Classification Of All- Ceramic Dental Restoration Materials

● According to the different contents of glass phase and crystal phase in the microstructure of the material, all-ceramic materials are divided into three categories:

① Feldspar porcelain. It is mainly a glass phase, which is made of three natural components: feldspar, quartz and kaolin sintered at high temperature. Feldspathic porcelain is the earliest ceramic material used in dentistry, and its optical properties are very close to those of enamel and dentin. However, due to its poor mechanical properties, the flexural strength is usually only 60-70MPa, so it is often used as porcelain-fused-to-metal restorations and fused-to-ceramic restorations.

② Glass ceramics. Containing both glass phase and crystal phase, also known as glass-ceramics, it is a type of composite material that combines crystal phase and glass and is made through high-temperature melting, molding, and heat treatment. Compared with amorphous glass, the addition or growth of crystalline fillers in the glass phase has greatly changed the mechanical and optical properties of glass-based ceramics, such as increasing the thermal expansion coefficient and toughness, changing the color and opalescence of the material sex and transparency.

③ Polycrystalline ceramics. It is a dense ceramic material that is directly sintered from crystals and does not contain glass or gas phases. It has high strength and hardness and is processed using CAD/CAM equipment. Due to the lack of glass phase, this type of material usually has very low transparency and needs to be decorated with veneer porcelain. Glass-based ceramics have good aesthetic properties. As the number of crystals increases, their strength becomes higher and higher, but their transparency becomes worse.

Highly transparent zirconia dentures

This classification method implies the relationship between ceramic composition and indications. However, the development of current polycrystalline ceramic microstructures, the advent of more translucent zirconia and stronger glass ceramics of reduced transparency, challenges this concept. Fundamental developments in ceramic technology in industry: The manufacturing process of these materials has shifted from natural ingredients (i.e. feldspar) to synthetic ceramics.

● According to the different chemical composition and microstructure of all-ceramic materials, all-ceramic materials are divided into the following three categories: glass-based ceramics, polycrystalline ceramics and resin-based ceramic materials. Compared with traditional ceramic materials, resin-based ceramic materials have special properties because they contain organic scaffolds. It has the following advantages: it is closer to the elastic modulus of dentin; it reduces the brittleness and hardness of the material, making it easier to cut; and it is more convenient Use resin to repair; the strength will not be affected after modification, and the clinical operation is simple; the wear on natural teeth is much less than that of glass ceramics; no thermal processing is required, and its design and production can be completed at the chairside.

With the progress of research on the structure and processing methods of zirconia materials, the performance of zirconia has gradually improved, and its clinical applications have become more widespread, such as artificial hip joints and more familiar oral restorations.