性模量与骨接近,机械强度较好,提高了抗腐蚀性。加入少量硬脂酸锌制备的Ti-In合金空隙更均匀。该类合金具有低弹性模量、中高强度、耐腐蚀和安全无毒的特点,适合作为口腔种植体的材料。更多还原

【Abstract】 Objective: The purpose of this study was to quantify the is tomorphometric properties of the bone-implant interface to analyze the use of small titanium crews as an orthodontic anchorage and to establish an adequate healing period. Ti alloys are used in orthopaedic applications owing to their appropriate mechanical properties and their excellent corrosion resistance. The release of titanium and the other alloying elements into the surrounding tissue has been reported due either to passive corrosion or accelerating processes such as wear.In study,the general toxicity tests including acutetoxicitytest, haemolysistest, MTT assay of Ti-In alloys were carried out.Materials and methods:In study miniscrews of 1.2 mm diameter and 8 mm length were used, A 1.2 mm pilot hole was drilled through the soft tissue and into the cortical bone. After insertion of the implants, a two mimiscrew was attached to serve as a hook for the application of the orthodontic force. Analysis of variance models were used to examine the effects of healing and application of force on the histomorphometric indices of the maxilla and mandible. The model comparison, corrected for a random dog effect, was used to correlate all measurements from the same dog. In addition, the method analyzed fixed effects for healing period, location (cup or molar), and all interactions. The starting elemental powders Ti, In and ZN had an average particle size. Subsequently, the samples were vacuum encapsulated in flexible rubber molds and cold isostatically pressed with a pressure of 700MPa for 5 s. The samples of blended powder with a pressure into a square 13mm with an edge length of 5mm.The microstructure was revealed by swabbing the, samples with a Kroll solution (3 ml HF, 6 ml HNO3, 100 ml H2O) for 10–20 s, shows the corresponding SEM micrographs.Green ,bodies were sintered in a niobium crucible under high vacuum conditions. The density of the sintered Ti–In samples was characterized by measuring the samples dimensions and weight. The activated samples were exposed to SBF with ionic concentrations nearly equal to human blood plasma.Corrosion potential and corrosion rate were measured using a Potentiostate machine. The corrosion test was performed in a solution (SBF) without dissolved oxygen at 37°C. Saturated Caromel Electrode was used for the standard electrode and platinum was used for the counter electrode. The experimental apparatus for the corrosion test was connected and controlled with an IBM computer. The corrosion rate was calculated using the Tafel extrapolation method.Acute toxicity test Thirthy white male mice were use as experimental animal. The weight of each mouse was about 20g. All of these animal were divided into three groups at random and there were 10 mice in each group.MTT (3-dimethylthiazol-2,5-diphenyltetrazolium bromide) colorimetric assay Osteoblast-like cells (MG-63) were plated at a density of 2.5×104 cells/100μl/well in 96-well plates. After overnight incubation, bisphosphonates were added at concentrations ranging from [10?4 ] to [10?12 ] and cultures continued for 24, 48, and 72 h. In continuation of the protocol, the medium was aspirated and 50μl of MTT was added to each well and cultures continued for 2 h at 37°C. This time period permitted the cellular conversion of MTT to insoluble formazan. The cells were thenlysed, and the formazan solubilized with acidic propanol at room temperature for 24 h. Two hundred microliters of supernatant were transferred to microplate wells and colorimetric changes were quantified in a microplate reader at the wavelength of 540 nm. The MTT assay was performed in triplicate and repeated in six cultures.Results: Miniscrews were achieved by67% of the 24 implants placed in 3 dogs and 100% of the elastomeric chain-loaded implants. All of the loaded implants remained integrated. Mandibular implants had higher bone-implant contact than maxillary implants. Within each arch, the significant histomorphometric indices noted for the "two-week unloaded" healing group were: increased labeling incidence, higher woven-to-lamellar-bone ratio, and increased osseous contact. Analysis of these data indicates that small titanium screws were able to function as rigid osseous anchorage against orthodontic load for 2 months with a minimal (under2 weeks) healing period. The mechanical properties of Ti–In alloy with the commercially used Ti alloys for implants were shown in. The yield strength (YS) and ultimate tensile strength (UTS) of the Ti–In alloy are above 1380 MPa. The Ti–In alloy has good mechanical properties compare to CP Ti. in The modulus of elasticity are 25 MPa, a loss of bone and weakness of bone fracture were increased in the interface between bone and implant. The modulus of elasticity of bone in a human body is 20 GPa. And that of CP Ti and the Ti–In alloy are about1380MPa, respectively. The new designed Ti–In alloy in this study approach a modulus of elasticity of bone compare to CP Ti.Conclusion: There are In this study, newly designed biomedical Ti–In alloy shows excellent several characteristics. At the first, this alloy material composed with non-toxic elements is adequate for biocompatibility. The next thing is better corrosion resistivity with In contents compared to conventional biomaterials such as CP Ti. The last thing is its superior mechanical properties such as UTS, YS and modulus of elasticity.更多还原