Great progress in dental restoration techniques has been established by the use of
ceramic materials since the 70’s. Ceramic materials show relative advantages, like
better esthetics, biocompatibility and chemical resistance. One problematic aspect of
ceramic materials and of dental ceramics in particular is their low mechanical
resistance and fracture toughness [1 2 ],
Osseointegrated dental implants have been used since 80’s in the rehabilitation of
partially and totally edentulous patients [13]. The metallic abutments used in
prosthetic restorations with implants must compromise the esthetic in some cases. To
minimise this problem, some implant systems developed ceramic abutments. The use
of alumina and zirconia biomaterials has been proposed. Aluminas have shown
excellent biocompatibility and wear resistance.
However zirconia exhibits low flexural strength and toughness. Pure zirconia cannot
be used in the manufacture o f parts without the addition o f stabilisers [13]. The
yttria-tetragonal zirconia polycrystal (Y-TZP) has become a popular alternative to
alumina as a biomaterial and is used in dental applications such as endodontic posts,
orthodontic brackets, crowns and bridges and in ceramic abutments. The ceramic has
also been extensively used in orthopedics’ implants [14] as shown in Figure 2.1.