Metal ceramic crowns are used indental practice has long been successful. They are strong, but have some drawbacks in terms of appearance. The effect of a living tooth is only partially created, no matter how carefully the color of the ceramic is chosen. This is due to the fact that the metal frame has its own color, completely disguise which does not always work. Another drawback of such prostheses is the negative effect of metal on the gum. Whole-ceramic crowns are free from these drawbacks, but they are far less durable than 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. Zirconia, which was used for prosthetics inmedical practice since 1969, are increasingly used to make dentures. Sometimes, not using its exact chemical name, this material is called simply zirconium. In dentistry, it is usually used to make the skeleton of dental crowns.
Crowns with a frame of zirconia, possessthe ability to transmit light comparable to the translucency of natural teeth, so they look natural and do not differ from natural teeth. At the same time they have strength, comparable with the strength of metal-ceramic crowns.
When manufacturing dentures, the basis forcrown is usually melted. Crowns made of zirconia are the exception. The laser scanner determines the shape of the future crown, the data is processed by a computer program, and the computer designs the crown model. Then a special machine, in accordance with the program specified by the computer, sawing from a single piece of zirconia is performed. The resulting crown has not only high accuracy, but also provides an impeccable appearance.
More recently, crowns made of ceramic materialswere placed only on the front teeth, that is, their use was caused, rather, by aesthetic considerations than practical application. The use of zirconia has no limitations. It is suitable for prosthetics of the front and chewing teeth, and also ideally combined with implants. Using this technology, make single crowns and extended bridges. Zirconium dioxide is hypoallergenic and absolutely bioinertal in relation to the human body material, therefore it can be used for prosthetics even in patients prone to allergic reactions. By the degree of bioinertity, it surpasses even gold.
Zirconia has highheat-insulating properties, so crowns protect teeth from sudden temperature changes. This is a real salvation for those patients whose teeth are sensitive to cold and hot food.
Crown frame is very thin, its thickness is only0.4 mm. Therefore, the ease of the design of the dental prosthesis provides almost instantaneous adaptation to the "new teeth". In addition, the frame of zirconia, in contrast to metal, does not deform with time. Ceramics designed specifically for these purposes and having a similar light permeability are used for facing the frame.
Many people are familiar with the fear of damaging the dentalCrown when eating too hard food. Zirconium dioxide will allow to get rid of this anxiety forever. If a microcrack occurs, the material independently restores its structure at the molecular level.
With dental prosthetics both metaland metal-ceramic crowns, a black rim often appears in the gum area. Crowns with a frame of zirconium dioxide, even with prolonged use, do not cause any changes in the gums.