Such crowns make without the content of metal, that is without metal cap.
Bezmetallovy crowns possess a much bigger esthetics as there is no need to paint over gray color of a metal cap. And on inspection at the doctor such crown is indistinguishable from tooth.
When processing tooth under bezmetallovy ceramics there is no need to immerse it under a gum that provides total absence of an inflammation of a gum near a crown. Ceramic-metal crowns need to be immersed surely under a gum to hide a gray rim of a metal cap. The Bezmetallovy ceramics is harmless to an organism, and metal in turn can render harm for zheludochno intestinal path. With crowns from bezmetallovy ceramics tooth is processed less, than for ceramic-metal crowns. In bezmetallovy crowns there is no need to mask a metal framework.
The Bezmetallovy ceramics is deprived of a metal framework, at the same time rather strong basis from special ceramics — zirconium oxide is applied. Crowns on the basis of oxide of zirconium demand smaller preparation of tissues of tooth as here masking of a metal framework is not necessary. The insignificant weight of bezmetallovy crowns significantly reduces load of basic teeth or implants.
The framework for a crown is made of zirconium oxide by method of computer milling, as explains production accuracy. Framework durability from oxide of zirconium of 600 MPa. At first the framework is made of zirconium oxide (on color of tooth), then ceramic weight is applied on a zirconium framework.
Oxide of zirconium of which the bezmetallovy ceramics consists is hypoallergenic material, and in a question of biocompatibility considerably surpasses any alloys, including gold. Favorable clinical results are confirmed with histologic researches: after annual contact with ceramics on the basis of zirconium oxide in an oral cavity no pathological changes are revealed. The only contraindication to use of designs on the basis of oxide of zirconium is the expressed deep bite and a bruksizm.
Stages of prosthetics of bezmetallovy kermiky:
Preparation of tooth under prosthetics by a bezmetallovy ceramic crown from oxide of zirconium demands special care, if to look without zirconium crown, then with surprise it is possible to find out that it passes light. It means that nelz to achieve a full esthetics if to put a metal pin in tooth.
Conclusion: by preparation of teeth under prosthetics by zirconium crowns it is necessary to use fiber glass pins, fiber glass stumps and photopolymeric materials which pass light. Of course, if to fit a prosthesis on live teeth, absolutely other question. No material to be compared to natural tissues of tooth.
Quality of a preparovka of tooth under zirconium crowns has to be ideal. Accurately created ledge on which there will be an edge of a crown demands qualitative pine forests and expensive turbine.
The print of otpreparirovanny teeth has to be made by qualitative materials of the last generation – And — silicones. It means the rights for a mistake at the expert is not present as all further process is brought to automatism. Later color of bezmetallovy ceramics, as a rule, in the conditions of natural lighting is selected. Specially to the patient there comes the technician, the smallest details are discussed.
Otpreparirovanny teeth are covered with provisional (temporary) crowns. It is necessary to cover both live and dead teeth as appearance of a gum entirely depends on temporary crowns. From that, how correctly they are adjusted and recorded on good cement. Cement for crowns has to be special, not containing an evgenol in the structure. The slightest impurity of an evgenol breaks process of hardening of constant cement for fixing of ready work.
The print goes to laboratory from it cast models which then scan by means of CAD/CAM technology (CAD — "computer aided design", that is computer design, CAM — "computer aided manufacturing" computer and programmable production). CAD/CAM technology, using mechanical and laser scanning, allows to make a design of future framework precisely and qualitatively.
After scanning of a print preparation from zirconium oxide from which the special milling car will cut future framework is selected. At this stage the difficulties: the framework can be snow-white or painted under color of tooth, preparations happen various thickness, etc. All this of course affects working costs.
Only after milling and assessment of future framework on model, the technician starts the art calculation of ceramics. At first the basic shape of tooth, then layer-by-layer drawing other layers of ceramics is recreated. The ceramics burns in a special oven, later glaze is applied on it. Generally, way long.
Fitting of a design in an oral cavity before a tsementirovka and if all esthetic nuances are observed, fixing on constant cement.
Complexity of production of zirconium crowns, so and cost of bezmetallovy ceramics also consists of all stages described above.