^ Goal classes: teach students to check wax structures of complete removable dentures and identify errors made at the stage of determining the central relationship of the jaws.

1. 
   The concept of articulation and occlusion.
2. 
   Types of occlusion. Signs central occlusion
3. 
   Checking the design of a partial removable denture.
4. 
   Height Determination Methods lower section and their characteristics.
5. 
   The sequence for determining the central relationship of the jaws.
6. 
   Methods of setting teeth.

Security questions

1. 
   Occlusion, types of occlusion. Signs of central occlusion in orthognathic occlusion.
2. 
   Methodology and sequence of testing the wax structure of prostheses.
3. 
   Requirements for production artificial teeth.
4. 
   Clinical signs and the doctor’s tactics when increasing or decreasing the height of the lower part of the face at the stage of determining the central relationship of the jaws.
5. 
   Clinical signs and physician tactics for errors associated with displacement lower jaw in the sagittal and horizontal planes when fixing the central relationship of the jaws.
6. 
   Errors caused by shift, deformation and deviation of the bases from the prosthetic bed when determining the central relationship of the jaws.

^ Checking the design of complete removable dentures – an important and responsible clinical stage of their manufacture, because At this stage, the results of all previous clinical and laboratory stages are assessed. All necessary adjustments and changes in the design of the prostheses should be made at this moment. Once the laboratory stages of complete dentures have been completed, there is no opportunity to make significant changes to the design of the dentures, whereas during the design verification phase, any necessary changes can be easily made.

CHECKING THE DESIGN OF THE PROSTHETIC OUTSIDE THE ORAL CAVITY (ON THE MODEL):

• 
  location of models in the articulator (occluder);
• 
  quality of working models;
• 
  marking anatomical landmarks on working models;
• 
  quality of engraving and isolation of relevant anatomical areas;
• 
  correspondence of base boundaries;
• 
  lack of balancing of the prosthesis base;
• 
  shape of the dentition;
• 
  correspondence of teeth placement taking into account anatomical landmarks;
• 
  occlusal relationships of the upper and lower dentures (according to the selected occlusal scheme);
• 
  the severity of the Spee and Wilson compensation curves;
• 
  presence and topography of reinforcing elements;
• 
  the presence of individual characteristics of the prosthesis base.

^ ERRORS IN DETERMINING THE CENTRAL RELATIONSHIP OF THE JAWS

1. Errors in finding and fixing the vertical component of occlusion (height of the lower part of the face)

^ 2. Errors in fixing the central relationship of the jaws, caused by displacement of the lower jaw relative to the upper.

^ GENERAL DIAGNOSTIC CRITERION: AT THE STAGE OF CHECKING THE DESIGN, REPEATING THE ERROR MADE WHEN DETERMINING AND FIXING THE CENTRAL RELATIONSHIP OF THE JAWS RESULTS IN NORMALIZATION OF OCCLUSION.

^ 3. Errors caused by displacement, deformation and deviation of the bases from the prosthetic bed when determining the central relationship of the jaws.

^ SITUATIONAL TASKS

1. When checking the wax structure of the dentures during an external examination
Patient M. has smoothness of the nasolabial folds and chin
dental folds, “knock” when closing teeth. In a state of physiological rest, there is no gap between the front teeth. With half open mouth
the anterior group of teeth of the upper jaw protrudes from under the upper lip
by 3-4 mm.

What mistake was made? At what stage of prosthetic manufacturing? Error elimination method.

2. In patient V., when checking the design of dentures in the oral cavity, a prognathic relationship of the dentition was established, predominantly
tubercular closure of the lateral teeth, sagittal gap between the anterior teeth, increased bite to the height of the tubercles of the lateral teeth.

When was the mistake made and what was it? Elimination method.

3. What are the signs of decline in the lower part of the face during checking the wax composition of prostheses and the doctor’s tactics in this case.

1. 
   At the stage of testing the design of the prosthesis, the patient was diagnosed with tubercle closure on right side, increasing the height of occlusion, shifting the center
   lower dentition to the right, gap between the lateral teeth on the left.

1. 
   When checking the design of the patient's dentures in the oral cavity, it was found that there is contact only in the frontal area and a gap between the lateral teeth. The lower third of the face is not enlarged. When checking the tightness of closure of the lateral teeth with a spatula, a gap appears.

LITERATURE

Main:

Additional:

LESSON 10

Subject: Fitting and application of laminar dentures in the absence of teeth. Rules for the use and correction of removable dentures.

^ Purpose of the lesson: be able to evaluate the quality of manufactured laminar dentures, master the methods of fitting and applying them, know the rules for correction and use of removable laminar dentures.

^ Questions necessary to understand the topic

1. 
   Fitting and application of partial removable laminar dentures.
2. 
   Clinical and laboratory stages of manufacturing complete removable laminar dentures.

Security questions

1. 
   What errors in the manufacture of prostheses can be identified by visual inspection?
   prostheses, the doctor’s tactics to eliminate them.
2. 
   Technique for fitting and applying complete removable dentures.
3. 
   Errors in the manufacture of prostheses identified at the stage of fitting and application, methods for eliminating them.
4. 
   Instructions for the patient on the rules of using prostheses.
5. 
   Correction of the prosthesis, methods of its implementation.
6. 
   What is the principle of completeness of treatment?

OOD diagram on the topic: “Fitting and application of complete removable plate dentures”

^ Correction technique for complete removable dentures

The patient is scheduled for correction the next day after the prosthesis is applied. Moreover, the patient is warned that dentures must be inserted into the oral cavity 2-3 hours before coming to the doctor. After clarifying complaints and examining the mucous membrane, areas where injury occurs (hyperemia, damage to the mucous membrane) are identified. Using a special marker, dentin or plaster powder, mark the area of ​​mucosal injury and apply a dried prosthesis. Then the prosthesis is removed from the mouth and a metal cutter is used to remove part of the plastic where there are imprints of marker, plaster, or dentin. You need to be very careful when removing the plastic in the area of ​​the transitional fold and the distal (posterior) border of the palate. Excessive removal of plastic in these areas can disrupt the fixation of the dentures.

^ Situational tasks

1. A 60-year-old patient complained of the inability to chew, pain in the masticatory muscles and temporomandibular joints. Pain occurs when using complete removable dentures. The dentures were made a month ago. The lower third of the face is enlarged. When you smile, the base of the removable denture on the upper jaw is exposed. When opening the mouth, the front teeth protrude 4-5 mm from under the upper lip. Diction is broken. Complete dentures were produced without a clinical phase of testing the wax-up design of complete dentures.

What mistake is made when making complete removable dentures? At what stage of production? How to eliminate the error in this patient?

2. When fitting and applying complete removable dentures, there is a decrease in the lower third of the face, pronounced nasolabial folds, and drooping corners of the mouth. When conducting a conversational test, the distance between the teeth of the upper and lower jaw is noted to be 8-9 mm.

What mistake was made during prosthetics? At what stage of prosthetic manufacturing? How to eliminate the error in this patient?

3. The patient uses complete removable dentures for 3 days. Complaints about poor fixation of the upper jaw prosthesis when eating and talking. When examining the oral cavity, the boundaries of the prosthesis cover the alveolar tubercles and are located within the transitional fold. By posterior border hard palate Blind fossae are clearly visible.

What is the reason for unsatisfactory fixation of the upper jaw prosthesis?
sti? How to fix the error?

4. During fitting and application of the prostheses, it was noted that they have
thick base. The lower third of the face is enlarged. In a state of physiological rest
there is no distance between the teeth. The teeth of the upper jaw protrude from
under the upper lip by 3-4 mm, the teeth of the lower jaw 2-3 mm above the red border of the lower lip. During the conversational test, teeth chattering can be heard.

What mistake was made when making a prosthesis? What should the doctor do to correct the error?

5. The patient came to the clinic with complaints about unsatisfactory fixation of the lower jaw prosthesis. Examination of the oral cavity revealed
standing 2 mm between the vestibular edge of the prosthesis and the transitional fold on the right.

What is the reason for poor fixation of the prosthesis? What is the doctor's tactics?

LITERATURE

Main:

1. 
   Lecture material from the Department of Orthopedic Dentistry of BSMU.
2. 
   Abolmasov N.G., Abolmasov N..N. and others. Orthopedic dentistry, M., 2002.
3. 
   Bushan M.G. Handbook of prosthetic dentistry. Chisinau, 1990.
4. 
   Voronov A.P., Lebedenko I.Yu., Voronov I.A. Orthopedic treatment patients with complete absence of teeth: Tutorial– M., 2006.
5. 
   Gavrilov E.I., Shcherbakov A.S. Orthopedic dentistry. M., 1984.
6. 
   Doynikov A.N., Sinitsin V.D. Dental materials science. M., 1986.
7. 
   Kopeikin V.N. Orthopedic dentistry. M., 1988.
8. 
   Kopeikin V.N., Bushan M.G., Voronov A.I., etc. Guide to orthopedic dentistry. M., 1998.
9. 
   Kopeikin V.N., Demner L.M. Dental technology. M., 1985.
10. 
    Kurlyandsky V.Yu. Orthopedic dentistry. M., 1977.
11. 
    Methods of fixation and stabilization of complete removable dentures: educational method. manual / S.A. Naumovich et al. - Minsk: BSMU, 2009.
12. 
    Shcherbakov A.S., Gavrilov E.N. and others. Orthopedic dentistry. St. Petersburg. 1999.

Additional:

1. 
   Vares, E. Ya. Restoration of complete loss of teeth. Donetsk, 1993
2. 
   Kalinina N.V., Zagorsky V.A. Prosthetics for complete loss of teeth. M., 1990
3. 
   Kalinina N.V. Prosthetics for complete loss of teeth. M., 1979
4. 
   Kopeikin V.N. Errors in orthopedic dentistry. M., 1998

LESSON 11

Subject: Long-term patient management tactics. Adaptation.

Purpose of the lesson: study the mechanisms of adaptation to complete removable dentures, train students in the methods of relining and repairing complete removable dentures, as well as tactics for managing patients in the long term,

^ Questions necessary to understand the topic

1. 
   Reaction of denture bed tissues to removable dentures.
2. 
   Clinical and laboratory stages of manufacturing complete removable laminar dentures

Security questions

1. 
   Adaptation of patients to dentures. Phases of adaptation to complete removable dentures.
2. 
   Nearest and long-term results full removable prosthetics
   plate prostheses.
3. 
   Relining bases of plate dentures, materials, methods.
4. 
   Causes of breakdowns and rules for repairing plastic prostheses.

^ ADAPTATION TO COMPLETE REMOVABLE DENTURES

Term "ADAPTATION"(from Latin adaptatio - device) in orthopedic dentistry implies the process of getting the patient accustomed to using dentures. Dentures are perceived by the organs and tissues of the oral cavity as a foreign body, being an irritant for nerve endings.

According to V.Yu. Kurlyandsky, the process of adaptation to prostheses can be considered as a manifestation of cortical inhibition of irritation reactions, occurring within a period of 10 to 33 days. In the case of repeated prosthetics, the time required for the patient to fully adapt to new prostheses is significantly reduced (up to 3-5 days).

V.Yu. Kurlyandsky distinguishes 3 phases of adaptation to dentures.

1 – irritation phase.

2 – partial braking phase.

3 – phase of complete braking.

1 – irritation phase, observed on the day of application of the prosthesis:

• 
  characterized by the patient’s fixed attention to the design features of the prosthesis;
• 
  increased salivation;
• 
  a sharp change in diction and phonation, lisp;
• 
  loss or significant decrease in chewing efficiency;
• 
  there may be a feeling of nausea;
• 
  hypertonicity of the masticatory muscles;
• 
  tense state of perioral tissues (lips, cheeks, etc.).

• 
  salivation normalizes and fades away gag reflex;
• 
  diction and phonation are restored;
• 
  chewing efficiency gradually increases;
• 
  Tension of the perioral tissues disappears.

• 
  the prosthesis is no longer foreign body for the patient;
• 
  the patient feels discomfort without a prosthesis;
• 
  complete adaptation of the neuromuscular state is observed;
• 
  restoration of chewing efficiency reaches its maximum.

• 
  eating relatively soft food;
• 
  eat food slowly;
• 
  eat food cut into relatively small pieces;
• 
  try to chew food with the lateral teeth of the right and left sides at the same time, chewing food should prevail over biting.

On initial stages adaptation to prostheses should be recommended to patients:

• 
  try to talk more;
• 
  slowly, focusing on diction, count out loud to 10;
• 
  read the text slowly, trying to focus on “difficult” sounds and sound combinations, repeating them until the pronunciation becomes “clearer”.

^ REBASE OF PLATES. PROSTHETICS

REBASE– a method of recreating the inner surface of a complete removable denture congruent with the relief of the tissues of the mucous membrane of the prosthetic bed.

INDICATIONS for relining the prosthesis:

• 
  violation of prosthesis fixation;
• 
  insufficient static stability of the prosthesis and the presence of excursions of the prosthesis relative to the mucous membrane;
• 
  systematic entry of food debris under the prosthesis;
• 
  mucosal injury.

• 
  absence of lesions of the mucous membrane;
• 
  acceptable relationships between antagonist teeth in the CO position and lateral occlusions;
• 
  correctly determined height of physiological rest and vertical component of occlusion;
• 
  correspondence of the peripheral borders of the prosthesis to the topography of the valve zone.

^ MATERIALS FOR RELINING COMPLETE REMOVABLE DENTURES

Temporary:

• 
  silicone materials of hot polymerization (long-term - more than 30 days);
• 
  silicone materials of cold polymerization (long-term - more than 30 days);
• 
  plasticized acrylates (short-term - less than 30 days).

• 
  
• 
  acrylic plastics of hot polymerization.

• 
  
• 
  hot polymerization silicone materials.

• 
  
• 
  acrylic plastics of cold polymerization.

• 
  plasticized acrylates (fabric conditioners)

• 
  acrylic plastics of cold polymerization;
• 
  cold polymerization silicone materials;
• 
  plasticized acrylates.

• 
  acrylic plastics of hot polymerization;
• 
  hot polymerization silicone materials;
• 
  plasticized acrylates.

^ COMPARATIVE CHARACTERISTICS OF ACRYLIC PLASTICS FOR REBASED DENTURES

^ CLINICAL REBASE OF COMPLETE REMOVABLE DENTURES USING SOFT MATERIALS

Indications to the use of soft lining materials:

• 
  the presence of areas in the area of ​​the prosthetic bed covered with thinned mucous membrane (exostoses, sharp edges of the sockets);
• 
  dry, unyielding mucous membrane of the prosthetic bed;
• 
  sharp and/or uneven atrophy of the alveolar process;
• 
  availability chronic diseases mucous membrane;
• 
  intolerance to acrylic plastics (“prosthetic stomatitis”);
• 
  direct (immediate) prosthetics;
• 
  maxillofacial prosthetics and postoperative prosthetics;
• 
  the presence of undercuts of the alveolar process (tubercles of the upper jaw, mushroom-shaped type of the alveolar process).

The optimal choice for long-term clinical relinings using soft pads are materials based on VPS (vinylpolysiloxane, additional type silicone).

Benefits The uses of VPS-based lining materials are:

• 
  production of a soft lining directly at a clinical appointment (one visit);
• 
  materials are easy to use and do not require additional equipment;
• 
  affordable cost of material;
• 
  the presence of a special adhesive that ensures a strong connection between the soft lining and the base of the prosthesis;
• 
  the materials are compatible with any acrylic-based base plastics;
• 
  spatially stable;
• 
  have good rheological properties;
• 
  biocompatible (does not contain methyl methacrylate);
• 
  have a neutral taste and smell;
• 
  characterized by stable color and practically do not interfere with the aesthetics of the prosthesis;
• 
  resistant to everyday denture care products;
• 
  can also be used for laboratory production of elastic pads.

^ FABRIC CONDITIONERS

(plasticized acrylic plastics)

Chemical structure:

Powder:

• 
  polyethyl methacrylate;
• 
  dye.

• 
  plasticizer - aromatic ethers (dibutyl phthalate, phthalyl butyl glycolate);
• 
  alcohol (ethyl/butyl/methyl) up to 30%.

Characteristic features: have good fluidity, sufficient for a long time remain plastic and deform in areas of high pressure. As the alcohol base evaporates, it hardens.

^ Scope of application:

• 
  to eliminate phenomena chronic inflammation mucous membrane of the prosthetic bed caused by mechanical or chemical irritants, infections and other reasons;
• 
  to form the relief of the prosthetic bed in the manufacture of immediate (imediate) prostheses;
• 
  as a soft lining material for short-term (1-2 weeks) relining;
• 
  for obtaining delayed functional impressions during relines complete dentures or re-prosthetics with complete removable dentures.

^ REPAIRING PLASTIC DENTURES

According to L.A. Pashkovskaya (1967), V.P. Grossman (1967), already in the first year of using acrylic plastic prostheses, the frequency of breakdowns ranges from 10 to 40%.

The causes of failure of removable laminar dentures can be divided into five groups:

1) insufficient strength of the base plates;

2) breakdowns associated with doctor errors made at certain stages of work;

3) breakdowns associated with errors made by the technician;

4) breakdowns associated with the patient’s careless attitude towards the prosthesis;

5) breakdowns associated with the discrepancy between the prosthetic bed and the base of the prosthesis as a result of jaw atrophy (if the recommended period of use is exceeded).

Plate prostheses for complete absence Teeth on both the upper and lower jaws most often break along the midline. This is facilitated by the weakening of the denture bases due to the deep notch for the labial frenulum, as well as the balancing of the upper denture on the torus with insufficient isolation of the latter. Clinical observations show that the area of ​​greatest surface tension is on the palatal part of the maxillary plate prosthesis, directly behind the central incisors. In addition, internal stresses in the base of the prosthesis, which arise due to a violation of the polymerization regime or rapid cooling of the prosthesis, as well as in the presence of various kinds inclusions.

Plastic dentures are repaired as follows. The fracture line is smeared with dichloroethane glue, the parts of the prosthesis are aligned along the fracture line and held for 3-4 minutes. A plaster model and a countermodel are cast using the glued prosthesis. After this, the prosthesis is removed from the model and disconnected. After gluing, use a cutter to widen the fracture line by 1-2 mm in each direction and make chamfers along the edges. The model and the counter-model are lubricated with Izokol insulating varnish, then the parts of the prosthesis are installed on the model, and the correct installation is checked with the counter-model.

Plastic dough is prepared from self-hardening plastics “Protacryl” or “Redont”. The prepared plastic dough (in the “stretching threads” phase) with a slight excess is placed along the fracture line and pressed with a counter-model. Polymerization of the plastic ends after 8-10 minutes, after which the prosthesis is processed.

The above repair technique can be used if it is necessary to add to the prosthesis artificial teeth. For this purpose, a cast of the jaw with the prosthesis and a cast of the antagonist teeth are taken. After casting the models, artificial teeth are selected according to color and size, then the edges of the prosthesis are refreshed with a milling cutter, plastic dough is applied and the teeth are packed into it. After 8-10 minutes, the prosthesis is processed.

Repairing plastic dentures can also be done in the laboratory.

In this case, the technician glues the prosthesis and casts the model using the method described above. After expanding the fracture line, the resulting gap is filled with molten wax and smoothed out at the level with the prosthesis. Then the model with the prosthesis is plastered in a ditch and the wax is replaced with plastic in the generally accepted way.

^ SITUATIONAL TASKS

1. The patient came to the clinic with complaints about the breakage of the prosthesis on the upper part. She has been using dentures for more than 5 years and notes poor fixation. Upon examination, a fracture of the prosthesis base along the torus line was discovered.

What is the doctor's tactics?

2. The patient came to the clinic with complaints about unsatisfactory fixation of a complete removable denture on the lower jaw. The prosthesis was made 5 years ago. When examining the oral cavity, a distance of 2 mm was found between the vestibular edge of the prosthesis and the transitional fold.

1. What is the reason for poor fixation of the prosthesis?

2. What is the doctor’s tactics?

3. The patient came to the clinic the next day after repairing complete removable dentures with complaints of pain, aggravated by chewing, in the area of ​​the alveolar process of the upper jaw on the left. The examination revealed that there is an area of ​​hyperemic and edematous mucous membrane in the area of ​​the transitional fold at the level of teeth 16, 17.

Please indicate your diagnosis. What will the doctor’s tactics be?

LITERATURE

Main:

1. 
   Lecture material from the Department of Orthopedic Dentistry of BSMU.
2. 
   Abolmasov N.G., Abolmasov N..N. and others. Orthopedic dentistry, M., 2002.
3. 
   Bushan M.G. Handbook of prosthetic dentistry. Chisinau, 1990.
4. 
   Voronov A.P., Lebedenko I.Yu., Voronov I.A. Orthopedic treatment of patients with complete absence of teeth: Textbook - M., 2006.
5. 
   Gavrilov E.I., Shcherbakov A.S. Orthopedic dentistry. M., 1984.
6. 
   Doynikov A.N., Sinitsin V.D. Dental materials science. M., 1986.
7. 
   Kopeikin V.N. Orthopedic dentistry. M., 1988.
8. 
   Kopeikin V.N., Bushan M.G., Voronov A.I., etc. Guide to orthopedic dentistry. M., 1998.
9. 
   Kopeikin V.N., Demner L.M. Dental technology. M., 1985.
10. 
    Kurlyandsky V.Yu. Orthopedic dentistry. M., 1977.
11. 
    Methods of fixation and stabilization of complete removable dentures: educational method. manual / S.A. Naumovich et al. - Minsk: BSMU, 2009.
12. 
    Shcherbakov A.S., Gavrilov E.N. and others. Orthopedic dentistry. St. Petersburg. 1999.

Additional:

1. 
   Vares, E. Ya. Restoration of complete loss of teeth. Donetsk, 1993
2. 
   Kalinina N.V., Zagorsky V.A. Prosthetics for complete loss of teeth. M., 1990
3. 
   Kalinina N.V. Prosthetics for complete loss of teeth. M., 1979
4. 
   Kopeikin V.N. Errors in orthopedic dentistry. M., 1998

Significant amount errors in prosthetics for patients with complete secondary adentia occurs at the stage of determining the central relationship of the jaws.

When determining the central relationship of the jaws using wax bases with rollers, the most common errors are such as overestimating or underestimating the height of the lower part of the face, fixing the rollers in an anterior or lateral relationship, which ultimately leads to disruption of the function of chewing, speech, aesthetic standards and harmony faces. The listed errors, as a rule, occur at the moment of fixing the upper wax roller to the heated lower wax roller. Even if incorrect fixation of the jaws is directly detected, the entire procedure, starting with fitting wax rollers in the oral cavity, determining the height of the lower third of the face, etc., has to be repeated.

In order to eliminate these errors, we proposed a new technique (RF Patent No. 2200501) for fixing the central relationship of the jaws using a metal plate, 0.5-0.7 mm thick, attached with molten wax to the occlusal surface of the lower wax roller and corresponding in shape.

After the final adjustment of the wax rollers (determining the prosthetic plane, the height of the lower third of the face and the formation of the vestibular oval), a uniform layer of wax corresponding to the thickness of the plate is removed from the lower wax roller. The plate is placed on the occlusal surface of the lower wax ridge so that it covers the vestibular perimeter by 1-2 mm, and is strengthened on it with molten wax. A wax base with a roller of the upper jaw and a roller with a metal plate of the lower jaw are fitted in the oral cavity and the central relationship of the jaws is determined. This is not always possible on the first try, but in the method we propose, this procedure can be repeated until the desired result is obtained, without fear of deformation of the wax rollers.

At the moment of fixation of the jaws in the central occlusion, the perimeter of the upper wax ridge is outlined with a pencil on the protruding part of the plate. Clinical guide lines for placing artificial teeth are drawn on the upper wax ridge and these lines are transferred with a pencil to the horizontal protruding edge of the metal plate of the lower jaw. Then the wax bases with rollers are installed on the model, they are compared in a central ratio according to the outlines and landmarks printed on the plate and fixed to each other with molten wax with inside models. After plastering the models into the articulator, the artificial teeth of the upper jaw are placed on a metal plate, which replaces the method of setting teeth on glass according to M.E. Vasilyev. Thus, the stage of manufacturing a plaster table with glass on the lower frame of the articulator is eliminated.

An important advantage of this method of fixing the central relationship of the jaws is that using a metal plate, it is possible to carry out anatomical alignment of teeth on the sagittal curve, using the Christensen phenomenon. To do this, after fitting the fitted wax rollers with a metal plate in the oral cavity, the patient is asked to push the lower jaw forward.

In this case, the ridges in the area of ​​the molars form a wedge-shaped gap, facing an acute angle forward. In this position, the distal edges of the plate on the right and left are folded up until they come into contact with the upper wax roller, and the resulting space is filled with softened wax and fixed to the lower roller with a hot spatula. Next, the cooled rollers are again placed in the mouth and the patient is asked to close the jaws in the position of the central jaw ratio. Thus, disocclusion is obtained in anterior section. The wax is cut from the distal part of the upper wax ridge until it makes tight contact with the metal plate along its entire length and an individual patient curve is obtained.

Using the proposed method of fixing the central relationship of the jaws in the complete absence of teeth, 43 patients were treated. All of them successfully use manufactured removable dentures, and note their individual naturalness at rest and while chewing food.

Thus, using the above-described technique, it is possible to avoid errors in determining the central relationship of the jaws and obtain a sagittal plane individually for each patient, which will allow the restoration of impaired functions of the dentofacial system and faster adaptation to removable dentures.

S.I. Abakarov, K.S. Adzhiev

ERRORS WHEN THE CENTRAL RELATIONSHIP IS INCORRECTLY FIXED

When checking the design of dentures, you can identify errors made in determining the central relationship of the jaws. These errors can be divided into five main groups.

Section I. Orthopedic treatment of patients with complete loss of teeth

Wrong definition height of the lower part of the face (overstatement or understatement). In orthopedic practice, it is customary to say that the bite is “high” or “low.” However, occlusion is a type of closure of the dentition. Therefore, there cannot be an overestimated or underestimated closure of the dentition.

In our opinion, it is more correct to talk about a decrease or increase in the interalveolar distance. When it is too high, the patient’s facial expression is somewhat surprised, the nasolabial and chin folds are smoothed, during a conversational test you can hear the “clattering” of teeth, the gap in the frontal region during a conversational test is less than 5 mm, there is no gap (2-3 mm) in a state of physiological rest.

This error is resolved as follows. If the upper dentition is set correctly, and the overestimation occurs due to the lower teeth, then it is necessary to remove the teeth from the lower wax base and make a new bite ridge or

Rice. 9.1. Variants of setting the front teeth in the vertical plane.

take the base with the bite block on which the central relationship of the jaws was established, and determine the height again. If the placement of the upper teeth is done incorrectly (the prosthetic plane is not maintained), then bite ridges are also made for the upper jaw. Then the central relationship of the jaws is determined again and the teeth are positioned.

When the interalveolar distance is underestimated, if upper teeth positioned correctly, a heated strip of wax is applied to the lower dentition and the central relationship of the jaws is redefined, bringing the height to normal. A new base with an occlusal ridge can be made for the lower jaw. If the reason for the low height is also the upper teeth, then it is necessary to redefine the central relationship of the jaws using new upper and lower ridges.

Fixation of the lower jaw with a displacement in the horizontal plane. Most

A common mistake when determining the central relationship of the jaws is to push the lower jaw forward and fix it in this position. When checking the structure, a prognathic relationship of the dentition is detected, predominantly tubercular closure of the lateral teeth, a gap between the front teeth, and an increase in the bite to the height of the tubercles (Fig. 9.2). This error is eliminated by redefining the centric relation with new occlusal ridges in the lateral parts of the lower jaw, and the anterior group of teeth is left for control.

A posterior displacement of the lower jaw when determining the central relationship of the jaws is possible with a “loose” joint. When checking, a progenic relationship of the dentition, tubercular closure of the lateral teeth, and an increase in the bite to the height of the tubercles are detected. The error is corrected by redefining the centric relation of the jaws with a new bite ridge on the lower jaw. However, it should be noted that this is not always possible, because such patients quite often fix the lower jaw in different positions and not always correctly (Fig. 9.3).

Checking the design of the prosthesis when the lower jaw is shifted to the right or

to the left, one can detect tubercular closure on the side opposite to the displacement, an increase in the bite, a shift in the center of the lower dentition to the opposite side, a gap between the lateral teeth on the side of the displacement. This error can be corrected by redefining the central relationship of the jaws with a new lower bite ridge (see Fig. 9.4, 9.5).

Errors caused by the separation or loose fit of the bite ridges to the prosthetic bed (model). These errors arise due to uneven compression of the bite ridges during fixation of the central relationship of the jaws. The reason for this may be poor fitting of the lower roller to the upper one, uneven heating of the lower roller with a hot spatula, or loose fit of the wax base to the model. Most often, the consequence of such an error in the clinic is the lack of contact between the chewing teeth on one or both sides (see Fig. 9.6). It is determined when administered between chewing teeth cold spatula. At the same time, the spatula is rotated around its axis, and at that moment you can observe how the wax bases fit tightly to the underlying tissues. This error is corrected by

Rice. 9.4. The relationship of the dentition when fixing the lower jaw is hymen.

Rice. 9.5. The relationship of the dentition when fixing the lower jaw to the right.

by applying a plate of heated wax to the area chewing teeth and bite redefinition.

Crushing the base when fixing the central relationship of the jaws. This can occur in cases where the occlusal ridges are not reinforced with arcuate wires or the alveolar part of the mandible is very narrow. When such bases are installed on the model, it is clear that they do not fit tightly to it. In the clinic, this error manifests itself in the form of an increased bite with uneven and indefinite tubercular contact of the lateral teeth, and a gap in the area of ​​the anterior teeth. The error has been corrected -

Rice. 9.6. The relationship of the dentition when the ridges move away or loosely fit to the model.

They are created by redefining the central relationship of the jaws using new rollers, often with rigid bases.

Fixation of the central relationship of the jaws when one of the wax bases is displaced. Under unfavorable anatomical conditions in the oral cavity (II degree of atrophy in the lower jaw and III degree of atrophy in the upper jaw) during fixation of the central relationship of the jaws, the upper or, which happens much more often, the lower wax base with the occlusal ridge may move forward or backward.

By checking the design of the prosthesis, one can observe the same picture as when fixing the lower jaw not in the central, but in the anterior or posterior relationship, which was described above. The error is corrected by re-defining the central relationship of the jaws using new rollers made on rigid bases. Subsequently, teeth are placed on these rigid plastic bases and the design of the dentures is checked. Application of hard In this case, bases are justified, since they are stable on the jaws, do not deform or move, like wax bases.

In all cases when, when checking the design of prostheses, And is-

Chapter 9. Checking the design of prostheses

Errors are corrected, the upper model is removed from the occluder or articulator and plastered in a new position.

This article is about checking the design of a complete removable denture. About mistakes (for example, overbite) and their correction.

In this article you will learn:

1. How to check the design of a complete removable denture after the technician has placed the teeth?
2. What mistakes might have been made before?
3. And how to eliminate them?

Stages of testing the prosthesis design

After the technician has installed the artificial teeth (this was in the last article), he gives me the wax bases. Mandatory with teeth on the models and in the articulator. I, in turn, must make sure of the quality of the work. It’s just that now that the bases of the prosthesis are made of wax, any mistake will be easy to correct.

My train of thought:

1) First I evaluate working models. They should not have pores, damage or chips. Any inaccuracy on the model will make the prosthesis unbearable. So if I don't like the model, I shoot again functional impression. Of course, this is difficult and unpleasant. But it will be much more unpleasant to remake a finished prosthesis.

2) The model must have markings, a midsagittal line, etc. (we talked about them in the previous article). Some should be isolated anatomical features patient (tori, bony protrusions, incisive papilla, if it is hypertrophied). Then the base will not touch them and injure them.

3) Then I estimate the boundaries of the bases:

Firstly: they should be as thick as the edge of the functional impression.

Secondly: They must fit snugly to the model throughout.

Thirdly: they must end exactly along the border of the future prosthesis

(On the upper jaw: 1-2 mm above the transitional fold, bypassing the frenulum of the upper lip and buccal cords. Distally, 1-2 mm overlaps the blind fossae (the place where the hard palate transitions to the soft palate).

On the lower jaw: 1-2 mm below the transitional fold, bypasses the frenulum of the lower lip and buccal cords and completely covers the mucous tubercle in the retromolar region. On the tongue side, the border passes through the junction of the gums and the mucous membrane of the floor of the oral cavity.)

4) I check to see if the bases are balanced.

Balancing a prosthesis is an uneven fit of the base to the prosthetic bed. The prosthesis seems to swing on the jaw.

5) I evaluate the setting of the teeth. Do they correspond to anatomical landmarks? I check whether the shape of the dentition is correct. Are there compensatory curves (Spee, Wilson). Is uniform occlusion created?

6) After a thorough check in the articulator, I remove the dentures from the models and disinfect them. After that, I put them on the patient’s jaws and test them, so to speak, in vivo.

7) First, I examine the patient’s face: is the height of the face restored, are the lips and cheeks sunken. How are the nasolabial and chin folds expressed, are the corners of the mouth drooping, and are the muscles tense?

8) Then I look into the patient's mouth. I check the position of the borders of the base and make sure that they fit tightly to the mucosa. I check again to see if the prosthesis is balanced.

9) I evaluate the position of the occlusal plane. It should be parallel to the pupillary line in the anterior region and the Camper line in the area of ​​the chewing teeth.

10) I look to see if the midline of the face coincides with the line between the central incisors, and whether each tooth has two antagonists.

11) I check if balanced occlusion is created. Those. is it in contact same amount teeth on the left and right half of the jaw with any type of occlusion (lateral, anterior).

12) I check the height of the lower part of the face. Normally, it is 2-4 mm less than the resting height. I measure the distance between two points at rest and at the position of central occlusion.

12.1) I can also use a speech test. When pronouncing the sound [v, f], upper incisors evenly touch the lower lip. They touch it exactly along the line of transition between the lip of the face and the lip of the vestibule of the mouth (dry to wet).

If the teeth are spaced and matched correctly, the patient will not have problems pronouncing these sounds.

13) And the last thing I check is aesthetics. The upper central incisors protrude from under the lip by 1-2 mm. When smiling, the lip rises to the level of the necks of the teeth. The gums are not visible.

14) I give the patient a mirror so that he can evaluate the prosthesis himself. Only after his approval do I give the prosthesis to the technician. He exchanges wax for plastic and prepares the prosthesis for delivery.

That is if everything went well. But there may be mistakes. I will tell you about them now.

Mistakes in the manufacture of complete removable dentures

Errors can be divided into 3 types.

• — When determining the height of the lower part of the face
• — When fixing central occlusion
• — When determining central occlusion

Errors in determining the height of the lower part of the face.

1. Overbite.

Why is this dangerous? With an overbite, the teeth are always in contact. The chewing muscles are tense. Because of this, there is a constant load on the prosthetic bed, which becomes injured and painful. Overload hurts and masticatory muscles. Teeth interfere with conversation and chatter. The patient has difficulty closing his lips. It is difficult to pronounce some sounds [p, b, m]. Joint damage may occur.

How to recognize? The height of the lower third of the face is too high. The difference between central occlusion and physiological rest is less than 2-4 mm. The patient has a surprised expression on his face. There are no nasolabial and chin folds. The muscles of the face and lips are tense.

What to do? If the teeth of the upper jaw are positioned correctly, you need to remove the teeth from the lower jaw, make a new bite ridge and determine the height of the lower part of the face (anatomically and physiologically).

If the teeth on the upper jaw are not positioned correctly (for example, they stick out from under the lip by more than 2 mm), you need to remove teeth from both jaws and make two bite ridges.

1. Underbite.

Why is it dangerous? The chewing efficiency of the denture decreases. Lips and cheeks are sunken. The chin protrudes forward. There may be drooling and angular cheilitis due to improper lip closure.

How to recognize? The height of the lower third of the face is reduced. The difference between central occlusion and physiological rest is more than 4 mm. The corners of the mouth look down. The nasolabial and chin folds are very well defined - an old face.

What to do? The algorithm is exactly the same as for overbite overestimation.

Errors in fixing central occlusion.

Anterior or lateral occlusions can be recorded by mistake.

1. Anterior occlusion was recorded.

Why is it dangerous? The denture is constantly being reset. It is impossible to wear.

How to recognize? The bite is too high. The gap between the upper and lower incisors, only the chewing teeth are in contact.

What to do? Remove teeth from the lower roller. Re-determine the central occlusion and fix it correctly.

1. Lateral occlusion was recorded.

It is also impossible to wear a prosthesis.

How to recognize? The bite is too high. The line between the central incisors is shifted to the left or right. On the displaced side there is no contact between the teeth. On the other side, the teeth meet cusp to cusp (lingual cusp of the lower teeth with the buccal cusp of the upper teeth).

What to do? The same as in the previous case.

Errors in determining central occlusion.

During the determination process, the base may become deformed, tear off from the prosthetic bed and move forward or backward.

1. Detachment of the base from the mucosa during determination of central occlusion

How to recognize? There is no contact between the teeth in any one place (where the separation occurred). You can check with a spatula. They try to insert the spatula between the antagonist teeth, but normally it does not fit through. He climbs where there was a gap.

What to do? Take a strip of wax, heat it up and place it on the artificial teeth in this place. The patient closes his mouth and the wax restores the required height. The models are re-plastered. The teeth are rearranged.

1. Mixing wax bases forward, backward, right or left.

How to recognize? The signs are the same as for improper fixation of the occlusion.

What to do? Teeth are removed from both jaws. Two bite ridges are made. And the central ratio is re-fixed.

1. Deformation of bases.

How to recognize? The signs are the same as when the base is torn off. It is possible to balance the prosthesis.

What to do? Completely redo wax bases with occlusal ridges.

Mistakes happen sometimes, that's okay. They just need to be noticed in time.

Checking the Design of a Complete Removable Denture updated: December 22, 2016 by: Alexey Vasilevsky

Target setting. Learn to recognize and eliminate the causes of errors when determining the central relationship of the jaws.

Rice. 143.

The stage of checking the design of removable dentures is very important and responsible, since at this stage all previous clinical and laboratory methods fabrication of prostheses and the necessary corrections can be made.
Even before the introduction of dentures into the oral cavity, the quality of the models in which wax will be replaced with plastic is checked. Pay attention to whether there are any chips in the model, pores, traces from a technical spatula when setting the teeth, and whether the transitional fold is well represented. If there are defects, it is necessary to take impressions again and cast new models.
Then they check the color, size, shape of the teeth and the correctness of their placement.
The frontal teeth are positioned in such a way that their lower 2/3 lie outward from the middle of the alveolar edge, and the front 2/3 lie in the center. (Sometimes this rule is broken and the teeth can be positioned outward if the upper lip.) The upper front teeth should overlap the lower ones by no more than 1 - 2 mm, since a large overlap can affect the stabilization of the dentures. The teeth should be placed in intercuspal contact. All teeth should have two antagonists, with the exception of the second upper molar and the first lower incisor. The chewing teeth should be in the middle of the alveolar arch, respecting the interalveolar lines.
The severity of the sagittal and transversal compensatory occlusal curves is monitored. Then they pay attention to the modeling of the wax base, the volume of its edges, and the degree of adherence to the model.
After a detailed study of the wax composition with teeth on models in an articulator or occluder, the dentures are inserted into the oral cavity and the correct location of the midline between the central incisors is monitored, which should coincide with the midline of the face. When the mouth is opened slightly, the cutting edges of the incisors should be visible, and when smiling, the teeth are exposed almost to the neck, but no more. The type of teeth should match the shape of the face. It is not recommended for older people to have very light teeth.
Patients are offered a speech test, in which the distance between the front teeth of the upper and lower jaws should be approximately 5 mm.
When checking the design of dentures, you can identify errors made in determining the central relationship of the jaws. These errors can be divided into 5 main groups.
1. Incorrect determination of the height of the lower part of the face (overestimation or underestimation).
If it is too high, the patient’s facial expression will be somewhat surprised, the nasolabial and chin folds will be smoothed out; during a conversational test, you can hear the “chattering” of teeth; the gap in the frontal area will be less than 5 mm, there is no clearance (2 - 3 mm) at physiological rest.
Eliminate the error as follows. If the upper dentition is set correctly, and the overestimation occurred due to the lower teeth, then it is necessary to remove the teeth from the lower wax base, make a new occlusal ridge, or take the base with a bite ridge, on which the central relationship of the jaws was determined, and redefine it again. In case the arrangement upper teeth done incorrectly (the prosthetic plane is not maintained), bite ridges are also made for the upper jaw. Then the central relationship of the jaws is determined again and the teeth are positioned.

Rice. 144
1 - the lower jaw is fixed in the sagittal position; 2 - the lower jaw is fixed with a shift to the right, (a - relationship of the models; b - relationship of the dentition).

If the height of the lower part of the face is underestimated, if the upper teeth are set correctly, a heated strip of wax is placed on the lower dentition and the central relationship of the jaws is redefined, bringing the height to normal. It is possible to make a new one for the lower jaw wax base with an occlusal roller. If the reason for the low height is also the upper teeth, it is necessary to redefine the central relationship of the jaws with the old upper and lower ridges, which are located by the technician.
2. Fixation of the lower jaw not in a central relationship, but in anterior, posterior or lateral (right, left).
Most common mistake when determining the central relationship of the jaws, the lower jaw is moved forward and fixed in this position. When checking the design, there will be a prognathic relationship of the dentition, predominantly tubercular closure of the lateral teeth, a gap between the front teeth, and an increase in the bite to the height of the cusps of the lateral teeth (Fig. 144).
The error is eliminated by redefining the central relationship with a new occlusal ridge in the lateral areas of the lower jaw, and the frontal group of teeth is left for control.
Posterior displacement of the lower jaw when determining the central ratio is possible with a “loose” joint. When checking, a progenic relationship of the dentition, tubercular closure of the lateral teeth, and an increase in the bite to the height of the tubercles are revealed (Fig. 145). This error is eliminated by redefining the central relationship of the jaws with a new bite ridge on the lower jaw. It should be noted that this is not always possible, because such patients quite often fix the lower jaw in a certain position, which is not always correct.

Rice. 145.
1 - displacement of the roller downwards on the upper jaw; 2 - displacement of the roller anteriorly (a - relationship of the models; b - relationship of the dentition).

By checking the design of the prosthesis when the lower jaw is displaced to the right or left, one can detect tubercular closure on the side opposite to the displacement, an increase in the bite, a shift in the center of the lower dentition to the opposite side, and a gap between the lateral teeth on the side of the displacement. The error can be corrected by redefining the central relationship of the jaws with a new lower bite ridge.
3. Errors caused by the separation or loose fit of the bite ridges to the prosthetic bed (model).
Such errors are caused by uneven compression of the bite ridges during fixation of the central relationship of the jaws. The reasons for this may be poor fitting of the lower roller to the upper one, uneven heating of the lower roller with a hot spatula, or loose fit of the wax base to the model. Most often, such an error in the clinic manifests itself in the absence of contact between the chewing teeth on one or both sides. It is determined by inserting a cold spatula between the chewing teeth. In this case, the spatula is rotated around its axis and observed how the wax bases fit tightly to the underlying tissues. The error is corrected by applying a plate of slightly heated wax in the area of ​​the chewing teeth and redefining the central occlusion.
4. Fixation of the central relationship of the jaws with simultaneous crushing of the base or occlusal ridge.
This error occurs in cases where the occlusal ridges are not reinforced with arcuate wires; the alveolar part on the lower jaw is very narrow. When establishing such bases on the model, it is clear that they do not fit tightly to the latter.
In the clinic, this error manifests itself in the form of an increased bite with uneven and indefinite cuspal contact of the lateral teeth, and a gap in the area of ​​the anterior teeth. It is corrected by redefining the central relationship of the jaws using new rollers, often with hard bases.
5. Fixation of the central relationship of the jaws when one of the wax bases is displaced in the horizontal plane.
Under unfavorable anatomical conditions in the oral cavity (II degree of atrophy on the lower jaw and III on the upper jaw), during fixation of the central relationship of the jaws, the upper or, much more often, the lower wax base with the occlusal ridge may move forward or backward.
When checking the design of the prosthesis, one can observe the same picture as when fixing the lower jaw not in a central, but in an anterior or posterior relationship. Errors are corrected by re-defining the central relationship of the jaws using new rollers made on rigid bases. Subsequently, teeth are placed on these rigid plastic bases and the design of the dentures is checked. The use of hard bases in this case is advisable, since they are stable on the jaws and do not deform or move like wax bases.
In all cases, if errors are discovered and corrected when checking the design of the prostheses, the upper model is knocked off the occluder or articulator and plastered in a new position.