In the lateral parts of the oral cavity, a solid cast 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 is the crown made of?
For the manufacture of cast crowns using alloys that have high strength. In modern dentistry, chromium-based materials are additionally alloyed with nickel and cobalt. The use of titanium has proven itself well. This metal is highly resistant to aggressive environments, does not darken, and also has high biocompatibility. One-piece crown may include precious metals. Gold crowns allow you to make the most accurate fit, as the metal has high ductility. They are good in operation, rarely break. However, the gold crown still wears out, besides it has a high cost. The main indications for prosthetics with one-piece crowns is the complete loss of one or more teeth, restoration of the functionality of the dentition.
The main types of cast dentures
To date, these types of cast crowns are distinguished:
- Dentures without spraying - look like the initial metal polished to a shine.
- One-piece crown with a dusting (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 is crowns with facing. As the facing material, plastic or cermet is used. Special pads cover the surface of the prosthesis in the smile area. Despite the good aesthetic appearance, such linings can be chipped. In addition, their cost increases significantly due to the use of expensive materials.
The first two types are used to replace the posterior teeth. If prosthetics of the anterior part of the dentition is necessary, then the third type is best suited. It is worth noting that the walls of the crown are quite thin (up to 1 mm). This significantly affects the preliminary filing of a living tooth.
Making a cast crown. The first clinical and laboratory stages
First of all, the dentist must conduct an examination of the oral cavity. If there are affected areas, they must be sanitized. The first clinical stage involves obtaining an impression of the dentition and the tooth itself for further casting. For this, special silicone masses are often used, which make it possible to fully display all the anatomical features. During this period, the patient can install special temporary structures. Their task is to accelerate the addiction of gums, to create an aesthetic effect. At the first laboratory stage, a collapsible gypsum model is made. Next, the prosthesis is cast into the occluder, a wax crown is modeled. After that, the wax is replaced with metal (in a special foundry laboratory). Then the solid cast crown is processed properly.
The second clinical and laboratory stage
At the second stage (clinical), the product is fit. In addition, grinding of the tooth is carried out for 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, the occlusal relations are checked. The prepared product is transferred to the laboratory. Polishing, grinding is done here. The manufacturing accuracy 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 work requires a large concentration of attention. Even a small size mismatch can cause difficulties when wearing a crown, constant pain and discomfort.
Final installation
The finished crown is fixed in the oral cavity. In this case, the immersion 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 antagonists close, there should be no discomfort. If necessary, grinding of a part of the material may be necessary. Also, if there is a lack of material, the crown can be sent again to the laboratory. If the prosthesis is suitable, the person does not feel it, then fixation with permanent cement occurs. It is worth noting that if cast crowns are installed, the stages of their manufacture take quite a long time - up to several weeks.
The main advantages of these crowns
First of all, solid cast crowns have a long service life. Since this technology allows you to fully display all the nuances of the anatomical structure, prostheses fit seamlessly into the dentition, no food falls under them, etc. All this allows you to wear them for more than 10 years. In the manufacture of bridges prosthesis is not used, and this additionally strengthens the crowns, prolongs their life. Another advantage is that more dental tissue is retained under the crown (as opposed to cermet). Since the thickness of the cast crown does not exceed 0.3-1 mm, the tooth is less susceptible to grinding. As a result, his life is extended. In addition, such prostheses are easy to manufacture. And, of course, the one-piece crown (photo below) is more affordable, its cost is relatively low.
Disadvantages of cast structures
Of course, such crowns are not suitable for front teeth. The minimum color choice - golden, silver - is one of the significant disadvantages of such a prosthetics. The metal has a large thermal conductivity, this can cause discomfort in the patient's oral cavity. Since hard alloys are used in the manufacture, crowns can provoke wear, deformation of the dentition of the opposite jaw. In addition, the production of solid cast crowns requires highly qualified specialist.