Biomedical Engineering Reference
In-Depth Information
9
Ceramic Materials for
Dental Prostheses
9.1. The place of ceramics in modern prosthetic dentistry
In dentistry, full metallic crowns and bridges have been
progressively abandoned due to their lack of esthetic and
biocompatibility properties, notably in terms of corrosion processes.
Nowadays, prostheses on natural teeth or on dental implants are most
often bilayered structures composed of a metal or ceramic framework,
which ensures the mechanical resistance of the prosthesis, and of a
veneering ceramic layer, which is less resistant but gives a natural
tooth appearance to the restoration (Figures 9.1 and 9.2). The first
esthetic crown, composed of porcelain fused to a platinum post, was
patented in 1885, while the actual porcelain-fused-to-metal (PFM)
concept, which provides an adequate chemical and micromechanical
bond between veneering ceramic and different types of metal alloys,
emerged in the 1960s. Now, PFM systems are considered to be the
gold standard in terms of survival rate [HEI
10]. However, ceramic
frameworks started to hit the market in the 1980s. Thus, some all-
ceramics are as old as non-precious alloys or titanium-based PFM
systems, and already show a 40-year clinical background. All
ceramics restorations definitively eliminate the disadvantages of the
metal. The earliest ceramic materials used as frameworks were glass-
based materials, but the appearance of computer-aided-design (CAD)
