ZIRCONIA CERAMICS: PROPERTIES AND CLASSIFICATION

Abstract

Introduction and aim: Zirconia is currently the most commonly used representative of polycrystalline dental ceramics. It is highly valued for its mechanical properties: hardness, strength and toughness. On the contrary, its aesthetics is percieved as a disadvantage. Its insufficient transparency makes it impossible to mimic the optical properties of enamel, and therefore its indication in monolithic form is often limited to distal sections only. This article discusses the properties of zirconia ceramics and its evolution. Particular emphasis is placed on the chemical-physical nature of the phenomena involved in determining the properties of dental zirconia. Conclusion: The economic potential of zirconia ceramics is proving to be a strong stimulant of its development. The aesthetic disadvantages of the material were the biggest limiting factor for its wider use. The simplest and earliest solution to this problem was the veneering of zirconia using high glass content ceramics. This combination of materials, however, was found to have relatively frequent complications associated with chipping of the surface layers of the veneer. The use of zirconia ceramics in monolithic form proved to be the most advantageous from a mechanical point of view. Therefore, the development of zirconia ceramics in the last ten years has gone in the direction of increasing the transparency of the zirconia ceramic itself. The result of these efforts has been the latest generation of zirconia ceramics, which have significantly improved aesthetics and can be used even in relatively aesthetically exposed areas. These new materials retain only a fraction of the mechanical durability of their predecessors, and therefore their indications are limited to three-unit bridges. However, they still significantly expand the portfolio of applications for monolithic zirconia ceramics and are becoming a suitable alternative to older materials used for crown and bridge fabrication.

Keywords

• zirconia ceramic
• zirconia
• polymorphism
• metastability
• transformation toughening
• low temperature degradation
• 3y-tzp
• 4y-tzp
• 5y-tzp