In the lateral parts of the oral cavity, a one-piece crown is often installed. This is necessary to restore the anatomical integrity of the dentition when, for various reasons, a person loses one or more teeth. This type of prosthetics allows you to save the functions of the jaw apparatus.
What materials are crowns made of
For the manufacture of solid crowns, alloys are used that have high strength. In modern dentistry, chromium-based materials are used, additionally alloyed with nickel and cob alt. The use of titanium has proven itself well. This metal is highly resistant to aggressive environments, does not darken, and also has high biocompatibility. A one-piece crown can also contain precious metals. Gold crowns allow you to make the most accurate fit, since the metal has a high ductility. They work well and rarely break. However, the gold crown still wears out, and it also has a high cost. Mainindications for prosthetics with cast crowns are the complete loss of one or more teeth, the restoration of the functionality of the dentition.
Main types of cast dentures
Today, these types of cast crowns are distinguished:
- Prostheses without spraying - have the appearance of the original metal, polished to a shine.
- One-piece crown with coating (most often golden). This type also has a drawback - spraying does not have a very favorable effect on the mucous membrane of the oral cavity.
- The third type - crowns with lining. As a facing material, plastic or cermet is used. Special overlays cover the surface of the prosthesis in the smile area. Despite the good aesthetic appearance, such overlays can chip off. In addition, their cost increases significantly due to the use of expensive materials.
The first two types are used to replace the side teeth. If you need prosthetics of the front of the dentition, then the third type is best suited. It should be noted that the walls of the crown are quite thin (up to 1 mm). This significantly affects the preliminary filing of a live tooth.
Production of a solid crown. First clinical and laboratory stages
First of all, the dentist must examine the oral cavity. If there are affected areas, they must be sanitized. The first clinical stage includes obtaining an impression of the dentition and the tooth itself for further casting. For thisoften use special silicone masses, which allow you to fully display all the anatomical features. During this period, the patient can install special temporary constructions. Their task is to accelerate the habituation of the gums, to create an aesthetic effect. At the first laboratory stage, a collapsible plaster model is made. Next, the prosthesis is plastered into the occluder, and a wax crown is modeled. After that, the wax is replaced by metal (in a special foundry laboratory). Then, the cast crown is processed properly.
Second clinical and laboratory stage
At the second stage (clinical) the fitting of the product takes place. Additionally, the tooth is ground down for a high-quality installation of the crown. The prosthesis is filled with wax, applied to the installation site. Excess material exits through a pre-drilled hole. Then the crown is removed, all inaccuracies are smoothed out, occlusal relationships are checked. The prepared product is transferred to the laboratory. This is where polishing and polishing takes place. The accuracy of manufacturing is checked on a plaster model. It is also important to evaluate how the prosthesis closes with parallel antagonist teeth. It is worth noting that the work requires a lot of concentration. Even a slight discrepancy in size can cause difficulties when wearing a crown, constant pain and discomfort.
Final installation
The finished crown is fixed in the oral cavity. Whereinimmersion of the end of the prosthesis under the gum should be minimal. The quality of the installation is also checked by how tightly the patient's tooth is covered. Also, when closing the antagonists, there should be no discomfort. If necessary, it may be necessary to grind part of the material. Also, if there is a lack of material, the crown can be sent again to the laboratory. If the prosthesis fits, the person does not feel it, then fixation occurs with permanent cement. It is worth noting that if solid crowns are installed, their manufacturing steps take quite a long time - up to several weeks.
The main advantages of these crowns
First of all, solid crowns have a long service life. Since this technology allows you to fully display all the nuances of the anatomical structure, the prostheses organically fit into the dentition, food does not get under them, etc. All this allows you to wear them for more than 10 years. In the manufacture of bridges, soldering is not used, and this additionally strengthens the crowns and prolongs their service life. Another advantage is that more dental tissue is preserved under the crown (unlike metal ceramics). Since the thickness of a solid crown does not exceed 0.3-1 mm, the tooth is less amenable to grinding. As a result, his life is extended. In addition, such prostheses are easy to manufacture. And, of course, a cast crown (photo below) is more affordable, its cost is relatively low.
Disadvantages of cast structures
Of course, for the front teeth, such crowns are notfit. The minimum choice of color - golden, silver - is one of the significant drawbacks of such prosthetics. The metal has a high thermal conductivity, this can cause discomfort in the patient's oral cavity. Since hard alloys are used in the manufacture, crowns can cause wear and deformation of the dentition of the opposite jaw. In addition, the production of cast crowns requires a highly qualified specialist.
