Zirconia- Strength, Weaknesses, Opportunities and Threats (SWOT)

Zirconia described as “ceramic steel” in 1975 by Garvie in a publication in Nature is currently used as the replacement material for metal in prosthetic rehabilitations including implantology. It has a favorable biological and esthetic outcome, interesting toughening mechanism when stressed thanks to its phase transformation capacity and its processing uses CAD-CAM technologies. There are however many zirconia materials on the market with differences in their mol% of Yttria needed to stabilize the zirconia in a tetragonal or cubic crystallographic phase. These phases, will determine the final mechanical and optical properties. This presentation is meant to provide an understanding of the zirconia material using a short SWOT analysis. “Strength and Opportunities” will be discussed along with “Weaknesses and Threads”. Some clinical failures (tooth supported, implant-supported and cantilever reconstructions) will be presented based on microscopy (SEM) evidences of failure origins and location on the fractured zirconia parts. These cases will highlight issues related to lab processing, framework design, connectors, surface treatment, occlusal contacts and risk assessment depending on the type of zirconia used.

Learning Objectives

1. Understand the phase transformation toughening capability of a zirconia
2. Understand the differences between the zirconias with respect to Yttria mol% and the consequences on the mechanical and optical properties
3. Learn from failure analysis of clinical cases
4. Keep in mind the SWOT when dealing with zirconia reconstructions