Patient-friendly definition from the DentistsDirectory.org dental glossary.
Zirconia (zirconium dioxide) is an advanced ceramic material that has transformed restorative and implant dentistry over the past two decades. It is extraordinarily strong for a ceramic — flexural strength values for dental zirconia range from 900 to over 1,200 MPa, exceeding many metal alloys — while being tooth-coloured, biocompatible, and resistant to corrosion. These properties have made it the dominant material for dental crowns and bridges in modern dentistry.
Dental zirconia comes in several formulations with different balances of strength and translucency. High-strength, less translucent zirconia (monolithic zirconia) is used for posterior crowns and bridges where maximum strength is the priority and the restoration is not highly visible. More translucent "aesthetic zirconia" formulations are better suited for anterior teeth where a natural, lifelike appearance is essential. Zirconia is also used for implant abutments (the connector between implant and crown) because it is metal-free, does not cause the grey halo under thin gums that titanium abutments can create, and is fully biocompatible.
The main alternative to zirconia for posterior crowns is porcelain-fused-to-metal (PFM), which has a metal inner framework with a porcelain outer layer. While PFM crowns are still used and reliable, their disadvantages include visible grey metal at the gum line (especially if gums recede), the potential for the porcelain to chip off the metal, and metal content that some patients prefer to avoid. Full-cast gold crowns remain the most durable option for severely bruxing patients but are rarely chosen for aesthetic reasons. For most patients, zirconia provides the best combination of strength, aesthetics, and biocompatibility currently available.