Crown (dentistry) - All-ceramic Restorations

All-ceramic Restorations

Inlays, onlays, porcelain veneers, crownlays and all varieties of crowns can also be fabricated out of ceramic materials, such as in CAD/CAM Dentistry or traditionally in a dental laboratory setting. CAD/CAM technology can allow for the immediate, same day delivery of these types restorations which are milled out of blocks of solid porcelain which matches the shade or color of the patients teeth. Traditionally, all-ceramic restorations have been made off site in a dental laboratory either out of feldspathic porcelains or pressed ceramics. This indirect method of fabrication involves molds and temporaries, but can yield quite beautiful end-results if communication between the laboratory and the dentist is sound. The greatest difference between these two differing modalities lies in the fact that the CAD/CAM route does not require temporization, while the laboratory-fabricated route does. Some argue that this lack of temporization can result in a decreased need for root canal therapy, as there is no temporary leakage between visits.

Restorations that are all-ceramic require wide shoulder margins and reductions of at least 1.0 - 1.5 mm across the occlusal (chewing) surfaces of the teeth. There are times where this reduction would be considered excessive, just as there are times when previous restorations or pathology require this much removal or more. Arguments against using all-ceramic restorations include a greater chance of fracture, when little to no enamel remains for proper adhesive bonding, or potentially when the patient clenches or grinds their teeth ("bruxes") excessively. Indications for using all-ceramic restorations include more aesthetic results, when metal compatibility issues exist, and when removal of less tooth structure is desired. All-ceramic restorations do not require resistance and retention form and consequently less surface area need be removed and the restoration will still stay in place by virtue of micromechanical and chemical bonding.

Ceramic materials such as lithium disilicate dental ceramics have recently been developed which provide greater strength and life-expectancy of dental restorations.