Dental occlusion treatment. Types of dental occlusion and effective methods of treating pathology

Many patients in dental clinics often do not understand the meaning of certain terms. For example, the concept of “articulation” arose many years ago, but its meaning is still not clear to everyone. Occlusion and bite, as well as articulation, are usually called different states of the masticatory apparatus. Some authors are of the opinion that occlusion is a kind of derivative of articulation. The term “occlusion” has something similar to the occlusion of teeth, it implies the relationship of closed dentition.

Articulation and occlusion - what is it?

Occlusion of teeth in dentistry is considered to be the careful abutment of the molars and premolars of the dental arches at physiological rest or during chewing. Correct occlusion of teeth can be considered long-term and high-quality work of the dental system with correct facial features. The contact of the cutting surfaces of the incisal groups of the teeth of both jaws contributes to the formation of direct occlusion, but the main signs of articulation are any movement of the jaw during speaking, swallowing, singing.

Occlusion and functioning occlusion have a close relationship in dental practice. Genetics influences the correct eruption of teeth, the formation of the condition of the jaws relative to each other and the quality of central occlusion. The absence of a burdened heredity in relatives does not negate the mandatory monitoring of the formation of the primary occlusion. Reasons contributing to the pathological formation of bite:

• long-term use of pacifiers;
• diseases of the retropharyngeal space;
• finger sucking.

From the age of three, a child develops swallowing skills. The presence of problems in the tonsils, adenoids, and sinuses contribute to the acquisition of pathological swallowing skills by the age of four. This, in turn, contributes to the formation of dental occlusion anomalies. It is important not to miss the moment and go for a consultation with the orthodontist on time. The specialist will determine the causative factors and prevent the development of the anomaly. In the early stages, the pathology of the development of the dental system is determined visually by the doctor. You should listen to your dentist's recommendations. The sooner the problem is identified, the more successful the treatment will be. Impaired jaw movement and chewing surface contacts have a negative impact on the process of eating and digesting food.

Some scientists are inclined to believe that jaw contact and jaw movements are closely related. These processes combine the work of both jaws relative to each other, the masticatory apparatus and joints.

Types of occlusion

The main development of the dental system occurs between four and six years of age. At this time, speech, eating and swallowing skills are developing, and the sacs of the eighth tooth buds are maturing. Development ends by the age of sixteen.

Dentists identify temporary closure of teeth during chewing and physiological rest. The types of occlusions are determined by the specifics of muscle contractions and joint movements. The classification is based on the motor function of the movable jaw.

The following types are distinguished:

• lateral occlusion is formed by shifting the dental arches to the left or right relative to each other;
• central occlusion - the contact surfaces of both dental arches are in contact with the opposing teeth at rest;
• anterior occlusion - the protruding lower jaw promotes close contact of the incisors of both jaws without movement.

It is easy to prevent the development of pathological closure of teeth in children with central occlusion if deficiencies are detected in a timely manner. The orthodontist will help the child acquire the correct skills to speak, eat and swallow.

Correct closure occurs in people with central occlusion with a specific location for each member of the dental arch. The contact of dental crowns and their motor function are combined in one dentofacial system.

Central

Central occlusion is identified when there is closure of the dental arches with the largest number of tubercles without jaw movement. The vertical facial line is located along the dividing line between the central incisors of both jaws. The muscles of the facial area contract synchronously. The joint at rest is determined without pathology.

Determination of central occlusion is carried out according to the following criteria:

The main indicator of the central state of rest is the close contact of the dental arches along the antagonistic tubercles. Central occlusion does not exist in the edentulous mouth, but there is central balance, the location of one object in relation to another. We are talking about the relationship of the jaws to each other. There may be no centric occlusion in centric relation

In centric relation there is no jaw contact because there are no teeth. The central ratio is constant for every person and does not change throughout life. Central occlusion can be restored during prosthetics using the central relationship of the jaws.

Front

This occlusion is very different from the central one. The closure of the frontal group of teeth in physiological rest occurs when the body of the jaw moves forward. The movable part of the joint is pushed forward - this is the main sign of anterior occlusion.

Characteristic dental contacts of anterior occlusion:

• the median facial line is aligned with the separation between the anterior incisors;
• characterized by contact between the cutting surfaces of the incisors in the frontal area;
• There are diamond-shaped spaces along the closure line.

Lateral

The lateral relationship of the dental arches occurs when the movable jaw moves to the side. Circular movements occur in the joint, which are not typical for central occlusion.

Characteristic conditions of lateral relation teeth:

• displacement of the midline of the face;
• contact points are formed by tubercles of the same name on the side of displacement and opposite ones on the opposite side when the dentofacial system is without movement.

Types of physiological occlusion

In dentistry, there are different types of occlusions that guarantee normal functioning of the oral cavity. The same applies to the bite. Any type of physiological bite preserves articulation, the process of chewing food, the oval of the face has the correct shape and smile.

It is customary to distinguish the following types of physiological occlusion:

• Orthognathic occlusion is characterized by careful contact of each crown of the upper tooth with the antagonist below. At rest, there are no gaps at the points of contact of the teeth. The upper incisal group covers the lower incisal group by a third of the tooth body.
• A progenic bite is formed by moving the movable jaw forward. The physiology of the joint is preserved.
• Direct bite or direct occlusion is distinguished by the contact of the cutting edges of the incisal groups of both jaws. Straight is when the dental arch of each plane runs parallel. This arrangement of the dentition is considered normal, but direct occlusion contributes to the development of pathological abrasion.
• Biprognathic bite is characterized by protrusion of the incisal groups of both jaws towards the vestibular surface. This advancement of the front teeth preserves the qualitative relationship of the chewing surfaces.

Malocclusion

There are quite a few cases of direct occlusion, but occlusion with changes in the classic closure of teeth is not uncommon. Types of abnormal bite:
(we recommend reading: treatment of mesial bite)

The beauty of our smile depends on the health of our teeth. This is an important part, but it is not enough. Even healthy teeth can be placed incorrectly in the mouth, resulting in a malocclusion. The upper and lower jaws, namely the movement of the latter, are involved in the process of human life. Chewing, swallowing, pronouncing sounds - all this is impossible without its normal functioning. The first and last action has its own peculiarity, which is directly related to the correct closure of the teeth of the upper and lower jaw. This phenomenon is called occlusion.

Occlusion of teeth

What is occlusion?

This Latin name means closing, clutch. Occlusion in dentistry refers to the work of the upper and lower jaws and their connection. Familiar for the common man. But it's not exactly the same thing. The concepts of functional occlusion intersect with each other in dental practice. The development of bite and occlusion depends on genetic predisposition. If such developmental anomalies are not observed in close blood relatives, then parents need to monitor their child during the development of dentition, and prevent the development of bad habits. Factors contributing to abnormal development of the jaw cannot be ignored. These include:

• prolonged sucking of a pacifier by a child;
• diseases of the nasopharynx;
• habit of thumb sucking.

Quite often, at the age of 4 years, a child develops the skills of improper swallowing. Dentists often associate such changes with various diseases of the upper respiratory tract. Such an incorrectly formed reflex leads to the development of incorrect occlusion. If changes are noticed, you should immediately consult a doctor. He will find out the reason and prevent abnormal development.

The dentist notices it in the early stages of its development. Prescribed treatment should be started as soon as possible. Eliminating initial changes in occlusion is very important, since improper contact of the teeth of the upper and lower jaw affects the chewing process.

Dentists often argue over the definitions of articulation and occlusion. The question is controversial. Some argue that articulation represents the process of rows touching during talking, chewing and other actions. And occlusion, in their opinion, is the position of the jaws at rest.

Another opinion speaks about the relationship of concepts. So, in their opinion, articulation is the main concept, and bite occlusion is its manifestation. But everyone agrees on one thing: the processes represent the interconnection of the rows of the upper and lower jaws, facial muscles, and joints.

Types of occlusion

The dental system is fully formed by the age of 16. But its main formation is associated with the period between 4-6 years of the baby’s life. It is during this period that the child develops the functions of chewing, speaking, and swallowing. The rudiments of the third molar are actively developing. Therefore, it is very important to monitor the development and, if necessary, prescribe treatment for occlusion in a timely manner. Avoid developing childhood bad oral habits. In the process of development in dentistry, temporary and permanent occlusion of teeth is distinguished.

Temporary

There is also another gradation of types of occlusion. Each of them has its own set of characteristics. Types of occlusion are determined by the characteristics of the jaw muscles and joints. Usually the work of the lower jaw is taken into account.

1. Central occlusion. The muscle groups that are responsible for the closure and position of the jaw bones are working correctly. Their actions are coordinated, uniform and smooth. Central occlusion and the central relationship of the jaws determine the arrangement of rows in the oral cavity. The connection of teeth occurs with the maximum number of contacts. The head and tubercle of the joint are characterized by close proximity to each other. Characteristically, the head of the lower jaw is close to the articular tubercle.
2. Anterior occlusion involves the coincidence of the position of the incisors in such a way that coincides with the central facial line. Characterized by visual pushing forward of the lower jaw. This occurs due to the work of the pterygoid muscles. The front teeth are in close contact with the cutting edges. There is a tubercular contact of the dentition. In anterior occlusion, normal occlusion is common. Its main difference from the central one is the close location of the head of the lower jaw to the articular tubercles and its displacement forward.
3. Distal occlusion. It is characterized by the position of the rows, in which visually the upper jaw looks larger than the lower jaw. This is an anomaly in many cases. There is underdevelopment of the lower jaw. The nose visually enlarges, the lips do not close, and a chin fold is noticeable. There are two subtypes of such occlusion of the dentition: dentoalveolar and skeletal.
4. Lateral occlusion of the jaw. Divided into right and left. Judging by the name, it is clear that this form of the disease is characterized by the lower jaw moving to one side. When the lower row is shifted to the right or left, they contact the same area of ​​the upper jaw. The head of the jaw is mobile, does not stay at the base of the joint on one side, and moves upward on the other. This violation of occlusion is accompanied by compression of the pterygoid lateral muscle. The center line of the face and front incisors shifts to one side.
5. Deep incisive occlusion has two degrees of developmental anomaly. The first is characterized by cutting-tubercular contact between the incisors of the jaws. Deep incisal occlusion in the second stage is marked by a clear lack of contact between these teeth.

Deep bite

Improper formation of the dentofacial system is diagnosed in early childhood, so it is possible to identify the defect and correct it even at the developmental stage. This will allow the child to develop the correct skills of swallowing, chewing, and speaking.

Correct implies the contact of the top and bottom rows. Bite is directly related to occlusion. The upper incisors cover the lower ones. The lateral bite shifts the row to the side. Often this goes together with lateral occlusion. They also observe if there is an oblique bite. If correct, the arrangement of teeth in a row corresponds to each other. There are different types of bites in dentistry: physiological and pathological groups.

Straight bite

It belongs to the physiological group. This is a kind of direct occlusion, when the incisors take a position of being on top of each other. This leads to rapid wear of the enamel and gradual tooth destruction. With a correct bite, the teeth overlap each other and the upper ones cover the lower ones by 1/3 of the visible part.

Pathological abrasion in a direct bite does not occur immediately; it takes a long time for a person to notice it. But with such an anomaly there are a number of side defects:

• reduction of a third of the lower part of the face;
• incorrect or incomplete functioning of the temporal mandibular joint;
• violation of diction.

Treatment is determined by the dentist together with the orthopedist. Mostly, non-advanced stages of direct bite are easily corrected in childhood by installing braces.

Physiological or correct bite

This is a variation of the natural proportion of the rows of the upper and lower jaws. It provides:

• absence of chewing and speech dysfunction;
• regular features of the lower part of the head;
• healthy condition of teeth and periodontium;
• full functioning of the jaw system.

Correct bite

Physiological occlusion has subtypes that differ in certain deviations from the norm, but are characterized by the physiological occlusal relationship of the upper and lower jaw. These include bites:

• progenic;
• bioprogenic;
• orthognastic;
• straight bite.

The last two subspecies are considered in dentistry to be the closest deviations from the norm. Therefore, often a dentist, after examining the oral cavity, may not prescribe treatment, since minor discrepancies with the norm are not a problem and do not require a solution.

Deep bite

It has a pronounced visual defect when the upper row of teeth overlaps the lower row by more than half of the crown. A deep bite makes it difficult to bite and chew food. The oral cavity becomes smaller, leading to difficulty swallowing.

This type of bite leads to abrasion of the upper row of teeth, since they are subject to a large load during eating. The work of the temporomandibular joint also changes. When the jaw moves, characteristic clicks appear in it. Frequent headaches are noticed.

But the most common negative consequences of an incorrect deep bite is injury to the oral mucosa. Such pathological changes often lead to inflammation of the gums, which leads to tooth loss.

We should not forget that it is easier to correct occlusion while the jawbone is forming. Therefore, it is important that diagnosis occurs on time and timely treatment gives positive results. Dentistry today has a lot of tools and techniques that are used with one goal, to make your smile healthy.

Transverse occlusal curves.

For orthopedic purposes, two main conditions are distinguished from the complex biodynamics of occlusion: articulation and occlusion. The most common definition of articulation is given by A.Ya. Katz, namely these are all possible positions and movements of the lower jaw in relation to the upper jaw, carried out through the masticatory muscles. This definition includes not only the chewing movements of the lower jaw, but also its movements during speaking, singing, etc., as well as various types of closure, that is, occlusion.

Occlusion is understood as a particular type of articulation, meaning the position of the lower jaw in which a certain number of teeth are in contact, that is, in closure. There are 4 main types of occlusion: 1) central; 2) front; 3) left side; 4) right lateral.

The nature of the closure of the dentition in the position of central occlusion is called occlusion. Most authors divide all types of bites into physiological and pathological.

Physiological ones include occlusions that provide full function of chewing, speech and aesthetic optimum. Pathological are those types of closure of the dentition in which the functions of chewing, speech or the appearance of a person are disrupted. These also include abnormal bites, which V.Yu. Kurlyandsky identifies bites as a separate, third group.

The division of occlusions into physiological and pathological is to a certain extent arbitrary, because a normal occlusion under certain conditions, for example, with periodontal diseases or the loss of individual teeth and their movement, can become pathological.

Physiological bites include: orthognathic (psalidodont, i.e. scissor-shaped), straight (labiodont, i.e. pincer-shaped), biprognathic (when the front teeth of both jaws, together with the alveolar ridges, are inclined anteriorly), opistognathic (when the front teeth together with the alveolar the ridges of both jaws are directed posteriorly).

The most common among Europeans (75–80%) is orthognathic occlusion. It is characterized by certain signs of central occlusion, some of which apply to all teeth, others only to the front or chewing teeth, and others to the joint and muscles.

Signs of central occlusion in orthognathic occlusion. The upper dentition has the shape of a semi-ellipse, the lower - a parabola.

The buccal cusps of the upper small and large molars are located outward from the same cusps of the lower premolars and molars. Thanks to this, the palatal cusps of the upper teeth fall into the longitudinal grooves of the lower ones, and the buccal cusps of the lower teeth of the same name - into the longitudinal grooves of the upper ones.

The overlap of the lower anterior and lateral teeth with the upper ones is explained by the fact that the upper dental arch is wider than the lower one. Due to this, the range of lateral movements of the lower jaw increases.

Each tooth, as a rule, intersects with two antagonists - the main and the secondary. Each upper tooth intersects with the lower tooth of the same name and behind, each lower tooth with the same upper and in front. The exception is the wisdom tooth of the upper jaw and the lower central incisor, which each have one antagonist. This feature of the relationship between the lower and upper teeth is explained by the fact that the upper central incisors are wider than the lower central incisors. For this reason, the upper teeth are displaced distally in relation to the teeth of the lower row. The upper wisdom tooth is narrower than the lower one, so the distal displacement of the upper dentition is aligned in the area of ​​the wisdom teeth and their posterior surfaces lie in the same plane.

The midlines passing between the central incisors of the upper and lower jaws lie in the same sagittal plane. This ensures an aesthetic optimum. Violation of symmetry makes a smile unattractive.

The upper front teeth overlap the lower teeth by approximately one-third of the crown height. The lower front teeth, with their cutting edges, contact the dental cusp of the upper teeth (incisal cusp contact).

The anterior buccal cusp of the upper first molar is located on the buccal side of the lower molar of the same name in its transverse groove, between the buccal cusps. The posterior buccal cusp of the first upper molar is located between the posterior buccal cusp of the lower molar of the same name and the anterior buccal cusp of the second lower molar. This position of the cusps of the molars of the upper and lower jaws is often called the mesiodistal relationship.

The mandibular head is located at the base of the posterior slope of the articular tubercle.

The muscles that lift the mandible are in a state of uniform contraction.

The initial position of the lower jaw when opening the mouth is central occlusion, or there may be a condition when the lips are closed and the lower jaw droops somewhat. At the same time, there is a gap of 2–4 between the dental rows (it is called the interocclusal space), that is, this position is characteristic of a state of relative physiological rest. In this case, the chewing muscles are in a state of minimal or, more correctly, optimal tone, that is, the muscles are resting. The vertical size of the lower third of the face is constant for each person and it is greater than that with central occlusion or the so-called occlusal height.

The interocclusal space is clinically defined as the difference between the resting height and the occlusal height using the same arbitrary points on the face. These points are chosen randomly.

The interocclusal space varies on average from 2 to 4 mm. However, in individuals it can vary from 1.5 to 7 mm. The clinical resting position changes throughout life as a result of tooth extraction and changes in occlusion.

With the voluntary closing movement of the lower jaw from a resting position, it moves directly to the position of central occlusion.

A state of relative physiological rest is one of the articulatory positions of the lower jaw with minimal activity of the masticatory muscles and complete relaxation of the facial muscles. The tone of the muscles that raise and lower the lower jaw is equal.

In diagnostic terms, it is advisable to consider the biomechanics of the lower jaw during meals and specify the relationship between the dentition and the elements of the temporomandibular joints. First, the visual and olfactory analyzers and the memory apparatus come into play. Based on the analysis of food, the trigger mechanism for the activity of the salivary glands and muscular system is activated, i.e. the optimal program of action is selected. The secretion of saliva makes it necessary to swallow it. At the same time, thanks to the contractile activity of the muscles, the lower jaw moves from a state of physiological rest to the central occlusal position, after which swallowing occurs. The closure of the dentition during swallowing is accompanied by a significant increase in the tone of the masticatory muscles and a certain force of jaw compression.

The lowering of the lower jaw occurs due to its heaviness and as a result of contraction of the muscles m. mylohyoideus, m. geniohyoideus, m. digastricus.

Vertical movements of the lower jaw correspond to the opening and closing of the mouth. It is typical for opening the mouth and introducing food into the mouth that at this moment the selected optimal action option is triggered, depending on the visual analysis of the nature of the food and the size of the food bolus. So, a sandwich, seeds are placed in the incisor group, fruits, meat - closer to the canine, nuts - to the premolars.

Thus, when the mouth opens, a spatial displacement of the entire lower jaw occurs.

Depending on the amplitude of mouth opening, one or another movement predominates. With slight opening of the mouth (whispering, quiet speech, drinking), rotation of the head around the transverse axis in the lower part of the joint predominates; with a more significant opening of the mouth (loud speech, biting food), the rotational movement is joined by the sliding of the head and disc along the slope of the articular tubercle down and forward. With maximum mouth opening, the articular discs and mandibular heads are installed on the tops of the articular tubercles. Further movement of the articular heads is delayed by the tension of the muscular and ligamentous apparatus, and again only rotational or hinge movement remains.

The movement of the articular heads when opening the mouth can be observed by placing the fingers in front of the tragus of the ear or inserting them into the external auditory canal. The amplitude of mouth opening is strictly individual. On average, it is 4–5 cm. The dentition of the lower jaw describes a curve when opening the mouth, the center of which lies in the middle of the articular head. Each tooth describes a certain curve.

Sagittal movements of the lower jaw. The forward movement of the lower jaw is carried out mainly due to bilateral contraction of the lateral pterygoid muscles and can be divided into two phases: in the first, the disk together with the head of the lower jaw slides along the articular surface of the tubercle, and then in the second phase, a hinge movement is added around the transverse axis passing through the heads. This movement occurs simultaneously in both joints.

The distance that the articular head travels is called the sagittal articular path. This path is characterized by a certain angle, which is formed by the intersection of a line that is a continuation of the sagittal articular path with the occlusal (prosthetic) plane. The latter is understood as a plane passing through the cutting edges of the first incisors of the lower jaw and the distal buccal cusps of the last molars. The angle of the sagittal articular path is individual and ranges from 20 to 40°, but its average value, according to Gysi, is 33°.

This combined pattern of movement of the lower jaw is found only in humans. The magnitude of the angle depends on the inclination, the degree of development of the articular tubercle and the amount of overlap by the upper anterior teeth of the lower anterior teeth. With deep overlap, rotation of the head will predominate; with small overlap, sliding will prevail. With a direct bite, the movements will be mainly sliding. Moving the lower jaw forward with an orthognathic bite is possible if the incisors of the lower jaw come out of the overlap, that is, the lowering of the lower jaw must first occur. This movement is accompanied by sliding of the lower incisors along the palatal surface of the upper ones until direct closure, that is, until anterior occlusion. The path taken by the lower incisors is called the sagittal incisal path. When it intersects with the occlusal (prosthetic) plane, an angle is formed, which is called the angle of the sagittal incisal path.

It is also strictly individual, but according to Gisi, it is in the range of 40–50°. Since during movement the mandibular articular head slides down and forward, the back part of the lower jaw naturally moves down and forward by the amount of incisal sliding. Consequently, when lowering the lower jaw, a distance between the chewing teeth should be formed equal to the amount of incisal overlap. However, normally it does not form and contact remains between the chewing teeth. This is possible due to the arrangement of the chewing teeth along a sagittal curve, called the Spee occlusal curve. Many people call it compensation.

The surface passing through the chewing areas and cutting edges of the teeth is called occlusal. In the area of ​​the lateral teeth, the occlusal surface has a curvature, its convexity directed downwards and called the sagittal occlusal curve. The occlusal curve is clearly visible after the eruption of all permanent teeth. It begins on the posterior contact surface of the first premolar and ends on the distal buccal cusp of the wisdom tooth. In practice, it is set according to the level of overlap of the lower buccal cusps with the upper ones.

There is significant disagreement regarding the origin of the sagittal occlusal curve. Gysi and Schroder associate its development with anteroposterior movements of the lower jaw. In their opinion, the appearance of curvature of the occlusal surface is associated with the functional adaptability of the dentition. The mechanism of this phenomenon was presented in the following form. When the lower jaw moves forward, its posterior part descends and a gap should appear between the last molars of the upper and lower jaws. Due to the presence of the sagittal curve, this gap closes (compensates) when the lower jaw moves forward. For this reason, they called this curve compensation.

In addition to the sagittal curve, there is a transversal curve. It passes through the chewing surfaces of the molars of the right and left sides in the transverse direction. The different levels of location of the buccal and palatal cusps due to the inclination of the teeth towards the cheek determine the presence of lateral (transversal) occlusal curves - Wilson curves with a different radius of curvature for each symmetrical pair of teeth. This curve is absent in the first premolars.

The sagittal curve ensures, when the lower jaw moves forward, contacts of the dentition at at least three points: between the incisors, between individual chewing teeth on the right and left sides. This phenomenon was first noted by Bonvill and in the literature is called Bonvill's three-point contact. In the absence of a curve, the chewing teeth do not contact and a wedge-shaped gap forms between them.

After biting, the food bolus, under the action of the contracting muscles of the tongue, gradually moves to the fangs, premolars, and molars. This movement is carried out by vertical displacement of the lower jaw from the position of central occlusion through indirect occlusion again to the central one. Gradually, the food bolus is separated into parts - the phase of crushing and grinding food. Food bolus moves from molars to premolars and back.

Lateral or transversal movements of the lower jaw are carried out mainly due to the contraction of the external pterygoid muscle on the side opposite to the movement and the anterior horizontal bundle of the temporal muscle on the side of the same name as the movement. The contraction of these muscles alternately on one side and the other creates lateral movements of the lower jaw, facilitating the rubbing of food between the chewing surfaces of the molars. On the contracted side of the human external pterygoid muscle (balancing side), the mandible moves down and forward and then deviates inward, that is, it follows a certain path called the lateral articular path. When the head deviates towards the middle, an angle is formed in relation to the original direction of movement. The apex of the angle will be on the articular head. This angle was first described by Benet and named after him; the average angle is 15–17°.

On the other side (working side), the head, remaining in the articular cavity, makes rotational movements around its vertical axis.

The articular head on the working side, performing a rotational movement around the vertical axis, remains in the fossa. During the rotational movement, the outer pole of the head moves posteriorly and can put pressure on the tissues behind the joint. The internal pole of the head moves along the distal slope of the articular tubercle, which causes uneven pressure on the disc.

During lateral movements, the lower jaw moves to the side: first to one, then through the central occlusion to the other. If we graphically depict these movements of the teeth, then the intersection of the lateral (transversal) incisal path when moving from right to left and vice versa forms an angle called the angle of the transversal incisal path or the Gothic angle.

This angle determines the range of lateral movements of the incisors; its value is 100–110. Thus, during lateral movement of the lower jaw, the Benet angle is the smallest, and the Gothic angle is the largest, and any point located on the remaining teeth between these two extreme values ​​moves with an angle of more than 15–17°, but less than 100–110°.

Of significant interest to orthopedists are the relationships between chewing teeth during lateral movements of the lower jaw. A person, having taken food into his mouth and bitten off, uses his tongue to move it to the area of ​​\u200b\u200bthe lateral teeth, while the cheeks are somewhat drawn inward, and the food is pushed between the lateral teeth. It is customary to distinguish between the working and balancing sides. On the working side, the teeth are set with cusps of the same name, and on the balancing side - with opposite cusps.

All chewing movements are very complex; they are carried out by the joint work of various muscles. When chewing food, the lower jaw describes an approximately closed cycle, in which certain phases can be distinguished.

From the position of central occlusion, the mouth first opens slightly, the lower jaw moves down and forward; continued opening of the mouth is a transition to lateral movement in the direction opposite to the contracted muscle. In the next phase, the lower jaw rises and the buccal cusps of the lower teeth on the same side meet the same cusps of the upper teeth, forming the working side. The food located between the teeth at this time is compressed, and when returned to the central occlusion and shifted to the other side, it is ground. On the opposite side, the teeth meet with opposite cusps. This phase is quickly followed by the next one, and the teeth slide into their original position, that is, into central occlusion. With these alternating movements, food is rubbed together.

The relationship between the sagittal incisal and articular tracts and the nature of occlusion has been studied by many authors. Bonneville, based on his research, derived the laws that were the basis for the construction of anatomical articulators.

The most important laws:

1) an equilateral Bonneville triangle with a side equal to 10 cm;

2) the nature of the cusps of the chewing teeth is directly dependent on the size of the incisal overlap;

3) the line of closure of the lateral teeth is curved in the sagittal direction;

4) when moving the lower jaw to the side on the working side - closure with the same tubercles, on the balancing side - with opposite ones. American mechanical engineer Hanau in 1925–26. expanded and deepened these provisions, substantiating them biologically and emphasizing the natural, directly proportional connection between the elements: 1) the sagittal articular path; 2) incisal overlap; 3) the height of the masticatory cusps, 4) the severity of the curve of Spee; 5) occlusal plane. This complex entered the literature under the name of the articulatory five of Hanau.

The patterns established by Hanau in the form of the so-called “Hanau Five” can be expressed in the form of the following formula.

Five Hanau:

Y – inclination of the sagittal articular path;

S – sagittal incisal path;

H – height of masticatory cusps;

OS – occlusal plane;

OK – occlusal curve.

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.

This term originates from Latin and means “closure.”

Central occlusion is a state of evenly distributed tension of the jaw muscles, while ensuring simultaneous contact of all surfaces of the elements of the dentition.

The need to determine central occlusion is to correctly manufacture a partial or removable denture.

Main features

Experts have determined the following indicators of central occlusion:

1. Muscular. Synchronous, normal contraction of the muscles responsible for the functioning of the lower jaw bone.
2. Articular. The surfaces of the articular heads of the lower jaw are located directly at the bases of the slopes of the articular tubercles, in the depths of the articular fossa.
3. Dental:

• full surface contact;
• opposite rows are brought together so that each unit is in contact with the same and the next element;
• the direction of the upper frontal incisors and the similar direction of the lower ones lie in a single sagittal plane;
• the overlap of the elements of the upper row of fragments of the lower one in the front part is 30% of the length;
• the anterior units contact in such a way that the edges of the lower fragments abut the palatine tubercles of the upper ones;
• the upper molar comes into contact with the lower one so that two-thirds of its area is combined with the first, and the rest with the second;

If we consider the transverse direction of the rows, then their buccal tubercles overlap, while the tubercles on the palate are oriented longitudinally, in the fissure between the buccal and lingual of the lower row.

Signs of correct row contact

• the rows converge in a single vertical plane;
• incisors and molars of both rows have a pair of antagonists;
• there is contact between units of the same name;
• the lower incisors do not have antagonists in the central part;
• the upper eighths have no antagonists.

Applies to anterior units only:

• if we conditionally divide the patient’s face into two symmetrical parts, then the line of symmetry should pass between the front elements of both rows;
• the upper row of fragments overlaps the lower one in the anterior zone to a height of 30% of the total crown size;
• the cutting edges of the lower units are in contact with the tubercles of the inner part of the upper ones.

Applies only to lateral ones:

• the buccal distal cusp of the upper row is based in the space between the 6th and 7th molars of the lower row;
• the lateral elements of the upper row close with the lower ones in such a way that they fall strictly into the intertubercular grooves.

Methods used

Central occlusion is determined at the stage of manufacturing prosthetic structures when several units are lost.

In this case, the height of the lower third of the face is of great importance. However, in the absence of a large number of units, this indicator may be violated and must be restored.

If the patient has partial adentia, several options for determining the indicator are used.

The presence of antagonists on both sides

The method is used when antagonists are present in all functional areas of the jaws.

In the presence of a large number of antagonists, the height of the lower third of the face is maintained and fixed.

The occlusion index is determined based on as many contact zones as possible of the same units of the upper and lower rows.

This option is the simplest, since it does not require the additional use of occlusal ridges or specialized orthopedic templates.

Presence of three occlusion points between antagonists

This method is used if the patient still has antagonists in the three main contact zones of the rows. At the same time, the small number of antagonists does not allow normal positioning of plaster casts of the jaw in the articulator.

In this case, the natural height of the lower third of the face is disrupted, and occlusal ridges made of wax or thermoplastic polymer are used to correctly match the casts.

The roller is placed on the bottom row, after which the patient brings his jaw together. After the roller is removed from the oral cavity, imprints of the antagonist contact zones remain on it.

These prints are subsequently used by technicians in the laboratory to position the casts and create a fully functional and correct, from an orthopedic point of view, prosthesis.

Absence of antagonistic pairs

The most labor-intensive scenario is the complete absence of the same elements on both jaws.

In this situation, instead of the position of central occlusion determine the central relationship of the jaws.

The procedure includes the following steps:

1. Work on the formation of a prosthetic plane, which is positioned along the chewing surfaces of the lateral units and is parallel to the beam. It is built from the lower point of the nasal septum to the upper edges of the ear canals.
2. Determination of the normal height of the lower third of the face.
3. Fixing the mesiodistal relationship of the upper and lower jaw due to wax or polymer bases with occlusal ridges.

Checking central occlusion with existing pairs of elements of the same name is carried out by closing the teeth and is carried out as follows:

• a thin strip of wax is placed on the already prepared and fitted contact surface of the occlusal roller and glued;
• the resulting structure is heated until the wax softens;
• heated templates are placed in the patient’s oral cavity;
• After bringing the jaws together, the teeth leave imprints on the wax strip.

It is these fingerprints that are used in the process of modeling central occlusion in the laboratory.

If, during the process of determining occlusion, the surfaces of the upper and lower rollers close, the specialist adjusts their contact surfaces.

Wedge-shaped cuts are made on the upper one, and a certain amount of material is cut off from the lower one, after which a wax strip is glued to the treated surface. After the rows are brought together again, the strip material is pressed into the cutouts.

The products are removed from the patient’s mouth and sent to the laboratory for subsequent production of a prosthesis.

Calculations for orthopedic purposes

In the process of creating prosthetic structures for malocclusion, an orthopedic specialist takes measurements of the heights of the lower third of the patient’s face using an anatomical and physiological method.

To do this, the height of the bite is measured in a state of complete reduction of the jaws, with central occlusion and in a state of physiological rest.

Payment procedure:

1. At the bottom of the nose, at the level of the nasal septum, the first mark is placed strictly in the center. In some cases, the specialist places a mark on the tip of the patient's nose.
2. In the center of the chin, a second mark is placed in its lower zone.
3. Measurement is taken between the applied marks heights in the state of central occlusion of the jaws. To do this, bases with bite ridges are placed in the patient’s oral cavity.
4. Re-measuring between marks is performed, but already in a state of physiological rest of the lower jaw. To do this, the specialist must distract the patient so that he really relaxes. In some cases, the patient is offered a glass of water. After a few sips, the muscles of the lower jaw really relax.
5. The results are recorded. However, the standardized indicator of normal bite height, which is 2-3 mm, is subtracted from the height at rest. And if after this the indicators are equal, we can talk about normal bite height.

If, when measuring the height based on the calculation results, a negative result is obtained - the lower third of the patient's face is understated. Accordingly, if the result deviates in a positive direction - overbite.

Techniques for correct positioning of the lower jaw

Correct positioning of the patient's jaw in the position of central occlusion involves the use of two methods of placement: functional and instrumental.

The main condition for correct placement is muscle relaxation of the jaw muscles.

Functional

The procedure for carrying out this method is as follows:

• the patient moves his head back slightly until the neck muscles tense, which prevents protrusion of the jaw;
• touches the tongue to the back of the palate, as close to the throat as possible;
• at this time, the specialist places his index fingers on the patient’s teeth, lightly pressing on them and at the same time slightly moving the corners of the mouth in different directions;
• the patient imitates swallowing food, which in almost 100% of cases leads to muscle relaxation and prevents jaw protrusion;
• When bringing the jaws together, the specialist touches the surfaces of the teeth and holds the corners of the mouth until it is completely closed.

In some cases, the procedure is repeated several times until complete muscle relaxation and correct reduction of both rows are achieved.

Instrumental

It is performed using specialized devices that copy jaw movements. It is used only in extremely serious situations, when bite deviations are significant and it is necessary to correct the position of the jaw using the physical efforts of a specialist.

Most often, when carrying out this method Larin apparatus is used and special orthopedic rulers that allow you to record jaw movements in several planes.

Errors allowed

Creating a prosthetic structure in conditions of malocclusion is a most complex orthopedic procedure, the quality of which depends 100% on the qualifications of the specialist and a responsible approach to work.

Violations in determining the position of central occlusion can lead to the following problems:

The bite is too high

• The folds of the face are smoothed, the relief of the nasolabial zone is poorly defined;
• the patient's face looks surprised;
• the patient feels tension when closing the mouth, while closing the lips;
• the patient feels that during communication the teeth are knocking against each other.

Low bite

• The folds of the face are strongly pronounced, especially in the chin area;
• the lower third of the face visually becomes smaller;
• the patient becomes like an elderly person;
• the corners of the mouth are lowered;
• lips sink;
• uncontrolled salivation.

Permanent anterior occlusion

• There is a noticeable gap between the front incisors;
• the lateral elements do not contact normally, tubercular reduction does not occur.

Permanent lateral occlusion

• Overbite;
• clearance on the offset side;
• shifting the bottom row to the side.

Reasons for such problems

1. Incorrect preparation of wax templates.
2. Insufficient softening of the material for taking impressions and impressions.
3. Violation of the integrity of wax forms due to their premature removal from the oral cavity.
4. Excessive jaw pressure on the ridges during impression taking.
5. Errors and violations on the part of the specialist.
6. Errors in the work of the technician.

The video provides additional information on the topic of the article.

conclusions

The procedure for determining the position of the central occlusion is only one stage of a complex and lengthy procedure for creating a prosthetic structure for the patient. But this stage can confidently be called the most significant and responsible.

The comfort of further use of the product by the patient and the absence of problems with the temporomandibular joint depend on the qualifications, professionalism and experience of the orthopedic specialist.

After all, various disorders in its work, although treatable, take a significant period of time, causing discomfort, pain and inconvenience to the patient.

Take care of your teeth, seek timely help from the dentist's office to maintain the health of your mouth and dentition for many years. In addition, taking care of your teeth and gums will help you avoid such unpleasant procedures described in our article.

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