Dental porcelain (also known as dental ceramic) is a porcelain used by a dental technician to create biocompatible lifelike crowns, bridges, and veneers for the patient. Evidence suggests they are effective (they are biocompatible, esthetic, insoluble and have hardness of 7 on the Mohs scale), although for three-unit molars porcelain fused to metal or in complete porcelain group only zirconia-based restorations are recommended.
The dentist will usually specify a shade or combination shades for different parts of the restoration, corresponding to a set of bottles in the lab containing the porcelain powder. A common shade system used is the Vita guide (Vita Classical and Vita 3D Master). There are two types of porcelain restorations: porcelain fused to metal and complete porcelain. For porcelain fused to metal, the black color of metal is first masked with an opaque layer to make it a shade of white and then consecutive layers are built up. The powder corresponding to the desired shade of dentine base is mixed with water, and then fired. Further layers are built up to mimic the natural translucency of the enamel of the tooth. The porcelain is fused to a semi-precious metal or precious metal such as gold, for extra strength. Many systems use an aluminium oxide or zirconium oxide or zirconia core instead of metal that makes complete porcelain restorations.
Recent developments in dental CAD-CAM technology utilize special partially sintered ceramic (zirconia), glass-bonded ceramic ("Vitablock") or glass-ceramic ("ips.emax" lithium disilicate) formed into machinable blocks, which are fired again after machining. CAD/CAM restorations created with glass-ceramic CEREC technology appear to last well.
Dental porcelain is generally regarded as biologically inert. However, other toxicities may exist from depleted uranium and some of the other accessory materials, and the fillings may increase wear on opposing teeth.
Famous quotes containing the word dental:
“[T]hose wholemeal breads ... look hand-thrown, like studio pottery, and are fine if you have all your teeth. But if not, then not. Perhaps the rise ... of the ... factory-made loaf, which may easily be mumbled to a pap betweeen gums, reflects the sorry state of the nation’s dental health.”
—Angela Carter (1940–1992)