Silicates: These are characterized by amorphous glass phase,
containing predominantly silica.
Oxide ceramics: It is notable that only oxide ceramics are used in
dentistry, since nonoxide ceramics are difficult to process. Oxide
ceramics contain a principal crystalline phase like Alumina.
Zirconia has very high fracture toughness.
Glass ceramics: These are type of ceramics that contains a glass
matrix phase & at least one crystal phase.
Although classification of dental ceramics based on composition
is not much of importance today, due to advances made, it is
included for historic importance.