Bone titanium

Kydd, W.L. and Daly, C.H. (1976) Bone-Titanium Implant Response to Mechanical Stress. J. Prosthet. Dent., 35, 567-571. 

Takeshita, F., Ayukawa, Y, lyama, S., Murai, K., and Suetsugu, T. (1997). Long-term evaluation of bone-titanium interface in rat tibiae using light microscopy, transmission electron microscopy, and image processing. /. Biomed. Mater. Res. 37,235-242. 

Davies, RE., Lowenberg, B., and Shiga, A. 1990. The bone-titanium interface in vitro.. Biomed. Mater. 

The materials used in a total joint replacement ate designed to enable the joint to function normally. The artificial components ate generally composed of a metal piece that fits closely into bone tissue. The metals ate varied and include stainless steel or alloys of cobalt, chrome, and titanium. The plastic material used in implants is a polyethylene that is extremely durable and wear-resistant. Also, a bone cement, a methacrylate, is often used to anchor the artificial joint materials into the bone. Cementiess joint replacements have mote tecentiy been developed. In these replacements, the prosthesis and the bone ate made to fit together without the need for bone cement. The implants ate press-fit into the bone. 

Hydroxyapaite, the mineral constituent of bone, is appHed to the surfaces of many dental implants for the purpose of increasing initial bone growth. Some iavestigators beHeve that an added benefit is that the hydroxyapatite shields the bone from the metal. However, titanium and its aHoy, Ti-6A1-4V, are biocompatible and have anchored successfuHy as dental implants without the hydroxyapatite coating. 

Surface preparation of the dental implant prior to implantation wiH have an effect on corrosion behavior, initial metal ion release, and interface tissue response (316). The titanium and titanium aHoy dental implants in present use have many forms to assist bone ingrowth attachment including cylinders with holes, screw threaded surfaces, porous surfaces, and other types of roughened surfaces. Methods used to produce porous surfaces iaclude arc plasma... 

A rapidly growing use in the medical field is for surgical implants as either bone plates and screws, joint replacements, or for the repair of cranial injuries. Here, titanium and its alloys have the advantages of complete compatibility with body fluids, low density, and low modulus. Applications also exist in dentistry. 

Q <3ZD Titanium is a metal that is often used in joint and bone replacement. 

Titanium s noncorrosive and lightweight properties make it useful in the manufacture of laboratory and medical equipment that will withstand acid and halogen salt corrosion. These same properties make it an excellent metal for surgical pins and screws in the repair of broken bones and joints. 

Carbon-epoxy plates are now used in bone surgery replacing the titanium plates that had been employed. Usually a layer of connective tissue forms around the composite plate. 

In the field of metallic powder applications, a method of plasma spray coating suitable for biomedical materials has been developed using titanium and calcium phosphate composite powder. By means of the mechanical shock process, the appropriate composite powder was prepared, and plasma sprayed on Ti substrate under a low-pressure argon atmosphere. A porous Ti coating layer was obtained in which the surface and the inside of the pores were covered thinly with hydroxyapatite. This surface coating is expected to show excellent bone ingrowth and fixation with bone (21). 

A number of crystal structures are known, viz. (OEP)TiO, (TPP)TiO, (OEPMe2)Ti (43).147 For all these complexes titanium has four nitrogen donors and a double-bone oxygen, resulting in a classical square pyramid. The information obtained from X-diffraction and EXAFS is in excellent agreement. 

As previously mentioned, the nickel—titanium alloys have been the most widely used shape memory alloys. This family of nickel—titanium alloys is known as Nitinol (Nickel Titanium Naval Ordnance Laboratory in honor of the place where this material behavior was first observed). Nitinol have been used for military, medical, safety, and robotics applications. Specific usages include hydraulic lines capable of F-14 fighter planes, medical tweezers, anchors for attaching tendons to bones, eyeglass frames, underwire brassieres, and antiscalding valves used in water faucets and shower heads (38,39). Nitinol can be used in robotics actuators and micromanipulators that simulate human muscle motion. The ability of Nitinol to exert a smooth, controlled force when activated is a mass advantage of this material family (5). 

A material is a biomaterial when it meets certain requirements it has to have the right physical and chemical properties and, in addition, be biocompatible, which means that it must not be rejected by the body. The material may not release any substances which might activate the host s immune system. As indicated earlier, the first biomaterials were metals and these still play an important part. Of all metals and alloys, titanium appears to be accepted best by tissues. Actually this is rather peculiar, as titanium is relatively rare in vegetable and animal tissue but relatively abundant in the earth s crust (0.2% of the mass of the earth s crust is titanium only six other metals are even more abundant). For some time now, titanium has been used in dental surgery and in attaching and replacing bones and joints. 

In 1952 professor Perlngvan Branemark in Lund, Sweden accidentally discovered the tissue-friendly properties of titanium. He was microscopically investigating living bone tissue on a titanium surface. After some time the titanium appeared to be irreversibly attached to the tissue. 

These last few decades many ceramic materials have been used as implants. This development will be discussed in the next paragraphs. As far as the present state of affairs is concerned, nature is still the best engineer. The ideal implant has not yet been found. Pure titanium is best tolerated by living tissue. However, increasingly often a porous surface layer is applied to the metal. In this way it is easier for the bone cells to attach themselves to the metal. In addition we now use materials which were thought to be unsuitable in the past. Improved surgical techniques and the development of antibiotics have been of vital importance here. 

By means of plasma syringes a coating is applied, mainly on tooth implants or hip joints made of titanium. Because the hip joint turns longitudinally in the HA jet, the coating obtains a layered structure. The surface is rough and porous, which guarantees a proper attachment of the human bone. 

Prior to true subsurface bone spectroscopy, Penel and coworkers obtained bone Raman spectra using a titanium chamber with a fused silica window placed in the calvaria of New Zealand rabbits [2]. With this apparatus they were able to study both bone tissue and implanted hydroxyapatite and P-tricalcium phosphate over a 8-month period. In addition to bone spectra, hemoglobin spectra were obtained close to blood vessels. 

Wang JY, Wicklund BH, Gustilo RB, et al. 1996b. Titanium, chromium and cobalt ions modulate the release of bone-associated cytokines by human monocytes/macrophages in vitro. Biomaterials 17 2233-2240. 

In the 1950s, surgeons discovered that titanium metal was not rejected by the body and so was ideal for mending broken bones. It has been used in operations for hip and knee replacements, inserting cranial plates for skull fractures, and even for attaching teeth, some of... 

For artists - and house painters - nothing came dose to matching the brilliance and depth of lead white and while there were alternatives, made from chalk, calcined bones, oyster shells, or even groundup pearls, they did not compare to lead white. Today this pigment is rarely used and that which is available is restricted to conservators and restorers. We are now aware how toxic this metal is - see page 204 -and lead white has been replaced by titanium dioxide, which delivers the same brilliant whiteness with no risk to health. 

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