| Ceramic Category (by Composition) | Specific Materials / Examples | Common Processing Method(s) | Etchable with HF Acid? |
|---|---|---|---|
| Glass-Based | Feldspathic ceramics (pure or leucite-reinforced) | Powder/Liquid “Slurry” | Yes |
| Glass-Based (with crystalline fillers) | • Leucite reinforced (e.g., IPS Empress CAD) • Lithium disilicate (e.g., IPS Emax CAD) • Zirconia reinforced lithium silicate (e.g., VITA Suprinity) | • Hot Ceramic Pressing (for leucite and lithium disilicate) • CAD/CAM (milling) | Yes |
| Glass-Infiltrated | (e.g., VITA In ceram Alumina, Spinell, Zirconia) | Slip Casting | No |
| Polycrystalline | • Alumina • Zirconia | CAD/CAM (milling of pre-sintered or fully sintered blocks) | No |
| Resin Matrix Ceramics (Hybrid) | • Nanoceramic particles in a polymer matrix • (e.g., Lava Ultimate, VITA Enamic) | CAD/CAM (milling); does not require firing | Yes (e.g., Enamic) |
| The classification of dental ceramics is often based primarily on their composition or their processing manner. The composition (specifically the ratio of glassy to crystalline phases) dictates key clinical properties such as aesthetics, strength, and the ability to be etched for adhesive bonding. |
Below is a comprehensive table detailing the different types of ceramics based on their composition, followed by a summary of common processing methods.
I. Classification of Dental Ceramics by Composition
This classification focuses on the material’s internal structure (glassy phase vs. crystalline fillers) and its resulting mechanical and bonding properties.
| Ceramic Type | Key Composition/Structure | Flexural Strength (FS) | Aesthetic Properties / Clinical Use | Etchability (with HF Acid) | Example(s) |
|---|---|---|---|---|---|
| Glass-Based Ceramics: Feldspathic | Mainly composed of feldspar, quartz, potash, and various metal oxides. Predominantly glass-based. | Pure: 50–80 MPa. Leucite Reinforced: ~160 MPa. | Very aesthetic (due to high glass content). Used as a monolithic ceramic for single-unit anterior prostheses, veneers, inlays, or onlays. | CAN ETCH. HF acid reacts with the silica in the glass matrix, enabling strong micromechanical bonding. | N/A |
| Glass-Based (with Crystalline Fillers): Leucite Reinforced | Glass matrix with leucite crystals. Leucite provides dispersion strengthening to stop crack propagation. | ~160 MPa. | Possess good aesthetic properties because the refractive index of the leucite crystals closely matches the surrounding glass matrix. | CAN BE ETCHED. | IPS Empress CAD. |
| Glass-Based (with Crystalline Fillers): Lithium Disilicate Reinforced | Glass matrix with an intertwined lithium disilicate structure. | 360–400 MPa. | Suited for single unit anterior crowns. | CAN BE ETCHED. | IPS Emax CAD. |
| Glass-Based (with Crystalline Fillers): Zirconia Reinforced Lithium Silicate | Similar to above, but with zirconia dispersed into the glassy matrix. | 460 MPa. | Higher flexural strength. | CAN BE ETCHED. | VITA Suprinity. |
| Polycrystalline Ceramics: Alumina | Highly crystalline structure, typically lacking a glassy phase. | 500–700 MPa. | Extremely strong, but often leads to poor aesthetics. | CANNOT ETCH (due to lack of glassy phase). | N/A |
| Polycrystalline Ceramics: Zirconia (Zirconia Dioxide) | Crystalline structure (zirconia dioxide), stabilized to maintain tetragonal form. Exhibits transformation toughening. | 900–1200 MPa. | Extremely high mechanical strength. Initially opaque, but high-translucency versions are now available. Used for crowns, bridges, etc.. | CANNOT ETCH (no glassy phases). Requires luting cements with sandblasting or MDP-containing cements. | N/A |
| Resin Matrix Ceramics (Hybrid Ceramics) | Nanoceramic particles in a high cross-linked polymeric matrix. | (Strength values not provided). | Material is not brittle and has good shock-absorbing characteristics. | CAN BE ETCHED (predominantly glassy ceramics). | VITA Enamic, Lava Ultimate. |
| Glass-Infiltrated Ceramics | A porous crystalline “skeleton” (e.g., alumina or zirconia) that is infiltrated with a glassy phase. | (Strength values not provided). | Very hard to make, leading to a loss of popularity. | CANNOT ETCH. | VITA In ceram family. |
II. Classification of Dental Ceramics by Processing Manner
The processing manner dictates the resulting homogeneity and strength of the final restoration.
| Processing Method | Description | Common Ceramic Type(s) | Key Advantages | Key Disadvantages |
|---|---|---|---|---|
| Powder/Liquid Building (Slurry Method) | Ceramic powder is mixed with liquid to form a slurry, which is painted onto a core and then fired (sintering). | Usually used for Feldspathic ceramics. | Highly translucent and aesthetic. Allows for good customisation and shade control. | Weak; shrinkage during firing; requires a skilled technician; poor technique can result in porosities/voids. |
| Hot Ceramic Pressing | A wax pattern is created, invested, and a plasticized ceramic ingot is pressed into the heated mold. | Usually used for Leucite based glass or Lithium disilicate. | Improved mechanical strength; reduced shrinkage (better dimensional stability); capable of producing highly aesthetic restorations. | Requires specialized, additional equipment; process can be time-consuming. |
| CAD/CAM (Computer Aided Design/Manufacture) | Ceramic blocks are milled (subtractive method) into the required shape and then often fired. | Zirconia, Lithium Disilicate, Resin Matrix Ceramics. | Simplified fabrication method; more durable and homogeneous material application; superior accuracy; chair-side option available. | Milling hardened (white) zirconia is very time-consuming and causes significant wear to the milling burs. |
| Slip Casting | A porous die is dipped into a ceramic slurry, absorbing water and leaving a thin layer that is fired and then infiltrated by molten glass. | Used for the In ceram family (Glass-Infiltrated Ceramics). | (Advantages not provided in source). | Very hard to make, which has contributed to its loss of popularity. |