Prosthetics is considered a common dental procedure. It involves the manufacture of structures, processing of teeth, taking impressions, fixing the prosthesis. The patient will need to go not only to the orthopedist. You also need to visit a specialist to take impressions of the teeth. This procedure is described in the article.
Concept
Impression of teeth - display of teeth, soft tissues and bone structures of the oral cavity on a special material. An impression is a material that has solidified after being removed from the mouth. It includes the contours of the teeth, the display of muco-alveolar strands and other structures: transverse palatine sutures on the upper jaw, frenulum, lips, tongue.
Without a cast of teeth, it will not be possible to make plaster models and orthopedic structures. Impressions are performed not only by orthopedic doctors, orthodontists also perform this procedure. With the help of casts, diagnostic or working models are created to study the pathological form of bite, measure the size of teeth, jaws.
What is the withdrawal for?
Dental impressions are required for:
- Brackets. These systems perform the correction of various pathologies of the teeth. Lingual braces are usually made based on individual impressions.
- Trainers. Thanks to the soft elastic tires, anomalies are eliminated. Since the facial aesthetics of the closure of teeth is different for everyone, an impression is made before installing the products.
- Records. Eliminate imperfect bite in childhood will turn out with plates. To put on the product in one motion, it is made on the basis of an individual cast.
- Removable dentures. When there is no possibility of prosthetics with fixed elements, removable dentures are created. They may be different, but they are all performed on the basis of dental impressions.
- Single crowns. If one or more teeth are lost, crowns are placed. To obtain a high-quality cast, 2 methods are used: polyester mass and an open spoon.
- Bridges. Impressions are made from the jaw several times. The first one is for creating the frame of the prosthesis, the second one is for the body.
- Individual abutments. An impression is taken before the implant is inserted into the gum. Based on the impression, the type of abutment is selected.
More impressions are needed for crown inlays, retention trays, aligners. Performing this procedure allows you to make high-quality dental appliances.
Views
Tooth impressions are divided according to different criteria. They can be:
- anatomical and functional;
- full, partial;
- alginate, silicone, polyester (by material);
- one-stage, two-stage;
- single-phase, two-phase;
- compression, decompression.
With the help of anatomical impressions, the state of teeth, soft tissues, bone structures is displayed during physiological rest. Such casts are performed more often, but they have their own indications.
Functional impressions involve the Herbst test, which produces an impression with shaped edges by retracting the cheeks, pulling the lips forward and opening the mouth wide. This is important, since taking into account these parameters will help to make a design that will not burden the patient's life. These impressions are usually made for complete removable prosthetics.
Hard materials
Different materials are used to make models. Dental impressions are often made from hard materials. The main one is crystalline gypsum. It is valued for its affordability, low cost, accurate imaging of dental and soft tissue impressions.
Now it is rarely used, since the gypsum with crystallization and hardening is removed from the mouth in parts, and the doctor needs to compare them into a single model. Also, plaster should not be used to take impressions of teeth that are highly mobile.
Elastic materials
You can make an impression of teeth from elastic materials. Alginate substances are actively used. Advantages include: accessibility, good representation of oral structures, color change duringkneading the material, which is evidence of its readiness to be added to the spoon.
Of the shortcomings, a strong deformation of the cast is distinguished. It is necessary to quickly cast plaster models. Alginates may not be suitable. Some crowns and bridges require an accurate representation of the gingival portion of the teeth in order to produce an accurate model. Such impressions are used for stamped crowns, inlays, complete removable dentures, clasp prosthetics. The representative in demand among dentists is the Stomalgin material.
Silicone
2 types of silicones are used: C-silicones and A-silicones. These names are obtained due to the reaction of polyaddition or polycondensation, which are the basis of the hardening masses. They are the best impression materials that provide an accurate representation of the gingiva and shoulder.
Before applying A-silicones, complete removal of moisture is not required. The disadvantage is the cost: it is high.
C-silicone is required to be isolated from mouth fluid. Such impressions are used for cast structures, for example, Puffy Speadex. These materials include "Dentol" - a material with guaiacol, clove oil and zinc oxide. It has good properties and pleasant taste.
Polyester
They are expensive, but they allow you to get an accurate display of the relief of the soft tissues of the oral cavity, teeth, bone formations. This helps to take an impression of the teeth with maximum detail.
Thermoplastic
As the name suggests,the state of these materials changes with the action of temperatures. During heating, the material softens, and during cooling, it hardens. The benefits of this type include:
- easy to use;
- good tray connection;
- reusable.
But there are also disadvantages:
- risk of impression deformation when removing the mass;
- not quite a good representation of the oral cavity.
This group includes Kerr masses 1, 2, 3:
- Used for relining prostheses from edentulous jaws. Also with this view, impressions are taken for prosthetics with complete adentia.
- Used in the manufacture of maxillofacial devices.
- Impressions are taken for half-crowns, inlays, some tires.
Modeling
Include various materials. The main ones are: wax, stearin, paraffin, their combinations. Benefits include:
- convenience;
- versatility;
- accurate representation of dental and soft tissue impressions.
The disadvantage is the high risk of deformation due to the softening of the wax under the influence of temperature.
Requirements
In order for a dental impression for prosthetics to be of high quality, it must meet the following requirements:
- Accurate display of dentition, oral folds, transverse palatine folds, frenulum, buccal alveolar bands.
- Exclusion of pores,deformations.
If there are deformations, pores, inaccurate display on the casts after removal from the teeth, a re-impression is required. After all, the accuracy of removal affects the ease of use and prevents injury from the product.
Preparatory work
Almost immediately after choosing a product, the doctor takes impressions. But before that, under local anesthesia, he performs the preparation of hard tissues of the teeth. Then you need to dry the mouth with cotton swabs. A special tool can be used - a gun.
Then the spoon is selected and tried on. When the size is determined, the material is kneaded. With the complete absence of teeth, a change occurs in the dentoalveolar system. If they are absent for a long time, there is a decrease in bone tissue, bone outgrowths appear - exostoses. Therefore, before taking an impression, surgical preparation of the oral cavity for prosthetics is required.
Withdrawal
How is a dental cast made? When the clinical situation is assessed, the material for the impression is selected, the teeth are processed, the impression material is mixed by the doctor and placed on the spoon. The cast is inserted into the oral cavity. Spoons come in:
- metal and non-metal;
- upper, lower;
- compression, decompression.
The size of the spoon is determined by the size, shape of the jaw, width, length of the dentition and the height of the crowns. Orthopedic doctors have standard spoons, thanks to the fitting of which you can determine the size.
But not in every case you can use standard spoons, sometimes it becomes necessary to create individual devices. The doctor can make the spoon himself. This work is done by a dental technician. Based on the clinical situation, the type of construction, the doctor selects the appropriate class of impressions, their type. Then the specialist kneads the material and takes an impression. Then the cast is washed under running water and treated with a disinfectant solution. Then the plaster is kneaded and the model is cast.
Cost
The price of a cast of teeth for braces can be different. This is determined by:
- individual features;
- selecting material.
An important nuance is the exact display of the gingival part. This will allow for high-quality prosthetics. Often, doctors suggest using expensive materials.
The success of treatment depends on the qualifications of the specialist. A competent doctor determines the need for the use of materials and selects a suitable prosthesis. Correctly made casts of teeth will help to perform high-quality treatment.
