From Volume 39, Issue 5, June 2012 | Pages 342-357
Zirconia restorations are now accepted and commonly prescribed in dentistry. However, these materials undergo hydrothermal ageing which can reduce their clinical performance. Appropriate handling is essential to limit the restorations’ susceptibility to low temperature degradation/ageing. Through appropriate clinical prescribing and laboratory manufacture, an aesthetic, strong and long-lasting restoration can be fabricated.
In ancient history zircon was known to be a gem. The name zirconium comes from Zargon which translates from Arabic to golden in colour. Zargon is a composite of two Persian words; Zar meaning gold and Gun meaning colour. Zirconium dioxide (ZrO2: zirconia) was first identified by a German chemist in 1789. The compound was used for a long time as part of a rare earth oxide mix to pigment ceramics. In its pure form, it is a white crystalline material and has three crystallographic forms, monoclinic, tetragonal and cubic. Monoclinic is the most naturally occurring form, while ‘cubic zirconia’ is rarely found in nature and is best known as a diamond simulant owing to a structural chemistry similar to cubic carbon and a high index of refraction. This is referred to as zircon by jewellers; however zircon is actually the mineral name for naturally occurring zirconium silicate.
Zirconia ceramic was first introduced to the medical profession in 1969 in the field of orthopaedics as a proposed material for hip replacements.1 Since then it has been described as ‘ceramic steel’2 and is widely used in both dentistry and medicine.3 Owing to its impressive flexural and compressive strengths of 900–1200 MPa and 2000 MPa, respectively,4 zirconia has developed into an efficient core material for all-ceramic restorations.
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