Inert ceramics of bioceramics
Inert ceramics of bioceramics
Classification of bio-inert ceramics:
Bio-inert medical ceramic materials include oxide ceramics, non-oxide ceramics, glass ceramics, etc. They are chemically stable, have good biocompatibility, are resistant to corrosion in vivo, do not degrade, and do not chemically bond with human tissues. Bio-inert ceramics commonly used in clinical practice include alumina ceramics, zirconia ceramics, zirconia toughened alumina ceramics, etc. Among them, the oxides of Al, Mg, Ti, and Zr are the most widely used. Bio-inert ceramics generally have high strength and wear resistance, and are mainly used in medical treatment to make artificial joints, artificial bones, oral implants, all-ceramic teeth and dental crowns.
(1) Alumina (Al2O3) ceramic material
Alumina has a variety of crystal forms, of which the high temperature crystal form α-Al2O3 has the best thermal stability and chemical stability, and the density of α-Al2O3 is 3.99g/cm³, which is lighter than stainless steel, titanium and titanium alloys. Common biomedical metallic material. α-Al2O3 is a crystal dominated by ionic bonds, and the bond strength is strong, which makes Al2O3 have a high melting point (2050 ° C), hardness, chemical resistance and elastic modulus. As early as 1969, alumina ceramics were tested as a permanent implantable bone prosthesis implanted in the femur of adult mongrel dogs, and it was found that polycrystalline alumina ceramics were inert to any environment, including biological environments, and their superior resistance. Abrasion resistance and high compressive strength. Alumina ceramics are extremely stable in the human body, with high hardness and almost no wear, which makes alumina ceramics the first biologically inert ceramics to be clinically used.
(2) Zirconia (ZrO2) ceramic material
Zirconia is an oxide ceramic with the highest fracture toughness at room temperature and is widely used as a structural material. Compared with alumina ceramics, zirconia ceramics have higher normal temperature strength and fracture toughness, and lower elastic modulus, but the hardness and wear resistance are not as good as alumina ceramics. Due to its excellent biocompatibility, zirconia has high fracture toughness and strength, and low elastic modulus. It is currently mainly used in artificial joints, tooth roots, crowns and all-ceramic teeth in the medical field. Highest dental restorative material. When paired with polyethylene for artificial joints, it has similar properties to alumina in terms of friction and lubrication. Zirconia ceramics have higher fracture toughness, and the clinical fracture rate of zirconia femoral head prostheses is lower than that of alumina ceramic femoral heads.
