zirconia: chance or risk?
Recently, Zirconia (zirconium oxide)-based ceramics have been introduced to dentistry because of their desirable esthetics, biocompatibility, superior fracture strength, and fracture toughness compared with other dental ceramic systems. The development of these materials, coupled with the new computer-aided design/computer-aided manufacturing (CAD/CAM) fabrication techniques, has created a wide range of applications for dental restorations. Core substructures for dental restorations can be fabricated from fully or partially sintered ceramic blanks using manually controlled copy-milling or CAD/CAM technology.
After milling, zirconia has to be veneered with porcelain in layering or press technique; however, Chipping of the veneering porcelain is reported as a common problem and has been labeled as its main clinical setback. To overcome this problem, (monolithic) full-contoured zirconia restorations can be fabricated with occlusal design without veneering.
Zirconia-based ceramic restorations can be cemented with traditional cements or bonded with adhesive resin cements. Self-adhesive resin cements offer less technique sensitivity than traditional cements, making them excellent choices for the cementation of appropriate zirconia-based ceramic restorations.
The objective of this lecture is to address the evolution of zirconia as a biomaterial; to explore the material’s physical, mechanical, optical properties; to identify the strengthening mechanism; and finally to describe the processing techniques, core\veneer interfacial effects and cementation procedures.