ABSTRACT
When an aesthetic appearance is required of a tooth restoration, traditionally a porcelain-fusedto-metal crown has been used. However, because of concerns about allergic reactions or biocompatibility (Sjogren et al., 2000), patients and dentists alike have come to prefer metal-free restorations. The use of ceramics makes it is possible to replicate the aesthetic characteristics and vitality of natural teeth (Ku et al., 2002) and ceramic materials are superior in terms of permeability to light and biocompatibility, but they can be inherently brittle and weak when placed under tensile and torsional stresses (Hwang & Yang, 2001). The use of reinforced glass-ceramic materials lessens the impact of this drawback. Survival rates of glass-ceramic crowns, even on posterior teeth, have far exceeded those of traditional all-porcelain crowns, despite having nearly equivalent strengths and thicknesses (Fradeani & Redemagni, 2002).
