Determination of bite in case of partial absence of teeth. Central jaw ratio: definition, methods. Making a diagnosis based on joint disorders

Central occlusion- this is a type of articulation in which the muscles that elevate the lower jaw are evenly and maximally tense on both sides. Because of this, when the jaws close, the maximum number of points come into contact with each other, which provokes the formation. The articular heads are always located at the very base of the tubercle slope.

Signs of central occlusion

The main signs of central occlusion include:

• each lower and upper tooth fits tightly with the opposite one (except for the central lower incisors and three upper molars);
• in the frontal region, absolutely all lower teeth overlap the upper teeth by no more than 1/3 of the crown;
• the upper right molar connects to the lower two teeth, covering 2/3 of them;
• the incisors of the lower jaw are in close contact with the palatine tubercles of the upper;
• the buccal tuberosities located on the lower jaw are overlapped by the upper ones;
• the palatine tubercles of the lower jaw are located between the lingual and buccal;
• between the lower and upper incisors, the midline is always in the same plane.

Determination of central occlusion

There are several methods for determining central occlusion:

1. Functional technique– the patient’s head is tilted back, the doctor places his index fingers on the teeth of the lower jaw and places special rollers in the corners of the mouth. The patient raises the tip of his tongue, touches the palate with it and swallows at the same time. When the mouth closes, you can see how the dentitions close together.
2. Instrumental technique– involves the use of a device that records jaw movements in the horizontal plane. When determining central occlusion in the case of partial absence of teeth, the tooth is forcibly moved by hand, pressing on the chin.
3. Anatomical and physiological method– determination of the state of physiological rest of the jaws.

At defects of the fourth group, i.e. in cases where there is not a single tooth in the mouth, as well as with defects of the third group, it is necessary to determine the height of the central occlusion and the horizontal (mesio-distal) position of the lower jaw.

At construction of a prosthetic plane two lines are taken into account: Camper’s and pupillary. In the area of ​​the lateral teeth, the cushion is formed parallel to the Camper line (nasal line), and in the area of ​​the front teeth - parallel to the line of the pupils.

Therefore, the definition central occlusion for defects The dentition of the fourth group consists not of two, as in the case of defects of the third group, but of three points: the determination of the prosthetic plane, the height of the central occlusion and the central position of the lower jaw. They begin by determining the prosthetic plane.

For this purpose, an upper basis is introduced with an occlusal roller into the patient’s oral cavity and trim the roller so that its edge is slightly visible from under the lip. This sets a line to determine the height of the cutting edges of the anterior teeth. Then they begin to build a prosthetic plane in the area of ​​the chewing teeth, for which two rulers are used,

One of them install on the face along the Camper line, and the other on the roller. The roller is cut until both rulers become parallel. Then a roller is formed in the area of ​​the front teeth. The ruler is placed on a roller in the area of ​​the front teeth and the roller is cut off until the ruler becomes parallel to the pupillary line, i.e., the horizontal line connecting the middles of both pupils.

Next moment is to determine the height of central occlusion, which is carried out according to the method used in cases of defects of the third group, i.e., according to the anatomical and physiological method. Having determined the relative rest height, the lower ridge is trimmed or extended so that the height of the central occlusion is 1-2 mm less than the rest height. Then they begin to determine the central position of the jaws.

This stage is also carried out according to the method indicated for cases of defects of the third group, but its implementation is associated with great difficulties, because with defects of the fourth group it is especially difficult to achieve closure of the rollers without displacement of the templates. To do this, you need to achieve simultaneous closure of the rollers and an equally tight fit over the entire surface.

Having received as a result correction of the lower roller closure without displacing the templates, remove the templates from the oral cavity, cool them in water and apply them to the models. At the same time, they check whether the templates are crushed. If the edges of the template lag behind the model, this indicates improper closure; in such cases, it is necessary to correct the lower ridge by re-correcting it (cutting off the wax) and reinserting it into the mouth.

Then cut on the surface of the upper roller four shallow wedge-shaped depressions, two on each side - one in the molar area and the other in the canine area (these depressions should not be parallel to each other). Having prepared a narrow strip of wax, heat it up, apply it to the roller of the lower template and soften the plate even more with a hot spatula.

After these preliminary manipulations insert the templates into the mouth and, holding the upper and lower plates with the thumb and forefinger of the left hand, invite the patient to cover his mouth a little and move the tip of the tongue up and back and with the right hand bring the lower jaw until the ridges are tightly closed. The templates are removed from the mouth, cooled and separated in cold water. Protrusions are formed on the lower roller, corresponding to the recesses made on the upper roller.

Then the templates are applied on the model, fold the latter, cut off the ridges from the vestibular and lingual sides so that when the ridges are closed, the upper roller transitions into the lower one smoothly without roughness, and the templates with the rollers are inserted into the mouth for the last time. If, when the rollers are closed, the transition of the upper roller to the lower one is as smooth in the mouth as on the models, then this convinces the doctor of the correct determination of the central occlusion for prosthetics of edentulous jaws.

Method for determining central occlusion wax templates with rollers is a classic one, and it is widely used in the dental prosthetics clinic.

However, this method has flaws, its use often entails errors. Errors are mainly due to the fact that with pronounced atrophy of the alveolar process, and especially with its complete absence, wax templates with bite ridges do not have stability on the jaws and are displaced during manipulations associated with determining the horizontal (central) relationship of the jaws. In addition, the slightest discrepancy in the height of the right and left sides of the roller or uneven pressure of the doctor’s fingers on its left or right side causes a reflexive shift of the lower jaw towards greater pressure. The possibility of deformation of wax rollers under the influence of oral temperature cannot be ruled out.

Finally, the need to retain templates on the jaws with the hands of a doctor also leads to frequent mistakes.

To eliminate these shortcomings and achieving more accurate results in determining the central relationship of the jaws, it is advisable to use the method of fixing central occlusion using plaster blocks.

This method in different versions proposed by A. I. Goldman, A. X. Topel and G. I. Sidorenko. The most effective and simple is the Sidorenko method.

This stage consists of establishing the relationships of the dentition in the horizontal, sagittal and transversal directions.

Central occlusion is the position from which the lower jaw begins its path and in which it ends. Central occlusion is characterized by maximum contact of all cutting and chewing surfaces of the teeth.

Interalveolar height is the distance between the alveolar processes of the upper and lower jaws in the position of central occlusion. With existing antagonists, the interalveolar height is fixed by natural teeth, and if they are lost, it becomes unfixed and should be determined.

From the point of view of the difficulty of determining central occlusion and interalveolar height, all dental rows can be divided into four groups. IN first group includes dentitions in which antagonists have been preserved, which are located in such a way that it is possible to compare models in the position of central occlusion without the use of wax bases with occlusal ridges. Co. second group These include dentitions in which there are antagonists, but they are located in such a way that it is impossible to compare models in the position of central occlusion without wax bases with occlusal ridges. Third group consist of jaws on which there are teeth, but there is not a single pair of antagonist teeth (unfixed interalveolar height). IN fourth group includes jaws devoid of teeth.

In the first two groups, with preserved antagonists, only central occlusion should be determined, and in the third and fourth interalveolar height And central occlusion (central relationship of the jaws).

In the presence of antagonist teeth, the definition of central occlusion is as follows:

On models, the doctor warms up the occlusal surfaces of the rollers and, while the wax is warm, introduces wax bases with occlusal rollers into the patient’s oral cavity. Then the doctor asks the patient to close the dentition until the antagonist teeth come into contact. In order to prevent the lower jaw from moving forward or to the sides, it is necessary to use one of the following techniques:

while closing the jaws, ask the patient to tilt his head back, reach the back third of the palate with the tip of his tongue, or swallow saliva. In the softened wax, teeth from the opposite jaw will leave clear imprints, which can be used to compare models in the position of central occlusion in the laboratory. In those areas where there are no antagonist teeth, softened wax rollers will connect to each other, fixing the bases in the desired position. The described method of fixing wax bases with occlusal ridges is called “ hot".

In the absence of a large number of teeth, when the occlusal ridges are long, or when making prosthetics for toothless jaws, the doctor uses another method called "cold". In this case, the doctor makes cuts (locks) on the occlusal surface of the upper ridges in two different directions, and cuts off a thin layer of wax from the lower ridges, instead of which he places a heated strip of wax. Then wax bases with occlusal ridges are introduced into the patient’s mouth, who is asked to close his jaws, controlling the position of the central occlusion. This method eliminates the strong heating of the rollers, which, if extended, can become deformed in the oral cavity.

Determining the central ratio of the jaws means determining the most functionally optimal position of the lower jaw in relation to the upper jaw in three mutually perpendicular planes - vertical, sagittal and transversal.

The stage of determining the central relationship of the jaws in the oral cavity is carried out in a certain sequence.

1. Fitting the wax base with occlusal ridges on the upper jaw:

· formation of the vestibular surface of the upper occlusal ridge (the future vestibular surface of the dentition of the upper jaw). In this case, the doctor focuses on the patient’s appearance (recession or protrusion of lips, cheeks, symmetry of natural facial folds and anatomical formations);

· determining the height of the upper occlusal ridge (to determine the level of the upper jaw incisors). When the lips are in a calm position, the cutting edge of the front teeth is located at the level of the lip incision or 1-2 mm lower. The line on which the cutting edges of the teeth will be located should be parallel to the line connecting the pupils - the pupillary line.

· creation of a prosthetic plane. In this case, the doctor focuses on the pupillary line in the frontal region and the nasal-ear lines in the lateral regions.

Pupillary line is a line connecting the patient’s pupils.

Naso-auricular line (Kamper horizontal) is a line connecting the center of the tragus of the ear and the lower edge of the wing of the nose.

To make the doctor’s work more convenient in this case, there is a device called N.I. Larina.

This article is about centric relation and centric occlusion. About bite height and resting height. She will tell you step by step how the doctor works, what methods he uses to determine central occlusion.

Article outline:

1. What is central occlusion and central jaw relation? And what is the difference between them?
2. Stages of determining the central ratio

Details:

• Methods for determining the lower third of the face. Anatomy - physiological method.
• Methods for fixing the CO after its determination.
• Drawing of anatomical landmarks on the finished base.

Let's begin our story.

1) The appointed patient came to the dentist. Today the plan is to determine the central ratio. The doctor greets his patient and puts on gloves and a mask. He sits the patient in a chair. The patient sits upright, leaning on the back of the chair. His head is slightly thrown back...

Oh yes! Something needs to be explained to you. Otherwise, you and I may not understand each other. These are words that will appear often in our story. Their meaning needs to be known exactly.

Central occlusion and central jaw relation

Concepts central occlusion And centric relation are often generalized, but their meanings are completely different.

Occlusion- This is the closing of teeth. No matter how the patient closes his mouth, if at least two teeth touch, this is occlusion. There are thousands of occlusion options, but it is impossible to see or determine them all. For a dentist, 4 types of occlusion are important:

• Front
• Rear
• Lateral (left and right)
• and Central

This is occlusion - uniform closure of teeth

Central occlusion– this is the maximum intertubercular closure of the teeth. That is, when as many teeth as possible for this person come into contact with each other. (Personally, I have 24).

If the patient has no teeth, then there is no central (or any) occlusion. But there is centric relation.

Ratio- This is the location of one object in relation to another. When we talk about jaw relationship, we are talking about how the mandible relates to the skull.

Central ratio- the most posterior position of the lower jaw, when the head of the joint is correctly located in the glenoid fossa. (Extreme anterosuperior and midsagittal position). There may be no occlusion in the centric relation.

In the centric relation, the joint occupies the most superior-posterior position

Unlike all types of occlusion, the centric relation does not change throughout life. If there were no diseases or injuries to the joint. Therefore, if it is impossible to determine the central occlusion (the patient has no teeth), the doctor recreates it, focusing on the central relationship of the jaws.

To continue the story, two more definitions are missing.

Resting height and bite height

Bite height– this is the distance between the upper and lower jaw in the position of central occlusion

Bite height - the distance between the upper and lower jaws in the position of central occlusion

Height of physiological rest is the distance between the upper and lower jaw when all jaw muscles are relaxed. Normally, it is usually 2-3 mm greater than the height of the bite.

Normally, it is 2-3 mm greater than the height of the bite

There may be an overbite overpriced or understated. Overbite with an incorrectly manufactured prosthesis. Roughly speaking, when artificial teeth are higher than their own. The doctor sees that the bite height is less rest height by 1 mm or equal to it or more than it

The lower third of the face is significantly larger than the middle

Understated– with pathological abrasion of teeth. But there is also the option of incorrectly manufacturing the prosthesis. The doctor sees that the height of the bite is greater than the resting height. And this difference is more than 3 mm. In order not to underestimate or overestimate the bite, the doctor measures the height of the lower part of the face.

In the photo on the left, the lower third of the face is smaller than the middle third

Now you know everything you need, and we can return to the doctor.

2) He received wax bases with bite ridges from the technician. Now he carefully examines them, assessing their quality:

• The boundaries of the bases correspond to those drawn on the model.
• The bases do not balance. That is, they fit tightly to the plaster model throughout.
• The wax rollers are made with high quality. They do not exfoliate and are of standard size (in the area of ​​the anterior teeth: height 1.8 - 2.0 cm, width 0.4 - 0.6 cm; in the area of ​​chewing teeth: height 0.8-1.2 cm, width 0. 8 – 1.0 cm).

3) The doctor removes the bases from the model and disinfects them with alcohol. And he cools them for 2-3 minutes in cold water.

4) The doctor places the upper wax base on the jaw and checks the quality of the base in the mouth: does it hold, does the boundaries correspond, is there any balancing.

6) After this, it forms the height of the roller in the anterior section. It all depends on the width of the red border of the patient’s lips. If the lip is medium, then the upper incisors (and in our case the ridge) stick out from under it by 1-2 mm. If the lip is thin, the doctor makes the roller stick out 2 mm. If it is too thick, the roller ends up to 2 mm under the lip.

The length of the incisor protruding from under the lip is about 2 mm

7) The doctor proceeds to forming the prosthetic plane. This is a rather difficult stage. We will dwell on it in more detail.

Formation of the prosthetic plane

“To draw a plane you need three points”

© Geometry

Occlusal plane

- a plane that passes through:

1) the point between the lower central incisors

2) and 3) points on the external posterior tubercles of the second chewing teeth.

Three dots:
1) Between the central incisors
2) and 3) Posterior buccal cusp of second molar

If you have teeth, then there is an occlusal plane. If there are no teeth, then there is no plane. The dentist's task is to restore it. And restore correctly.

Prosthetic plane

Like the occlusal plane, only on a denture

- This is the occlusal plane of a complete removable denture. It should run exactly where the occlusal plane once was. But the dentist is not a psychic; he cannot see the past. How will he determine where she had a patient 20 years ago?

After many studies, scientists have established that the occlusal plane in the anterior jaw is parallel to the line connecting the pupils. And in the lateral section (this was discovered by Camper) - a line connecting the lower edge of the nasal septum (subnosal) with the middle of the tragus of the ear. This line is called the Camper horizontal.

The doctor's task- ensure that the prosthetic plane - the plane of the wax ridge on the upper jaw - is parallel to these two lines (Kamper's horizontal and the pupillary line).

The doctor divides the entire prosthetic plane into three segments: one frontal and two lateral. He starts from the frontal section. And makes the plane of the frontal ridge parallel to the pupillary line. To achieve this he uses two rulers. The doctor places one ruler at the level of the pupils, and attaches the second to the wax roller.

One ruler is installed along the pupillary line, the second is glued to the bite block

He achieves parallelism between the two rulers. The dentist adds or cuts wax from the roller, focusing on the upper lip. As we described above, the edge of the roller should evenly protrude from under the lip by 1-2 mm.

Next, the doctor forms the lateral sections. To do this, the ruler is installed along the Camper (nose-ear) line. And they achieve parallelism with the prosthetic plane. The doctor builds up or removes wax in the same way as he did in the anterior section.

The ruler along the Camper horizontal is parallel to the occlusal plane in the lateral section

After this, he smoothes the entire prosthetic plane. It is convenient to use for this

Naisha apparatus.

The Naisha apparatus is a heated inclined plane with a wax collector.

The base with bite rollers is applied to the heated surface. The wax melts evenly over the entire surface of the roller, in one plane. As a result, it turns out perfectly smooth.

The melted wax is collected in a wax collector, which is shaped like a blank for new rollers.

Determination of the height of the lower part of the face

Dentists divide the patient's face into thirds:

Upper third– from the beginning of hair growth to the line of the upper edge of the eyebrows.

Middle third– from the upper edge of the eyebrows to the lower edge of the nasal septum.

Lower third– from the lower edge of the nasal septum to the very bottom of the chin.

The lower third of the face is significantly larger than the middle

All thirds are normally approximately equal to each other. But with changes in the height of the bite, the height of the lower third of the face also changes.

There are four ways to determine the height of the lower part of the face (and the height of the bite accordingly):

• Anatomical
• Anthropometric
• Anatomical and physiological
• Functional-physiological (hardware)

Anatomical method

Determination method by eye. The doctor uses it at the stage of checking the teeth setting to see if the technician has overestimated the bite. He looks for signs of overbite: whether the nasolabial folds are smoothed, whether the cheeks and lips are tense, etc.

Anthropometric method

Based on the equality of all third parties. Different authors have proposed different anatomical landmarks (Wootsword: the distance between the corner of the mouth and the corner of the nose is equal to the distance between the tip of the nose and the chin, Jupitz, Gisi, etc.). But all these options are inaccurate and usually overestimate the actual height of the bite.

Anatomical and physiological method

Based on the fact that The height of the bite is 2-3 mm less than the resting height.

The doctor determines the height of the face using wax bases with occlusal ridges. To do this, he first determines the height of the lower third of the face in a state of physiological rest. The doctor draws two dots on the patient: one on the upper jaw, the second on the lower jaw. It is important that both are on the center line of the face.

The doctor draws two dots on the patient

The doctor measures the distance between these points when all the patient's jaw muscles are relaxed. To relax him, the doctor talks to him about abstract topics, or asks him to swallow his saliva several times. After this, the patient’s jaw takes a position of physiological rest.

The doctor measures the distance between the points in a position of physiological rest

The doctor measures the distance between the points and subtracts 2-3 mm from it. Remember, normally it is this number that distinguishes physiological rest from the position of central occlusion. The dentist trims or extends the lower bite ridge. And measures the distance between the drawn points until it becomes as it should (rest height minus 2-3 mm).

The inaccuracy of this method is that some people need a difference of 2-3 mm, while others need 5 mm. And it is impossible to calculate it accurately. Therefore, you just need to assume that it is 2-3 mm for everyone and hope that the prosthesis will work.

Whether the doctor has correctly determined the interalveolar height is checked using a conversational test. He asks the patient to pronounce sounds and syllables ( o, i, si, z, p, f). When pronouncing each sound, the patient will open his mouth to a certain width. For example, when pronouncing the sound [o], the mouth opens 5-6 mm. If it is wider, then the doctor determined the height incorrectly.

When pronouncing the sound “O”, the distance between the teeth (ridges) is 6 mm

Functional-physiological method

It is based on the fact that the masticatory muscles develop maximum strength only in a certain position of the jaw. Namely, in the position of central occlusion.

How does chewing force depend on the position of the lower jaw?

If there are bodybuilders among you, you will understand my comparison. When you pump your biceps, if you extend your arms halfway, it will be easy to lift a barbell weighing 100 kg. But if you straighten them completely, then lifting it will be much more difficult. The same is true for the lower jaw.

The thicker the arrow, the greater the muscle strength

This method uses a special device - AOCO (Apparatus for Determining Central Occlusion). Hard individual spoons are made for the patient. They are edged and inserted into the patient's mouth. A sensor is attached to the lower spoon, into which pins are inserted. They make it difficult to close your mouth, i.e. set the bite height. And the sensor measures chewing pressure at the height of this pin.

AOCO (Apparatus for Determining Central Occlusion)

First, a pin is used that is significantly higher than the patient's bite. And record the force of jaw pressure. Then use a pin 0.5 mm shorter than the first one. And so on. When the bite height is lower than optimal even by 0.5 mm, the chewing force is reduced by almost half. And the desired bite height is equal to the previous pin. This method allows you to determine the bite height with an accuracy of 0.5 mm.

Our dentist uses the anatomical and physiological method. It is the simplest and relatively accurate.

10) The doctor determines the central relationship of the jaws.

At this stage, you cannot simply tell the patient, close your mouth correctly. Even my grandmother often complained that these words were confusing: “And you don’t know how to shut your mouth. It seems that no matter how you close it, everything is right.”

To close the mouth “correctly,” the doctor places his index fingers on the bite ridges in the area of ​​the chewing teeth of the lower jaw and at the same time pushes the corners of the mouth apart. Next, he asks the patient to touch the posterior edge of the hard palate with his tongue (It is better to make a wax button in this place - not all patients know where the posterior edge of the hard palate is.) and swallow the saliva. The doctor removes his fingers from the chewing surface of the roller, but continues to move the corners of the mouth apart. When swallowing saliva, the patient will close his mouth “correctly.” They repeat this several times until the doctor is absolutely sure that this is the correct central ratio.

11) Next stage. The doctor fixes the rollers in a central ratio.

Fixation of the central relationship of the jaws

To do this, he makes notches on the upper jaw roller (usually in the form of the letter X) using a heated spatula. On the lower roller, opposite the notches, the doctor cuts off a little wax, and in its place glues a heated wax plate. The patient closes his mouth “correctly”. The heated wax flows into the notches. The result is a kind of key by which the technician will be able to compare models in the articulator in the future.

Notches in the form of the letter X

There is one more- more difficult - method of fixing the central ratio. It was invented by Chernykh and Khmelevsky.

They glue two metal plates onto the bases with wax. There is a pin attached to the top plate. The lower one is covered with a thin layer of wax. The patient closes his mouth and moves his lower jaw forward, backward and to the sides. And the pin draws on wax. As a result, different arcs and stripes are drawn on the bottom plate. And the most anterior point of these lines (with the most posterior position of the upper jaw) corresponds to the central relationship of the jaws. On top of the lower metal plate they glue another one - celluloid. Glue it so that the recess in it is at the very front point. And the pin should fall into this recess when the mouth is “correctly” closed. If this happens, then the central relation is determined correctly. And the bases are fixed in this position.

12) The doctor takes out bases with a certain central ratio from the patient’s mouth. Checks their quality on the model (everything we talked about somewhere above), cools it, disconnects it. Inserts it into the oral cavity again and again checks the “correctness” of closing the mouth. The key must fit into the lock.

13) The last stage remains. The doctor puts indicative lines on the bases. The technician will place the artificial teeth along these lines.

Midline, canine line and smile line

Apply vertically to the upper base midline- this is the line that divides the entire face in half. The doctor focuses on the philtrum. The midline divides it in half.

Another vertical line - canine line- runs along the left and right edges of the wing of the nose. It corresponds to the middle of the maxillary canine. This line is parallel to the midline.

Doctor draws horizontally smile line- This is the line that runs along the lower edge of the red border of the lips when the patient smiles. It determines the height of the teeth. The technician makes the necks of the artificial teeth above this line so that the artificial gum is not visible when smiling.

The doctor takes out wax bases with occlusal ridges from the oral cavity, puts them on the model, connects them to each other and hands them over to the technician.

The next time he will see them with artificial teeth already installed - an almost complete removable denture. And now our hero says goodbye to the patient, wishes him all the best, and prepares to accept the next one.

Determination of the central relationship of the jaws with complete loss of teeth updated: December 22, 2016 by: Alexey Vasilevsky

BRIDGES. FITMENT OF ARTIFICIAL STAMPED SUPPORT CROWNS AND OBTAINING IMPRESSIONS.

II. Lesson duration: 3 lessons. hours.

III. Learning goal.

Learn to determine central occlusion with a fixed bite height, familiarize yourself with possible errors in this case and ways to eliminate them. To teach students how to fit crowns and take plaster impressions when making an intermediate part of a bridge.

The nature and volume of academic work outside the schedule

1. Questions for monitoring (self-monitoring) the results of mastering educational material:

Features of determining central occlusion in 1-2 groups of dentition defects (according to Betelman).

Clinical techniques for establishing the horizontal (mesiodistal) position of the lower jaw.

Methods for fixing central occlusion. Possible errors in determining central occlusion and ways to eliminate them.

Method of checking (fitting) abutment crowns and taking plaster impressions with fitted crowns.

2. UIRS. Schematic sketches, note-taking:

Requirements for bite patterns.

Features of the clinical stages of manufacturing bridges made of precious metals.

3. Practical skills:

Determine central occlusion in groups 1-2 of dentition defects.

Fix central occlusion for groups 1-2 of dentition defects.

Fit abutment crowns when making a bridge.

Take a plaster impression to make the intermediate part of the bridge.

4. Repeat:

Physical and technological properties of precious alloys that are used for the manufacture of fixed dentures.

Reflexes of the masticatory apparatus.

Groups of dentition defects to determine central occlusion (according to A.I. Betelman).

a/ main:

1. Abolmasov N.G., Abolmasov N.N. and others. Orthopedic dentistry. SGMA, 2000. – 576 p.
2. Shcherbakov A.S., Gavrilov E.I., Trezubov V.N., Zhulev E.N. Orthopedic dentistry. Textbook St. Petersburg 1997. - 261-263, 192-195.
3. Orthopedic dentistry: Textbook / E.I. Gavrilov, A.S. Shcherbakov. M.: Medicine, 1984. - p. 120, 200-210, 267-269, 371-372.
4. Kristab S.I. Orthopedic dentistry K., 1986, p. 152-154,69-70.
5. Orthopedic dentistry, ed. Kopeikina V.N., M., 1988, p. 192-206.
6. Dentistry: Guide to practical exercises. Borovsky E.V., Kopeikin V.N., Kolesov A.A., Shargorodsky A.G. M., 1987, p. 342-345.
7. Kopeikin V.N., Demner L.M. Dental technology. M., 1983, p. 209-211.
8. Doynikov A.M., Sinitsin V.D. Dental materials science. M.: Medicine, 1986, - p. 37-39, 41-42, 90-91.

b/ additional:

1. Guide to prosthetic dentistry. Ed. Kopeikina. - M.: Medicine,

1993, p. 218-230.

2. E.N.Zhulev. Fixed dentures. Theory, clinic and laboratory technology.

N. Novgorod. 1995, p. 312-327.

3. Guide to prosthetic dentistry. Ed. A.I. Evdokimov. M.:

Medicine. 1974.- p. 162-165, 268-298.

4. Pogodin V.S., Ponomareva V.A. Guide for dental technicians M.: Medicine,

1983, p. 39-46, 49-53.

5. Bushan M.G., Kalamkarov K.A. Complications during dental prosthetics and their

prevention. - Chisinau, 1983.- p. 116-118.

When considering the issue of groups of defects when determining central occlusion, it is necessary to pay attention to the fact that the orthopedic dentist must make a denture so that it satisfies the patient aesthetically and functionally. On the way to achieving this goal, a very important step is the determination of central occlusion, because any dental prosthesis (inlay, crown, bridge, pin tooth, etc.) must be prepared taking into account the closure of natural antagonist teeth in the position of central occlusion. Manufacturing prostheses without taking this into account leads to the fact that the patient will not be able to use the manufactured prosthesis and it has to be remade. This is why it is always recommended to take an impression of both jaws to make bridge crowns. This allows the dental technician not only to take into account the shape of a symmetrical tooth on the opposite side of the jaw, but also the nature of the closure of antagonist teeth.

When making fixed dentures, a doctor and a dental technician are faced with various types of dentition defects. A.I. When determining central occlusion, Betelman conditionally divided the ratio of jaws with dentition defects into 4 groups.

The first group is characterized by the presence in the oral cavity of at least 3 pairs of antagonizing teeth. In this case, the teeth on the upper and lower jaws must be positioned so that the models can be compared without using bite block templates. To do this, it is necessary that articulating pairs of teeth be on both the left and right sides of the dentition in the area of ​​the lateral teeth and in the anterior area.

The second group is characterized by the presence of only one or several pairs of antagonizing teeth, but the models, despite the large number of teeth, cannot be correctly assembled without wax bases with bite ridges.

The third group includes defects in which there are teeth in the oral cavity, but there is not a single antagonistic pair.

The fourth group of defects includes cases with complete absence of teeth on both jaws.

In the first group of defects, the central occlusion is not determined in the clinic, and the dental technician makes models, focusing on ground-in areas (articulatory facets) on the occlusal surface of the teeth and casts them into an occluder or articulator.

In the second group, central occlusion is determined using wax bases with bite ridges. For this purpose, the rollers are adjusted so that the opposing teeth remaining in the oral cavity can close completely in a state of central occlusion. Then a strip of wax is strongly heated, glued to the bite ridges and the patient is asked to close his teeth in the position of central occlusion. Imprints of teeth that do not have antagonists are formed on the bite ridges, and due to this, when they are transferred to models, the latter are easily compared in the position of central occlusion. If the teeth remaining in the mouth are located on one side, but there are no teeth on the other, then to correctly align the occlusal (bite) ridges, wedge-shaped cuts are made on one of the ridges. These cuts leave imprints on another roller, to which a heated wax plate is glued. To ensure that the patient does not move the lower jaw when closing the jaws with bite patterns, various tests are proposed when determining the horizontal position of the teeth.

Some authors suggest that the patient tilt his head back, since in this position the tension of the neck muscles prevents the lower jaw from moving forward, others recommend closing the jaws while swallowing.

There is a method of closing the mouth while the tip of the tongue touches the soft palate, biting the lateral areas of the dentition with the doctor’s fingers, which are retracted to the sides while biting.

Fixing the wax templates on the jaws with the left hand, the patient is asked to close his mouth a little and move the tip of the tongue upward and backward. Then they place their right hand on the patient’s chin and invite him to raise the lower jaw until the ridges are tightly closed. This only controls, but does not direct the movement of the lower jaw. Then the template is removed from the mouth, dipped in cold water, and then reinserted into the mouth. This is done several times to check the closure of the jaws. At the same time, check the tightness of the closure of the rollers. For this purpose, a spatula is inserted into the thickness of the roller from the outside and, trying to move the roller in the interalveolar direction, check the tightness of the fit of the upper roller to the lower one. The absence of vibrations of the roller indicates their tight closure.

When determining central occlusion in groups I and II of dentition defects, errors are most often possible due to incorrect determination of the medio-distal position of the lower jaw (anterior or lateral occlusions). This is due to the fact that the absence of teeth on one side leads to a reflex shift of the lower jaw towards the opposing natural teeth. When the height of the bite on the bolsters is too high, the antagonist teeth do not close together.

In practical healthcare, there is a method for determining central occlusion using gypsum blocks (A.I. Goldman, G.I. Sidorenko), it is as follows. After taking impressions from both jaws in the presence of antagonist teeth, you need to fill the area of ​​the dentition defect with plaster and ask the patient to close the jaws until the remaining teeth close. When the plaster hardens, the patient opens his mouth and the plaster blocks are removed. Using plaster blocks, the dental technician can match models in the centric occlusion position.

After determining the central occlusion, the dental technician compares the models, fixes them in this position using sticks and boiling wax and plaster them into the occluder or articulator.

During the survey of students, the teacher draws students' attention to the fact that fitting crowns is one of the most critical clinical stages. With careful and careful monitoring, you can identify all the mistakes made at the previous stages of crown manufacturing. Most of them are fixable. If the technician has identified defects in the preparation of the teeth and they are noted on the plaster stamp, then the doctor, when starting to fit the crown, must once again check the quality of the preparation and eliminate the mistakes he made (additionally prepare the teeth). It is necessary to pay attention to the anatomical shape of the crown and its belonging to a given tooth according to the N of the dress, marked on the plaster stamp, and the dental formula. If it does not correspond to the anatomical shape of a natural tooth, then such a crown must be remade, since this defect cannot be corrected in the clinic.

Only then do they begin to check whether the crown meets all other requirements. The procedure for fitting crowns is described in the method. development of practical lesson No. 7, topic 25.

It should be noted here that when making abutment crowns, the doctor and dental technician must mentally construct the entire prosthesis as a whole. Already at this stage, you should think about the intermediate part of the bridge, especially if it is made in the anterior part of the dentition. In some cases there is too much space left for facets, in others, on the contrary, not enough. Therefore, even when modeling the crowns, it is possible, to a certain extent, to reduce or increase this prosthesis. In addition, by appropriate modeling of the crown, the position of the tooth in relation to its neighbors or antagonists can be corrected if there is an anomaly in the position or shape of the teeth. All this is checked or corrected when fitting the crowns. Sometimes even a slight tilt of the crown in one direction or another radically affects the aesthetic qualities of the entire prosthesis. In the process of fitting crowns, the density of the crown’s coverage of the neck of the abutment tooth, the depth of its advancement under the gum, and its relationship with antagonists in various occlusions during the movement of the lower jaw are checked.

After a thorough check (fitting) of the crowns, a plaster impression is taken from the entire dentition along with the crowns. It is advisable to install the crowns in the impression, then you can check the depth of advancement of the crowns under the gingival margin. Central occlusion is determined together with the crowns and fixed with wax rollers or plaster mantles, plaster is applied from the vestibular side and an imprint of the vestibular surface of the teeth of the lower and upper jaw in the position of central occlusion is obtained. The crowns are removed from the supporting teeth and, together with impressions and wax rolls or plaster mantles, are sent to the dental laboratory.

In practice, a simplified method is often used (an occlusal impression is obtained): plaster is applied to the supporting crowns and the patient is asked to close the teeth; the correct closure of the teeth is checked using the teeth free of plaster. With this method, working and auxiliary impressions are obtained and the central occlusion is recorded. Crowns are inserted into the corresponding impressions and models are cast to obtain a simplified plaster occluder.

The teacher should explain to students that this method has disadvantages:

1. When applying plaster to the crowns, the patient reflexively shifts the jaw.

2. Between the supporting crowns and the antagonists, a layer of gypsum is formed, and if the technician models the intermediate part in such a plaster occluder, then it will exceed the bite, and the chewing surface of artificial teeth has to be filed down in the clinic, which leads to disruption of the chewing surface (cusps), and such a prosthesis will not be complete.

IX. Self-study assignment: Topic No. 54.

methodological development _________________________________

Date of preparation ________________________

Discussion date

Methodological development

revised _________________________________

Discussion date

at the cathedral meeting _______________________

Protocol N ____ dated ___________________________

Manager's signature department _________________________________

"APPROVED"

"____" ______________ 2009

Head department

orthopedic dentistry

Doctor of Medical Sciences, Prof.______V.P.Golik

METHODOLOGICAL DEVELOPMENT

practical lesson for 3rd year teachers, V semester

Lesson No. 17.

(Laboratory)

I . Topic 54:

MODELING RULES AND TECHNOLOGICAL STAGES OF MANUFACTURING AN INTERMEDIATE PART OF A BRIDGE. CLINICAL REQUIREMENTS FOR IT, PROCESSING, FINISHING, FITTING, SOLDERING OF THE INTERMEDIATE PART OF A BRIDGE WITH SUPPORTING CROWNS.

II. Lesson duration: 6 hours. hours. (3*2)

III. Learning goal.

Learn to model the intermediate part of the prosthesis, familiarize yourself with the technical stages of manufacturing a bridge.

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