Dental Ceramics and Their Applications

The temperature at which ceramic materials are heated to achieve a desired structure. It can be high (over 1300°C), medium (1100-1300°C), low (850-1100°C), or ultra-low (under 850°C).

Ceramics containing a mixture of glass and crystals, offering good aesthetics but lower mechanical strength. Examples include porcelain and feldspathic ceramics.

Ceramics predominantly composed of metallic oxides, providing high strength but lower aesthetics. Examples include alumina and zirconia.

A fabrication method where ceramic powder is heated and compacted into layers, creating a final structure. It can be applied on a metal framework, platinum foil, refractory cast, or hydrothermal glass.

A fabrication method that involves melting a ceramic block and pouring it into a mold. The cast framework is then subjected to ceramization (crystallization).

A fabrication method that involves a framework made from oxide ceramics, either through CAD/CAM or handmade, followed by glass infusion and veneering.

A fabrication process involving a molten glass ingot pressed into a wax pattern mold, followed by veneering.

A fabrication method that uses a computer-aided design (CAD) system to create a ceramic structure from a block using subtractive processes such as milling, sonoerosion, or electrophoresis.

A type of dental ceramic restoration where a ceramic core is infiltrated with glass, enhancing its aesthetic properties.

Ceramic restorations made from aluminum oxide, offering high resistance but less aesthetic appeal. Often used for strong backbones in other restorations.

Ceramic restorations featuring a ceramic core made from zirconium oxide, known for its strength and natural-looking whiteness. Often used as a base in other restorations.

A process that involves bonding dental ceramic material onto a metal framework, allowing for creating durable and aesthetically pleasing crown and bridges.

The process of creating a ceramic core by sintering, a heat treatment method that bonds ceramic particles together at high temperatures, leading to a durable structure.

Metal-bonded ceramics, also known as porcelain-fused-to-metal (PFM) restorations, are made by fusing ceramic to a metal framework. This technique is used for crowns and dental bridges, where the metal provides strength and the ceramic creates a natural-looking restoration. The process involves sintering, which is a high-temperature process that bonds the components together.

Traditional feldspathic ceramics are a type of ceramic used in dentistry. They are known for their excellent esthetics and biocompatibility. These ceramics are composed primarily of feldspar, a mineral that gives them a translucent, natural-looking appearance.

Alumina-reinforced feldspathic ceramic is a modified version of traditional feldspathic ceramic. It incorporates alumina, a strong oxide, to enhance its strength. This makes it more resistant to fracture and suitable for structures under high stress.

Spinell-reinforced feldspathic ceramic is another modified variety of feldspathic ceramic. Spinell, a magnesium oxide, is incorporated to further increase the ceramic's strength, making it suitable for applications where resilience is crucial.

Leucite-reinforced feldspathic ceramic is a type of ceramic where leucite, a potassium aluminum silicate, is added to improve its strength and increase its translucency. This type of ceramic is often used for inlays, veneers, and crowns.

Silicate ceramics are a common category of ceramics used in dentistry. They are known for their biocompatibility and esthetics. These ceramics are further divided into two subcategories: feldspathic ceramics and glass ceramics.

Glass ceramics are a type of silicate ceramic with a glassy structure. They offer good strength and esthetics, and they can be processed using various techniques. Common examples include those with leucite, fluormica, lithium disilicate, and hydroxyapatite.

Hydroxyapatite ceramics are a type of ceramic that mimics the composition of natural bone. This biocompatibility makes them ideal for filling bone defects and promoting bone growth. They often are used in conjunction with lithium disilicate ceramics in dental restorations.

When the Coefficient of Thermal Expansion (CTE) of ceramic is greater than that of the metal, the ceramic will shrink more during cooling. However, the metal will restrict this shrinkage, resulting in tension within the ceramic and compression within the metal. This tension can create cracks on the ceramic surface.

When the CTE of ceramic is less than that of the metal, the metal will shrink more during cooling. This creates compressive forces on the ceramic, reducing the risk of cracking. This scenario is ideal for dental restorations as it minimizes stress.

These ceramics offer excellent aesthetics due to the size and arrangement of crystals, as well as the refractive indices of the glass and crystalline phases. The needle-like crystals of tetrasilicate of mica help resist micro-crack propagation, contributing to strength.

Lithium disilicate glass-ceramics have a relatively high CTE compared to traditional feldspathic ceramics. This difference can cause compatibility issues when veneering.

Hydroxyapatite glass-ceramics are specifically designed to have a CTE that matches lithium disilicate ceramics. This solves the compatibility issue and allows for strong, aesthetic restorations.

These glass-ceramics require a specific fabrication process involving pressure or CAD/CAM technology to achieve the desired structure and strength.

They offer excellent flexural strength, making them suitable for various restorations. They can be either lightly opaque or translucent depending on the specific application and aesthetic requirements.

They can be used as a core material for restorations, which is then veneered with aesthetic ceramics for a more natural appearance.