Zirconia versus metal: a preliminary comparative analysis of ceramic veneer behavior.

Purpose: Clinical studies have revealed a high rate of fracture for porcelain-veneered zirconia-based restorations that varies between 6% and 15% over a 3- to 5-year period. These are high values compared to the 4% fracture rate shown by conventional metal-ceramic restorations over 10 years. To date, little in vitro research has been carried out on the fracture resistance of the new generation of ceramic crowns.