Ceramic-metal crowns have been used in dental practice for a long time and quite successfully. They are durable, but have some disadvantages in terms of appearance. The effect of a living tooth is only partially created, no matter how carefully the color of the ceramics is selected. This is due to the fact that the metal of the frame has its own color, which cannot always be completely masked. Another disadvantage of such prostheses is the negative effect of metal on the gums. All-ceramic crowns are devoid of these drawbacks, but they are far from being as durable as crowns with a metal frame.
In modern dentistry, when choosing materials for prosthetics, not only its functional, but also aesthetic properties are taken into account. Zirconium dioxide which has been used for prosthetics in medical practice since 1969, is increasingly used for the manufacture of dentures. Sometimes, without using its exact chemical name, this material is simply called zirconium. In dentistry, it is usually used to make a dental crown frame .
Crowns with a zirconia framework have the ability to transmit light, comparable to the light transmission of natural teeth, therefore they look natural and do not differ from natural teeth. Moreover, they have a strength comparable to the strength of ceramic-metal crowns.
In the manufacture of dentures, the base for the crown is usually melted. Zirconia crowns are an exception. Using a laser scanner, the shape of the future crown is determined, the data is processed by a computer program, and the computer designs the crown model. Then, using a special apparatus, in accordance with the program set by the computer, sawing from a single piece of zirconia is performed. The resulting crown is not only highly accurate, but also provides a flawless appearance.
More recently, crowns made of ceramic materials were installed only on the front teeth, that is, their use was caused more by aesthetic considerations than by practical application. The use of zirconia is not limited. It is suitable for prosthetics of anterior and masticatory teeth, and also ideally combines with implants. Using this technology, single crowns and extended bridges are made. Zirconia is a hypoallergenic and absolutely bioinert material in relation to the human body, therefore it can be used for prosthetics even in patients prone to allergic reactions. In terms of bioinertness, it surpasses even gold.
Zirconium dioxide has high heat-insulating properties, therefore crowns protect teeth from sudden temperature changes. This is a real salvation for those patients whose teeth are sensitive to cold and hot food.
The crown frame is very thin, its thickness is only 0.4 mm. Therefore, the ease of construction of the denture provides almost instant addiction to the "new teeth". In addition, the zirconia framework, unlike metal, does not deform with time. For the cladding of the frame, ceramics are used, designed specifically for these purposes and having similar light transmission.
Many are familiar with the fear of damaging the tooth crown when biting too hard foods. Zirconia will permanently get rid of this anxiety. If a microcrack occurs, the material independently restores its structure at the molecular level.
With dental prosthetics with both metal and ceramic-metal crowns, a black rim often appears in the gum area. Crowns with a zirconia framework, even with prolonged use, do not cause any changes in the gums.