Message Dr_Arut » Mon May 16, 2016 5:23 am

To obtain a functional impression in dentistry, an individual tray is used, which is made from an anatomical cast. An individual tray matches the prosthetic bed as closely as possible and allows for functional testing, so the impression more accurately reflects it. There are four main methods for making custom spoons, listed below in chronological order.

Making an individual spoon from quick-hardening plastic;
Making an individual spoon from a thermoplastic plastic plate using vacuum molding;
Making an individual spoon from a photopolymer composite plate;
3D printing.

The oldest and most common method is to make a spoon from cold polymerized plastic (Protacryl-M, etc.). To do this, a plaster model is cast from ordinary plaster (class II) based on an anatomical cast. Trim the model using a trimmer. Draw the border of the future individual spoon with a chemical pencil. Usually the border extends 1-2 mm before reaching the vestibule of the oral cavity, i.e. 1-2 mm shorter than the edge of the removable denture base. Also, the edge of the spoon does not reach the frenulum and cords by 1-2 mm. This space is necessary for proper shaping of the edges using thermoplastic or viscous silicone impression compounds.

Making an individual spoon from quick-hardening plastic.
After completing the drawing of the boundaries, the undercuts are isolated with wax so that the finished individual spoon can be removed from the model. Heat up the base wax plate and press it evenly onto the model. Cut it along the previously drawn border. In the area of the palate and alveolar processes in the lateral section, round or square holes (windows) are made in the wax to create restrictions on an individual tray, which in these areas will be in contact with the oral mucosa. This is done to create a uniform gap between the spoon and the mucous membrane, which will be filled with corrective silicone mass. The window area is lubricated with insulating varnish (Izokol-69, Pikasep, Vaseline, vegetable oil, etc.).

Next, cold polymerized plastic is mixed according to the manufacturer's instructions (usually in a 2:1 weight ratio of powder to monomer). The easiest way to model a spoon made of cold-polymerized plastic is to use a special silicone mold with a base-shaped model several millimeters high. A thin plastic film (cling film, etc.) is spread on the bottom of the mold, the mixed plastic is poured into the mold, leveled in the mold and covered with a second layer of film on top. It is left for a few minutes for the plastic to mature and enter the “test stage”. After this, the top (second) layer of film is removed, the top side of the plastic is pressed against the model, accordingly it turns over and the bottom layer of film is on top. Next, the plastic is adapted to the model through the film. The film is also removed from the excess, i.e. plastic that extends beyond the boundaries of the spoon is modeled as a handle. If it is necessary to model the supports for the fingers on the spoon in the side sections, then this is also done from the surplus.

Next, the dental technician waits for the plastic to harden. After hardening, remove the spoon from the plaster model and, if necessary, separate the wax from the spoon. Shortens the spoon according to the drawn boundaries on the model. If necessary, perforations are made on the tray for better adhesion to the impression material.

A. Film on the form;
B. Filling the mold with plastic and placing a second film on top;
IN. Modeling a spoon;
G. View of the finished spoon.
Advantages:

Cheapness;
Lack of grips in the undercut area;
No need for special equipment.

Flaws:

Toxicity as the technician inhales monomer fumes;
Limited simulation time;
Inconvenience of grinding the spoon (the material can melt and clog the cutter);
The need to isolate undercuts on the model;
Inconvenience of modeling a handle.

The invention relates to the field of medicine, namely to orthopedic dentistry, and can be used in clinical practice for the manufacture of individual trays of both jaws for prosthetics with complete removable plate dentures. For the upper jaw, a plastic plate is first made - a template, according to the shape of which a substrate from a metal plate with a double-sided polyvinyl chloride coating is bent, the palate is formed, for which a plate of heated base wax is cut to the shape of the inner edge of the side of the substrate and the plate is poured to the edge of the side of the substrate with heated wax, fitted the base is placed on the alveolar process of the upper jaw, the outer edge of the edge of the fitted base is pasted over with sprue wax, the back section of the base in the area of the tubercles of the upper jaw is cut with scissors and pasted over with sprue wax heated on a burner, the base is fitted on the alveolar process of the patient's upper jaw and the edges are processed using functional tests, then the substrate is transferred to an individual tray, for which the inner surface of the substrate is covered with a thin layer of basic silicone impression mass, the substrate is fitted to the alveolar process of the upper jaw and functional tests are carried out to process the silicone mass at the edge of the sides of the substrate, and after vulcanization of the impression mass an individual tray for the upper jaw is obtained jaws. For the lower jaw, a plastic plate is first made - a template, according to the shape of which a backing from a metal plate with a double-sided polyvinyl chloride coating is bent, it is fitted to the alveolar process of the patient's lower jaw, the edge of the side of the backing is pasted over with sprue wax and again fitted to the alveolar process of the lower jaw, while functional tests, then the substrate is transferred to an individual tray, for which the inner surface of the substrate is covered with a thin layer of basic silicone impression mass, it is placed on the alveolar process of the lower jaw and functional tests are carried out to process the silicone mass at the edge of the sides of the substrate, and after vulcanization of the impression mass an individual spoon for the lower jaw. The technical result is the ability to make precise correction and fit of the substrate directly in the patient’s oral cavity, which leads to the elimination of the stages of taking preliminary anatomical impressions, casting plaster models and making individual plastic trays based on them, thereby reducing the number of visits and reducing the labor intensity of the process of making individual trays .

There is a known method for making an individual tray from wax directly in the oral cavity, followed by obtaining a working functional cast from it, developed at CITO by G.B. Brakhman and Z.V. Kopp (V.Yu. Kurlyandsky. Orthopedic dentistry. - M., Medicine, 1968, p.349). However, the wax spoon in the mouth cannot withstand excessive pressure under the influence of temperature, and the resulting impression is inaccurate.

There is a known method, recommended in the presence of sharp degrees of atrophy in the lower jaw, of taking a preliminary impression with an individual wax tray made in the oral cavity, with the production of a rigid individual tray based on the resulting model, with the help of which functional impressions are taken, then working models are cast, from which the wax ones are made bases with occlusal ridges and determine the height of the lower part of the face and the central relationship of the jaws (Doinikov A.I., B.V. Svirin. Obtaining a functional cast of an edentulous lower jaw and designing prostheses with sharp degrees of atrophy of its alveolar part. Methodological recommendations, M ., 1981) The disadvantage of this method is its significant labor intensity.

There is a known method of using a special set of trays for toothless jaws (SR ivotrey, universal & spezial trays (Ivoclar company), designed for simultaneous taking of indicative impressions from both jaws with the mouth closed (“Impression materials in dentistry” edited by T.I. Ibragimova, N.A. Tsalikova, pp. 40-42). During the taking of an impression, the height of the lower part of the face is recorded. However, with this method it is impossible to use the resulting impressions for taking functional tests.

The technology for manufacturing individual impression trays using light-curing materials is known, for example Luxa Tray rosa transparent u blau (KOHLER) individo lux (Voco) (“Impression materials in dentistry” edited by T.I. Ibragimov, N.A. Tsalikova, p. 106). Since such spoons are made from models in accordance with anatomical casts, they are expensive, very fragile and can injure the oral mucosa with the sharp edges of the plastic.

The closest, according to the authors, analogue (prototype) is a method for producing individual spoons from self-hardening plastics using wax compression matrices (Optimization of the method of taking functional impressions from toothless jaws. B.P. Markov, E.S. Iroshnikova, V.Yu. Kabanov / Textbook. - MGMSU, 2004). To make matrices on auxiliary plaster models, the boundaries of the trays are marked, which, according to the authors, should not reach the deepest parts of the transitional fold by 2-3 mm (taking into account the stretching of the boundaries when obtaining preliminary casts), the mandibular tubercles should overlap strictly along the distal edge , and the maxillary-hyoid line is no more than 1 mm. The compression matrix for the upper jaw is made from two layers of base wax, and for the lower jaw - from three. A layer of self-hardening plastic is applied to the inner surface of the matrix cooled in water, it is compressed under pressure, and the boundaries of the spoon are clarified using functional tests. The disadvantages of the prototype include the complexity and labor intensity of the technology. Since the spoon is prepared according to an auxiliary plaster model cast in an anatomical cast taken from a toothless jaw with a standard spoon, this leads to stretching of the mucous membrane and inaccuracies in the transfer of anatomical features.

The main problem to be solved by the present invention is the development of a method for manufacturing an individual tray using a plastic atraumatic material that has good adhesion to both wax and impression mass, and the possibility of directly carrying out precise correction and fitting in the patient’s oral cavity. This will improve the quality of treatment, simplify the technology for manufacturing an individual spoon and reduce the number of visits to the doctor by the patient.

The proposed method for making an individual spoon using the example of the upper jaw is as follows. A plastic plate is made - a template for the upper jaw. According to the shape of the template, a substrate is bent from a metal plate with a double-sided polyvinyl chloride coating (PE-X/Al/PE-X), which has good adhesion to both wax and impression mass. At the ends of the support, dovetail-shaped incisions are made in the area of the tubercles of the alveolar processes of the upper jaw. To form the palate, a plate of heated base wax is cut to the shape of the inner edge of the substrate edge and the plate is poured onto the edge of the substrate edge with heated wax. The substrate is fitted to the alveolar process of the upper jaw, the outer edge of the side of the fitted substrate is pasted over with sprue wax with a diameter of 2.5-3.0 mm, the rear section of the support in the area of the tubercles of the upper jaw is cut with scissors and pasted over with sprue wax heated on a burner. The support is placed on the alveolar process of the patient's upper jaw and the sides are processed using functional tests. To transfer the substrate into an individual tray, the inner surface of the substrate is covered with a thin layer of base silicone impression mass. The backing material ensures good adhesion to the silicone impression mass. The substrate is placed on the alveolar process of the upper jaw and functional tests are carried out to process the silicone mass at the edge of the sides of the substrate. After vulcanization of the impression mass, an individual tray for the upper jaw is obtained.

When making an individual tray for the lower jaw, first a plastic plate is also made - a template for the lower jaw, according to the shape of which a substrate from a metal plate with a polyvinyl chloride coating is bent, and it is modified. The substrate is fitted to the alveolar process of the patient’s lower jaw so that the edge of the side of the substrate does not reach the transitional fold of the oral mucosa by 1.5-2.0 mm, bypassing the natural frenulum and cords. The edge of the side of the support is pasted over with sprue wax and again fitted onto the alveolar process of the lower jaw, while functional tests are carried out in which the sides of the support are processed by the facial and chewing muscles of the lips and cheeks. Then the substrate is transferred to an individual tray, for which the inner surface of the substrate is covered with a thin layer of base silicone impression mass. Next, the support is fitted to the alveolar process of the lower jaw and functional tests are carried out to process the silicone mass at the edge of the sides of the support, and after vulcanization of the impression mass, an individual tray for the lower jaw is obtained.

The proposed method for making an individual spoon has the following advantages:

1. The substrate material is plastic and atraumatic in relation to the oral mucosa.

2. The metallized layer of the substrate allows for precise correction and fitting of the substrate directly in the patient’s oral cavity, which leads to the elimination of the stages of taking preliminary anatomical impressions, casting plaster models and making individual plastic trays based on them.

3. The substrate material has good adhesion to wax and impression mass, which eliminates the need to use bonding systems. This allows one-step production of occlusal wax rolls on an individual tray, with the help of which the height of the lower part of the face is determined and the central relationship of the jaws is fixed. Therefore, another stage is excluded (i.e., the patient’s visit to the dentist) - determining the height of the lower part of the face and fixing the central relationship of the jaws using wax bases with occlusal wax rollers.

4. After special processing of the wax occlusal ridges located on the ridges of the resulting individual trays, according to the Christensen phenomenon, it is possible, by adding a thin corrective layer of silicone impression mass (spidex cream), to obtain accurate functional casts simultaneously from the upper and lower jaws during the natural physiological period movements of the patient’s lower jaw, which was not possible before when taking functional impressions with other types of individual trays.

The proposed features, namely the production of a plastic plate - a template for the upper jaw, according to the shape of which a substrate from a metal plate with a polyvinyl chloride coating is bent, the formation of the palate, for which a plate of heated base wax is cut to the shape of the inner edge of the side of the substrate and the plate is poured to the edge of the side of the substrate while heated wax, fitting the support to the alveolar process of the upper jaw, gluing the outer edge of the edge of the fitted support with sprue wax, trimming the back section of the support in the area of the tubercles of the upper jaw and gluing it with sprue wax, fitting the support to the alveolar process of the patient's upper jaw, processing the sides of the support using functional tests , transferring the substrate into an individual tray, for which the inner surface of the substrate is covered with a thin layer of basic silicone impression mass, the substrate is fitted to the alveolar process of the upper jaw and functional tests are carried out to process the silicone mass at the edge of the sides of the substrate, obtaining an individual tray for the upper jaw after vulcanization of the impression mass , as well as the following features - production of a plastic plate - a template for the lower jaw, according to the shape of which a backing from a metal plate with a polyvinyl chloride coating is bent, fitting it to the alveolar process of the patient’s lower jaw, gluing the edge of the side of the backing with sprue wax, fitting the backing to the alveolar process of the lower jaw with carrying out functional tests, transferring the substrate into an individual tray, for which the inner surface of the substrate is covered with a thin layer of basic silicone impression mass, fitted to the alveolar process of the lower jaw and functional tests are carried out to process the silicone mass at the edge of the sides of the substrate, obtaining an individual impression mass after vulcanization trays for the lower jaw were not found in known solutions, which allows us to conclude that the proposed solution meets the criteria of “novelty” and “technical level”.

When making an individual tray for the lower jaw, a groove is made from a 2.7 mm thick metal plate with polyvinyl chloride coating on both sides in accordance with the plastic template for the lower jaw. The lingual side of a piece of backing is leveled using crampons and, as a result, becomes flat from a semicircular one. Examining the alveolar processes of the oral cavity, the doctor determines their width, height, notes the severity of the frenulum and forms a base from the above-described metal-polymer blank right at the chair. Places for bridles and cords are cut out using a tip with a carborundum disc. The cut edge of the substrate is smoothed with a carborundum head. The support is treated with alcohol and placed in the oral cavity on the lower jaw. In this case, the substrate is easily bent using crampon forceps to the shape of the patient’s alveolar process. The sides of the substrate do not reach the transitional fold and the floor of the oral cavity by 2-3 mm, if conditions allow - the height of the alveolar process.

The edge of the side of the substrate is processed with a carborundum stone or head and a wax flagellum 2-3 mm thick is glued to it along the entire length. The wax is heated over a gas burner or alcohol lamp and the substrate is inserted into the patient's oral cavity. In this case, the patient is asked to perform functional movements of the cheeks and tongue according to the MGMSU method. In places where there is a highly pliable mucous membrane of the alveolar process and loose mucous membrane, in these projections the substrate is perforated using a carbide cylindrical bur No. 3.

A basic soft silicone impression mass (Optasil, Speedex) is placed into a custom-fitted substrate. The mass is placed in a thin, even layer on the inner surface of the substrate, introduced into the patient’s oral cavity and placed on the alveolar process along the specified boundaries, after which functional movements of the lips and cheeks are performed again. After vulcanization of the impression mass, the resulting finished tray is removed from the oral cavity, while the center of the alveolar ridge is marked on the tray and a wax occlusal roller of standard sizes is attached to the tray along this mark

An individual tray for the upper jaw is made slightly differently. The initial stage of making a metal-polymer base for the upper jaw is the same as for the lower jaw. The difference is that at the ends of the base, cuts 8-10 mm long are made with dental scissors and the edges are bent inward, recreating the shape of the tubercles of the upper jaw, and the missing part of the palate on the base is formed from a wax plate 3-5 mm thick. The edge of the side of the support is also treated with a carborundum stone, pasted over with a wax strip 3 mm thick, the heated support is inserted into the patient’s mouth and placed on the upper jaw. The patient is asked to carry out a series of functional movements developed according to the MGMSU method for the upper jaw.

The same as on an individual base fitted to the lower jaw, on a fitted base of the upper jaw in places of pliable and loose mucous membrane, as well as in the area 15 14|24 25 teeth are perforated with a carbide cylindrical bur No. 3. A thin layer of silicone base impression mass (Optasil, Speedex) is applied to the substrate and it is inserted into the patient’s oral cavity and placed on the upper jaw. In this case, the patient is asked to repeat the functional movements until the impression mass is completely vulcanized. The center of the alveolar ridge is marked on the substrate, a hole is made in the impression mass in the area 15 14|24 25 teeth and an occlusal wax roll of standard sizes is attached to the resulting tray.

In this way, individual metal-polymer trays with functional casts are prepared. Wax occlusal ridges are prepared on the trays for further functional and phonetic tests and final preparation of functional casts.

Individual trays with functional casts and occlusal wax ridges are inserted into the oral cavity and placed on the alveolar processes. A prosthetic plane is created on the upper occlusal ridge using a Sorokin arch. According to the Christensen phenomenon, the articulatory surfaces of wax occlusal ridges are processed. On the upper occlusal ridge, grooves are made in the area 16 15|25 26 teeth.

The further technique is as follows: trays with occlusal ridges are removed from the oral cavity and a thin layer of duplicating silicone impression mass is placed in the trays, the trays are reinserted into the patient’s oral cavity and he is asked to carry out a series of functional and phonetic tests, which allows the final formation of functional impressions in the cavity mouth

Occlusal ridge on the lower individual tray in the area with 16| By |26 cut in height by 1.5-2 mm. A softened wax roller 2-3 mm thick is applied to this place and the patient’s jaws are closed in a centric relation. The trays are removed from the mouth, cooled and the occlusal ridges are separated using a spatula. Then the spoons are reinserted into the oral cavity and the central relationship of the jaws is once again controlled. Appropriate markings are made on the upper and lower occlusal ridges. The spoons are removed from the mouth. Based on functional casts taken from the upper and lower jaws, jaw models are cast from superplaster.

Patient K., age 72 years, complained of poor chewing of food, gastrointestinal upset, and impaired diction. Two and a half months ago, she was provided with complete removable plate dentures at the Ivanovo clinic. The patient has been using similar prostheses for 20 years. Can't get used to the latest dentures. Multiple denture adjustments do not bring relief. Can only chew soft foods; harder foods cause pain. Recently, pain has appeared in the epigastric region, a feeling of heaviness, and belching after eating. When talking, the patient swallows saliva and makes hissing sounds.

When examining the oral cavity, an average uniform atrophy of the alveolar process of the upper jaw is observed (II degree of atrophy according to A.I. Doynikov). On the lower jaw, the alveolar ridge is pronounced in the frontal area (IV degree of atrophy according to A.I. Doynikov) The mucous membrane of the oral cavity and alveolar processes swollen and hyperemic, especially in the area of the tubercles of the upper jaw and in the retromolar areas of the alveolar process of the lower jaw. When examining the oral cavity with fitted dentures, an external examination reveals a slight decrease in the lower third of the face. On the occlusal surfaces of the dentition when checking the density of contacts using Bausch cards in the area single contacts were noted, there was no density of contact between the fissure-tubercle contacts. During palpation examination, balancing of the prosthesis on the alveolar process of the lower jaw was observed; a slight balancing was observed in the prosthesis fitted to the upper jaw.

The patient was asked to make new dentures using the alternative method described above, having previously treated the oral mucosa. After following the recommendations, the patient came to the appointment and on the first visit, templates were made from polyvinyl chloride plastic with a thickness of 0.8 mm according to the shape of the alveolar processes of the upper and lower jaws. Based on them, bases for the upper and lower jaws were made from a metal plate with a double-sided polyvinyl chloride coating (PVC material). In the patient’s oral cavity, they were placed on the alveolar processes and, using silicone impression mass, spidex cream, were transferred to individual trays. Then occlusal wax ridges were cast onto the trays, with the help of which the height of the lower third of the face was determined (having previously determined the prosthetic plane). The occlusal surface of the ridges was treated according to the Christensen phenomenon and, using silicone impression mass, spidex cream, functional impressions were taken simultaneously at the time of physiological movements of the lower jaw with the jaws in a closed position.

Then the central relationship of the jaws was registered in the patient and the work was transferred to the dental laboratory. Models were made from supergypsum casts, which were installed in the average position of the interframe space of a hinged-ellipse-type articulator and fitted to the articulator frames. Using a special device, artificial teeth were placed on the wax base of the upper jaw model. The placement of teeth on the wax base of the lower jaw model was done along the occlusal surface of the dentition located on the wax base of the lower jaw model.

On the second visit, the patient’s denture design was checked: the height of the lower part of the face, the density of closure of the dentition, the color and shape of the artificial teeth were checked, and then the wax bases with artificial teeth were transferred to the laboratory to replace the wax with plastic.

On the third visit, the patient was fitted with complete removable plate dentures for the upper and lower jaws. The contact density of the occlusal surfaces of the dentition was checked using Bausch cards. A check was made of the sliding of the occlusal surfaces of the dentition during sagittal and transversal movements of the lower jaw. Two supercontacts were identified, which were removed using a spherical bur.

A week later, the prostheses were re-corrected. There was a small lesion in the retromolar region of the alveolar process of the lower jaw on the lingual side on the right; correction was carried out with a carborundum head. After this, no corrections to the prostheses were performed. Diction improved, and with good chewing of food, epigastric pain disappeared.

A method for manufacturing individual trays for the upper and lower jaws, characterized in that for the upper jaw, a plastic plate is first made - a template, according to the shape of which a substrate from a metal plate with a polyvinyl chloride double-sided coating is bent, the palate is formed, for which a plate of heated base wax is cut to the shape of the inner the edges of the edge of the substrate and pour the plate to the edge of the edge of the substrate with heated wax, apply the substrate to the alveolar process of the upper jaw, the outer edge of the edge of the applied substrate is pasted over with sprue wax, the back section of the support in the area of the tubercles of the upper jaw is cut with scissors and pasted over with gating wax heated on a burner, the support is adjusted on the alveolar process of the patient's upper jaw and the edges are processed using functional tests, then the substrate is transferred to an individual tray, for which the inner surface of the substrate is covered with a thin layer of basic silicone impression mass, the substrate is fitted to the alveolar process of the upper jaw and functional tests are carried out to process the silicone mass the edges of the sides of the substrate, and after vulcanization of the impression mass, an individual tray for the upper jaw is obtained; for the lower jaw, first a plastic plate is made - a template, according to the shape of which a substrate is bent from a metal plate with a polyvinyl chloride coating on both sides, it is fitted to the alveolar process of the patient's lower jaw, the edge of the side of the substrate is pasted over with sprue wax and again fitted to the alveolar process of the lower jaw, while functional tests, then the substrate is transferred to an individual tray, for which the inner surface of the substrate is covered with a thin layer of basic silicone impression mass, it is placed on the alveolar process of the lower jaw and functional tests are carried out to process the silicone mass at the edge of the sides of the substrate, and after vulcanization of the impression mass an individual spoon for the lower jaw.

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Stages of making a custom spoon. Individual spoons

Report on the topic: Methods for making individual spoons. Functional tests. Functional casts, classification. Justification for the choice of impression material. Characteristics of various impression materials. Completed by a 4th year student gr. Art. – 402 a Aryslanova E. Kh.

No. Elements of Self-Control Stages of work Methodology 1. Plaster model cast according to an anatomical impression Along the transitional fold, bypassing the frenulum of the cheeks, lips, tongue, capturing the tubercles Draw with a chemical. h. and retromolar pencil tubercles of the lower jaw border of the spoon. and passing on the palate by 2 mm. distally beyond line “A” 2. Heat the plate over Visually monitor the flame until the standard fit is accurate. AKR-P plate, uniform If it is not available, use an alcohol lamp, soften it, reheat it and use a spatula. crimp it to crimp the plate. models. 3. Chemical pencil. Transfer the boundary to the surface. Monitor the accuracy of the crimped plate.

4. 5. 6. Scissors, drill, fisure bur, cutter. Achieve accurate Adjust the border of coincidence of the border of the spoon according to the markings of the spoon with the markings using a drill. on the model. Wire, crampon forceps Bend a handle from orthodontic wire or a paper clip. To do this, bend the paper clip in half and bend the ends along the alveolar process. The height of the handle should be 1 - 1.5 cm. The ends should diverge in the direction of the alveolar ridge. Alcohol lamp, crampon tongs. Attach the handle to the spoon. To do this, heat the bent ends, holding it with crampon tongs and immerse it in the plate. The handle should be fixed at an angle of 45 degrees to the plane of the tray and protrude in the mesial direction.

Indications Accurate impressions for crowns, bridges, partial and complete dentures Benefits Easy modeling and adaptation Long working time Odorless Reuse of excess material Curing in a standard laboratory curing oven with UV or halogen light (wavelength 240 - 520 nm) Optimal thickness Supertec

n The technique for manufacturing individual spoons and base spoons from self-hardening plastic carboplast is as follows. The prepared plaster model is treated with isokol insulating varnish. Then the carboplast plastic is kneaded and the spoon is molded on the model. The mass hardens in air for 3-5 minutes. The processing and polishing of the spoon is ordinary.

1. Plaster model obtained from an anatomical impression Draw the border of the tray with a chemical pencil. Along the transitional fold, bypassing the frenulum of the cheeks, lips, tongue, capturing the tubercles in. h. and retromolar tubercles of the lower jaw and passing on the palate by 2 mm. distally beyond line “A” 2. Base wax, spatula, alcohol lamp. Model, according to the marked boundaries, using softened wax on the model an individual spoon and a handle for it. Check the correspondence of the boundaries and the exact fit of the wax reproduction to the surface of the model. Cuvette, clasp, “Izokol”. Prepare the model for plastering into the ditch in the reverse way and plastering. Evaporate the wax, treat the cuvette with Izokol. After opening the cuvette, check the integrity of the model, the accuracy of the comparison of the cuvette, and the quality of the application of Izokol. 4. Base plastic. Prepare plastic dough, place it on the model, place it under a press, and polymerize the plastic. The correct ratio of powder and liquid, observe the polymerization mode. 5. Tools and finished individual spoon materials for sanding. grinding. 3. The spoon should not be rough, it should fit within the boundaries.

For the upper jaw. 1. Base wax, alcohol lamp Fold the wax plate crosswise in three, heat it up and round one edge, then squeeze the tubercle of the upper jaw, the alveolar process in the mouth, press it to the palate, remove, cool, trim off the excess, then soften again and repeat the compression, controlling border with the movement of the cheeks, lips, and then form the rear edge behind the line “A”. The individual wax tray should fit snugly to all surfaces of the prosthetic field, not enter the moving mucous membrane, bypassing all folds and the frenulum of the tongue.

For the lower jaw. 2. Base wax, alcohol lamp. Fold the wax plate (2/3 of it) lengthwise into thirds, crimp it according to the model, being sure to include the retromolar space. Once the formation is complete, wire is laid along the spoon and reinforced with an additional roll of wax. The spoon should lie motionless on the alveolar process, grasping the retromolar tubercle.

Currently, it is common to make a basic individual spoon from self-hardening plastics 1. Plaster model, self-hardening plastic, chemical pencil, base wax, drill, abrasives for plastic. Use a pencil to draw the boundaries of the spoon on the plaster model. Heat the wax plate, press the model tightly and trim off the excess wax according to the boundaries. Heat it again and press a new piece of wax on top of this one, slightly overlapping its edge. Then remove the wax plates, lubricate the model with Izokol, mix the plastic, lay it in an even layer on the model and press it with the second, upper plate of wax, remove excess plastic behind the edges of the wax plate. After the plastic has hardened, process the edges and make a handle (on a wax plate can be strengthened. Uniform heating of the plates, tight crimping of the model, exact matching of the boundaries, elasticity of the plastic dough, complete hardening, good mechanical processing.

When fitting a spoon on the upper jaw, it should be taken into account that the border of the prosthesis on the vestibular side should cover the pliable mucous membrane, slightly squeezing it and located 1-2 mm below the transitional fold, be in contact with its dome (mobile mucous membrane) and have a concave vestibular surface. With this configuration, the edges of the prosthesis will fit tightly, and the fixation will be better, since this prevents air from entering under the prosthesis. The position of the impression along line “A” is important for fixing the prosthesis. It should end in this place on the soft palate, moving onto it by 1-2 mm. The soft palate should be photographed in an elevated position. If this condition is not met, the impression will be taken with the palate lowered. In this case, the prosthesis will not fit well during eating and talking, since the soft palate rises, allowing air to pass under the prosthesis. In order to press out the soft palate when taking an impression, a strip of thermoplastic mass is applied to the palatal edge of the spoon, possibly wax 4-5 mm wide and 2-3 mm thick. However, it should not be placed on the edge of the tray in a place where it can push back the pterygomaxillary fold, that is, the alveolar tubercles should be free. Then the spoon is inserted into the mouth and pressed against the palate with the mouth half closed. When the mass hardens, the spoon is removed from the mouth.

The fitting of an individual tray to the lower jaw also begins with the release of the frenulum of the lip and tongue, as well as the lateral bands by creating recesses in the edge of the prosthesis. This can be done with a narrow fissure bur, discs, or a wheel-shaped head. The guideline for determining the distal border is the mucous tubercles (tuberculum mucosum). They are covered with a spoon partially or completely, depending on their shape, location, consistency, presence or absence of pain on palpation. There is no consensus on this issue and it is decided individually. On the lingual side in the lateral sections, the spoon should overlap the internal oblique line if it is round in shape and reach it if it is sharp, but its posterior lingual edge must be in the muscle-free triangle. If there are exostoses in the anterior part of the alveolar process, the spoon blocks them, leaving the excretory ducts of the sublingual glands free.

1. Ask the patient to swallow saliva. If at the same time the spoon is thrown off, it is necessary to shorten its edge from the place behind the tubercle to the mandibular-hyoid line. 2. Then ask the patient to slowly open his mouth. If the tray rises from behind, then it is shortened in the area from the tubercles to the place where the second molar will later stand (2). You can grind the spoon very close to the bumps, but they should never be left loose. If the front part of the spoon is raised, then its edge on the vestibular side is ground off in the area between the fangs (3). 3. Run your tongue along the red border of your lower lip. If the spoon rises, then grind its edge running along the maxillary-hyoid line (4). 4. Touch the tip of your tongue to your cheek with your mouth half closed. The location of the required correction is located 1 cm from the midline on the hyoid edge of the tray (5). When the tongue moves to the left, correction may be required on the right side; when the tongue moves to the right, correction may be required on the left side.

5. Run your tongue along the red border of your upper lip. Correction of the edge of the spoon is done at the frenulum of the tongue in a concave manner, but not in the form of a groove (6). 6. Active movements of facial muscles, pulling the lips forward. If the spoon rises at the same time, then you need to shorten its outer edge between the fangs again (3). Between the canine and the second premolar along the vestibular edge of the tray there is a place where the edge of it, which goes too deep, is pushed out passively by the tissue. If you place your index fingers slightly below the corners of the mouth and make massaging movements without pressure, then in this place (7) you can clearly feel the edge of the spoon going too deep. All movements, except the last one, must be performed by the patients themselves.

1. Wide open mouth. If the spoon moves, then the edge must be shortened. 2. Cheek sucking. If the spoon moves, then its edge in the area of the buccal frenulum should be shortened (3). 3. Lip stretching. If the spoon is displaced, its edge should be shortened in the anterior section (4).

Functional tray - functional impression The purpose of taking a functional impression is to: determine the maximum area of support for the prosthesis base, taking into account muscle movements.

The functional cast should convey: On the upper jaw: the transitional fold, the crest of the jaw with the tubercles of the upper jaw (Tuber maxillaris) and the palate, the transition from the hard to the soft palate (A-line), the frenulum and cords On the lower jaw: the crest of the jaw with the retromolar triangle (Trigonum retromolare) transitional fold and sublingual areas of the beginning of the muscles and ligaments of the lingual and buccal muscles of the frenulum and cords

Functional casts, classification n n n - By the method of edge design: With the help of passive movements Chewing and other types of movements With the help of functional tests Their combinations By the degree of pressure on the mucous membrane: Under pressure (compression) With minimal pressure (decompression or unloading) differentiated By the pressure method on the mucous membrane of the prosthetic bed: Arbitrary Dosed Chewable Combined

Compression impression according to E. I. Gavrilov. When using a compression impression, the buffer zones of the hard palate partially absorb chewing pressure and thereby provide some unloading of the alveolar processes, reducing their atrophy. Compression impressions are taken under certain conditions: 1 – only a rigid tray is used, 2 – only thermoplastic materials or materials of the same density are used to remove the impression, 3 – during removal, continuous pressure is applied, stopping only after the material has completely cured. Continuity of pressure is ensured by the effort of the doctor’s hands, or by the use of special devices, under bite pressure. Compression impressions are indicated for minor atrophy of the alveolar processes and dense mucous membrane.

Decompression impressions. The impression material reflects all the details of the prosthetic bed without distortion. In this case, liquid impression materials are used. The fixation of prostheses made using decompression impressions is relatively weak. Decompression impressions are indicated for complete atrophy of the alveolar processes and increased sensitivity of the mucous membrane.

Differentiated impressions. Provide selective load on individual areas of the prosthetic bed depending on their functional endurance. To do this, either isolate on the model those areas that must be unloaded, or create perforations in an individual tray in the areas where the mucous membrane is unloaded. Before taking an impression, it is necessary to decorate the edges of the impression tray with thermal mass or wax. the impression is taken under arbitrary or chewing pressure. Differentiated impressions are indicated for uneven atrophy of the alveolar process and the presence of a pronounced palatal torus.

Type of impression TYPE OF MATERIAL Compression Plaster, dentol, repin, alginate masses (GC Aroma Fine (GC), Dust Free III (DMG)), polyester masses (Pentamix (3 M ESPE)) Decompression Silicone impression materials: Alphasil C-silicones (Omicron ), Speedex (coltene), Zetaflow (Zhermack), Xonigum-Putty, Dentstar (DMG), A-silicones GC Exajet, Betasil (GC), Bisico, thermomass, dentofol, thiodent, sielast Combined Combinations of the above types of materials

Gypsum. Soft, used for impressions Gypsum has long been the main material for impressions. This is due to its availability and low cost. In addition, it gives a clear imprint of the surface of the tissues of the prosthetic bed, is harmless, does not have an unpleasant taste or odor, practically does not shrink, does not dissolve in saliva, does not swell when wetted with water and is easily separated from the model using the simplest release agents. When taking an impression with plaster on the upper jaw, the tray with plaster is pressed in the direction from the distal teeth to the medial ones. On the lower jaw it is the other way around. When taking an impression with plaster, complications are possible: vomiting, soft tissue injury, tooth extraction, tooth fracture, dislocation of the lower jaw, jaw fracture, aspiration.

DENTOL-S Dentol-S is an impression material based on the zinc oxide guaiacol system and consists of two pastes - guaiacol paste No. 1 (red) and zinc oxide paste No. 2 (white). PURPOSE: Dentol-S is used to take high-precision impressions of the oral cavity. It is especially advisable to use Dentol-S when obtaining accurate impressions from toothless jaws, when the oral mucosa is loose, with a functional design of their edges. The presence of single teeth is not an obstacle to obtaining this type of impression. PROPERTIES: Dentol-S has great plasticity before structuring, and in the first minutes after structuring it has some elasticity. This property allows you to obtain impressions that accurately reflect the tissues of the prosthetic bed and avoid delays and distortions when making an impression.

REPIN Repin is an impression material based on the zinc oxide eugenol system, consisting of two pastes - eugenol paste No. 1 (brown) and zinc oxide paste No. 2 (white). PURPOSE: the paste has proven itself in practice as an excellent mass for making impressions of large surfaces of the mucous membrane, especially for impressions of edentulous jaws. Repin can also be used for temporary fixation of fixed dentures. PROPERTIES: zinc oxide eugenol paste has elasticity, which allows you to obtain prints with a distinct microrelief image, and the ability to harden in a humid environment. The correct consistency of the paste eliminates the possibility of forced compression of soft tissues and allows immaculate processing of prints according to the individual characteristics of the patient.

ALGINATE MASSES Alginates are elastic impression materials. The raw material for producing alginates is seaweed. The alginate material powder contains sodium or potassium salts of alginic acid (15%), which are highly soluble in water, calcium sulfate (about 12%), and sodium phosphate – a retarder (2%). Inorganic fillers (talc, zinc oxide) determine the viscosity of the material and its stability after hardening and make up the bulk of the powder (70%). Additionally, alginate powder contains small amounts of colorants, flavors, fragrances and fluoride compounds to enhance the surface strength of the plaster model.

Properties of Alginates The viscosity of the kneaded alginate material largely depends on the amount of water added during kneading. Therefore, it is necessary to adhere to the proportions of water and powder suggested by the manufacturer. Detail Accuracy The accuracy with which alginate impression compounds are able to convey detail is determined by the size of the powder granules and the type of macromolecules formed. The accuracy limit for small object transmission is approximately 50 m (according to ISO 1563). This detail accuracy is not as good as that of silicone impression materials, so alginates should not be used to take impressions for working models on which inlays, crowns and bridges will be made.

Dimensional stability Water in the polymerized alginate is in an unbound form between the macromolecules. Therefore, depending on the conditions under which the finished impression is stored, water may be easily absorbed by the material if there is excess water, or the material may lose water and dry out. Accumulation or loss of water causes changes in the original dimensions of the casts, so plaster casts should be obtained immediately after the casts are taken. Elasticity Due to the presence of a cross-linked macromolecular structure, the polymerized alginate material has elasticity, which allows the imaging of undercut areas. However, this elasticity is even less than that of hydrocolloid impression masses. Alginate impression material fails at 50% pressure and at relatively low tensile loads. Therefore, extensive undercuts, such as wide interdental spaces and spaces under pontics, must be isolated in the patient's mouth before taking an alginate impression. It is also necessary to remember that the alginate layer between the teeth and the impression tray must be at least 5 mm thick. Plastic impression trays should not be used. This requirement is explained by the fact that the elastic deformation of the alginate during impression removal will be so great that the original shape of the impression will not be completely restored and permanent plastic deformation will remain.

Disinfection The problem with disinfecting alginate impressions is that alginates can only remain in an aqueous environment for a short time without significant water absorption and dimensional disturbance. However, research shows that the use of sodium hypochlorite (household bleach) effectively disinfects alginate impressions within minutes without degrading the quality of the impressions.

Hydrohum alginate Elastic alginate with fast setting setting time: 2 min 10 sec PROPERTIES - rapid absorption of water; - easy mixing; - homogeneous mass; - long-term preservation of casts

Orthoprint alginate Characteristics: Super elastic alginate Shortest processing and setting time Pleasant vanilla smell to reduce the gag reflex Yellow color Dust-free Advantages: Fast absorption of water Easy mixing Homogeneous mass, surface smooth and compact Long-term preservation of impressions Setting time 1 minute 50 seconds

Upin Premium YPEEN PREMIUM Alginate impression material standard packaging 450 g per bag For taking impressions in the manufacture of partial removable dentures, preliminary impressions in the manufacture of complete removable dentures (for the manufacture of individual impression trays), for taking impressions in orthodontic practice, impressions for the manufacture of working models, temporary crowns and bridges. Alginate impression material that is easy to mix, has optimal viscosity, short curing time, optimal working time, provides excellent detail transfer, and is highly compatible with plaster.

Face alginate Clinical recommendations Chromatic three-phase alginate of reduced viscosity. Recommended if you have a pliable mucous membrane. Suitable for beginners. Characteristics Chromatic three-phase alginate: - Violet phase: mixing time - Red phase: processing time - White phase: insertion into the oral cavity Short processing and setting time Thixotropic Hardness after gelation Chlorophyll aroma

Polyester masses are a fairly promising group of impression materials. Contains various polyesters, plasticizers and inert fillers. Properties. The polymerization reaction takes place according to the polyaddition type, i.e., without the release of by-products. In this regard, they differ in very small linear shrinkage. Stable, however, not flexible enough. To mix the main and catalytic masses, new automatic mixing systems such as Pentamix (ЗМ/ESPE) are used, which prevent the formation of bubbles

Silicone impression materials The main advantages of Alphasil C-silicones: Working time varies depending on the amount of catalyst Low percentage of shrinkage High precision and elasticity Shelf life of the impression - 1 week All materials have hydrophilic and thixotropic properties

Disadvantages: - Not ideal quality when taking impressions with retraction threads - Requires thorough manual mixing of masses and catalysts of different consistency - Difficulty in exact dosage of the catalyst, everything is “by eye” - You cannot cast models from the impression multiple times - Sensitivity to moisture - hygroscopicity. - Low hydrophilicity - Insufficient adhesion to the spoon - The literature describes the possibility of a toxic effect - No automatic mixing - Somewhat excessive rigidity of the base mass

The main advantages of Betasil A-silicones: Ease of mixing and precise dosage of the mass and catalyst due to the 1: 1 proportion Excellent hydrophilic and thixotropic properties of the mass Elasticity and tensile strength Ideal restoration of shape after deformation Thanks to the high quality of the impression mass, the impression can be used repeatedly The thermoactive formula allows adjust the hardening time of the material depending on the temperature. The total operating time varies from 2 to 4 minutes. Disadvantages: - Cannot be mixed with latex gloves - A-silicones are somewhat more expensive than S-silicones

Thermoplastic masses soften at a temperature of 50 -70°C and become hard at oral temperature (37°C). n Thermoplastic compounds do not provide an accurate representation of the details of the prosthetic bed. The relief of the mucous membrane on the impression appears smoothed, since the mass has low fluidity. An accurate representation of the dentition cannot be obtained using a thermoplastic mass due to its hardening after cooling. Therefore, when the teeth are tilted, the equators of the teeth are pronounced during removal, the impression is deformed.

Tiodent is a completely non-shrinking material, which makes it possible to preserve impressions for a long time. The high elasticity of the impression mass before receiving an impression and plasticity before vulcanization make it possible to obtain impressions that display the relief of hard and soft tissues of the oral cavity. Sielast Advantages High elasticity of the impression. High print accuracy. Good shape recovery after deformation. Several models can be cast from one impression.

sta. Metal spoons can be reused after appropriate treatment (sterilization). They can be solid cast without perforations or with perforations for mechanical fixation of the impression material in the tray (Fig. 30).

Plastic spoons are intended for single use and are supplied in sealed (vacuum) packaging. They have different sizes and shapes and are usually produced with perforations. The more varied the choice of trays, the greater the possibilities the doctor has for taking an impression. The shape and size of the impression tray are determined by the shape of the jaw, the severity of the edentulous alveolar part and other conditions that are reflected in the production of impression trays. For example, a set of 23 spoons for toothless upper and lower jaws called Stock is presented by the company "COE" (USA) in the following types: round (8 pcs.), rectangular (8 pcs.), triangular (7 pcs.). Some companies produce spoons for toothless jaws in sets with 5 sizes for the lower and upper jaws.

Rice. 30. Standard metal spoons for edentulous upper and lower jaws

Making and using individual spoons

Individual spoon is an impression tray designed to take the final impression and made in accordance with the anatomical and topographical features of the dental system of a given patient. The materials for their manufacture can be divided into the following groups:

– wax (at present, individual wax spoons are not used, but rigid spoons are preferred);

– cold polymerization plastics (the most common group);

– light-curing materials (are increasingly used);

– thermoplastics.

Combined use of materials is possible.

Such a spoon facilitates viewing during fitting, makes it possible to see places of compression of the mucous membrane and more clearly determine the distal border (Fig. 32).

Rice. 31. Individual tray for the upper edentulous jaw Tiefziehhmaterial Erkorit

3.5 mm (Erkodent GmbH, Pfalzgrafenweiler)

Rice. 32. Functional tray made of transparent material during fitting on the upper jaw

There are many methods for making individual spoons, but most of them, for one reason or another, are not used in practical healthcare. Methods can be divided into direct, in which the doctor makes a spoon directly in the patient’s mouth and takes an impression in one visit, and indirect (extraoral, laboratory) - with the preliminary receipt of a model and the participation of a dental technician.

In recent years, preference has been given to laboratory methods for making individual spoons, which in turn can be divided:

– for production on a plaster model by palpation compression of self-hardening plastic in the dough-like stage;

– a technique of compression pressing of plastic, which involves wax modeling of a spoon, the use of detachable molds and the use of polymerization techniques (high or low temperature);

– injection molding technique - the difference from the previous one is the use a syringe press and a special cuvette with sprue channels;

– vacuum pressing technique using special molders and blanks-plates of thermoplastic polymers of various thicknesses, which are pressed according to the model and cut along the boundaries;

– manufacturing from light-curing polymers (the plate is crimped according to the model and polymerized in a special box);

– method of making spoons using bulk modeling technology - application polymer powder onto the surface of the plaster model, followed by impregnation with the monomer liquid until saturation and polymerization in a pneumatic polymerizer at 3 atm.

The method has become widespread direct manufacture

molding an individual spoon from acrylic self-hardening plastic dough applied to a plaster model of the jaw (palpator-method

compression). However, it cannot be considered promising for the following reasons:

– an individual spoon is made from plastic dough that is in the stage of stretching threads, when significant deformations are observed that distort the macro-relief of the surface (the edges of spoons when manufactured using this method very often move away from the boundaries in the area of the transition fold, which occurs due to linear shrinkage of the material

V process of exothermic polymerization reaction);

– evaporation of a monomer (methyl methacrylate), which has a high toxic-allergic effects, and prolonged contact with the skin of a dental technician’s hands do not contribute to improving human health;

– there is no clear repetition of the microrelief;

– a polymerization process, the big disadvantage of which is significant surface deformation and the formation of gas porosity.

However, along with negative qualities, this technique also has positive ones. Thus, if it is necessary to use less fluid impression materials that do not allow obtaining the thinnest layers of impression material in the space between the tray and the mucous membrane, the use of this technique is completely justified. In this case, impression materials compensate relatively effectively for inaccuracies and minor deformations of the surface of the tray (E. S. Kalivradzhiyan, E. A. Leshcheva, N. A. Golubev, T. A. Gordeeva, N. G. Mashkova, S. V. Polukazakov ). The disadvantages listed above can be eliminated if you use

develop methods of compression or injection molding of self-hardening plastics in the production of individual spoons. Factors hindering the development of these techniques are the large consumption of investment and modeling materials, as well as significant time, energy and labor costs.

Currently, the method of producing

making an individual spoon from light-curing polymers . They can be produced in the form of plates or in a block (Fig. 33).

Rice. 33. Plates of light-curing polymer

Based on the anatomical impression, a plaster model is made, on which the border of the future individual base tray is drawn. A plate of non-polymerized plastic is taken and pressed tightly onto the model. The excess is cut off with a scalpel (Fig. 34, a). A handle is made from the scraps and, if necessary, the edges of the spoon are thickened (Fig. 34, b). Then the model with the crimped spoon is placed in a special light-curing apparatus (Fig. 34, c). When the plastic is ready, the edges are ground with a carborundum head and a cutter and recesses are made for the labial frenulum and cheek folds.

Rice. 34. Method for making an individual spoon from light-curing polymers

Many authors consider the most effective method to obtain a compression functional impression using a plastic base spoon with wax bite ridges. Bite ridges on a rigid base make it possible to obtain an impression under the control of chewing pressure and achieve the most approximate picture of the loading and compression of the mucous membrane by the prosthesis base (Fig. 35, 36).

Rice. 35. Individual tray for the upper jaw with a bite block

Rice. 36. Individual tray for the lower edentulous jaw with bite ridges and a handle for easy fitting and taking a functional impression

Some Western companies produce standard individual trays that allow you to simultaneously take an impression from the upper and lower jaw with registration of the central relationship of the jaws, for example, double plastic trays SR-Ivotrey from Ivoclar-Vivadent (Liechtenstein) (Fig. 37).

Rice. 37. Set of impression trays SR-Ivotrey

The company "Detax" (Germany) produces a special set of SI-PLAST TRAYS for taking impressions, which contains: 4 perforated plastic trays of different sizes for the upper jaw and 4 perforated plastic trays of different sizes for the lower jaw, 4 palatal templates, as well as 8 removable metal grips that are suitable for atrophied jaws (Fig. 38).

Fig.38. Set of SI-PLAST TRAYS

Method of obtaining an anatomical impression

To obtain an anatomical impression, it is necessary to choose the right standard metal or plastic spoon. Its shape and size are determined by the size of the jaw. For these purposes, a dental compass is used, which allows you to determine the distance between the ridges or their slopes in the lateral sections. When choosing a spoon, you need to take into account some anatomical features of the oral cavity. So, in the lower jaw, you need to pay special attention to the lingual side of the spoon, which should be made longer than the outer one in order to have

the ability to push the soft tissues of the floor of the mouth deeper. In addition to a correctly selected impression tray, the impression material is of no small importance for obtaining a high-quality anatomical impression. The choice of material depends on the degree of atrophy of the alveolar processes and alveolar part, the condition of the soft tissues, as well as the degree of pliability of the mucous membrane. Thus, with slight uniform atrophy of the jaws, alginate impression materials and thermoplastic masses can be used. In case of severe atrophy of the jaws, it is recommended to use materials that allow the tissues to move back to half their maximum mobility. In such cases, it is advisable to choose silicone and polyvinylsiloxane masses. In case of severe atrophy of the jaws, complicated by a “loose ridge,” it is necessary to take an impression without pressure using plastic alginate masses with high fluidity, low density and increased working time compared to alginates used in orthodontics or fixed prosthetics.

IN Currently, there are modern techniques for obtaining anatomical impressions. They are used for minor atrophy of the jaws. This is a combined technique for taking anatomical impressions using hydrocolloid materials with alginates and simultaneously taking impressions from both jaws, which gives optimal results.

IN In particularly complex cases, such as complex jaw prosthetics, the most effective way to add mass and obtain an impression is to obtain a differentiated impression using two-component alginate masses. To do this, alginate is injected into the syringe.

material of high fluidity, and in the impression tray of low fluidity. Using a syringe, the alginate mass is introduced into the area of the transitional fold, frenulum and cords, the area of the midline of the hard palate, then a tray with impression material is inserted into the oral cavity.

Before the procedure for taking an impression, the mouth is rinsed with a weak antiseptic solution (potassium permanganate, chlorhexidine, Duplexol or PreEmp). The corners of the patient's mouth are lubricated with Vaseline or a special antiseptic cream, for example Vico-1 produced by Galenika (Yugoslavia). For good adhesion of the impression mass to the surface of the tray, it is recommended to pre-treat its edges with adhesive sprays or a special adhesive glue. The material is mixed with a metal or plastic spatula in a rubber cup, on glass, waxed or coated paper, or in mechanical mixers. The impression material prepared in accordance with the instructions is placed in the tray flush with the sides. Excess mass (material) is used to coat the vault of the palate and the vestibule of the oral cavity in the area of the alveolar tubercles on the upper jaw or the lateral sections of the sublingual protrusion.

wanderings on the bottom. These are the most difficult areas for impression material to reach. Air bubbles can form here, leading to gross defects in the print. The spoon is inserted into the oral cavity with its left side, which moves the left corner of the mouth. Then, using a dental mirror or a lingual spatula, held by the doctor’s left hand, the right corner of the mouth is pulled back, and the spoon is placed in the oral cavity. It is centered, with the handle positioned along the midline of the face. Then the tray is pressed so that the alveolar part is immersed in the impression mass. In this case, first the pressure is applied in the posterior sections, then on the anterior section of the jaw. This prevents the mass from flowing into the throat. Excess impression material moves forward. When squeezing out the mass in the area of the soft palate, it is carefully removed with a dental mirror. When taking an impression (especially of the upper jaw), the patient’s head should be vertical or tilted forward. All this prevents the provocation of the gag reflex and the aspiration of mass or saliva into the larynx and trachea. Holding the spoon with the fingers of the right hand, the doctor forms the vestibular edge of the impression with his left hand. At the same time, on the upper jaw, he grabs the upper lip and cheek with his fingers, pulls them down and to the sides, and then lightly presses them against the side of the spoon. On the lower jaw, the lower lip is pulled upward, after which it is also slightly pressed against the side of the spoon. The lingual edge of the lower impression is formed by lifting and protruding the tongue. After the impression material has hardened, the impression is removed from the oral cavity. When assessing the impression, pay attention to how the space behind the maxillary tuberosities, the retromolar space has opened up, whether the frenulum is clearly visible, whether there are pores, etc. The impressions removed from the patient’s mouth are rinsed with a stream of running water for 1 minute. This simple step will reduce microbial contamination of the impression by approximately 50% and reduce the risk of hospital-acquired infection. The impressions must then be immersed in a disinfectant solution. At the end of the procedure, they are removed from the solution and washed with a stream of water for 0.5–1 min to remove residual disinfectant. The boundaries of future individual trays are marked on the impressions with a chemical pencil and transferred to the dental laboratory for their manufacture, where the technician casts the models. Transportation to the dental laboratory should not allow deformation and prolonged compression to avoid damage to the impression.

Taking an impression may be complicated by the gag reflex. To prevent this, you need to accurately select the impression tray. A long spoon irritates the soft palate and pterygomaxillary folds. If a gag reflex occurs, elastic masses should be used, and in a minimal amount. Before taking an impression, it is useful to try on the tray several times, getting the patient used to it. During the procedure, the patient

The ent is given the correct position (a slight tilt of the head forward) and asked not to move his tongue and breathe deeply through his nose. These simple techniques, as well as appropriate psychological preparation, make it possible in some cases to eliminate the urge to vomit. If, with an increased gag reflex, these measures do not produce results, special drug preparation must be carried out. To do this, the mucous membrane of the tongue root, pterygomaxillary folds, the anterior part of the soft palate and the posterior third of the hard palate are sprayed with a 10% solution of lidocaine (Hungary), legacaine (Germany) or Peril-spray (France) containing a 3.5% solution tetracaine hydrochloride. However, this may completely remove the protective gag reflex and result in saliva leakage or aspiration of impression material into the larynx. Small doses (0.0015–0.002 g) of the antipsychotic haloperidol, prescribed 45–60 minutes before the impression procedure, have a good antiemetic effect. As mentioned above, impressions are taken sequentially - first from one jaw and then from the other.

Full fixation and stabilization of removable dentures on edentulous jaws is achieved provided that the boundaries of the base correspond to the transitional fold, the relief of the prosthetic bed is congruent and the inner surface of the base is congruent. Therefore, using only an anatomical impression is not enough. Only by taking a functional impression can one obtain a clear image of the macro- and microrelief of the mucous membrane and determine the exact boundaries of the prosthesis. For this purpose, individual impression trays are used. To make individual trays, you need a good anatomical impression, which reveals all areas of the prosthetic bed.

Fitting individual spoons

To take a functional impression, individual trays must be carefully placed in the patient’s oral cavity. Each functional test allows you to accurately identify the relief in a particular area of the prosthetic bed and create a marginal closing valve. Most often in educational publications the fitting technique is described using functional tests according to Herbst. The indication for the use of the Herbst technique is: the absence of atrophy of the alveolar processes and the orthognathic relationship of the edentulous jaws. 10–15% of patients with complete tooth loss meet these conditions.

According to this technique, after introducing an individual spoon into the oral cavity, the patient makes certain groups of movements, and if the spoon moves, then its borders are shortened in a certain place. Recently, it has become believed that functional tests are of great importance, but they should be used to fit individual spoons (especially the lower one) with such precision as described in the Herbst method

(Table 1), is impractical due to the reduction in the boundaries of the spoons. It is believed that tests should be carried out with a reduced amplitude of movement, this is especially true for the lower jaw.

Table 1

	Fitting individual spoons using the Herbst method


		violation of its fixation
		violation of its fixation
	Fitting a spoon to the upper jaw
	Swallowing	Distal border along line A
	Wide mouth opening	Zone of maxillary cusps and retromolar
		area with vestibular surface
	Cheek suction	The vestibular surface on the right and left in the area
		sty of buccal mucous cords
		End of table. 1

		Individual tray correction zone in case of
		violation of its fixation
		violation of its fixation
	Lip pulling	Vestibular surface in the area of the frenulum
		upper lip
	Fitting a spoon to the lower jaw
	Swallowing	On the lingual side from the mucous tubercle to the che-
		mylohyoid line
	Wide mouth opening	If the spoon is dropped from behind, then it is shortened
		from the vestibular side from the mucous tubercle to
		projections of the first molar, but if the spoon is dumped -
		is formed in the frontal region, then it is shortened with
		vestibular side between the canines
	Run the tip of your tongue along	Along the maxillo-lingual line
	red border top and bottom

	Touch the tip of your tongue to	Lingual surface in the premolar area
	cheeks with half-closed mouth
	Stick the tip of your tongue forward	Lingual surface in the area of the frenulum of the tongue
	towards the tip of the nose
	Lip stretching with a tube	Vestibular surface between canines

Fitting an individual spoon to the upper jaw. Particular attention is paid to the distal border of the individual spoon, which is recommended to be marked with a line in the patient’s oral cavity before fitting the spoon. 1–2 mm distal to the foramen cecum (or line A) (Fig. 39).

Functional impression It is customary to call an impression that reflects the state of the tissues of the prosthetic bed during any movements of the lips, cheeks, or tongue. The method for its production was first developed by Schrott in 1864.

Classification of prints.

Received the greatest popularity classification of prints according to E.I. Gavrilov. It was based on the following basic principles.

1. The principle of the sequence of laboratory and clinical techniques for the manufacture of prostheses. On this basis, a distinction is made between preliminary (indicative) and final impressions. Preliminary impressions are taken with a standard spoon. Diagnostic models of jaws are cast from them, allowing one to study the relationships of the dentition, alveolar ridges of edentulous jaws, the relief of the hard palate and other features that are important for making a diagnosis, drawing up a plan for preparing the oral cavity for prosthetics, and the prosthetics plan itself. The same technique makes it possible to determine approximately and produce individual spoon . Based on the final impressions, a working model is cast.

2. A method of designing the edges of the impression, allowing the prosthesis to have a closing circular valve that provides one degree or another of its fixation. In accordance with this, anatomical and functional impressions .

According to the method of edge design E.I. Gavrilov subdivides functional impressions , designed using:

A) passive movements;

B) chewing and other movements;

B) functional tests.

Between anatomical and functional impressions It is impossible to draw a clear boundary. Essentially, there are no purely anatomical impressions. When taking an impression with a standard spoon, when forming its edges, they always use functional (though not sufficiently substantiated) tests. On the other side, functional impression represents a negative reflection of anatomical formations (palatal ridge, alveolar tubercle, transverse palatine folds, etc.) that do not change their position during movements of the lower jaw, tongue and the functions of other organs. Therefore, it is completely natural that functional impression has signs of anatomical, and vice versa.

3. The degree of pressure or the degree of squeezing of the mucous membrane.

According to the degree of its pressing, functional impressions are divided into:

1) compression or obtained under pressure, which can be arbitrary, chewing, dosed;

2) differentiated (combined);

Individual spoons.

Under any clinical conditions, the edentulous jaw should only be removed functional impression individual spoon.

Individual spoons can be made from:

1) metal (steel, aluminum) by stamping;

2) plastics:

A) basic (fluorax, ethacryl, yarocryl) polymerization method;

B) quick-hardening (redonta, protacryl) using the free-forming method;

c) standard plastic plates AKR-P;

D) light-curing plastic;

3) solar-cured materials with polymerization in special chambers or using a solar lamp;

4) thermoplastic impression masses (Stens);

5) wax.

Individual spoons produced in the laboratory or directly in front of the patient.

Making a custom spoon from plastic in a laboratory way.

In this case, an anatomical cast is taken with a standard spoon and a plaster model is cast from it. On the model, the dental technician draws the boundaries of the future individual spoon.

On the upper jaw, the border of the tray passes from the vestibular side along the transitional fold, not reaching the deepest point of its arch by 1-2 mm. On the distal side, it overlaps the maxillary tuberosities and runs along line “A” behind the palatine fossae by 1-2 mm.

On the lower jaw, the border of the spoon passes from the vestibular side along the transitional fold, not reaching 1-2 mm to the deepest point of its arch, while bypassing the cords and frenulum of the lip. In the retromolar region, it is located behind the mucous tubercle, overlapping it by 1-2 mm.

On the lingual side, the border of the spoon overlaps the area corresponding to the retroalveolar region (muscleless triangle), not reaching the deepest place of the sublingual space by 1-2 mm and going around the frenulum of the tongue.

From the above it is clear that both on the upper and lower jaw individual spoon border extends 2-3 mm less than the boundaries of the prosthesis. This is done so that there is space left for the impression material. The extruded impression material forms the edges of the impression. And, conversely, the distal boundaries of the tray must be larger than the boundaries of the prosthesis so that the anatomical formations, which are landmarks of the distal edge of the prosthesis, are well imprinted when taking an impression.

After drawing the boundaries, the dental technician covers the model with Izokol insulating varnish and begins making a custom spoon from quick-hardening or base plastic.

For making a custom spoon From quick-hardening plastic, the required amount of material is kneaded to a dough-like stage and a plate is made from it in the shape of the upper or lower jaw, which is pressed onto the model along the outlined boundaries. Small pieces of plastic “dough” are then used to make a handle perpendicular to the surface of the spoon, rather than tilted forward. This position of the handle will not interfere with the design of the edges of the print. If the alveolar part of the lower jaw is significantly atrophied and the tray is narrow, then the handle is made wider, almost to the premolars: with such a handle, the doctor’s fingers will not deform the edges of the impression when they hold it on the jaw

After the plastic has hardened (10-15 minutes), the spoon is removed from the model and processed with cutters and carborundum heads ( individual spoon do not polish), ensuring that the edges of the spoon correspond to the boundaries marked on the model. The thickness of the edge of the spoon should be at least 1.5 mm, because With a thinner edge, it is difficult to obtain the volume of the edge of the print.

Individual spoon can be made from base plastic by polymerization. To do this, the heated wax plate is pressed tightly onto the model, giving it the shape of an impression tray, and excess wax is cut off with a spatula along the marked boundaries. The wax mold of the spoon is plastered into the cuvette in the reverse way and the wax is replaced with plastic.

When making a spoon from AKR-P plastic, standard plates are softened in hot water and crimped according to the model. The excess is cut off with scissors after the corresponding area has been softened. The handle is made from scraps of material and glued to the spoon with a hot spatula (the heat melts and welds the plastic).

Individual plastic spoons refer to hard spoons. They can be used, as well as thermoplastic trays, to take compression impressions.

Advantages and disadvantages of custom plastic impression trays. Plastic spoons are rigid and do not deform in the oral cavity, but, like any laboratory-made spoons (in two visits), they require subsequent correction in the oral cavity. In addition, spoons made in this way provide a modified display of soft tissues, because they are compressed and stretched during the taking of the anatomical impression.

Individual wax trays for the upper and lower jaws

Individual wax spoons can be produced both in the laboratory and directly in the oral cavity. Wax trays using the CITO method are made in one visit directly on the jaw of the prosthetic patient. Such spoons are more accurate than individual ones made from an anatomical cast, because they display the soft tissues of the prosthetic bed at rest. The disadvantage of such trays is that the soft wax is deformed during fitting in the oral cavity and when taking an impression (it cannot withstand pressure), so the wax spoon can only be used to remove decompression impressions. Individual spoons , regardless of the method and what material they were made from, must be placed in the oral cavity. A correctly fitted spoon sticks to the jaw and does not lag behind it when moving the lips and cheeks. It has become widespread in our country technique for fitting individual spoons using functional Herbst tests.

Five tests are used on the lower jaw:

1) swallowing and wide opening of the mouth;

2) movement of the tongue to the sides along the red border of the upper and lower lips;

3) touching the cheeks with the tip of the tongue with the mouth half closed;

4) movement of the tip of the tongue forward beyond the lips towards the tip of the nose;

5) pulling the lips forward.

Three tests are used on the upper jaw:

1) wide mouth opening;

2) cheek suction;

3) shifting the lips forward (pulling).

Obtaining a functional impression.

After fitting an individual tray, they begin to obtain a functional impression.

Obtaining an impression consists of the following steps:

1) fitting an individual spoon;

2) applying the impression mass to the tray;

3) inserting a spoon with the mass into the oral cavity;

4) forming the edges of the impression and conducting functional tests;

5) making an impression and evaluating it.

It should be accepted as a rule that functional impression, ensuring good fixation of the prosthesis, can be obtained only if the anatomical impression reflects all the structures of the prosthetic field and some functional features of the tissues surrounding the prosthetic bed. Upon receipt functional impression they are just being clarified.

There are unloading or decompression and compression impressions.

Typically, the value of a compression or relief impression is associated with the fixation of the prosthesis and its effect on the mucous membrane of the prosthetic bed. However, the value of a particular impression-taking technique is determined by the influence of the prosthesis on the course of the process of atrophy of the alveolar process.

Unloading (decompression) impressions are obtained without pressure or with minimal pressure of the impression mass on the tissue of the prosthetic bed.

The disadvantage of the unloading impression is that the buffer zones of the hard palate are not subject to compression, and all the pressure from the prosthesis is transferred to the alveolar process, increasing its atrophy.

When receiving a decompression impression, the impression material must reflect every detail of the oral mucosa without distortion so that the microrelief of the prosthesis base exactly matches the surface structure of the prosthetic bed. Therefore, such impressions can only be obtained using impression compounds that have high fluidity and do not require much effort to remove the impression. Such masses include low-viscosity silicone pastes: exaflex, xanthoprene, alfazil, as well as zinc oxide eugenol pastes. The impression obtained using liquid plaster (according to Brachman) usually provides just such a perception of the surface relief of the tissues of the prosthetic bed. Some authors believe that if several holes are drilled in the impression tray to drain excess impression material, then the pressure of the impression mass on the mucous membrane can be reduced.

It is known that the fixation of prostheses made using decompression impressions is weak, but they can be used if there are certain indications.

Such indications include:

1) significant or complete atrophy of the alveolar processes and mucous membrane;

2) increased sensitivity of the mucous membrane;

3) uniformly pliable mucous membrane of the prosthetic bed.

Compression impressions are designed to take advantage of the pliability of the mucous membrane, so they are removed under high pressure, ensuring compression of the buffer zones. When they talk about a compression impression, they primarily mean compression of the vessels of the prosthetic bed. The decrease in tissue volume and its vertical compliance are directly dependent on the degree of filling of the vascular bed. The use of compression impressions is recommended in the presence of loose mucous membranes with good pliability.

A prosthesis made using a compression impression does not load the alveolar ridge; outside of chewing, it rests only on the tissues of the buffer zones, like pillows. When chewing, under the influence of masticatory pressure, the vessels of the buffer zones are emptied of blood, the prosthesis settles somewhat and transfers pressure not only to the buffer zones, but also to the alveolar part. Thus, the alveolar process is unloaded, which prevents its atrophy.

A prosthesis made using a compression impression has good fixation, because the pliable mucous membrane of the valve zone is in closer contact with the edge of the prosthesis.

The compression impression is taken under continuous pressure , providing compression of the vessels of the mucous membrane of the hard palate and their emptying. To obtain such a print, certain conditions must be met:

1) you need a hard spoon;

2) the impression must be taken using a low-flow mass or thermoplastic mass;

3) compression must be continuous, stopping only after the mass hardens. Continuity can be ensured by manual force (voluntary pressure). But it is more convenient and correct to take a compression impression under the chewing pressure of the muscles that elevate the mandible, i.e. under bite pressure, which is created by the patient himself, or with the help of special devices that make it possible to create a strictly defined pressure (dosed) taking into account the individual characteristics of the tissues of the prosthetic bed and masticatory muscles.

For obtaining a functional impression They use thermoplastic masses such as dentofol, otrokor, orthlast, etc.

The convenience of using thermoplastic masses is explained by their following properties:

1) they have an extended plasticity phase, which allows for functional tests necessary to obtain a high-quality impression;

2) during impression taking they always have the same consistency;

3) they do not dissolve in saliva;

4) distribute pressure evenly;

5) allow you to repeatedly insert an impression into the oral cavity and carry out correction, because new portions of the mass merge with old portions without deforming the print.

However, thermoplastic masses have certain disadvantages. These include: inaccurate print due to low fluidity; deformation in the presence of retention points. When cooled with water, they harden unevenly and may become deformed when removed from the mouth.

It should be recognized that when using the above methods for obtaining an impression, in some cases it is not possible to ensure a complete functional reflection of the prosthetic field. The tissues of the prosthetic field and the active muscles surrounding it are not the same in relief, relative volume, physiological status during chewing or speaking, as well as during the day. The physical and emotional state of a person also has a great influence on the condition of the prosthetic bed and the surrounding muscles. Whatever method of taking an impression is used, further adaptation of the prosthesis base to the tissues of the prosthetic field, the relationship of the dentition and the force of chewing pressure is necessary, as well as adaptation of the patient and fitting of the prosthesis over a certain period of time.

The wide variety of clinical conditions encountered for prosthetics necessitates the use of a differentiated impression. We should proceed from the general position that there is no single method shown in all cases. In this regard, the method of obtaining an impression in each specific case must be chosen taking into account the patient’s age, constitutional and individual characteristics of the jaw tissues, i.e. in all cases a differentiated approach is required. In cases where the tissues of the prosthetic bed in different areas are not identical in their relief and structure, the biophysical properties of each element of the prosthetic bed should be taken into account. When taking an impression, tissues with pronounced spring properties should be under greater load, while tissues of unloaded zones (in the area of the torus, incisive papilla, etc.) should not be overly loaded.

Selective pressure on the underlying tissues, depending on their anatomical and functional characteristics and biophysical properties, may be important due to the need to prevent premature atrophy of the soft and bone tissues of edentulous jaws by redistributing the chewing pressure of the prosthesis base.

Consequently, depending on the anatomical and physiological characteristics of the prosthetic bed, it is possible to obtain images of the mucous membrane in various functional states. At the same time, it is recommended to obtain unloading impressions in case of thin, atrophic and excessively pliable (“dangling” ridge) mucous membrane. Compression casts are indicated for loose, highly pliable mucous membranes. The best effect can be achieved only by using differentiated casts obtained with different degrees of compression of the mucous membrane, taking into account its compliance in different areas of the prosthetic bed.

Requirements for a functional impression:

1) have an accurate and clear imprint of the surface of the mucous membrane of the prosthetic bed without areas and pores blurred by saliva;

2) have a uniform thickness of the edge and layer of impression material at the base of the tray lumens;

3) have an accurate display of the “A” line and blind fossae;

4) the edges of the print must be smooth and rounded;

5) the entire impression must be removed from the oral cavity.

Casting working models.

After receiving the print, they begin to evaluate it: they check whether the material is pressed in any areas, whether the edges are well formed, and what their volume is. Air pores are not allowed. Then the suction force of the print is determined. To do this, the impression is inserted into the oral cavity, pressed against the prosthetic bed, and an attempt is made to tear it away from the bed by the handle of the spoon. If this is difficult, this means that the fixation is good. If all requirements are met, the impressions are sent to the laboratory to continue work.

To prevent disruption of the valve zone on the model during its opening, edging of the edges of the print is necessary. It is carried out as follows. A strip of wax 2-3 mm thick and 5 mm wide is layered 3-5 mm below the edge of the impression. After this, the model is cast in the usual way. The dental technician, when cutting the model, removes excess plaster only within the border, without thereby disturbing the areas of the mucous membrane of the transitional fold in which the edge of the impression was placed. After receiving the model, the wax is removed, and along its edge a clear, functionally designed border and a three-dimensionally reproduced valve zone remain on the model. If the integrity of the transitional fold is violated, modeling the edge of the prosthesis in accordance with the valve zone becomes impossible, because the marginal closing valve will have defects, which will lead to failure of fixation of the prosthesis.

Making plaster models of toothless jaws is slightly different from making those for removable dentures for partial dentition defects. Models with toothless jaws undergo special engraving.

Existing tubercles and swellings are removed from plaster models with a spatula. They are formed from the presence of small bubbles on the surface of the impression. After general inspection, the maxillary model is prepared for the creation of a peripheral valve on the palatal surface.

Using a spatula, a small layer of gypsum with a depth of 0.5-1.0 mm and varying widths is engraved in the area of the transition of the hard palate to the soft palate. Such engraving of the model leads to the formation of an elevation at the border of the prosthesis, which sinks into the pliable tissue. The pressing of soft tissues on the valve zone corresponds to the creation of a palatal valve for a prosthesis on the upper jaw.