Lastnosti in uporaba cirkonijeve oksidne biokeramike v medicini
Properties and clinical application of zirconia bioceramics in medicine

slovenian

2013

volume 82, issue 12

bio-ceramics   biocompatibility   zirconia ceramic

Slovensko zdravniško društvo
(Obvezni izvod spletne publikacije)

Background: A group of in organic non-metal biomaterials, that are commonly used in clinical medicine to replace or repair tissues, can be classifiedas a bioceramics. This group includes bioactive glasses, glass-ceramics, hydroxy-apatiteand some other calcium phosphates. In addition, some bio-inert engineering ceramics materialshave become increasingly utilised, aluminumoxide, zirconium oxide and their composites being the most popular. With the developement of yttria stabilized tetragonal zirconium oxide ceramics (Y-TZP) medical community received a high strength biomaterial that is currently a material of choice for the manufacturing of medical devices. Y-TZP ceramics is becoming also increasingly used in dental medicine, where frameworks are manufactured by the use of computer-assisted technology. Conclusions: The article describes the basic properties of zirconia oxide ceramics important for the use in clinical medicine; high strengthand fracture toughness, biocompatibility and negligible radiation. The ageing issue of this particular material, which is attributable to the thermo-dynamical instability of tetragonal zirconium oxide in hydrothermal conditions, is also discussed. When exposed to an aqueous environ mentover long periods of time, the surface of the Y-TZP ceramic will start transforming spontaneously into the monoclinic structure. The mechanism leading to the t-m transformation istemperature-dependent and is accompanied by extensive micro-cracking, which ultimately leads to strength degradation. The degradation might influence the clinical success rate of medical devices and therefore Y-TZP femoral heads are no longer made of pure zirconium oxide. Composites of zirconium and aluminium oxides are used instead, that are currently the strongest ceramic materials used in clinical medicine. In this work the clinical application of zirconia oxide ceramics in dental medicine is also presented. Conventional porcelain fused to metal technique is successfully replaced with Y-TZP ceramics in some clinical situations that are described in detail. It is important that computer design of the zirconia frameworks shortens and simplifies laboratory procedures and contributes to a precise final product.

10.10.2014