Dental Ceramics:
➢ Ceramic: material produced by burning or firing.
➢ Ceramics is a compound of metallic and non-metallic
elements joined by ionic bonds.
○ Ionic bonds: strong, and they are directional
○ they do not tolerate bending.
○ This intolerance to distortion makes ceramics
brittle.
➢ Silicon (Si), zirconium (Zr), and aluminum (Al) are
common metallic elements that occur in dental ceramics in combination with oxygen.
Phases in Dental Ceramics:
➢ Amorphous (glossy) phase:
○ The amorphous areas have disruptions in the metal-oxygen
crystal arrays by metal ions called fluxes
■ Like sodium or potassium
○ These interrupting ions have several effects on ceramic
properties:
■ Reduced strength
■ Lower fusing temperature
■ More transparency
➢ Crystalline Phase:
○ Has more ideal Crystal structure
○ These areas make the ceramic more opaque
○ Stronger with higher fusing temperature.
➢ The overall strength and optical properties, as well as the clinical use
of ceramic, depend on the relative abundance of the amorphous and
glassy phases.
Types of Ceramics in Dentistry Today:
&
, towe
point
1. Feldspathic or Glassy Ceramics ( Porcelain)
➢ oldest of the dental ceramics
➢ highly esthetic, but relatively weak.
➢ This type of ceramic results when feldspar (K2O-Al2O3- SiO2), silica (SiO2),
and alumina (Al2O3) are fired together with fluxes such as sodium carbonate
(Na2CO3) or potassium carbonate(K2CO3).
○ During the firing, large areas of amorphous (often called a matrix)
ceramic are formed, with small islands of a crystalline phase called
leucite (K[AlSi2O6]).
➢ Opacity may be achieved by titanium oxide or tin oxide.
➢ Metal oxides are added to the powder to provide a wide variety of colors of the porcelain
➢ Oxides of:
○ Iron: act as brown pigments
○ Copper: act as green pigments
○ Titanium: yellowish-brown pigments
○ Cobalt: blue pigments
➢ Porcelain is the most esthetic but the weakest of the ceramics
➢ Amorphous ceramic phases are weaker and more soluble than crystalline phases
➢ A pure amorphous phase is transparent, like window glass.
➢ Glassy Ceramics: classified according to their fusing temperature
○ Calso called sintering temperature
○ High Fusing: 1288 - 1371℃
■ Used to make denture teeth and other types of very hard ceramic
○ Medium Fusing: 1093-1260℃
■ Used to fabricate some all-ceramic jacket crowns, these crowns are relatively
weak and non-conservative
○ Low Fusing: 871-1066℃
■ Used for veneering ceramic-alloy and all-ceramic restorations.
2. Glass-Dominated Ceramics
➢ Contain increased amounts of crystalline phase relative to the glassy ceramics;
➢ Crystals may be leucite or fluoroapatite.
➢ Higher strength with sufficient translucency to serve in esthetic applications
➢ Cannot be used for posterior crowns or bridges.
➢ Uses :
○ Excellent choices for alloy-veneering ceramics.
○ Anterior all-ceramic crowns that are not under excessive occlusal force
3. Crystalline-Dominated Ceramics
➢ About 70 % of the volume of a crystalline phase.
➢ The spaces between the crystals are occupied by an amorphous silica glass.
➢ The crystalline phase is generally either:
○ I. Spinel (MgAl2O4),
○ II. Zirconia (ZrO2), alumina (Al2O3),
○ III. Lithium disilicate . (Li2Si2O5)
➢ The spinel-based ceramics have the lowest strengths, whereas the
zirconia-alumina– based ceramics have the highest strengths.
➢ Ceramic: material produced by burning or firing.
➢ Ceramics is a compound of metallic and non-metallic
elements joined by ionic bonds.
○ Ionic bonds: strong, and they are directional
○ they do not tolerate bending.
○ This intolerance to distortion makes ceramics
brittle.
➢ Silicon (Si), zirconium (Zr), and aluminum (Al) are
common metallic elements that occur in dental ceramics in combination with oxygen.
Phases in Dental Ceramics:
➢ Amorphous (glossy) phase:
○ The amorphous areas have disruptions in the metal-oxygen
crystal arrays by metal ions called fluxes
■ Like sodium or potassium
○ These interrupting ions have several effects on ceramic
properties:
■ Reduced strength
■ Lower fusing temperature
■ More transparency
➢ Crystalline Phase:
○ Has more ideal Crystal structure
○ These areas make the ceramic more opaque
○ Stronger with higher fusing temperature.
➢ The overall strength and optical properties, as well as the clinical use
of ceramic, depend on the relative abundance of the amorphous and
glassy phases.
Types of Ceramics in Dentistry Today:
&
, towe
point
1. Feldspathic or Glassy Ceramics ( Porcelain)
➢ oldest of the dental ceramics
➢ highly esthetic, but relatively weak.
➢ This type of ceramic results when feldspar (K2O-Al2O3- SiO2), silica (SiO2),
and alumina (Al2O3) are fired together with fluxes such as sodium carbonate
(Na2CO3) or potassium carbonate(K2CO3).
○ During the firing, large areas of amorphous (often called a matrix)
ceramic are formed, with small islands of a crystalline phase called
leucite (K[AlSi2O6]).
➢ Opacity may be achieved by titanium oxide or tin oxide.
➢ Metal oxides are added to the powder to provide a wide variety of colors of the porcelain
➢ Oxides of:
○ Iron: act as brown pigments
○ Copper: act as green pigments
○ Titanium: yellowish-brown pigments
○ Cobalt: blue pigments
➢ Porcelain is the most esthetic but the weakest of the ceramics
➢ Amorphous ceramic phases are weaker and more soluble than crystalline phases
➢ A pure amorphous phase is transparent, like window glass.
➢ Glassy Ceramics: classified according to their fusing temperature
○ Calso called sintering temperature
○ High Fusing: 1288 - 1371℃
■ Used to make denture teeth and other types of very hard ceramic
○ Medium Fusing: 1093-1260℃
■ Used to fabricate some all-ceramic jacket crowns, these crowns are relatively
weak and non-conservative
○ Low Fusing: 871-1066℃
■ Used for veneering ceramic-alloy and all-ceramic restorations.
2. Glass-Dominated Ceramics
➢ Contain increased amounts of crystalline phase relative to the glassy ceramics;
➢ Crystals may be leucite or fluoroapatite.
➢ Higher strength with sufficient translucency to serve in esthetic applications
➢ Cannot be used for posterior crowns or bridges.
➢ Uses :
○ Excellent choices for alloy-veneering ceramics.
○ Anterior all-ceramic crowns that are not under excessive occlusal force
3. Crystalline-Dominated Ceramics
➢ About 70 % of the volume of a crystalline phase.
➢ The spaces between the crystals are occupied by an amorphous silica glass.
➢ The crystalline phase is generally either:
○ I. Spinel (MgAl2O4),
○ II. Zirconia (ZrO2), alumina (Al2O3),
○ III. Lithium disilicate . (Li2Si2O5)
➢ The spinel-based ceramics have the lowest strengths, whereas the
zirconia-alumina– based ceramics have the highest strengths.
