Herbst test: functional impression of an individual tray in dentistry, especially for edentulous jaws

The Herbst test is a procedure, the essence of which is the manufacture of an individual impression tray in dentistry, used for further prosthetics and setting of teeth.

It is carried out for each patient separately. This makes it possible to take into account all the features of his jaw, which makes it possible to obtain a good product for the dentist to perform further manipulations.

Herbst impression taking technique

The Gavrilov classification of making impressions calls the Herbst method for upper and lower jaws functional breakdown. The resulting products fit evenly with the prosthetic fields. For this purpose, an individual dental spoon is fitted.

At the same time, the release is performed bridles on the cheeks, lower lip and tongue with the formation of grooves along the edges of the product. The mucous tubercles are covered completely or in parts. It depends on their size and location.

An important point is the overlap of the false maxillary-hyoid lines while maintaining the possibility of saliva output by the ducts of the submandibular

glands. When creating custom spoons for toothless jaws it is necessary to take into account possible changes in the structure of the gums.

The main material for clarifying the boundaries of the impression is gypsum. Also, dentists can use silicone, which allows you to use its plastic properties for a long period of time.

Mandibular impression

The functional impression is performed in 6 stages:

1. The first test is accompanied by the installation of the workpiece on the lower jaw. After that, the patient covers his mouth and swallows saliva. During this manipulation, the muscles that compress the pharynx contract. Dropping the spoon is accompanied by its distal shortening.
2. At the second stage, the patient's tongue rests first on the left cheek, and then on the right. When dropping the workpiece, you need to shorten it near the inner oblique lines.
3. The third test is performed by touching the patient's tongue to the corners of the mouth. When the spoon is displaced, it decreases in zones 3, 4 and 5 on the oral side.
4. In the fourth stage, patients stick out their tongues and try to reach them up to the nose. After that, the tongue is carried over the upper lip. During these manipulations, the chin muscles are tense. If the spoon is displaced, it must be shortened by the front teeth from the side of the mouth.
5. The anatomical impression at the fifth test is determined by the tension of the pterygomandibular muscles with a wide opening of the mouth. The device is shortened distally.
6. The sixth test is used to isolate the vestibular border of the product. The patient retracts his cheeks and, when he is displaced, shortening is performed in the zone of 6, 7 and 8 teeth. Next, the patient pulls out his lips with a tube. The tension of the chin muscles helps to drop the spoon, after which it is done in the corresponding area.

Impression from the upper jaw

The procedure consists of 4 stages, according to modern classifications of individual impressions using functional tests. The first test consists of placing the spoons on the upper jaw. For this purpose, the patient opens his mouth wide. Due to the displacement of the product, it is shortened behind the modular cusp.

During the second test, the patient retracts his cheeks. Dropping with cheek strands is accompanied by a decrease in the size of the spoon about 6, 7 and 8 teeth, where the zone of the buccal muscles is located.

At the third stage, the upper lip is pulled down and forward. Due to the displacement of the spoon, it is shortened near the 3rd, 4th and 5th teeth.

During the fourth individual test, the patient pulls out the lips with a tube. After the displacement, it is shortened near the 12 teeth near the incisor muscles.

Carrying out functional tests according to Herbst is considered complete in the absence of displacements. Fitting is carried out with movements with careful movements in order to avoid significant reductions in the boundaries of the base.