Current status of zirconia-based fixed restorations.

Zirconium dioxide (zirconia) ceramics are currently used for fixed restorations as a framework material due to their mechanical and optical properties. This review article describes the current status of zirconia-based fixed restorations, including results of current in vitro studies and the clinical performance of these restorations. Adaptation of zirconia-based restorations fabricated with CAD/CAM technology is within an acceptable range to meet clinical requirements. In terms of fracture resistance, zirconia-based fixed partial dentures (FPDs) have the potential to withstand physiological occlusal forces applied in the posterior region, and therefore provide interesting alternatives to metal-ceramic restorations. Clinical evaluations have indicated an excellent clinical survival of zirconia-based FPDs and crown restorations. However, some clinical studies have revealed a high incidence of chipping of veneered porcelain. Full-coverage zirconia-based restorations with adequate retention do not require resin bonding for definitive cementation. Resin bonding, however, may be advantageous in certain clinical situations and is a necessity for bonded restorations, such as resin-bonded FPDs. Combined surface treatment using airborne particle abrasion and specific adhesives with a hydrophobic phosphate monomer are currently reliable for bonding to zirconia ceramics. Further clinical and in vitro studies are needed to obtain long-term clinical information on zirconia-based restorations.