BITE (occlusio) — interposition top and bottom dentitions (teeth) at the fullest smykaniye of teeth antagonists. The item is of great importance for process of chewing, a cut it is almost impossible without smykaniye of teeth. Therefore for normal P.'s providing, it is necessary to watch its correct development, preservation of a complete set of healthy teeth, and in case of their loss to replace the absent teeth with full-fledged prostheses (see. Dentures ).
The mandible which is movably connected to a base of skull by means of a temporal and mandibular joint (see. Jaws ), can move in the vertical, sagittal and transverzalny directions. All movements of a mandible make an articulation, any smykaniye of teeth at the same time is called occlusion (see. Articulation of teeth ). During a nibble and chewing of food teeth are closed at various provisions of a mandible, at the same time alternate vertical (central), sagittal (lobbies) and transverzalny (side) occlusions (see. Chewing ).
Central occlusion is the initial and final provision for all chewing movements of a mandible. At the central occlusion the line passing between the central cutters top and bottom jaws usually matches a midline of the person, all masseters are strained, and force of reduction of the muscles lifting a mandible prevails, heads of a mandible are symmetrized in mandibular poles, their front surface adjoins (together with joint disks) to the basis of joint hillocks. It is normal concepts P. and the central occlusion match. At the aberrations connected with the shift of a mandible instead of the central occlusion so-called usual occlusion is established, edges it is also characterized by the maximum number of contacts between teeth antagonists at the wrong provision of heads of a mandible.
Sagittal occlusion corresponds to a phase of a nibble of food: side teeth are separated, between them there is a gleam, width to-rogo depends on depth of incisal overlapping; along with contacts on foreteeth contacts can remain on distal hillocks of the last painters (second or third). It is so-called trekhpunktny contact of Bonvill (fig. 1). It should be provided at statement of false teeth on prostheses for toothless jaws.
Transverzalny occlusions (right and left) arise at the chewing movements of a mandible in a phase of a razmelcheniye of food. During the chewing distinguish the service side and opposite to it — balancing. On the service side buccal hillocks of top and bottom side teeth contact, between palatal and lingual hillocks of these teeth the small crack appears (width apprx. 1 mm). Buccal hillocks of the lower teeth are installed on the balancing side against palatal hillocks of teeth antagonists (or mezhbugrovy fissures), but do not contact; the crack between them is more, than on the service side (apprx. 2 mm). Lingual hillocks of the lower teeth and buccal upper teeth remain out of occlusion — «balance».
The surfaces of dentitions contacting at their smykaniye call occlusal. Occlusal surfaces are bent in the sagittal and transverzalny directions that promotes emergence of contacts between teeth at the chewing movements of a mandible, compensating the dissociation of dentitions appearing at the same time.
In prosthetics of the line, to-rymi this curvature (occlusal curves) is designated, are called compensatory. The sagittal occlusal curve is known also as a curve Shpy (fig. 2).
For the purpose of the correct formation of an occlusal surface of dentitions at statement of false teeth the plane which is conditionally located according to the straight lines connecting cutting edges of the lower cutters and distal hillocks of the lower second or third (last) painters at close teeth (fig. 2) is used occlusal (horizontal, protetichesky). In the absence of teeth the arrangement of this plane is defined rather some front signs. P. Camper established that the occlusal plane is parallel to the line connecting a front nasal awn and bottom edge of outside acoustical pass (fig. 2). This line is called a kamperovsky horizontal or the nosoushny line. On a face it is projected from the basis of a wing of a nose to the middle of a trestle of an auricle. The frontal site of the occlusal plane is parallel to the line connecting both pupils at directly looking eyes.
The interocclusal space, in limits to-rogo during chewing movements moves dentition of a mandible concerning dentition of an upper jaw, is called the occlusal field. It is limited at the movements of a mandible to a regional smykaniye of cutters forward, and at lateral motions — contact of buccal hillocks of premolar tooths and painters on the service side.
At the person teeth appear twice, in the put terms and in a certain sequence since 6 months of life (see. Teeth ). In 2,5 years milk P. forms, in 6 years replacement of milk teeth with second teeth begins, and by 13 — 14 years P. Molochny is established constant, replaceable and constant bites have the features.
Milk Item. it is presented by 20 teeth which differ from constants in the size, a form and color. Tooth arches have the form of a semi-circle. A ratio of teeth in milk P. fissure bugrovoye; each tooth, except the lower central cutters and upper second painters, is closed with two teeth antagonists. The cutting hillocks of upper canines get between the lower canines and the first painters; distal surfaces of the second painters completing dentitions are in one vertical plane (fig. 3).
Replaceable Item. it is characterized by existence of at the same time milk and second teeth. In this period most often there are dentoalveolar anomalies therefore children aged from 6 up to 13 years especially need observation of the stomatologist.
Constant Item. includes 32 teeth, including the third painters, or so-called wisdom teeth; the upper tooth arch has the form of a semi-ellipse, lower — parabolas; upper dentition is wider lower thanks to what increase in the area of the occlusal field at the chewing movements of a mandible is provided. Teeth in dentition densely adjoin to each other the side surfaces (contact points); each tooth contacts to two next teeth (except the last painters) and is closed with two antagonists, except for the lower central cutters and upper third painters who have on one antagonist. At a smykaniye of dentitions upper cutters block lower on 1/3 heights of their crowns, cutting edges of the lower cutters lean on tooth hillocks on a palatal (lingual) surface of upper cutters; buccal hillocks of upper side teeth block the corresponding hillocks of the lower teeth; upper canines get at a smykaniye of teeth between the lower canines and the first premolar tooths; mesial and buccal hillocks of upper first painters keep within front grooves between buccal hillocks of the lower first painters. The described signs correspond to orthognathic P. which is considered by many specialists as a standard of norm (fig. 4, a).
To kinds of the normal Item. belong: a physiological prognathism — a moderate vystoyaniye, or antelocation, an upper jaw and a physiological progeny — a moderate vystoyaniye of dentition of a mandible (fig. 4, b) with a structure of face bones, typical for these P. (see. Person ); an orthogenesis, or direct P. — a regional smykaniye of cutters and the hillocks of top and bottom side teeth of the same name (fig. 4, c); a biprognatiya — a simultaneous deviation forward (vestibulyarno) top and bottom foreteeth (fig. 4, d); Opistognatiya — a simultaneous inclination back (orally) top and bottom foreteeth.
In comparison with orthognathic P. other kinds of norm are more inclined to complications. So, the prognathism is often combined with deep P., the progeny — with open P., quite often accompanies an orthogenesis the increased erasability of teeth, the biprognatiya and Opistognatiya contribute to the diseases of a parodont in foreteeth arising under the influence of side load of them at a nibble of food. As a result of the listed and other deviations of P. becomes abnormal, or pathological.
Anomalies of a bite
Anomalies of the Bitecan clinically be shown in the form of deformation of dentitions and their wrong smykaniye in the sagittal, transverzalny and vertical directions.
To sagittal anomalies Items belong disturbances of a smykaniye of dentitions in the perednezadny direction (in relation to the vertical plane): patol. prognathism (prognathic, or distal, P.) and patol. progeny (progenichesky, or mesial, P.). Patol. the prognathism is characterized by more or less considerable vystoyaniye of teeth of an upper jaw, or distal position of teeth of a mandible (fig. 5, a). Different forms of a prognathism are presented in special classifications (see below). At patol. progenies (mesial P.) teeth of a mandible considerably act ahead of teeth of an upper jaw (fig. 5, b). Treat its versions: the true progeny differing in a peculiar structure of face bones and relative increase in the sizes of a mandible; frontal progenies, at a cut are in so-called return P. only cutters, and the forced progeny caused by the mesial shift of a mandible owing to any inconvenience at a smykaniye of teeth. Various combinations of these forms meet. Increase in corners of a mandible and a vystoyaniye of a chin is typical for a true progeny. At a frontal progeny retraction of an upper lip is noticeable. The forced progeny at a smykaniye of teeth gives to the face so-called whimsical expression.
Transverzalny anomalies of the Item. define in relation to the sagittal plane. They are observed at unilateral or bilateral narrowing or expansion of dentitions or laterposition of a mandible, and also at their combination. Kinds of cross P. which can be unilateral when there is a unilateral return (atypical) smykaniye of frontal or side teeth or and that and others (fig. 5, c), and bilateral belong to such anomalies, at Krom side teeth are in the return smykaniye, and lobbies — in correct. An external sign of cross P. — the asymmetry of the person especially noticeable at laterposition of a mandible.
Vertical anomalies of the Item. are caused by disturbance of level of an occlusal surface of dentitions and are defined in relation to the horizontal plane. The main anomalies of this group — the deep and open Item. Deep P. is called such smykaniye of teeth, at Krom foreteeth substantially block crowns of teeth antagonists, in side sites of dentitions alveolar shoots are underdeveloped, crowns of teeth low. At deep P. the lower cutters do not lean on tooth hillocks of upper cutters and slide off to their gingival edge owing to what conditions for continuous traumatizing a mucous membrane of a gingiva and the sky are created; the bottom of the person usually is considerably shortened due to reduction of a pla of distal position of a chin. Open P. is characterized by existence of a crack between dentitions at their smykaniye — a thicket in foreteeth, is more rare in side sites of dentitions. Only cutters, cutters and canines or premolar tooths can not contact at the same time, and only the last painters are sometimes closed. Weight of anomalies is defined by the size of a crack, i.e. the number of not articulating teeth (fig. 5, d). At open P. the bottom of the person is extended, language keeps within a crack between dentitions that happens it is visible at a conversation, and sometimes and at rest; especially the speech is considerably violated.
In view of the fact that the quantity and a variety of anomalies of P. is high, the great value is gained by their classification. The standard international classification is Angle's classification (E. N of Angle) offered them in 1899 and assumed in the subsequent classifications as a basis. In his opinion, the relative positioning of dentitions is defined during eruption of the first constant painters. At their proper (neutral) correlation peredneshchechny hillocks of upper first painters get at a smykaniye of dentitions to grooves between peredneshchechny hillocks of the lower first painters. All anomalies of P. at which the first painters are in a neutral ratio are referred by Angle to the first class (fig. 6, a); if the lower first painters are displaced in relation to upper distally (back) — to the second class (fig. 6, c), mezialno (forward) — to the third (fig. 6, d). Angle divided anomalies of the second class into two subclasses: the first is characterized by a protrusion of upper cutters (a vestibular deviation) and existence we rub, the second — a retruziya of upper cutters (an oral inclination) and their close situation with a naleganiye at each other. In this classification only sagittal anomalies of P. are presented; all others are carried to the wrong position of separate teeth or their groups.
Angle's classification it changed and supplemented with many stomatologists. In our country the first classification of anomalies of P. was offered by N. I. Agapov (1928) who distinguished anomalies of teeth, jaws and the Item. It divided bites into 5 classes with subclasses (groups).
A. Ya. Katts (1933) tried to coordinate P.'s anomalies to disturbance of functions of certain muscles. I. L. Zlotnik (1952) distinguishes types P. (respectively three groups of classification of Katts) and their character, meaning various complications, i.e. the wrong position of teeth, deformations of dentitions, etc., and uses at the same time Lisher's terminology (Lischer, 1926): The item is neutral, distal, mesial.
A. I. Betelman (1956) distinguishes P.'s anomalies in the sagittal, vertical and transversal directions, divides each view of different forms and connects P.'s anomalies with dysfunction of certain groups of muscles (on Kattsa) In D. A. Kalvelis's classification (1957) dentoalveolar anomalies are divided into anomalies of teeth, dentitions and P., and the last are distributed on 3 groups: sagittal, transversal and vertical anomalies. In classification terms are used: prognathism, progeny, open and deep Item. According to classification of B. Yu. Kurlyandsky (1958), P.'s anomalies are grouped in a sign of an underdevelopment or excessive development of jaws. L. V. Ilyina-Markosyan (1967) offered the classification based on a sign of shift of a mandible at a smykaniye of teeth — from the central occlusion in the wrong usual occlusion. After division into sagittal, transversal and vertical anomalies of P. are divided into anomalies without the shift of a mandible (group A) and with the shift of a mandible (group B). The group B includes the anomalies combining signs of the first and second groups. In classification terms are used: anterialny, posterialny, laterialny bite. X. A. Kalamkarov (1972) distinguishes anomalies of development of teeth, anomalies of development of jaws, the combined anomalies of development of teeth and jaws. Cross P., deep P. and the open Item belong to ratio distortions of dentitions a prognathic or progenichesky ratio (foreteeth, front and side teeth or dentitions).
Except the anomalies systematized in the given classifications also others are observed patol. P.'s changes arising in connection with destruction of teeth and with their loss owing to caries (see. Caries of tooth ), diseases of a parodont (see. Periodontosis ) and other reasons. The so-called decreasing P. — a consequence of the increased erasability of teeth (fig. 7) or their mobility which are especially amplifying after loss of side teeth belongs to such changes. At the same time the provision of heads of a mandible changes, load of them increases that can lead to diseases of a temporal and mandibular joint (see. Kostena syndrome ). Also the deformations of dentitions and alveolar shoots of jaws arising later losses of separate teeth or their groups belong to age changes of P. The teeth which lost a support are displaced towards a free interval and an opposite jaw. If it occurs at children's or young age, then crowns of teeth move together with an alveolar shoot and their size does not change — so-called zuboalveolyarny lengthening. Adults and at elderly people in such cases have teeth which do not have antagonists as if move forward from holes, their roots are gradually bared, and height of crowns increases (see. Popova phenomenon ). Such disturbances of the occlusal plane complicate prosthetics, and sometimes make it impossible without preliminary shortening or removal of the displaced teeth.
At P.'s anomalies the nibble and chewing of food, a pronunciation are broken, the area of the occlusal field is reduced, the chewing movements of a mandible quite often are at a loss. The wrong smykaniye of teeth can be the cause of biting of a mucous membrane of gingival edge of teeth antagonists, a hard palate, lips, cheeks or language, developing of diseases of a parodont and a temporal and mandibular joint, and also disturbance of esthetic harmony of the person.
At inspection of the patient with pathology of dentoalveolar system study intra oral and front signs and symptoms of anomalies of P., carry out special clinical functional trials by means of which reveal various dysfunctions of bodies and muscles of zubo-maxillofacial area connected with P.'s anomalies; by means of the diagnostic equipment (a goniometer, a simmetroskop, various compasses, etc.) perform anthropometrical measurements in an oral cavity, on a face and on diagnostic models of jaws; if necessary use telex-ray analysis (see), a rinopnevmografiya, a miotonometriya, a mastikatsiografiya (see. Chewing ), electromyography (see), etc.
In view of the fact that the majority of anomalies of P. arises at children, well organized prevention is important for the correct formation of P.
The wrong P.'s correction requires orthodontic treatment, in process to-rogo special devices and devices are used (see. Orthodontic methods of treatment ). Early correction of deviations of P. reduces terms of treatment and provides its steady positive takes.
At adults it is also necessary to eliminate whenever possible revealed P.'s disturbances, including actions for their elimination in the plan of orthopedic treatment (see. Dentures ) as its first and main phase.
Kurland V. Yu. Orthopedic stomatology, Atlas, t. 2, page 110, 155, M., 1970; it, Orthopedic stomatology, page 12, etc., M., 1977; Okushko V. P. The anomalies of dentoalveolar system connected with addictions and their treatment, M., 1975; The Guide to orthopedic stomatology, under the editorship of A. I. Evdokimov, page 246, M., 1974; The Reference book on stomatology, under the editorship of A. I. Rybakov and G. M. Ivashchenko, page 353, 302, M., 1977; Uzhumetskene I. I. Methods of a research in orthodontics, M., 1970.
L. V. Ilyina-Markosyan.