How to make a basis with occlusal rollers. Model casting and production of wax bases with occlusal rollers

Central jaw ratio ( distal articular position of the mandible, terminal articulation) is a reproducible position of central occlusion in the absence of antagonists or complete absence of teeth.

There are several definitions of the position of the central ratio, which characterize only the position of the articular surfaces and the articular disc, the mutual arrangement of the jaws in three mutually perpendicular planes, and from this position the lower jaw can freely perform lateral movements. This position is not determined by the type of bite and the presence of teeth.

« Okeson describes this position as most musculoskeletal stable position mandible ».

"The central relationship can be defined as the position of the lower jaw relative to the upper jaw, in which the articular head-disk joints are in the highest position on the slopes of the articular tubercles, regardless of the position of the teeth and the height of the occlusion" (Peter E. Dawson).

Central ratio (centricrelation) - gnatological concept that defines the relationship between anatomical elements in the temporomandibular joints, determined by muscular balance in a position in which the articular discs located on the articular heads come into contact with the surface of the articular fossae with their thinnest part. This definition has evolved over time.

According to the latest edition of The Glossary of Prosthodontics Terms, this concept means:

1. The ratio of the lower and upper jaw in which the condyle is in contact with the thinnest (vascularless) part of the articular disc. This complex is located in a position above and anterior to the articular bulge, the position is independent of dental contacts. Clinically, it can be determined when the lower jaw is directed upward and anteriorly. This boils down to pure rotational movement around a transverse, horizontal hinge axis.

2. The greatest physiological retrusion of the lower jaw relative to the upper, from which movements can occur. Such conditions can be observed with varying degrees of separation of the jaws. Movements occur around the hinge axis.

3. The greatest retrusion of the lower jaw relative to the upper, when the condyles are in the articular fossae, in the most posterior, relaxed position, in which lateral movements are possible with little separation of the jaws.

4. The most posterior position of the lower jaw relative to the upper jaw, in which movements of the lower jaw can occur at a given height of occlusion (Boucher).

5. Such an arrangement of the lower jaw relative to the upper, when the condyles and articular discs occupy the most centric and highest position. This position is difficult to determine in the anatomical aspect, but it is determined clinically by analyzing the articulation of the lower jaw in a fixed boundary articulation axis (with an error of up to 25 mm). Those. is the clinically defined position of the mandible relative to the maxilla in which the condyle complex is most superior to the glenoid fossa and opposite the distal slope of the articular bulge (Ash).

6. The ratio of the lower and upper jaw, in which the condyles are in their highest position relative to the articular fossa. This arrangement is not observed in case of dysfunction of the chewing organ.

7. Clinically determined position of the mandible relative to the maxilla, in which both condyles occupy their highest and most anterior position. It cannot be determined in case of soreness or internal disturbances in the joints (Rams fjord).

prosthesis spoon individual

Gypsum models for prosthetic purposes are divided into working (main) and auxiliary.

A working model is called a model on which a denture is directly made.

An auxiliary model is called, on which the shape of the occlusal surface of the dentition of the opposite jaw is reproduced.

The production of working models consists of the following stages: 1) processing of the cast; 2) pouring the cast with plaster; 3) separation of the cast; 4) model processing.

Impression processing. The processing of the impression is carried out in different ways, depending on the impression material and whether the impression was taken from a jaw with teeth or from a toothless jaw. If the cast is taken with the help of plaster, then when the cast is removed, even from a toothless jaw, one or another number of parts is formed.

The model must be placed on the table without any inclination and have a thickness (height) at its thinnest point of at least 10 mm. The model should not be damaged, chipped, scratched. To avoid smoothing the relief, it is not recommended to trim a wet model and use mechanical devices for trimming with irrigation of the model with water. The boundaries of the prosthesis bases on the models are applied by the doctor.

The border of the prosthesis base on the upper jaw from the vestibular side passes along the transitional fold and coincides with the groove on the model. In the distal part, the basis completely covers the alveolar tubercles, connecting the hamular notches along the line "A". Bridle upper lip and buccal folds of the mucous membrane bypass the edge of the prosthesis.

The basis of the lower prosthesis also ends at the transitional fold. In the distal section, it overlaps the muco-muscular tubercle. Bridle lower lip, the frenulum of the tongue and the buccal folds are not closed by the edge of the prosthesis.

In addition to drawing the boundaries of the future prosthesis, lines are drawn in the middle alveolar process, median lines, bringing them to back side. Mark the boundaries of the alveolar tubercles, outline the contours of the torus and exostoses.

In order to prevent trauma to the mucous membrane, balance and breakage of the prosthesis, the bony protrusions of the jaws are isolated. Isolation is performed using lead foil 0.3-0.5 mm thick, cutting out a plate equal to the size of the bone protrusion and gluing it to the model with cement or glue. You can use a sticky plaster, the number of layers of which is applied to the model, depending on the severity of the torus or exostosis. Isolation should be maintained until the full fabrication of the prosthesis. After polishing the prosthesis, the insulating material is removed and the edge around it is smoothed.

Obtaining wax bases with occlusal rollers

A wax plate heated on one side is placed on the model with the other side, and while the wax is in a plastic state, it is carefully pressed over the model.

In the grooves (grooves), the wax is pressed against the model with the help of the rounded end of the spatula and the edge of the wax plate is immediately bent up, filling the entire groove with plastic wax. Trim off excess wax.

Occlusal ridges made from monolithic blanks or from fused base wax, twisted into a tight roll, is usually located in the middle of the alveolar process. With a significant discrepancy in the size of the models, the rollers are made wider to ensure maximum contact of the upper rollers with the lower ones in the oral cavity.

AT anterior section rollers are made 8 mm wide, in the side ones - 10 mm. The height of the ridges depends on the degree of atrophy of the alveolar processes and ranges from 10 to 15 mm.

Determination of interalveolar height and height lower third faces is one of the critical stages in prosthetics for patients with complete loss of teeth, because in this case, the doctor does not have clear signs that help to orientate in patients with partially preserved teeth.

Currently, there are two methods for determining the height of the lower third of the face or interalveolar height: anthropometric and anatomical-functional. The second method is more commonly used.

It consists of the following points:

• 1) design of the upper bite template, taking into account appearance the patient;
• 2) building a prosthetic plane;
• 3) determination of the interalveolar height or the height of the lower third of the face;
• 4) determining the central position of the lower jaw;
• 5) fixing a certain ratio of jaws;
• 6) drawing reference lines. After carrying out all the actions according to this scheme, the doctor determines the shape and color of the teeth, focusing on the type of face, the age of the patient, the presence or absence of bad habits etc.

With a large atrophy of the alveolar process in the lower jaw, at the moment of fixing a certain ratio of the jaws, a shift in the lower bite pattern may occur, as a result of which an unusual position of the lower jaw will be fixed. In order to prevent displacement of the lower bite template posteriorly and prevent a mistake, the dental technician on the bite template in the area of ​​the fifth or sixth teeth from the vestibular side simulates tides, on which the doctor will put a large and index fingers hands while fixing the central ratio, not allowing the bite template to move.

Production of wax bases with bite rollers.

For determining central occlusion with partial defects in the dentition and the complete absence of teeth, it is necessary to make wax bases with occlusal wax rollers on plaster models of the jaws. On a model moistened with water, with a prosthetic bed previously outlined in pencil, a wax base is first made. The wax plate is heated on one side above the burner and applied with the unheated side to the model, while thumb press it against the palatal surface of the model and the edentulous areas of the alveolar process. The formation of the wax base on the model of the upper jaw starts from deep areas hard palate, pass to the alveolar process and end on vestibular side, firmly pressing the wax to the transitional fold.

On the model of the lower jaw, a wax base is formed first from the lingual surface and ends on the vestibular one. With a heated spatula, wax is cut along the border of the future prosthesis, marked with a pencil on the model. To avoid deformation of the wax base, models can be strengthened with a curved wire, strengthening it with heated wax. A wire (copper or iron) with a cross section of 1-1.5 mm is bent in the shape of an alveolar ridge and, with the help of tweezers, in a state slightly heated above the burner flame, is inserted into the thickness of the wax base and poured with molten wax. Then proceed to the formation of occlusal rollers. The wax plate is heated over the flame of the burner from both sides and rolled up. Rollers 1 cm wide and 1-1.5 cm high are placed on a wax base in the center

alveolar process in places where there are no teeth, and glued to the base all over with melted wax. The rollers should be wider than the remaining teeth and flush with them. With a heated spatula, the surface of the rollers is made smooth with a bevel at the ends.

Determination of central occlusion and ratio of the jaws.

Central occlusion is determined: templates with occlusal rollers are wiped with alcohol, rinsed, inserted into the mouth and the patient is asked to carefully close his teeth. If the opposing teeth are separated, the rollers are trimmed; if the teeth are closed, and the rollers are separated, wax is layered on the latter until the teeth and rollers are in contact. The position of the central occlusion is determined by the occlusion of the teeth. After that, a strip of wax is placed on the occlusal surface of the fitted roller, glued, and then softened with a hot spatula. Without allowing the wax to cool, the templates are inserted into the mouth and the patient is asked to close his teeth. On the softened surface of the wax, imprints of teeth remain, they serve as a guide for drawing up a model in a central ratio, indicative lines are applied in the anterior part of the roller.

Otherwise, they act if the occlusal surface of the upper and lower rollers are closed. In this case, transverse wedge-shaped grooves are made on the occlusal surface of the upper bite roller. From the lower roller, opposite the cuts, they remove thin layer and attach a heated strip of wax. Then the patient is asked to close his jaws; the heated wax of the lower roller enters the groove on top view wedge-shaped projections. The rollers are removed from the oral cavity, cooled and installed on models that are plastered into the occluder.

Production of wax bases with occlusal rollers

1. Wax base.

2. Reinforcement.

3. Wax roller.

Figure 14. Making wax bases with occlusal rollers.

Production of wax bases with occlusal rollers.

An occluder is an apparatus that reproduces only opening and closing of all types of jaw movements. The occluder is used in the design of dentures.

Figure 15. Occluder.

Technique of plastering models in the occluder.

After determining the central occlusion, the models fastened together must be plastered into the occluder. To do this, models with wax bases are inserted into the occluder, making sure that the height pin of the occluder rests against the platform of the lower frame. There must be a place for plaster between the models and the arches of the occluder. Gypsum is kneaded, a small amount of it is applied to the smooth surface of the table and the lower frame of the occluder is immersed in it. A small amount of gypsum is also applied, and the models fastened together are placed on it, while centering. The plinth of the lower model is covered with gypsum using a spatula and the gypsum is smoothed so that it completely covers the outer arc of the frame and the plinth of the model. At the same time, make sure that the height pin constantly touches the model. Carefully, so as not to break the plaster teeth, open the occluder and remove the wax bases with occlusal rollers from the models.

MATERIALS SCIENCE

Basic materials- materials from which prostheses are directly made.

Auxiliary materials- materials used at various stages of the manufacture of prostheses.

Scheme 6. Characteristics of the main and auxiliary materials.

The technique for making wax bases with occlusal rollers does not differ from that described above. However, in view of total absence teeth on the jaws, it is necessary to know and strictly adhere to the size and location of the occlusal ridges in the anterior and lateral sections, to strictly observe the boundaries of the basis of the prosthesis, its thickness and fit to the model.

On a plaster model, previously moistened with water, a wax plate is pressed and the edges are trimmed along the marked boundaries. Having strengthened the wire arc on the oral slope of the alveolar part (process), occlusal ridges are prepared from durable wax and modeled according to the shape of the jaw. The width of the ridge on the upper jaw in the anterior section should be 3-5 mm, in the lateral sections 8-10 mm and end at a distance of 5 mm from the middle of the maxillary tubercle. The front section of the upper roller is located at a distance of 8-10 mm anterior to the center of the incisive papilla. The height of the roller in the anterior part of the model of the upper jaw is 15–20 mm, distal 10–12 mm, on the model of the lower jaw 10–15 mm.

Then the vestibular and oral surfaces of the occlusal ridges are modeled, achieving a direct transition to the surface of the wax base. The angle formed by the vestibular (oral) surface with the occlusal plane of the ridge should be 90--100°.

When working on solid bases, the latter are made by replacing the wax base with plastic according to the generally accepted method. Plastic bases are fitted in the oral cavity with a check of their fixation on edentulous jaws, clarification of boundaries and thickness. Then wax occlusal rollers are made and placed on solid bases in compliance with the requirements described above.

The use of solid bases for subsequent work in the clinic to determine the central ratio toothless jaws and checking the design of prostheses facilitates the work of the doctor, prevents errors and improves the fixation of finished prostheses.

They are used for significant atrophy bone base jaws and for conducting phonetic tests at the stage of checking the design of prostheses.

Definition of central ratio toothless jaws- the clinical stage at which the doctor creates the conditions for the correct design of the dentition and the prosthesis as a whole. It includes the following operations:

• 1) establishing the height of the occlusal ridge of the upper jaw in the anterior region;
• 2) definition of the occlusal plane;
• 3) determination of the interalveolar height;
• 4) determination and fixation of the central ratio of edentulous jaws;
• 5) applying anatomical landmarks to the vestibular surface of the occlusal ridges for setting artificial teeth (midline of the face, line of fangs and line of a smile).

To determine the central occlusion, it is necessary to make wax bases with occlusal wax rollers on plaster models of the jaws. A plate of dental wax is uniformly heated only on one side over a burner flame or over an electric stove. The softened plate is placed on the plaster model of the jaw with the unheated side and the thumb is pressed against the palatal surface of the model and to the edentulous areas of the alveolar process, trying not to push through and thin it.

The formation of the wax base begins on a plaster model of the upper jaw from deep areas of the hard palate, passes to the alveolar process and ends on the vestibular side, pressing the wax firmly against the transitional fold. On the model of the lower jaw, a wax base is formed first from the lingual surface and also ends on the vestibular surface. With a heated spatula, wax is cut along the border of the future prosthesis, marked with a pencil on the model (Fig. 123, a). To avoid deformation of the wax base at the temperature of the oral cavity, it is strengthened with wire. An aluminum wire is bent along the anterior and lateral sections of the palatal surface, heated and inserted into the wax base, additionally strengthening it with heated wax (Fig. 123, b). Then proceed to the formation of occlusal rollers. Rollers are made from a plate of dental wax heated over a flame on both sides and rolled up. More economical in terms of time and material is the method of casting blanks of occlusal ridges in a standard form from wax residues. Rollers 1 cm wide and 1-1.5 cm high are placed on a wax base in the center of the alveolar process in the areas of missing teeth and glued to the base throughout with melted wax. The rollers should be wider than the remaining teeth and flush with them. With a heated spatula, the surface of the rollers is made smooth with a bevel at the ends.

To determine central occlusion, the doctor glues a heated strip of wax to the rollers, removes wax bases with occlusal rollers from plaster models and inserts them into the patient's oral cavity. When the jaws are closed, the imprints of the antagonist teeth remain on the softened occlusal roller. In the absence of anterior teeth on the occlusal ridges, the doctor must mark the midline (cosmetic center), the smile line and the canine line for the selection and setting of the anterior teeth. After determining the central occlusion and drawing landmarks, the doctor removes the wax bases

Rice. 123. Stages of making wax bases with occlusal rollers. Explanation in the text.

Ditch. 124. Drawing up models in the position of central occlusion. Explanation in the text.

from the oral cavity, imposes them on plaster models jaws and, accordingly, the imprints of the antagonist teeth on the occlusal ridges make up the models in the position of central occlusion. To avoid errors in determining the central occlusion, the doctor in the patient's mouth checks the density of contact between the occlusal ridges and between the remaining antagonists. In this state, the models are strengthened among themselves and transferred to the laboratory. In the dental laboratory, the dental technician can assemble and fasten the models together according to the impressions of the teeth on the wax roller in the position of the central occlusion determined by the doctor using sticks (Fig. 124).