April 24, 2017

A Zirconia Option for Anterior Restorations

Article - Dentistry Today April 2017 - Written By Robert A. Lowe, DDS

As digital impression scanning, computer-assisted design (CAD), and computer-assisted milling (CAM) are becoming more commonplace in dentistry, the use of high-strength ceramics, such as lithium disilicate and zirconia, are quickly becoming the main laboratory-fabricated restorative choices for many dentists. Lithium disilicate can be a very aesthetic material for both anterior and posterior full- and partial-coverage restorations, as it also exhibits higher strength and fracture toughness over conventional feldspathic and leucite-reinforced ceramics.

High-translucency (HT) ingots have improved the aesthetic quality but cannot always mask the color of a dark preparation. Zirconium oxide restorative materials got their start as tooth-colored replacements for traditional full-gold crowns on posterior teeth. Conservative posterior tooth preparations, similar to prep designs for gold, could be done because of the high strength of the material. However, early zirconia materials were very opaque and only indicated for first or second molars. Because zirconia is a metallic oxide (zirconium oxide), it can be used like a PFM crown to cover dark tooth preparations, and it can also be cemented with a conventional (nonadhesive) cement. Lithium disilicate and zirconia blocks can be designed and milled by the lab team to full contour, making them less labor intensive and less costly to the doctor. Since there are certain clinical indications where zirconia might be a desirable choice for use in the aesthetic zone, the challenge has been to provide the necessary aesthetic characteristics that are required for anterior restorations.

The following case report looks at an anterior case replacing previously placed feldspathic full-coverage restorations, while comparing lithium disilicate to a new aesthetic zirconia material (ArgenZ Anterior).

Read complete article here: http://dentistrytoday.com/articles/10280