Methods for fixing central occlusion. Determination and fixation of central occlusion

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.

Among the common manipulations that have to be addressed when designing various prostheses is the determination of central occlusion. Without taking it into account, not a single structure can function normally (from crowns to complete removable dentures).

The central closure of the dentition (central occlusion) is characterized by a certain relationship of the jaws in the vertical, sagittal and transversal directions. Relationships in the vertical direction are usually called the height of central occlusion, or bite height; relationships in the sagittal and transversal directions are called the horizontal position of the lower jaw in relation to the upper jaw.

When determining central occlusion in persons with partial loss of teeth, three groups of dentition defects are distinguished. The first group is characterized by the presence in the oral cavity of at least three pairs of articulating teeth, located symmetrically in the frontal and lateral areas of the jaws. The second group is characterized by the presence of one or more pairs of interlocking teeth located in one or two areas of the jaw. In the third group of defects in the oral cavity there is not a single pair of antagonizing teeth, i.e., despite the presence of teeth on both jaws, central occlusion is not fixed on them.

For the first group of defects, jaw models can be installed in the central closure (occlusion) along the ground-in occlusal surfaces of the teeth. In the second group of defects, articulating teeth fix the height of the central occlusion and the horizontal position of the lower jaw, so it is necessary to transfer these tooth relationships to the occluder using bite ridges made in a dental prosthetic laboratory or gypsum blocks. Depending on the clinical conditions, templates with bite ridges are made for one or both jaws. Templates with rollers are inserted into the oral cavity, trimmed or built up until the opposing teeth close in the same way as they did without the rollers. A heated strip of wax is glued to the occlusal surface of one of the rollers, the roller is inserted into the oral cavity and the patient is asked to close his teeth in central occlusion. Imprints of teeth that do not have antagonists are formed on the occlusal ridges. Templates with bite ridges are removed from the oral cavity, transferred to models and, based on the impressions of the teeth in the bite ridges, jaw models are folded in central occlusion.

Central occlusion in this group of defects can also be fixed by introducing a plaster test with the teeth closed in areas of the jaws free from opposing teeth.

After crystallization of the gypsum, the patient is asked to open his mouth and gypsum blocks are removed from the mouth, on which the alveolar areas and teeth of the upper jaw are fixed on one side, and the opposite areas of the lower jaw are fixed on the other side. The blocks are cut, placed in the corresponding places of the jaw models, and then the models are folded over them and plaster in the occluder.

In the third group of defects, the determination of central occlusion comes down to determining the height of the central occlusion and the horizontal position of the teeth.

The most common anatomical and physiological method for determining the height of central occlusion. Its measurement is carried out on the basis of facial anatomical signs (nasolabial folds, lip closure, corners of the mouth, height of the lower third of the face), which are assessed after some functional tests (speech, opening and closing of the mouth). These tests are carried out in order to distract the patient from moving the lower jaw forward and establish it in a state of relative physiological rest, when the lips are closed without tension, the nasolabial folds are moderately pronounced, the corners of the mouth are not drooping, and the lower third of the face is not shortened.

The distance between the jaws in a state of physiological rest of each jaw is 2-3 mm greater than when the teeth are closed in central occlusion, which underlies the anatomical and physiological method, which consists of the following: between two arbitrarily marked points on the upper and lower jaws (on tip of the nose, in the area of ​​the upper lip and chin) at the moment of physiological relative rest of the muscles, points are marked, the distance between which is measured with a spatula or ruler. Subtracting 2.5-3 mm from the resulting distance, the height of the central occlusion is obtained.

Templates with bite ridges are inserted into the mouth and trimmed to the desired height. If there are 3-4 teeth on the jaw, located in different parts of it, you can limit yourself to one template with a bite block made for the opposite jaw.

The anthropometric method of determining the height of the bite based on the law of the golden section (using Hering's compass) has only historical significance, because ancient faces are rare, especially in old age. Therefore, it is necessary to determine not the conditional height of central occlusion, but the one that the patient has at the time of the loss of the last pair of antagonizing teeth.

The horizontal position of the teeth or the neutral position of the lower jaw is determined by various methods. Some patients set the lower jaw into the correct position without any effort on the part of the doctor. You can also ask the patient to touch the back edge of the upper template with the tip of his tongue or to swallow saliva while closing his mouth. For the same purpose, the doctor inserts the thumb and index finger of the left hand into the patient’s mouth, fixing the upper template with a roller on the jaw. In this case, the right hand is placed on the chin and the lower jaw is brought to the upper jaw until the ridges are tightly closed. Then the rollers are removed from the mouth, immersed in cold water and reinserted into the mouth. To connect the bite ridges to each other, i.e., to fix the central occlusion, use a heated strip of wax attached to one of the ridges. In places where teeth are missing, indentations are made on the hard roller, into which heated wax is pressed when the jaws are compressed, forming locks. It is better to apply a heated strip of wax not over the entire bite ridge, but in several pieces in places where there will be imprints of the teeth of the opposite jaw or grooves will be cut out. The rollers glued together are removed from the oral cavity, cooled and separated, then they are placed on the models and the tightness of the templates to the models is checked. The templates with the rollers are inserted into the mouth again, the coincidence of the recesses with the protrusions is checked, as well as the coincidence of the teeth with their imprints on the wax roller.

After fixing the central occlusion, the models are plastered in an occluder and dentures are constructed on them.

In the fourth group of defects, in addition to the specified parameters, a prosthetic plane is constructed.

Muscle signs: muscles that lift the lower jaw (masseter, temporal, medial pterygoid) contract simultaneously and evenly;

Joint signs: the articular heads are located at the base of the slope of the articular tubercle, in the depths of the articular fossa;

Dental signs:

1) between the teeth of the upper and lower jaw there is the most dense fissure-tubercle contact;

2) each upper and lower tooth closes with two antagonists: the upper one with the same and behind the lower one; the lower one - with the same name and the one in front of the upper one. The exceptions are the upper third molars and lower central incisors;

3) the midlines between the upper and central lower incisors lie in the same sagittal plane;

4) the upper teeth overlap the lower teeth in the frontal region by no more than ⅓ of the length of the crown;

5) the cutting edge of the lower incisors is in contact with the palatal tubercles of the upper incisors;

6) the upper first molar meets the two lower molars and covers ⅔ of the first molar and ⅓ of the second. The medial buccal cusp of the upper first molar fits into the transverse intercuspal fissure of the lower first molar;

7) in the transverse direction, the buccal cusps of the lower teeth overlap the buccal cusps of the upper teeth, and the palatal cusps of the upper teeth are located in the longitudinal fissure between the buccal and lingual cusps of the lower teeth.

Signs of anterior occlusion

Muscle signs: this type of occlusion is formed when the lower jaw moves forward by contraction of the external pterygoid muscles and horizontal fibers of the temporal muscles.

Joint signs: the articular heads slide along the slope of the articular tubercle forward and down to the apex. In this case, the path taken by them is called sagittal articular.

Dental signs:

1) the front teeth of the upper and lower jaws are closed by the cutting edges (end-to-end);

2) the midline of the face coincides with the midline passing between the central teeth of the upper and lower jaws;

3) the lateral teeth do not close (tubercle contact), diamond-shaped gaps form between them (disocclusion). The size of the gap depends on the depth of the incisal overlap at the central closure of the dentition. It is greater in persons with a deep bite and absent in persons with a straight bite.

Signs of lateral occlusion (using the example of the right one)

Muscle signs: occurs when the lower jaw shifts to the right and is characterized by the fact that the left lateral pterygoid muscle is in a state of contraction.

Joint signs: V In the left joint, the articular head is located at the top of the articular tubercle and moves forward, down and inward. In relation to the sagittal plane, it is formed articular path angle (Benett's angle). This side is called balancing. On the offset side - right (working side), the articular head is located in the articular fossa, rotating around its axis and slightly upward.

With lateral occlusion, the lower jaw is displaced by the amount of the cusps of the upper teeth. Dental signs:

1) the central line passing between the central incisors is “broken” and shifted by the amount of lateral displacement;

2) the teeth on the right are closed by the cusps of the same name (working side). The teeth on the left meet with opposite cusps, the lower buccal cusps meet the upper palatal cusps (balancing side).

All types of occlusion, as well as any movements of the lower jaw, occur as a result of the work of muscles - they are dynamic moments.

The position of the lower jaw (static) is the so-called a state of relative physiological rest. The muscles are in a state of minimal tension or functional equilibrium. The tone of the muscles that elevate the mandible is balanced by the force of contraction of the muscles that depress the mandible, as well as the weight of the body of the mandible. The articular heads are located in the articular fossae, the dentition is separated by 2 - 3 mm, the lips are closed, the nasolabial and chin folds are moderately pronounced.

Bite

Bite- this is the nature of the closure of teeth in the position of central occlusion.

Classification of bites:

1. Physiological occlusion, providing full function of chewing, speech and aesthetic optimum.

A) orthognathic- characterized by all the signs of central occlusion;

b) straight- also has all the signs of central occlusion, with the exception of the signs characteristic of the frontal region: the cutting edges of the upper teeth do not overlap the lower ones, but meet end to end (the central line coincides);

V) physiological prognathia (biprognathia)- the front teeth are inclined forward (vestibular) along with the alveolar process;

G) physiological opistognathia- the front teeth (upper and lower) are inclined orally.

2. Pathological occlusion, in which the function of chewing, speech, and a person’s appearance is impaired.

a) deep;

b) open;

c) cross;

d) prognathia;

d) progeny.

The division of occlusions into physiological and pathological is arbitrary, since with the loss of individual teeth or periodontopathies, tooth displacement occurs, and a normal occlusion can become pathological.

Occlusion of teeth- this is the closure of dentition or individual teeth for a short or long period of time. Occlusion is divided into the following types: central, anterior and lateral.

Central occlusion. This type of occlusion is characterized by the closure of teeth with the maximum number of interdental contacts. With this disease, the head of the lower jaw is very close to the base of the articular tubercle. It should also be noted that all jaw muscles contract evenly and simultaneously. These muscles move the lower jaw. Due to this position, lateral movements of the lower jaw are very likely.

Anterior occlusion. With anterior occlusion, the lower jaw moves forward. With anterior occlusion, it can be completely observed. If the bite is normal, then the midline of the face coincides with the midline of the central incisors. Anterior occlusion is very similar to central. However, there is a difference in the location of the head of the mandible. With anterior occlusion, they are closer to the articular tubercles and slightly moved forward.

Lateral occlusion. This type of occlusion occurs when the lower jaw shifts to the left or right. The head of the lower jaw becomes mobile. But it remains at the base of the joint. At the same time, on the other side it moves upward. If posterior occlusion occurs, a displacement of the lower jaw occurs. At the same time, it loses its central location. During this, the heads of the joints move upward. The posterior temporal muscles suffer. They are in constant tension. The functions of the lower jaw are partially impaired. She stops moving sideways.

These types of occlusions are called physiological and in some cases are considered the norm. However, there is also pathological occlusion in dentistry. Pathological occlusions are dangerous because when they occur, absolutely all functions of the masticatory apparatus are disrupted. Such conditions are characteristic of certain diseases that can cause dental occlusion: periodontal disease, tooth loss, malocclusion and jaw deformation, increased wear of teeth.

It should be noted that occlusion is directly related to the bite of teeth. You could even say that these are the same concept. In this regard, it is necessary to analyze the types and causes of pathological bites or occlusions.

Distal bite

This type of bite is different in many ways. A distinctive feature is an overdeveloped upper jaw. It is not good. The fact is that with such a bite the distribution of the chewing load is disrupted. It is more convenient for a person to bite food with the side teeth. In this regard, it is the lateral teeth that are very susceptible to caries. In order to hide a non-aesthetic defect, the patient in most cases pulls the lower lip towards the upper lip. To eliminate this type of malocclusion, many experts recommend completely removing the teeth in the upper jaw and then installing implants. However, now there are ones that give very positive results.

Causes of occlusion

  • Genetic predisposition.
  • Chronic ENT diseases that occurred in childhood. Moreover, they were accompanied by the fact that the child was breathing not through his nose, but through his mouth.
  • Bad habits, such as thumb sucking in childhood, can lead to this type of bite.

Straight bite

A direct bite is very similar to a physiological bite, so it is difficult to distinguish between them. However, there are differences. In a straight bite, the teeth contact each other with their cutting edges. And normally they should go after each other. Doctors sometimes say that this is absolutely normal. Although, this is not true. the fact is that the contacting cutting surfaces subsequently lead to pathological abrasion of the teeth. Over time, teeth begin to wear down. This leads to changes in the joints, and then restrictions on mouth opening may occur. Such a bite necessarily requires appropriate treatment. And the treatment consists of placing special silicone mouth guards on the cutting interacting surfaces of the teeth.

Deep bite

With a deep bite, the lower teeth overlap the upper teeth by more than half. Such a bite can be developed not only on the front part of the jaw, but also on the side parts. This type of bite (occlusion) is dangerous because a disease such as periodontal disease can develop very early. In addition, such patients may be at risk of developing periodontitis (). The mucous membrane of the mouth suffers greatly, as it is constantly damaged by the teeth. In addition, the volume of the oral cavity decreases, and this leads to disturbances in swallowing food and breathing. In most cases, some groups of frontal teeth are worn down. Patients complain of crunching, clicking and pain in the joints. Prosthetics for such a bite is very difficult.

Open bite

In an open bite, the patient's teeth do not close together at all. Accordingly, they do not contact each other in any way. This type of bite can occur in the front and sides. In addition, both single teeth and entire groups of teeth can be involved in such a process. In places where the teeth cannot close, the process of chewing food is disrupted. It follows from this that the more teeth do not close, the harder it is to chew food. And accordingly, problems arise from the digestive system. In addition, patients with such a bite suffer from speech impairments.

Causes:

  • Prolonged pacifier use and thumb sucking in childhood.
  • Almost all ENT diseases.
  • Improper swallowing function during the formation and growth of teeth in childhood.

Dental occlusion must be detected in the early stages. Accordingly, treatment should be started on time. Basically, these diseases are “laid in” from childhood due to the child’s bad habits. That's why. To prevent occlusion from occurring, you should monitor your children very closely.

Occlusion is the most complete closure between the cutting edges or chewing surfaces of the teeth, which occurs simultaneously with evenly contracted chewing muscles. This concept also includes dynamic characteristics that make it possible to determine the work of the muscles of the face and the temporomandibular joint.

Correct occlusion is extremely important for the proper functioning of the entire dentofacial apparatus. It provides the necessary load on the teeth and alveolar processes, eliminates periodontal overload, and is responsible for the correct functioning of the temporomandibular joint and all facial muscles. With its anomalies, which are observed in the absence of teeth in a row, periodontal diseases and other functional disorders of the dental system, not only facial aesthetics suffers. They can also cause increased tooth wear, joint inflammation, muscle strain and gastrointestinal disturbances. That is why any anomalies in dental occlusion require treatment.

Types of dental occlusion

All movements of the lower jaw are ensured by the work of muscles, which means that types of occlusion must be described in dynamics. They distinguish between static and dynamic; some researchers also distinguish occlusion at rest, which is determined by closed lips and teeth open by several millimeters. Static occlusion characterizes the position of the jaws during their usual compression relative to each other. Dynamic describes their interaction during movement.

Different sources emphasize different aspects of central occlusion. Some look, first of all, at the location of the mandibular joint, others consider the condition (full contraction) of the masticatory and temporal muscles to be of paramount importance. However, in orthopedics and restorations, when it is important to correctly calculate the relationship of teeth in rows, dentists prefer characteristics that can be assessed visually, without the use of complex devices. We are talking about the maximum closing area in compliance with the formulas:

  • the sagittal central line of the face lies between the anterior incisors of the upper and lower jaws;
  • the lower incisors rest against the palatine tubercles of the upper ones, and their crowns overlap by one third;
  • the teeth have close contact with the two antagonists, except for the third molars and the lower anterior incisors.

A slight advancement of the lower jaw forms anterior occlusion. An imaginary vertical midline separates the upper and lower anterior incisors, which in turn are in contact with the cutting edges.

The upper and lower molars may not meet evenly, forming a cusp contact.

Posterior occlusion is characterized by movement of the lower jaw towards the back of the head.

With lateral occlusion, the sagittal line is broken with a shift to the right or left, the teeth of one, working, side touch the same cusps of their antagonists, while on the other - balancing - the opposite ones (upper palatal with lower cheek).

Some characteristics of the occlusal system have genetic causes, while others are developed during growth. Hereditary factors can affect the shape, size of the jaws, muscle development, teething, and the functional apparatus is formed under the influence of various internal and external factors during the development of the jaws.

Understanding occlusion is very important during restoration and orthopedic work in dentistry, so that the function of the masticatory apparatus is restored as fully as possible.

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.


Occlusion- this is the simultaneous and simultaneous closure of a group of teeth or dentitions in a certain period of time with contraction of the masticatory muscles and the corresponding position of the elements of the temporomandibular joint. Occlusion- a particular type of articulation.

There are five types of occlusion:

. central;

Front;

Lateral left;

Lateral right;

Rear.

Each of them is characterized by dental, muscle and joint characteristics.

Physiological central occlusion in orthognathic occlusion is characterized by a number of signs:



. between the teeth of the upper and lower jaws there is the most dense fissure-tubercle contact;

Each upper and lower tooth intersects with two antagonists: the upper one - with the same and behind the lower one; lower - with the same name and in front of the upper (with the exception of the upper third molars and central lower incisors);

The midlines between the central upper and lower incisors lie in the same sagittal plane;

The upper teeth overlap the lower teeth in the anterior region by no more than 1/3 of the length of the crown;

The cutting edge of the lower incisors contacts the palatal cusps of the upper incisors;

The upper first molar meets the two lower molars and covers 2/3 of the first molar and 1/3 of the second; the medial buccal cusp of the upper first molar enters the transverse intercuspal fissure of the lower first molar;

In the vestibulo-oral direction, the vestibular cusps of the lower teeth overlap the vestibular cusps of the upper teeth, and the oral cusps of the upper teeth are located in the longitudinal fissure between the vestibular and oral cusps of the lower teeth;

The muscles that elevate the mandible (masticatory, temporal, medial pterygoid) contract simultaneously and evenly;

The heads of the lower jaw are located at the base of the slope of the articular tubercle, in the depths of the articular fossa.

Determination of central occlusion is one of the important stages of prosthetics for partial loss of teeth. It consists in determining the relationships of the dentition in the horizontal, sagittal and transversal directions. Directly related to central occlusion has the height of the lower part of the face. With existing antagonists, the height of the lower part of the face is fixed by natural teeth. When they are lost, it becomes unfixed and must be determined. With the loss of fixed height of the lower face, the ability to . In this case, we can talk about determining the central relationship of the jaws.

With partial loss of teeth, the following clinical options for determining central occlusion are possible:

. Antagonist teeth are preserved in three functionally oriented groups of teeth: in the area of ​​the anterior and chewing teeth on the right and left sides. The height of the lower part of the face is fixed by natural teeth. Central occlusion are established based on the maximum number of occlusal contacts, without resorting to the manufacture of wax occlusal ridges. This method for determining central occlusion should be used when defects are included, resulting from the loss of 2 teeth in the lateral section or 4 in the anterior section.

Antagonist teeth are present, but they are located only in two functionally oriented groups (anterior and lateral sections or only in the lateral sections on the right or left). In this case, compare the models in position central occlusion only possible using occlusal wax rollers. The definition of central occlusion is to fit the occlusal ridge of the lower jaw to the upper jaw and fix the mesiodistal relationship of the jaws or to fit one of the occlusal ridges to the teeth of the opposite jaw while maintaining the closure of the antagonist teeth.

There are teeth in the oral cavity, but there is not a single pair of antagonist teeth (no dental occlusion is observed). In this case we are talking about central relationship of the jaws. It consists of several stages:

- formation of a prosthetic plane;

Determination of the height of the lower part of the face;

Fixation of the mesiodistal relationship of the jaws.

To fix the central relationship of the jaws in the 2nd and 3rd cases, it is necessary to make wax (preferably plastic) bases with occlusal wax rollers.


There are the following methods for establishing the lower jaw in the position of central occlusion:


. Functional method- to set the lower jaw in position central occlusion The patient's head is tilted back slightly. At the same time, the neck muscles tense slightly, preventing the lower jaw from moving forward. Then the index fingers are placed on the occlusal surface of the lower teeth or the wax roll in the area of ​​the molars so that they simultaneously touch the corners of the mouth, slightly pushing them to the sides. After this, the patient is asked to raise the tip of the tongue, touch it to the posterior parts of the hard palate and at the same time make a swallowing movement. This technique almost always eliminates the reflex forward movement of the lower jaw. When the patient closes his mouth and the bite ridges or occlusal surfaces of the teeth begin to come together, the index fingers lying on them are moved out in such a way that they do not interrupt the connection with the corners of the mouth, moving them apart. Closing the mouth using the techniques described should be repeated several times until it becomes clear that the correct closure of the dentition is taking place.

. Instrumental method involves the use of a device that records movements of the lower jaw in the horizontal plane. Central occlusion position corresponds to the apex of the “Gothic angle” formed when recording laterotrusive and protrusive movements of the lower jaw. In case of partial absence of teeth, this method is rarely used, only in difficult cases of clinical practice. In this case, the lower jaw is forcibly displaced by pressing the doctor’s hand on the patient’s chin to ensure alignment.

In case of significant absence of teeth, and most importantly - in the absence of pairs of antagonists, the formation of the occlusal surface is carried out using the Larin apparatus or two special rulers. The occlusal surface should run parallel to the pupillary line in the frontal plane, and parallel to the nasal line in the lateral regions. The height of the plane of the occlusal wax roller should correspond to the line of lip closure. After determining the height of the lower part of the face, the lower wax roller is adjusted to the upper one. The ridges should close tightly in the anteroposterior and transversal directions, and their buccal surfaces should be in the same plane. When closing the mouth, the wax rollers simultaneously touch in the anterior and lateral sections, and the wax bases fit tightly to the surface of the mucous membrane. All corrections are carried out only on the ridge of the jaw where the smallest number of teeth are preserved (wax is added or excess is removed using a heated spatula).


There are several methods for determining the height of the lower part of the face.


. Anatomical- based on the study of facial configuration.

. Anthropometric- based on data on the proportions of individual parts of the face.

. Anatomical and physiological method is based on determining the state of relative physiological rest of the lower jaw, such a position of the lower jaw in which the masticatory muscles are in a state of minimal tension (tone), the lips touch each other freely, without tension, the corners of the mouth are slightly raised, the nasolabial and chin folds are clear pronounced, the dentition is open (the interocclusal gap is on average 2-4 mm), the heads of the lower jaw are located at the base of the slope of the articular tubercle. During the conversation with the patient, dots are applied at the base of the nose and the protruding part of the chin. At the end of the conversation, when the lower jaw is in a state of physiological rest, measure the distance between the marked points. Then wax bases with bite ridges are introduced into the mouth, the patient closes his mouth, most often in central occlusion, and the distance between the two points is measured again. It should be 2-4 mm less than the resting height. If, when closing, the distance is greater than or equal to the state at rest, then the height of the lower part of the face is increased, excess wax should be removed from the lower roller. If, when closing, the distance obtained is less than 2-4 mm, then the height of the lower part of the face is reduced and a layer of wax should be added to the roller. Sometimes a conversational test is used as a functional addition to the anatomical method. The patient is asked to say a few words - “satisfactory” and “now”, while monitoring the degree of separation of the rollers. Normally, the separation is 2-3 mm. If the gap between the ridges is more than 3 mm, the height of the lower part of the face is reduced, and if it is less than 2 mm, then it is too high.

To fix the mesiodistal relationship of the jaws, triangular notches are made to the thickness of the wax plate on the upper ridge in the area of ​​closure with the ridge of the lower jaw. On the roller in contact with the antagonist teeth, 1-2 mm of wax is removed and a softened wax plate is placed on the chewing surface, fixed to the roller with a hot spatula. Bite rollers are inserted into the patient's oral cavity, and he closes his mouth in the position of central occlusion until the wax hardens.

If the front group of teeth is missing, the following guidelines must be drawn:

. cosmetic center line (middle line)- for setting the central incisors;

. fang line- a perpendicular is drawn from the wings of the nose to the vestibular surface of the occlusal ridge; this line determines the width of the front teeth to the middle of the canine;

. smile line- to determine the height of the front teeth; When the patient smiles, it should be located just above the line of the necks of the teeth.

The wax rolls are removed from the mouth, cooled, separated, excess wax is removed, and folded along the formed grooves and protrusions.

After determination of central occlusion or central relationship, the models attached to each other must be plastered into an articulator (occluder).

Wax base with occlusal ridges.

Border of the prosthesis on the lower jaw.

Border of the denture on the upper jaw.

Edging of the cast.

Before obtaining the working model, the technician will frame the functional cast.

With the help of edging, it is possible to convey the relief of the edge of the print, first on the model, then on the prosthesis. In addition, the edging helps to protect the edges from damage when opening.

Along the transitional fold, it can be slightly higher, going around the frenulum of the upper lip and buccal cords, overlapping the retromolar cusps, moving to the palatal side to line A, overlapping the blind fossae by 2-3 mm.

Similarly from the vestibular side and from behind, overlapping the mucous tubercle, the internal oblique line by 2 mm, from the side of the tongue, retreating 3 mm from the sublingual fold, going around the frenulum of the tongue.

Height 1.5 cm

Frontal width: 0.8 mm

Width in the chewing area 10 mm

1st stage. Determining the height of the upper roller. The cushion protrudes 2 mm from under the upper lip.

2nd stage. Determination of the prosthetic plane along the pupillary line for the anterior teeth and along the nasal line for the lateral teeth.

3rd stage. Determination of bite height for the lower jaw:

a) anthropometric method (golden section method). The device consists of two compasses. They are connected in such a way that the legs of the large compass are separated in the extreme and middle ratios. Only on one leg the larger segment is located closer to the hinge, and the second one is further from it.

Operating principle: the first end of the compass is placed on the tip of the nose, and the second on the chin tubercle.

b) Anatomical and physiological method. The loss of a fixed interalveolar height leads to a change in the position of all anatomical formations surrounding the oral fissure: the lips sink, the nasolabial folds become deep, the chin moves forward, and the height of the lower third of the face decreases.

Principles of action: The patient is engaged in a short conversation. Upon completion, the lower jaw is set at rest, and the lips close freely, adjacent to each other. In this position, the doctor measures the distance between two points.

Then templates with bite ridges are inserted into the mouth and the patient is asked to close them. It should be remembered that the interalveolar height must be determined in the position of central occlusion. After insertion of the bite ridges, the distance between the clinical points is measured again. It should be 2-3 mm less than the resting height.

After the interalveolar height has been determined, attention is paid to the tissues around the oral cavity. With the correct height, the normal contours of the lower third of the face are restored. If the height is reduced, the corners of the mouth droop, the nasolabial folds become pronounced, and the upper lip shortens. In this regard, one test is indicative: if you touch the line where the lips close with your fingertip, they instantly open, which does not happen if they lie freely.



Determination of the central relationship of the jaws in the complete absence of teeth.

1. determining the height of the occlusal ridge for the upper jaw. The lower edge of the occlusal ridge of the upper jaw should be flush with the upper lip or visible from under it by 1.0-1.5 mm.

2. Determination of the prosthetic plane along the pupillary line for the anterior teeth and along the nasal line for the lateral teeth.

3. Determination of the height of the lower part of the face. In case of complete absence of teeth, the occlusal height is established, i.e. the distance between the alveolar ridges of the upper and lower jaws in the central

4. Fixation of the central relationship of the jaws.

5. Applying landmarks to the vestibular surface of the wax rolls. On the occlusal ridges, the doctor marks the main landmarks necessary for the dental technician to design dentures for edentulous jaws.

Selection of artificial teeth.

The size, shape, and color of teeth are selected by the doctor according to your face type, taking into account age.

3 face types:

Square

Triangular

Oval

Chewing teeth have pronounced cusps and deep fissures; such teeth quickly wear down and are capable of shedding the prosthesis. There are teeth whose tubercles are directed in the sagittal direction. In a similar way, Sapozhnikov developed chewing teeth that correspond to a spherical surface and do not have blocking points, therefore they do not contribute to the shedding of the prosthesis.

There are various dental deficiencies:

1. softness and abrasion - lead to underestimation of the bite height.

2. Insufficient color fastness of plastic teeth.

The structure of the articulator.

The articulator consists of two frames: upper and lower.

They articulate with each other at three points: in the area of ​​the articular and incisal areas. They have an inclined position, corresponding to the angles of the sogittal articular and incisal tracts. A movable vertical pin is attached to the anterior section of the upper frame, resting on the incisal platform of the lower frame and maintaining the height of the bite. The height pin has an incisal pin, which is pointed at the midline and incisal point.

Glass installation.

1) The placement of teeth begins with the upper jaw. To do this, the existing base with occlusal ridges is removed and a new wax base is formed according to the model.

2) Glass is attached to the occlusal ridge of the base of the upper jaw with molten wax. The base with occlusal ridges is removed from the lower jaw model and a new one is formed, strictly along the boundaries of the neutral zone.

A wax roller is placed in the area of ​​the lingual surface of the alveolar ridge and attached to the base with molten wax. Close the occluder until the pin rests on the incisal platform. The glass is attached with molten wax to the roller on the lower jaw. After this, the base with occlusal ridges is removed from the model of the upper jaw, a new base is made from wax, a setting roller is installed and we begin setting up the teeth.

Positioning of teeth with an orthognathic relationship of toothless jaws on glass.

The upper central incisors are located on either side of the center line. The cutting edges touch the glass. The neck is tilted towards the oral side, and they are at the level of a smile.

The lateral incisors are 0.5 mm behind the glass, the neck is directed towards the oral side and slightly below the level of the smile.

The fang touches the glass with its tearing tubercle, the neck is directed towards the vestibular side and slightly below the level of the smile.

The 1st premolar touches the glass with its buccal cusp, the palatal cusp lags behind the glass by 1 mm.

The 2nd premolar touches the glass with two cusps.

The 1st molar touches the glass with the medial palatal cusp, the distal palatal cusp lags behind by 0.5 mm, the distal buccal cusp lags behind by 1 mm, the mesial buccal cusp lags behind by 1.5 mm.

The 2nd molar does not touch the glass. The medial palatal tubercle lags behind the glass by 0.5 mm, the distal palatal tubercle by 1 mm, the distal buccal tubercle by 1.5 mm, the medial buccal tubercle by 2 mm. Thanks to this arrangement in relation to the plane of the glass, sagittal and transvesal curves are formed, providing many contact points during chewing movements of the lower jaw.

The anterior teeth are positioned so that 2/3 of the tooth is in front of the alveolar ridge and 1/3 is behind. For lateral teeth, it is desirable that the axis of the tooth coincides with the middle of the alveolar ridge.

Neck twist.

The anterior teeth are placed with an inclination towards the distal side. The premolars are placed straight. Molars with a medial inclination.

Direct bite.

To bring the direct bite closer to the orthognathic one, you need to slightly grind the lower front teeth on the vestibular side.

With crossbite.

We swap the chewing teeth: lower chewing teeth to the upper jaw, upper chewing teeth to the lower jaw.

Positioning of teeth in the progenic relationship of toothless jaws.

Progeny is the advancement of the lower jaw in front.

If the progeny is senile, then we strive to place the teeth in a straight bite. If progeny is hostile, then it is cross-positioned. The front teeth are brought forward or we place the incisors in a direct bite: the central incisors touch the glass, the lateral ones lag behind by 0.5 mm, the canines touch. The 1st premolar touches the buccal cusp, the 2nd premolar is not placed. The 1st molar touches both buccal cusps, the palatal cusps are 1 mm behind. The 2nd molar touches the anterior buccal cusp, and the rest are raised.

Positioning of teeth during prognathism.

The first premolars in the lower jaw are removed. The frontal teeth of the upper jaw are placed on the groove and made pilots. Chewing teeth are placed according to orthognathy.

Setting teeth on a spherical surface.

Teeth are positioned in a simple hinged occluder using an individually designed occlusal surface or standard plates. Central occlusion is determined by the doctor in the oral cavity.

The base is replaced with a base made of harder wax. Occlusal ridges are made of wax with the addition of corundum. Thanks to the use of the Christensen phenomenon, the occlusal ridge for the upper jaw acquires a convex shape in the area of ​​the lateral teeth, and the occlusal ridge for the lower jaw acquires a concave shape. A better fit of the rollers to each other is ensured by rubbing them in the oral cavity with pumice gruel during all kinds of movements of the lower jaw. The upper and lower jaws are held together in the oral cavity by metal hooks in the central occlusion. Then we take it out and install it on the model. Plaster in an occluder. Setting begins with the lower roller. After determining the occlusal height in the clinic, a standard metal staging platform is placed on the wax roller of the base of the lower jaw and fixed with molten wax. The base with the occlusal roller and the placement platform is reintroduced into the patient’s oral cavity and correction is made by adding wax in accordance with the sagittal and transversal movements of the lower jaw. Then the rollers with bases are fixed in the position of central occlusion in the occludator and the teeth are placed on the upper base along a spherical plate mounted on the occlusal roller for the lower jaw.

Napadov-Sapozhnikov staging methods.

The staging area consists of three parts, expressed in the form of an ellipse. The two side platforms are connected using hinges. The radius of the surface is 9 cm. In the lateral sections there is ... the prosthesis, arrows are restored - pointers that have the direction of the radius of the spherical surface.

Using these plates, the doctor determines the central relationship of the jaws in occlusion. The dental technician will fix it into the occluder. The occlusal ridges of the lower jaw are cut off in the lateral areas and, under the control of the occlusal ridge of the upper jaw, a spherical platform is installed on the lower ridge. Then the base with occlusal ridges is removed from the upper jaw model, and arrow-pointers are inserted into the slots of the side parts. The side parts are installed in such a way that the pointer arrows coincide with the tops of the alveolar processes of the common jaws.

Having installed the staging platform on the alveolar part of the lower jaw model, firmly fix its side parts with molten wax, removing the arrow indicators and begin to place the teeth on the upper jaw.

Modeling of prosthetic bases.

The thickness of the denture base for the upper jaw should be uniform. The surface must be level. The edges of the base must be exactly along the border and correspond to the edge of the functional cast. The teeth should be free of wax and there should be rounded ridges in the neck area.

On the lower wax base, in the area of ​​the vestibular surfaces of the necks of the front teeth, a small protrusion is modeled, which helps stabilize the prosthesis due to the adherence of the circular muscles of the oral cavity.

The lingual side is modeled smoothly. On the upper jaw, the prosthesis on the vestibular side in the area of ​​the front teeth along the transitional fold is modeled with a closing valve in the form of a roller.

Checking the wax structure in the oral cavity.

The modeled prosthesis is sent to the doctor.

Checking in the occluder: 1) how the border of the prosthesis is. 2) tightness of the prosthesis base. 3) thickness of the base. 4) placement of teeth, whether contacts are maintained. 5) on the integrity of the model.

Checking in the oral cavity: 1) correct placement of teeth. 2) degree of fixation. 3) contact density. 4) determination of central occlusion.

Also in the oral cavity they look at the appearance of the patient with dentures, at the height of the front teeth. Check the frequency of pronunciation of sounds. With an overbite, external signs change, and pain in the temporomandibular joint is also detected. In this case, the doctor must determine which jaw caused the overbite.

If the bite height is too low, a wax plate is applied to the lower dentition and the patient again bites in a state of physiological rest.

With large atrophy of the alveolar process on the lower jaw, at the time of fixation, a shift of the wax template may occur, which will be recorded as an unusual position of the jaw. To prevent mistakes, rollers (tides) are modeled on the lower wax template in the premolar area on the vestibular side, with the help of which the doctor, when determining central occlusion, applies fingers on both sides, which prevents the roller from moving.

In all cases associated with errors in determining central occlusion, the artificial teeth are rearranged. To do this, the doctor gives the dental technician an occluder with one broken jaw.

After correcting all errors, the doctor rechecks.

Final modeling.

During the final modeling, the technician secures the separated teeth with wax while checking the design. Design of the edges of the prosthesis. A closing roller is made on the vestibular side, which provides better fixation of the prosthesis. The inner surface of the tooth is not filled with wax, so as not to change the function of speech.

The distal edge of the cushion is reduced to nothing. The base is glued along the entire perimeter of the model and smoothed.

Possible errors during verification.

1) When applying protea in the oral cavity, there are errors in the closure of the teeth (the setting of the teeth is altered).

2) Inconsistency of the border of the prosthetic bed (if when handing over the prosthesis, then relining the prosthesis, i.e. 1) a small layer of plastic is removed from the inside, the plastic is spread out, lubricated with oil, sanded, deformation of the base, not accurate display. 2) we take an impression using the same prosthesis, plaster the finished prosthesis into a cuvette, open the cuvette, add an impression mass (gasket) and put plastic in its place.

3) Deformation of the base - incorrect gluing of the impression or inaccurate representation of the prosthetic bed (relining)

Cosmetic corrections.

To make the prosthesis look more natural, cosmetic adjustments are made.

1) deasthemas are made between the front teeth

2) Tremas are made between the chewing teeth

3) superimposition of one tooth on another.

Fitting the finished prosthesis in the oral cavity, rules of use and correction.

The doctor inserts the prosthesis into the oral cavity and makes a carbon copy correction of the teeth.

The fixation is checked: the upper jaw is pressed with a finger on the central incisors, a finger is placed on the lower jaw in the area of ​​the 4.5th tooth and the prosthesis is rocked. The next day, the patient is prescribed a correction (various pain points are identified; before the visit, the patient must put on the prosthesis an hour before. The doctor removes the prosthesis, and in those places where the prosthesis pressed, redness is visible. And these places are marked with a chemical pencil. The prosthesis is put on the patient, and then it is removed again, and from the side of the mucous membrane, the chemical pencil is transferred to the base. They are removed with a bur. The bite of the cheeks also occurs, so the chewing tubercles on the lower jaw are undermined, the fangs are removed from contact. Then the next correction is done in 7 days.

Adaptation to the prosthesis.

After a short period of time, salivation and vomiting increase.

In the process of addiction there are separate phases:

1) inhibited reaction to the prosthesis as to a stimulus.

2) Formation of new motor functions and pronunciation of sounds.

3) Adaptation of muscle activity to the new alveolar height.

4) Reflex restructuring of muscle and joint activity.

In addition to reactions to the introduction of a prosthesis in the oral cavity, the actions of the prosthesis are distinguished:

side(in addition to speech impairment, self-cleaning of the mucous membrane, a greenhouse effect (vacuum) also occurs,

traumatic(marked along the edges of the prosthesis)

toxic(allergy to monomer, irritation to mucous membrane).

In prosthetic dentistry the term "occlusion" is used. It refers to the closure of teeth. There are 4 main occlusions and many intermediate ones. The first include central, front and 2 lateral.

Central occlusion is characterized by maximum contact of the surfaces of the opposing teeth. It is considered the initial and final stages of articulation, since the first stage begins with the release of the lower jaw from the state of central occlusion, and the last ends with its return to its original state.

Articulation in dentistry refers to the entire complex of movements (chewing and non-chewing) performed by the lower jaw, and possible options for occlusion.

One type of articulation is central occlusion. With it, the muscle fibers that elevate the lower jaw are maximally and evenly tense on both sides.

Signs of correct bite

They are used for determining central occlusion (or central relationship of the jaws). Correct bite in dentistry is called orthognathic. It is determined by the following criteria:

  1. On the upper jaw, each tooth is located opposite (antagonizes) the one of the same name and behind the lower one. Each lower one, in turn, antagonizes the upper tooth of the same name, standing in front. Exceptions are the central incisors, as well as the last teeth located on the upper jaw. They are located opposite only the lower teeth of the same name.
  2. The central incisors of the lower and upper jaws are separated by one midline.
  3. The lower front teeth overlap the upper front teeth by approximately 1/3 of the height.
  4. The medial (lying inwardly, closer to the midline) vestibular tubercle on the upper first molar (third tooth from the end) is located in the transverse groove of the lower first molar.

It is worth saying that these signs can only be detected in an intact (undamaged, non-pathological) bite.

Specifics of application of criteria

As practice shows, most people first of all lose the first molars, the relative position of which determines the content of the fourth sign.

If we talk about the third criterion, then, as a rule, it is not applied when determining the central relationship of the jaws.

The first two signs are considered the most reliable clinically. The essence of central occlusion is the maximum contact of the surfaces of teeth located opposite each other, regardless of their number. Accordingly, with an intact bite or such a number of teeth that would be sufficient for determining the central ratio of the jaws, you can use signs characteristic of their ethnic or even pathological position. The fact is that the latter also differs, albeit in a distorted, but characteristic arrangement of the jaws.

If, due to secondary (acquired) adentia (partial/complete loss of teeth), the number of signs decreases, determination of the central relationship of the jaws can be carried out with a careful examination of the facets (flat surfaces) of the last pair of oppositely located (antagonizing) teeth. In their complete absence, the state of central occlusion is determined by indirect signs.

Central jaw ratio: definition

In the presence of opposing teeth, the centric relation is quite easy to determine. Difficulties arise when the patient does not have them.

In the second case, the specialist needs to establish the most advantageous in functional terms central relationship of the jaws. Definition position is carried out in three planes, mutually perpendicular to each other: horizontal, frontal and sagittal (longitudinal). At the same time, the doctor does not have the necessary guidelines.

Of course, as the task becomes more complex, the likelihood of medical errors when determining the central relationship of the jaws.

Incorrect determination of vertical size: consequences

The interalveolar height (the distance between the jaws) is determined in the frontal plane. A correct understanding of this process will eliminate errors in determining the central relationship of the jaws. Each incorrect movement provokes certain morphological and functional disorders with characteristic symptoms.

For example, with an increase in the vertical size (interalveolar height), teeth chattering is observed during eating, and in some cases during conversation. In addition, patients report rapid fatigue of the masticatory muscles.

A decrease in interalveolar height causes even more negative consequences.

Thus, as the distance between the parts fixed by prostheses decreases, the vertical size of the lower third of the face decreases. At the same time, the upper lip becomes shorter, the nasolabial folds become deeper, and the corners of the mouth droop. As a result, a person’s face acquires senile features. You can often observe maceration of the skin in the corners of the mouth (pathological swelling that occurs with prolonged contact with water).

It is also worth saying that a decrease in the vertical size leads to a decrease in the functionality of the prosthesis. This fact was proven by chewing tests.

As the jaws shrink, the oral cavity also shrinks. This, in turn, leads to constraint in the movements of the tongue and speech disorders. Accordingly, in this case, patients can talk about rapid fatigue of the masticatory muscles.

Errors in determining the central relationship of the jaws lead to a change in the position of the mandibular head in the articular fossa. The head moves deeper, and the thick posterior layer of the articular disc puts pressure on the neurovascular bundle. Patients often begin to experience pain in this area.

Incorrect determination of interalveolar height also affects the design of prostheses. If it is overestimated, the products become massive. When the height is reduced, the dentures are low with short teeth.

Determination of the central ratio of edentulous jaws

The process includes:

  1. Preparation of bite ridges.
  2. Determination of the vertical distance between the jaws.
  3. Determination of the central position of the lower jaw.
  4. Drawing lines on rollers.
  5. Bonding models.

Let's look at some stages separately.

Preparing the rollers

During this stage:

  1. The boundaries of the wax templates are specified.
  2. The vestibular surface and the thickness of the upper ridge are formed.
  3. The height of the upper roller is determined.
  4. A prosthetic plane is formed. It acts as a guide for the correct placement of the staging glass.

Clarification of the boundaries consists of eliminating interference with the fixation of the roller on the prosthetic bed. It helps prevent deformation of the upper lip. The technician checks all the boundaries of the template, freeing the frenulum of the tongue, lips, cheeks, pterygomaxillary and lateral folds of the mucosa from it.

The formation of the thickness of the upper bite ridge and vestibular surface is influenced by a number of circumstances.

Atrophy after tooth loss manifests itself differently in different areas. On the lower jaw, for example, the bone decreases first from the lingual surface and the top of the ridge. On the contrary, the bone begins to disappear from the apex and vestibular surface.

At the same time, the alveolar arch narrows, and the conditions for setting teeth worsen significantly. In the anterior section, there is a retraction of the upper lip, as a result of which the face acquires senile features.

The height of the top roller is determined taking into account the following factors. When the jaws are closed, the cutting edges of the upper central incisors coincide with the line of contact of the lips. When speaking, they protrude about 1-2 mm from under the lip. A person looks several years older if the edges of the incisors are not visible when smiling.

The template is inserted into the mouth and the patient is asked to close their lips. A line is drawn on the roller along which the height is set. If the edge of the roller is below the line of contact, it is shortened; if above, it is extended with a strip of wax. Then the height of the roller is checked with the mouth half open. Its edge should protrude 1-2 mm from under the upper lip.

Having determined the height of the roller, the specialist brings the occlusal surface in line with the line of the pupils. For this, two rulers are used. One is installed on the pupillary line, the other on the occlusal plane of the roller. If they are parallel, then all actions were performed correctly.

Lateral sections

As a result of measuring a large number of skulls, it was revealed that the occlusal surface of the lateral teeth is parallel to the Camper horizontal. This is the line of contact between the lower edge of the auditory (external) canal and the nasal spine.

On the face, the horizontal line runs along the nasal line, which connects the base of the wing with the middle of the tragus.

Two rulers are also used to check parallelism.

Adjusting the lower and upper rollers

When fitting, it is important to achieve complete closure of the elements in the anteroposterior and transversal (transverse) directions and the location of the buccal areas in the same plane.

Any adjustments that may be necessary are made on the lower roller only. For well-fitted elements, the surfaces are in close contact along the entire length. When the jaws close, they fit both in the lateral and anterior sections.

First you need to check the contact in the anteroposterior direction. In case of non-simultaneous closure, a displacement of the roller can be noted. All identified deficiencies are eliminated by building up or removing wax in the corresponding sections of the roller.

Transverse direction

At determining the central relationship of the jaws in the patient’s complete absence of teeth It is quite difficult to identify violations of the contact of the occlusal areas of the ridges in the transverse direction.

When closing the mouth, they first lie on the right and then on the left. In some cases, the violation is not noticeable. This is due to the fact that when the rollers are closed, there is no gap between them. This situation, in turn, is due to the fact that the templates sag on one side. Accordingly, a gap is formed between the mucous membrane and the ridges, which is not visible to the specialist.

To detect it, a cold spatula is inserted between the elements. If the fit of the rollers is tight and they lie on the same ridge, it will not be possible to insert the tool without effort.

Determination of interalveolar height: general information

It consists in finding the distance between the processes of the jaws that is most convenient for the work of muscles and joints, ensuring better fixation and operation of the prosthesis. At determining the central relationship of the jaws with complete loss of teeth based on the interalveolar height, facial contours are restored. Thus, the aesthetic part of the issue of prosthetics is also resolved.

Finding the interalveolar height is, in fact, a step in determining the vertical component central relationship of the jaws. Definition distances are currently carried out in two ways: anatomical-functional and anthropometric. Let's take a closer look at them.

Anthropometric method

When using it, the following guidelines are used:

  • line AC is divided by point B in the average and extreme ratio;
  • line ac is divided in the same ratio by point b, and line ac or ab by point d;
  • Frankfurt horizontal - Fe;
  • naso-auricular line - cl e.

Anthropometric method for determining the central ratio jaws is based on information about the proportionality of individual areas of the face.

The German philosopher and poet of the 19th century, Adolf Zeising, in his works developed the law of proportionality of division. He found several points through which the human body is divided according to the “golden section” principle. Finding them involves quite complex mathematical constructions and calculations. The solution of the problem is facilitated by the use of a Heringer compass. This tool automatically determines the desired section point.

Method for determining central occlusion and jaw relationship is as follows. The patient should be asked to open his mouth wide. The extreme leg of the Heringer compass is placed on the tip of the nose, and the second leg is placed on the chin tubercle. The distance between them will be divided by the middle leg in the middle and extreme positions. The larger figure corresponds to the distance between points with adjacent rollers or teeth.

There is another method for determining the central relationship of the jaws - according to Wordsworth-White. It is based on the equality of the distances from the center of the pupils to the line where the lips meet and from the base of the nasal septum to the bottom of the chin.

Alternative

It is worth noting that the above can be used with classical As practice shows, they do not give accurate results, therefore they are used with some restrictions. The anatomical and functional method of determining and fixing the central relationship of the jaws is considered optimal.

Technique of the anatomical-functional method

The patient is involved in a short conversation, which is not related to prosthetics. Upon completion, the lower jaw is brought to a state of rest; The lips usually close freely. In this position, the specialist measures the distance between the marks on the chin and the base of the nasal septum.

Templates with rollers are inserted into the mouth. The patient is asked to close them. The interalveolar height is determined with the central position of the lower jaw. When processing the rollers, the mouth closes and opens repeatedly. As a rule, the patient places the lower jaw in the central position.

After introducing the rollers, the specialist again measures the distance - the occlusal height - between the above points. It should be 2-3 mm less than the resting height.

If the height of the lower third of the face when the ridges are closed and at rest is equal, then the interalveolar distance is increased. If the occlusal height is more than 3 mm below the resting height, the height of the lower ridge should be increased.

After the measurements, the specialist pays attention to the tissues around the mouth. If the interalveolar height is correct, the normal lines of the lower third of the face are restored. If the reading is low, the corners of the mouth will droop, the nasolabial folds will become more pronounced, and the upper lip will become shorter. If such signs are identified, it is necessary to take measurements again.

If the interalveolar height increases, the closure of the lips is accompanied by a certain tension, the nasolabial folds are smoothed out, and the upper lip becomes longer. In such a situation, the following test is very indicative. When you touch the closure line with your fingertip, your lips instantly open, which is not typical for a situation where they fit loosely.

Conversation test

It is considered the second addition to the anatomical technique.

After identifying the interalveolar height, the specialist asks the patient to pronounce individual syllables or letters (f, p, o, m, e, etc.). The doctor monitors the level of separation of the rollers. If the interalveolar height is normal, it is about 5-6 mm. If the distance is greater than 6mm, a reduction in height may be necessary. If it is less than 5 mm, then the height can be increased accordingly.