The Effect Of Titanium Surface Characteristics On The Biological Sealing

Percutaneous device is an object foreign to the body placed through the skin such that a permanent defect is created, which is very important in the field of biomaterials science and engineering. Because of the needs in clinics, they have to remain in situ for a relative long time, such as percutaneous pipe for the nutrient materials and drugs exchange, skin windows for the observation and collection of the internal body information, and the intermediate prosthesis for the implantable limb et al. But till now, there are no very satisfied materials which can be used as percutaneous device in clinics, and the most difficult thing is the achievement of biological sealing. The failure of biological sealing will result in the bacterial infection and skin downgrowth, and finally losing. Since 1950, various materials, such as silicone rubber, polyester, polypropylene, tantalum, carbon, hydroxyapatite and bioinert titanium have been used as materials for percutaneous devices. However, these materials have many serious problems, such as: poor biocompatibility or poor mechanical property, which result in gaps between the implants and skin tissue or the broken of implants. In order to achieve the percutaneous sealing, it is very necessary to make the surface of the implants attach to the different tissues tightly. In this study, the relationship among the surface characteristics of the materials, the properties of the interface of tissue/materials with the formation and maintenance of the biological sealing, and the biologicalreactions to Ti with different surface characteristics as well, ?have been systematically studied.It has to satisfy the following both of the conditions to achieve percutaneous sealing at least: the first is the formation of tight attachment between the materials and skin, and the second is the excellent biocompatibility between the materials and the subcutaneous tissues in order to attain the firmly fixation.Firstly, in this paper, the bioactive anodic-oxidized Ti with uniform micorpores was used to be the percutaneous part. The suface was composed of lots of rutile, and the other was anatase. When the anodic oxidized Ti was immersed in SBF, a layer of bone-like apatite could precipitate on the surface. And when the epithelium cells were cultured on this kind of surface, the pseudopod of the cells were interlocked in the microrough surface, which showed that the epithelium cells was very biocompatible with the anodic oxidized surface. The adherence of the cells would improve the ability not to be sheded from the surface and firmly settlement.Secondly, in order to improve the biocompatibility and increase the attachment strength between the materials and subcutaneous tissues, anodic oxidized Ti and porous Ti with a layer of pre-precipitated CaP were introduced. When the anodic oxidized Ti was implanted into the rabbits subcutaneously, a layer of calcium phosphate deposited on the surface very quickly, and the attachment strength of the soft tissue/materials increased with the time. The alignment of the fibrous tissue appeared with some angle to the interface, rather than parallel to it. The results indicated that the newly formed calcium phosphate layer could induce the surrounding fibrous tissues or collagen ingrowth into its structure, thus to improve the attachment strength of the soft tissue to the materials. The more fibrous tissue was perpendicular to the interface, the more the attachment of tissues to implants was firmly. Anodic oxidized Ti was very effective to anchor the subcutaneous tissues, since the calcium phosphate played a very important role in the attachment of soft tissue to the materials. Meanwhile, porous Ti has beingstudied for a long time, because it combined the three-dimension scaffold with its excellent mechanical properties and biocompatibility. The interconnected pores and suitable surface micropores provided the ingrowth of tissues with frames. The pre-precipitated bone-like apatite will endow the porous Ti with biological activity. After implanted subcutaneously, the fibr...