Metal alloys implant material

Currently, the materials of choice for most bone implantations are metals and metal alloys. These materials have the advantage of... 

Nickel allergy is an adverse effect of the use of nickel-containing medical apphances, such as orthopedic metal alloys, dental materials, and implants (9), and allergic reactions are common. Nickel allergy and contact dermatitis with nickel-based apphances have been reviewed (10). 

ASTM F 746 Standard Test Method for Pitting or Crevice Corrosion of Metallic Surgical Implant Materials Measurement of pitting or crevice tendency by measuring repassivation tendency after polarization at noble potential. Applicable only to passive alloys. 

Metals and metal alloys are not without their disadvantages as hiomaterials, however. Although they tend to he quite stable in a biological system, they are not completely inert. They do react to some extent, meaning the metal implant can deteriorate over time. A number of methods have been devised to reduce this problem. For example, metal implants are sometimes attached to existing bone with a ceramic material, which acts as a buffer between the metal and the living material in hone. 

During the past few years the microhardness technique has frequently been applied to the characterization of super-hard-surfaced polymers obtained by ion implantation and to plasma-deposited hard amorphous carbon films (Balta Calleja Fakirov, 1997). These products represent an entirely new class of materials that are lightweight and have the flexibility of polymers combined with a surface microhardness and wear resistance greater than those of metallic alloys (Lee et al., 1996). 

The present contribution focuses on the effect of various elements added by ion implantation on the isothermal and cyclic oxidation behaviour of the 7-Ti A1 based inter-metallic alloys Ti-48Al-2Cr and Ti-48Al-2Cr-2Nb at 800°C in air.These particular materials were selected since the ternary chromium addition improves the mechanical properties especially room temperature ductility [9-11] and the quaternary niobium addition improves the oxidation resistance [8, 14, 15]. Comparison will be made between materials modified by ion implantation and alloys in which elements were added by alloying techniques. 

Most medical reports have been concerned with the suitability of various titanium alloys as implant materials. Such implants in dogs have shown soft tissue to have a high tolerance for titanium metal, based on a lack of irritation, good wound healing properties, and encapsulation of the metal by fibrous tissues (Nordman and Berlin 1986). 

Scaffolds can be produced from a variety of materials, including metals, ceramics, and polymers. In dental and bone implants, metallic alloys are preferred [4, 5], while ceramics with good osteoconductivity have been used for bone tissue... 

The surface preparation procedures described in ASTM F 86 passivate stainless steels and cobalt alloys. Titanium materials do not require this passivation. It is not clear what the ideal surface for the metal implants should be, and this will continue to be an aspect of studies relating to interfaces of these materials with the body. The condition of the surface may influence ion release. 

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