TEETH

From Big Medical Encyclopedia

TEETH (dentes) — the educations consisting preferential of solid fabrics, located in an oral cavity and intended for a nibble, keeping and chewing of food, and also participating in formation of some sounds of the speech.

A comparative anatomy

In the evolutionary relation 3. are derivatives of the scales covering a body at the remote ancestors of the vertebrata living in an aqueous medium. Process of a bookmark 3. it is possible to track on an example a rvzvitiya of a germ of a shark, at to-rogo the outgrowths corresponding future 3., appear along with laying of skin scales and morphologically differ in nothing from it; later the scales located; in jaws, increases in sizes and gets a structure of teeth.

3. animal different types differ with way of an attachment to jaws, a form and the number of changes 3. There are three types of an attachment 3. to jaws: 1) on edge of a jaw (akrodontny 3.); 2) an outer edge to an inner edge of a jaw (pleurodont 3.) 3) fixing of roots 3. in bone cells of jaws (thecodont 3.). Akrodontnye 3. are available for sharks and bony fishes; they can be formed not only on jaws, but also in language, bones of a bottom of a skull, in a drink. Pleurodont 3. are available for some species of lizards: Thecodont 3. for the first time appeared at ancient reptiles, such 3. and at extant crocodiles and alligators. More perfect thecodont 3. — at the highest vertebrata and mammals. At the lowest vertebrata Z. function short term to a measure of deleting are replaced with new; such type of replacement 3. the polyphyodontism nazyvtsya. It is observed at sharks, bony fishes, amphibians, reptiles. Sharks on jaws have several rows 3., and the functioning row is located on edge of a jaw, the others 3. form gradually and replace functioning 3.; at each subsequent shift 3. become larger than previous. At mammals 3. change once at young age (diphyodontism) and at some species of mammals they do not change during all life (monofiodontizm). Difiodontny and monofiodontny systems in the course of evolution came from polifiodontny system of ancient vertebrata. At different types of mammals quantity replaced 3. unequally. So, at marsupials only one changes 3., at the highest mammals and the person cutters, canines and small radical 3 change., big radical 3. have no previous milk the Ratio of solid fabrics 3. (enamels, dentine and cement) and their structure at various representatives of fauna vary. 3. sharks have only an emalepodobny covering, by origin corresponding to dentine. It is so-called vitrodentin, the apatite crystals driving in its structure which is characterized by a parallel arrangement that does it transparent. It is located on a layer of an opaque durodentin with the wrong arrangement of apatite crystals. Enamel covers 3. amphibians, but a layer its thin has also no the prismatic structure characteristic of enamel of the highest vertebrata. Enamel reaches considerable development in 3. preying animals. At some animals enamel for the second time is reduced as, e.g., on tusks of an elephant, canines of a boar.

Dentine meets in all true 3., however its structure happens variously; there are several types of dentine. Orthodentin, acellular, avascular, penetrated by tubules with shoots of fibrilloblasts, is characteristic for 3. the highest mammals and person. Vasodentin is penetrated by blood vessels; it makes a basis 3. at some fishes, whales. Osteodentin contains dentinal tubules and bone cells.

Cement is a part of the device strengthening 3. in a bone alveolus therefore it appears along with development of roots and formation of thecodont system, for the first time — in 3. crocodiles.

Form 3. it is also various. Conical shape is simplest (at the majority of fishes); at the same time all 3. can be identical (gomodontizm). However already at a part of predatory fishes along with conical shape appear Z., which surface is covered with hillocks, i.e. distinction between separate types functioning 3 is noted. (see the Heterodontism). At amphibians 3. generally identical, also remind a cone in a form. Reptiles have some distinctions between separate groups 3. Even more accurate distinction is observed at mammals; their lobbies are allocated 3. (dolotovidny — cutters), canines (cone-shaped), tubercular lozhnokorenny and istinnokorenny, having a difficult folded and tubercular surface.

Cutters are most developed at rodents; they are covered with a layer of enamel, firmer on the periphery thanks to what teeth samozatachivatsya. Strongly developed canines are characteristic of preying animals. At some animals big canines are a male sign, for example canines at a boar tusks at an elephant; often teeth are the tool of protection and attack.

Fig. 1. The scheme of complication of a form of a crown of teeth in the course of phylogenesis: 1 — a gaplodontny (cone-shaped) form; 2 — protodontny (emergence of additional tops ahead and behind from main); 3 — trikodontny (three-gear); 4 — trituberkulyarny (trekhbugorny) — teeth are located a triangle; 5 — four-grumous; 6 — bunodontny (the rounded-off tops); 7 - folded; 8 — cup, under each drawing the diagrammatic representation of an arrangement of hillocks is given (dorsal view).

According to Osborn's theories (H. F. Osborn, 1907) the uniform of painters and premolar tooths of mammals was formed by gradual complication of simple cone-shaped tooth (a gaplodontny form — fig. 1,1). Complication consisted in emergence of additional tops ahead and behind from the main top (a protodontny form — fig. 1, 2); the three-gear shape of tooth was so created (a trikodontny form — fig. 1, 3). Roots of these 3. found a tendency to longitudinal splitting. The following phases of development are characterized by the shift of tops: one of tops is displaced knutr, and another knaruzh; being located in the form of a triangle (trituberkulyarnaya a form — fig. 1, 4). Similar form 3. remained at some insectivorous animals. Subsequent changes are connected with emergence of one more hillock and formation, thus, of a four-grumous crown (fig. 1, 5). The last form is initial for development of various types 3. modern mammals.

Formation of small and big molars happened in close connection with feeding habits of animals. So, at insectivorous and preying animals hillocks are connected by the acute cutting crests (a so-called sekodontny form). The bunodontny form (fig. 1,6) at a cut of top of hillocks is characteristic of omnivores and the person are rounded off. At solid-hoofed animals hillocks 3. are connected by crests (a folded form — fig. 1, 7). At the highest herbivorous the cup form 3 forms. (fig. 1, 8). Together with it at some mammals secondary simplification 3 is observed. with formation of one-grumous forms (at dolphins) or three-grumous (at seals). Change of a shape of teeth was followed also by change of their quantity. At the lowest vertebrata quantity 3. reached several hundred. Some modern animals also have a large number 3., e.g. at an opossum 54 teeth, at a mole - 44. At more highly organized animals number 3. it is reduced. At subhuman primates a tooth formula and a form 3. same, as well as at the person.

Embryology

Development 3. represents complex process which, beginning at different stages of an embryogenesis, continues up to 18 — 20 years. In development 3. it is possible to allocate three main periods: bookmark and formation of dental germs, differentiation of dental germs, histogenesis of solid fabrics 3.

A bookmark and formation of dental germs at the person begins on 6 — 8th week of embryonal life. The multilayer epithelium covering an oral pole forms a thickening (the tooth roller) along top and bottom edge of primary oral crack. This thickening gradually grows into the subject mesenchyma. The epithelial plate lasting on all edge of an oral crack results. Soon this plate is split on two: front, or lip, and tooth, located at right angle to lip. The front plate, in turn, is divided, turning into the fillet separating a rudiment of a lip and cheeks from rudiments of gums. The tooth plate gradually gets a form of the arch put in a mesenchyma top and bottom jaws. Along free edge of tooth plates there are growths of an epithelium having an appearance of kolbovidny protrusions on 10 in each jaw, according to number future milk 3. These epithelial growths carry the name «tooth bodies» (enamel bodies). On the 10th week of embryonal life the mesenchyma therefore it takes a form of a cap or a bowl begins to grow into each tooth body; the growing mesenchyma received the name a tooth nipple. In process of growth the tooth body gradually stands apart from a tooth plate and remains only a thin coat of epithelial cells connected to it; this tyazh is called a neck of tooth body. Along with isolation of tooth body around it from a mesenchyma the so-called tooth sack forms. Thus, the tooth body, a tooth nipple and a tooth sack are a part of the created dental germ.

Fig. 3. Microdrug of a cut of a jaw of an embryo of the person of 3,5 months; a rudiment of tooth in the period of a differentiation: 1 — internal cells of tooth body; 2 — an epithelium of an oral cavity; 3 — a tooth plate; 4 — a pulp of tooth (enamel) body; 5 — outside cells of tooth body; 6 — a layer of fibrilloblasts; 7 — a tooth nipple; 8 — edge of tooth body; 9 — a bone alveolus; coloring hematoxylin-eosine.

The differentiation of dental germs is characterized by a number of the processes happening in a dental germ and in the fabrics surrounding it, namely in originally homogeneous cells of a rudiment there is a differentiation to allocation various in a form and function of cellular elements (tsvetn. fig. 3). In tooth body between cells of the central department the liquid stratifying cells which gradually turn out the connected cytoplasmatic bridges that reminds reticular fabric begins to collect. These cells received the name of a pulp of tooth body. The internal cells of tooth body located on border with a tooth nipple get a high cylindrical form; they give rise to enameloblasta (adenoameloblastomas) — to the cells building enamel. The cells located on an outer surface of tooth body are flattened. On edge of tooth body internal enamel cells pass into superficial.

Electronic microscopic examinations allowed to obtain data on features of the organization of cells of tooth body. Outside cells of this body connect by means of desmosomes; in their endoplasm the developed lamellar complex, a granular cytoplasmic reticulum and a small amount of mitochondrions is found. Between outside epithelial cells of this body and surrounding connecting fabric of a tooth sack the basal membrane consisting of an electronic tight coat, thickness apprx. 10 — 22 nanometers is located.

The cells of a pulp of tooth body lying in close proximity to outside cells have the flattened appearance and are divided by small intercellular spaces, on structure they do not differ from outside cells of tooth body. As approaching the central department of body intercellular spaces increase, cells get a star-shaped form, giving long branchy cytoplasmatic shoots. In their cytoplasm the lamellar complex consisting of small bubbles and tanks and the tubules of a cytoplasmic reticulum bearing on themselves ribosomes comes to light. Connection of cells of this layer among themselves and also happens to cells of a periblast by means of desmosomes. Internal cells of tooth body are located in one row on a basal membrane, edges separates them from connecting fabric of a tooth nipple. The membrane has thickness apprx. 30 nanometers and corresponds to position of future enamel and dentinal border. The ultrastructure of internal enamel cells changes up to the beginning of an enamelogenesis. At early stages of a differentiation they contain an underdeveloped cytoplasmic reticulum, a small lamellar complex and rather large number of free ribosomes.

A part of cells of a pulp of tooth body, adjacent to its internal cells, makes a so-called medine. This layer consists of 2 — 3 rows of the cells divided by small intercellular spaces. Cells of a medine differ in high activity of a row of fermental systems (acid phosphatase, a galactosidase, a succinatedehydrogenase) and play, apparently, an important role in the course of an enamelogenesis. Directly after formation of tooth body mitotic division of cells meets in all its departments. But then in process of a differentiation mitotic activity of the cells making it sharply decreases and remains only in cells of a medine.

Fig. 2. The scheme of the Diffraction pattern of two fibrilloblasts in a stage of an odontogenesis: 1 — dentine; 2 — predentin; 3 — a shoot of fibrilloblasts; 4 — a body of a fibrilloblast; 5 — a kernel; 6 — mitochondrions; 7 — a lamellar complex; 8 — a lysosome; 9 — a cytoplasmic reticulum; 10 — the conjunction of the next fibrilloblasts; 11 — secretory granules; 12 — fibrilla; 13 — a dentinal tubule.

The tooth nipple increases in sizes, a large number of blood vessels grows into it. On its surface on border with internal cells of tooth body several rows of the cells with sharply basphilic cytoplasm which received the name of fibrilloblasts — cells with which active participation dentine is formed are formed. Fibrilloblasts (fig. 2) have the extended form; in their cytoplasm well developed lamellar complex, a cytoplasmic reticulum and numerous mitochondrions comes to light.

The period of a differentiation of dental germs is replaced by the period of a histogenesis, during to-rogo there are a dentine and enamel of crowns milk 3. Development of roots happens already in postembryonal life and synchronizes the beginning of eruption milk 3.

Fig. 4. Microdrug of a cut of a jaw of an embryo of the person of 5 months; a rudiment of an upper cutter in the period of a histogenesis: 1 — enameloblasta; 2 — enamel; 3 — dentine; 4 — a layer of fibrilloblasts; 5 — an epithelium of an oral cavity; 6th blood vessels of a tooth sack; 7 — a tooth nipple; coloring hematoxylin-eosine.
Fig. 3. The diffraction pattern of dentine of tooth with a shoot of a fibrilloblast in a dentinal tubule of an embryo of the person of 34 weeks: 1 — substance of dentine; 2 — a shoot of a fibrilloblast in a dentinal tubule; 3 — a zone of peritubulyarny dentine; x 25000.

The histogenesis of solid tissues of tooth begins at the end of the 4th month of embryonal life (tsvetn. fig. 4). The first fabric, edges it is formed in the course of a histogenesis, dentine is. Formation of dentine happens at vigorous activity of fibrilloblasts which cosecrete initial components for creation of fibrous structures of dentine; formation of fibrilla is made already out of cytoplasm of fibrilloblasts. Just before the beginning of formation of dentine the structure of fibrilloblasts undergoes a number of changes. The kernel of fibrilloblasts moves by that end of a cell which is turned to a tooth nipple. The cytoplasmic reticulum increases, takes a canalicular form and together with a lamellar complex is located over a kernel. The first signs of formation of dentine are expressed in emergence between fibrilloblasts of the fine argyrophil fibers going in the radial direction (so-called fiber of Korff). They join in the main substance of not calciphied dentine, or predentin. When the layer of predentin with radial fibers reaches in thickness of 60 — 80 microns, formation of new layers of predentin in which fibers have already tangential direction begins, i.e. go parallel to a surface of a tooth nipple (so-called fiber of Ebner). Along with adjournment of first coats of predentin fibrilloblasts form shoots which are gradually immured in the main substance of not calciphied dentine; fibrilloblasts remain in outside departments of a tooth nipple. It is feature of development of the dentine representing acellular fabric: fibrilloblasts as if send only the shoots which pass in dentinal tubules (fig. 3) to dentine.

Calcification of dentine begins at the end of the 5th month of embryonic development; in this process the important role also belongs to the fibrilloblasts transporting by means of the shoots mineral substances in the main substance of dentine.

Just before the beginning of a mineralization of dentine there is a nek-swarm a consolidation of the main substance of dentine. Mineral salts in the form of crystals of hydrooxyapatite are laid in the main substance of dentine on the course of collagenic fibers; a part of crystals is postponed in the form of spheres or calcospherites, each of which consists of the extended crystals located radially in relation to the center of a calcospherite. There is an opinion that such peculiar arrangement of salts in the form of spheres, or globuly, is feature of calcification of dentine and depends on structure of its main substance. The first deposits of dentine have low electron density and contain a small amount of thin collagenic fibrilla of 1,5 — 2 nanometers in dia.; further density of the main substance of dentine increases, collagenic fibrilla becomes thicker.

Fig. 4. The diffraction pattern of a shoot of an enameloblast in young enamel: 1 — enameloblastichesky spheres in cytoplasm of a shoot of an enameloblast; 2 — the allocated secret of enameloblastichesky spheres; 3 — young enamel; x 55600.

Development of enamel begins soon after the beginning of formation of dentine and is characterized by increase in mass of a cytoplasmic reticulum and lamellar complex in enameloblasta. In cytoplasm of enameloblast a large number of free ribosomes which move closer to the edge of a cell turned to a layer of the formed dentine collects. This end of a cell is extended, reaching in length of 4 microns and forming a shoot (so-called fiber of Toms); then in shoots there are round or oval granules surrounded with a cover and. containing electronic and dense substance; the enamelogenesis occurs by secretion of contents of these granules of an enameloblastama in intercellular space. In process of accumulation of the main substance of enamel of an enameloblasta are removed to the periphery (fig. 4). Again formed material of an organic basis of enamel consists of small granules, between to-rymi there is a substance with a low electron density. Before calcification density of organic matter increases. Calcification of enamel happens at once after emergence of the first portions of its organic matter. Salts of calcium are laid in enamel in the form of crystals of apatite, shaped thin plates. Enameloblasta after end of an enamelogenesis are reduced, their remains are a part of a cuticle of enamel (a nasmitovy cover). Idea that everyone enameloblast gradually turns into an enamel column at electronic microscopic examinations was not confirmed. Formation of enamel columns happens out of cytoplasm of these cells. For an explanation of a prismatic structure of enamel the hypothesis of the preferential orientation of crystals of apatite determined by the direction of the front of a mineralization is offered.

Fig. 5. The scheme of development of root vaginas in the lower two-root and upper three-root teeth by merge of outgrowths (1) of edge of an epithelial vagina to formation of the place of separation — bifurcation (2) future roots.

Development of roots of milk teeth, begins shortly before eruption of crowns, almost completely created by this time. By the beginning of development of a root of edge of tooth body, consisting of two rows of epithelial cells — internal and outside, intensively expand like a sleeve and grow into a surrounding mesenchyma. This education is called an epithelial root vagina (a vagina of Gertviga) and as if defines a form of future root 3. From mesenchymal cells of a tooth nipple, adjacent from within to an epithelial root vagina, fibrilloblasts which begin to build dentine of a root form. After formation of first coats of dentine the epithelial vagina burgeons mezenkhimny cells of a tooth sack. From these cells tsementoblasta which on an outer surface of dentine of a root lay cement are differentiated. In multi-rooted 3. the epithelial vagina giving the form to future roots 3. and having originally an appearance of a full sleeve, it is divided depending on a type of tooth into two or three channels. It occurs because certain sites of an epithelial vagina are turned in inside, grow towards each other, and is formed of originally one wide opening two or three narrower (fig. 5). Further from edges of each of these openings the epithelium begins to grow, forming a vagina on number of future roots.

Fig. 5. The scheme of relationship of the cut-through milk teeth with rudiments of the second teeth which are stuffed up in the thickness of jaws: 1 — the cut-through milk teeth; 2 — the forming rudiments of second teeth directly adjacent to roots of milk teeth.

Development of second teeth happens similar to development of milk. Source of formation of constants 3. the same tooth plate serves, from a cut rudiments milk 3 develop. Laying of constants 3. begins with the 5th month of embryonal life; along bottom edge of a tooth plate behind each rudiment milk 3. tooth bodies of constant cutters, canines and small radical 3 are formed. (tsvetn. fig. 5). These groups 3. are called replacing since in a constant bite they replace corresponding milk 3. In a milk bite is not present small radical 3.; painters of a milk bite are replaced with constants small radical 3.

Laying of constants big radical 3. occurs later. So, rudiment of the first big radical 3. the rudiment of third big radical (wisdom tooth) — on the fourth and even the fifth year of life is put in the middle of the first year of life of the child, and. This results from the fact that for all 3. there is not enough place in a jaw of a fruit and only when there is intensive growth of a jaw of the child to the simultaneous growth of a kzada of a tooth plate, conditions for laying of constants big radical 3 appear. As they have no predecessors in a milk bite, them call additional 3.

Structure of a rudiment of constants 3. does not differ from rudiments milk. Here too there are an epithelial tooth body, a tooth nipple and a tooth sack. Development of solid fabrics of constants 3. occurs in the same sequence, as milk, i.e. at first dentine, then enamel and cement is formed.

Anatomy

Fig. 6. Second teeth top and bottom jaws: 1 — cutters; 2 — canines; 3 — small radical (premolar tooths); 4 — big radical (painters).

3. are located in jaws so that their crowns form so-called tooth arches, or ranks. The tooth arch of an upper jaw has the form of a semi-ellipse, and lower — a form of a parabola. Each dentition of the adult contains 16 teeth (fig. 6): 4 cutters, 2 canines, 4 small radical 3., or premolar tooth, and 6 big radical 3., or painters. At a smykaniye of jaws 3. a top and bottom row are closed in a certain situation (see. Articulation of teeth ). Tooth arches separate an entrance of the mouth from actually oral cavity. Connection of a root 3. happens to a wall of a bone hole as a so-called vkolachivaniye (gomphosis) — a kind of connection of bones. The sheaf holding a root 3 in a hole., consists of the bunches of connective tissue fibers going diversely; it is called a root cover, a pericementum, or periodontium (see). The bunches of this sheaf which are at an entrance to an alveolus and people around a neck 3., are called a circular sheaf 3. (lig. circulare dentis).

Order of an arrangement 3. in jaws represent graphically in the form of a so-called tooth formula; it is most accepted for designation of constants 3. to use the Arab figures, and milk — Roman. The tooth formula represents as if a mirror image of dentitions where everyone 3, is designated by figure; by drawing up a formula proceed from position of the patient sitting opposite to the doctor. The horizontal line divides top and bottom jaws, and vertical — 3. right and left side.

In a comparative anatomy the tooth formula where 3 is accepted. write down from left to right, since cutters in dentition on one half of a jaw (figures designate the number of group 3.). E.g., for the adult it will look so:

Structure of teeth

Fig. 7. The scheme of a structure of a big molar (the right half of tooth is given in a section): 1 — enamel; 2 — dentine; 3 — a pulp cavity; 4 — a bone alveolus; 5 — cement; 6 — the channel of a fang; 7 — a periodontium; 8 — a fang; 9 — a neck of tooth; 10 — a crown of tooth.

Everyone 3. consists of a crown — part 3., the gingiva acting over a surface, a root — the part shipped in a bone hole of jaws and a neck — the waist 3. between a crown and a root (fig. 7). Neck 3. it is densely covered by a gingiva, the epithelium a cut forms strong connection with enamel here (see. Desna ). Various in the functional relation 3. differ among themselves in a form of a crown and by quantity of roots. Inside 3. there is a cavity filled with a pulp 3. This cavity (pulp cavity) passes into roots, forming root channels which open at top of a root an opening. In a crown 3. distinguish an occlusal surface (a surface of a smykaniye 3.), respectively cutting edge of cutters and canines; vestibular surface (lip and buccal); the lingual surface (turned into an oral cavity) and two contact surfaces — medial and distal.

Of the same name 3. the right and left half of jaws differ; there are signs, on the Crimea it is possible to establish situation 3. in a jaw: the sign of a corner of a crown is that a corner between a chewing and medial contact surface 3. more sharply than a corner between a chewing and distal contact surface; a sign of curvature of enamel — from the vestibular party 3. enamel is thickened in the medial direction; a sign of a root — a top of a root 3. deviates in the lateral party in relation to a longitudinal axis of a crown.

Structure of second teeth. Cutters (dentes incisivi) in number of eight are located in the middle of a tooth arch, on four on a top and bottom jaw; distinguish medial and lateral cutters. Upper medial, or central, cutters are larger than other cutters; the crown of cutters has the dolotoobrazny form, is convex from a vestibular surface. The medial surface and cutting edge of a crown of medial cutters meet at right angle, the distal edge in the place of contact with a cutting edge is rounded. The lingual surface of cutters is bent, in its cervical part there is a hillock. The root is slightly thickened from sides, the top of a root is rounded off and slightly rejected in the lateral party. Lateral upper cutters have the rounded-off form of a crown, convex from a vestibular surface, corners between cutting and side edges are rounded also off (the distal corner is rounded more off). From a lingual surface the crown is bent and has hillocks in a cervical part. The root in a form is similar to a root of a medial cutter.

The lower cutters there are less upper. A crown their narrow, the root is squeezed from sides. Medial lower cutters have the narrow extended crown with right angles between a cutting edge and side surfaces. A vestibular surface convex, lingual — concave. In cervical area from a lingual surface the median hillock is located. Side surfaces have the form of a wedge. Crowns of the lower lateral cutters of a dolotoobrazny form with expansion to a cutting edge, a medial corner of a crown more acute, distal stupid, slightly rounded off. A vestibular surface convex, lingual — bent with the expressed hillock in cervical area.

Canines (dentes canini) are located on two on each jaw (only four); upper are larger than lower. A crown of a rhomboid outline, a cutting edge in the form of the pointed ledge disposed closer to the medial party 3. On a lingual surface of a crown regional crests are visible, between to-rymi there are deepenings. The root is long, it is strongly squeezed from sides. The lower canines on a configuration of a crown remind upper. The cutting edge also bears on itself the pointed ledge displaced medially. A lingual surface flat or concave, crests are developed poorly.

Small molars, or premolar tooths (dentes praemolares), are located on four in each jaw: two with left and two on the right side. Upper small radical 3. more largely than lower. The first upper premolar tooths have the crown of an oval form reminding a crown of a canine; the cutting edge has a ledge — a hillock, from to-rogo on a buccal surface to a neck 3. there is a convex roller; a proximal and distal corner of a cutting edge of a crown are identical. The root is squeezed in the mediodistalny direction, on it the longitudinal furrow is visible, sometimes it is divided into two roots. The chewing surface has two chewing hillocks from which lingual is larger than buccal. These hillocks are divided by a groove, edge does not reach edges of a crown. Lingual surface of a crown convex, smooth. The cavity of a crown of a cylindrical form, has two ledges according to an arrangement of hillocks. The channel is wide, it is compressed from sides. The second upper premolar tooth is similar on a structure with the first. Vestibular surface of a crown of a convex and oval form; the chewing surface has two chewing hillocks of the identical sizes. Most often there is one root and one channel.

Lower small radical 3. have smaller in comparison with upper the size of a crown, but longer root. The first lower premolar tooth in a form of a crown reminds a canine. A buccal surface of a crown convex with the longitudinal roller. The chewing surface has two hillocks, between to-rymi there passes the crest. On each side from a crest two poles are located. Lingual surface convex. The root is more often single, sometimes double. Cavity 3. big, rounded shape with two ledges, the channel wide, is sometimes doubled. The second lower premolar tooth has a semi-spherical crown. Buccal and lingual surfaces convex. The cutting edge has a wide hillock. A chewing surface more often two-grumous, sometimes there are three hillocks. The root is single, a cavity of a crown cylindrical, the channel wide.

Big radical 3., or painters (dentes molares), total number 12, are located on 6 on a top and bottom jaw, on 3 from each party. The third painter call 3. wisdom. Big radical 3. have a massive crown and several roots. Crowns of the first squared upper painters with the rounded edges. A buccal surface quadrangular with a longitudinal furrow. On a cutting edge from the buccal party there are two hillocks — medial and distal. The lingual surface is also divided by a longitudinal furrow. On contact surfaces with next 3. — two ledges: lingual and buccal. On a medial surface at a buccal ledge a peculiar hillock of t — a so-called medial and lingual eminence, or Karabelli's hillock is often noticeable. The chewing surface has a rhomboid or square contour with two buccal and two lingual hillocks which are divided by grooves. There are three roots, from them two buccal (medial and distal) and one palatal. Roots either disperse, or are parallel each other. A cavity of a crown wide, root channels are various on width, the widest channel at a palatal root, in a buccal and medial root in 60% of cases two channels.

The second upper painters are a little other than the first; their crowns are compressed in the mediodistalny direction on a chewing surface there are four hillocks, less often three or only two hillocks more often (palatal and buccal). Korney — two buccal and one lingual. From them shchechnomedialny sometimes grows together with lingual. More often the roots dispersing. The cavity of a crown big, channels — three, at accretion of roots an accrete root supports two channels.

Third upper painters, or 3. wisdom, they are very changeable in a form and size, but usually less first and second upper painters and lower 3. wisdom. The most frequent form of a chewing surface — three-grumous with two buccal and one lingual hillocks, but happens also four hillocks. The quantity of roots three or two, but happens also one (accrete), usually buccal roots grow together. The cavity is wide, channels irrespective of number of roots — three.

Lower big radical 3. slightly less two roots — medial and distal also have upper. Crowns of the first squared lower painters. Their buccal surface is divided by two longitudinal grooves into three ledges. The lingual surface is divided a longitudinal furrow into two parts. The chewing surface contains five hillocks, from them three — on the buccal party of a crown and two on lingual. Roots two: medial — wide, a wedge-shaped form, both distal — narrower and short. Cavity of a crown cubical. Than channels three (in a medial root two channels), is more rare — four.

The second lower painters have a crown of a cubic form. On its buccal surface there passes the vertical furrow dividing a crown into two convex parts. On a chewing surface four hillocks — two buccal and two lingual, divided by the grooves meeting in the center and forming here a pole.

The third lower painters (wisdom teeth), as well as upper, are very changeable in size and a form. They there are less other lower painters, but is larger upper 3. wisdom. On a chewing surface more often there are four hillocks, five are more rare or three. Roots are short, sometimes grow together together, often have the bent form. A cavity of a crown of irregular shape, channels three, from them two in a medial root.

Structure of milk teeth. Milk 3. function before replacement with their constants, i.e. up to 13 — 14 years of the child. Aged from 6 up to 14 years, during change 3., the so-called replaceable bite is formed, in Krom are available both milk, and constant 3. At the same time in a milk bite is not present small radical 3., during the change constants small radical 3. replace milk big radical. Generally milk 3. have the same form, as constants 3., but there are some differences. Milk 3. it is less by the sizes, enamel of more yellow shade, roots shorter. Hillocks of milk cutters and canines on the cutting surface are expressed more weakly.

On a buccal surface of the first upper milk painter the hillock is well developed; on a chewing surface from a buccal cutting edge to the central pole there is a crest, the same crest goes also from a lingual surface. Upper milk painters have three roots — two buccal and one lingual; roots disperse. Second milk upper painter the largest of all milk 3.; it is similar to the first the constant painter.

The lower milk painters differ among themselves on a structure: the first lower painter has on a chewing surface two — four hillocks, the buccal and medial hillock, roots two — medial and distal is always well developed; the second milk painter is similar on a structure to the first constant painter, has two roots.

Blood supply, an innervation, the Lymph drainage

Blood supply is carried out by branches of a maxillary artery (a. maxillaris) departing from an outside carotid artery. From a maxillary artery to 3. an upper jaw depart a back upper alveolar artery (a. alveolaris sup. post.) and from its continuation — an infraorbital artery (a. infraorbitalis) — front upper alveolar arteries (aa. alveolares sup. ant.). To 3. the mandible suits the lower alveolar artery (a. alveolaris inf.), edges goes in the mandibular channel, giving on the way tooth branches (rr. dentales). These tooth branches are included into root canals through an apical opening of a root. Similar tooth branches depart from front and back upper alveolar arteries.

Veins accompany the arteries of the same name, a venous blood gathers in an alate texture (plexus venosus pterygoideus) which is in an infratemporal pole. Veins 3. an upper jaw have communication with veins of an eye-socket.

Fig. 6. Scheme of blood supply and innervation of teeth: 1 — a trigeminal node; 2 — a maxillary nerve; 3 — a maxillary artery; 4 — an optic nerve; 5 — the lower eye vein; 6 — an infraorbital nerve; 7 — an upper eye vein; 8 — upper alveolar branches and an upper tooth texture; 9 — the lower tooth texture; 10 — the lower alveolar artery; 11 — the lower alveolar vein (BNA); 12 — the general carotid artery; 13 — an internal jugular vein; 14 — a retromandibular vein; 15 — the lower alveolar nerve; 16 — a lingual nerve; 17 — an outside carotid artery; 18 — an alate veniplex.

Blood supply of a pulp extremely plentiful (tsvetn. fig. 6). Through an apical opening the large arterial vessel accompanied by one or two veins enters a pulp; on the course of the root channel the artery gives the lateral branches going to a layer of fibrilloblasts. In the field of a coronal pulp the branching of blood vessels forms dense network. Especially dense texture of small precapillary vessels and capillaries is formed in a subodontoblastichesky layer. From here capillary loops get into a layer of fibrilloblasts. Capillaries pass into veins which have very thin walls and considerably bigger diameter, than an artery.

The innervation comes from branches of a trifacial. At the same time 3. an upper jaw are innervated by upper alveolar nerves (nn. alveolares sup.), from which front upper alveolar branches approach cutters (rr. alveolares sup. ant.), to premolar tooths — an average upper alveolar branch (of alveolaris sup. medius) and to painters — back upper alveolar branches (rr. alveolares sup. post.). These branches form an upper tooth texture (plexus dentalis sup.), giving the tooth branches entering the root canal together with an artery. 3. a mandible are innervated by branches of a nizhnealveolyarny nerve (n. alveolaris inf.), which, taking place in the mandibular channel, is divided into the stipitates forming the lower tooth texture (plexus dentalis inf.), giving the lower tooth branches (rr. dentales inf.), going to a pulp via the root channel.

Outflow of a lymph from 3. an upper jaw occurs on taking away limf, to vessels in submental (nodi lymphatici submentales), Submandibular (nodi lymphatici submandibulares), parotid (nodi lymphatici parotidei) and occipital (nodi lymphatici occipitales) limf, nodes, and from 3. a mandible — Submandibular limf, nodes.

Histology

the Enamel covering a crown Z., is its hardest fabric. The thickest coat of enamel (1,6 — 1,7 mm) is on chewing hillocks; on side surfaces of a crown the layer is much thinner than it. Hardness of enamel fluctuates from 250 to 300 units of Vikkers (5 times less than the hardness of quartz).

Fig. 8. Microdrug of a shlif of enamel of tooth of the person: alternation of dark and ghost lines in the radial direction is expressed (Gunter's strips — Shregera); x 20.
Fig. 9. Microdrug of a shlif of tooth of the person: slanting dark lines (Rettsius's line) in enamel are expressed; x 20.

Enamel consists of enamel columns to dia. 3 — 6 microns which pass through all its thickness. A part of enamel columns, being gradually narrowed, disappears, without reaching the surface of enamel; some prisms are divided into two, and connection of two prisms in one sometimes is found. On the course enamel, prisms form s-shaped bends therefore on a longitudinal shlif 3. one sites of an enamel column are cut off longwise, and others cross. Alternation is longitudinal and cross soshlifovanny sites of enamel columns creates the effect which is expressed in emergence on shlifa of enamel of the dark and ghost lines going in the radial direction — so-called strips of Gunter — Shregera (fig. 8). On shlifa of enamel still the lines going in the slanting direction — so-called lines of Rettsius (fig. 9) are visible. On a cross shlif 3. these lines are located in the form of concentric circles, reminding a cut of a tree. These lines connect with recurrence, and also disturbance of process of education and calcification of enamel in this connection on the course of enamel columns the sites with the high and smaller content of salts of lime which are differently refracting light that causes emergence of parallel lines meet.

Fig. 10. Microdrug of cross section of a rudiment of tooth of the child: the arkadoobrazny form of enamel columns is characteristic; x 200.

Disturbance of an enamelogenesis can result from the postponed diseases or a lack of food of early children's age. E.g., on shlifa 3. the so-called neonatal line in the form of a dark strip in enamel milk 3 is noticeable.; it as if is border between the enamel formed till the birth and after the birth. The origin of this line is explained with disturbance of calcification of enamel in the period of adaptation of the newborn child to exogenous food. In enamel columns there is cross striation, edges as considers a number of authors, is reflection of a day-night rhythm of adjournment of salts of calcium in prisms. Scott (D. Century of Scott, 1955), having studied 2000 prisms 3. the person, found out that 57% from them on cross section have the arkadoobrazny form (fig. 10), or a form of scales, 31% — polygonal, 2% — roundish and hexagonal and 10% have the wrong outlines.

Fig. 11. The diffraction pattern two a number of the lying enamel columns which structure is presented by the crystals of hydrooxyapatite located fanlikely and skintight to each other.
Fig. 12. The diffraction pattern of longitudinal section of enamel columns illustrating an arrangement of crystals in prisms and interprismatic substance: 1 — a cover of an enamel column; 2 — interprismatic substance; 3 — substance of an enamel column: x 13200

Enamel contains a large amount of mineral salts (96 — 97%), organic matters make 3 — 4%. By electronic microscopic examinations it is established that a base unit of enamel columns — crystals of hydrooxyapatite, skintight to each other. In prisms they are located fanlikely, i.e. lie at an angle to each other, and this corner is open in the direction of the surface of enamel (fig. 11). Crystals of a hexagonal form, their sizes vary from 300 to 1000 nanometers in length and from 40 to 120 nanometers width. Concerning a way of connection of enamel columns there are several points of view. One authors consider that prisms are connected by organic interprismatic matter, others deny availability of this substance and explain strong connection of prisms with penetration of crystals from one prism in another, next. It is established that interprismatic substance of the created enamel consists of the same crystals of hydrooxyapatite, as well as prisms, but differs in orientation of crystals (fig. 12). Amount of interprismatic substance variously, sometimes it is absent at all and prisms adjoin directly. Most of the researchers who are engaged in a submicroscopy denies existence of covers of prisms, considering their emergence on diffraction patterns as an artifact.

Fig. 13. The diffraction pattern of cross section of organic matter of enamel after decalcification: 1 — covers of enamel columns; 2 — substance of an enamel column; X 10500.

Difficult is a question of relationship of organic and inorganic components of enamel. At decalcification (fig. 13) of ultrathin sections of enamel in it the peculiar fine fibrillar structures presented by the proteins close to a keratin are found.

Fig. 14. Microdrug of a cross shlif of tooth: 1 — an enamel plate; 2 — an enamel bunch; x 100.

According to Scott and Nilen's data (M. of U. Nylen, 1962), organic matter is located in the form of the thinnest layers between crystals of hydrooxyapatite. In enamel so-called enamel bunches and enamel plates (fig. 14) consisting of not calciphied organic matter meet; enamel

bunches are located at enamel and dentinal border. Enamel plates — the fine taenioid structures passing through all thickness of enamel; are visible generally on cross shlifa 3.

Fig. 15. Microdrug of a shlif of a fang: a side anastomosis departs from dentinal tubules (1) (are specified by shooters); X 400.
Fig. 16. Microdrug of a shlif of a crown of tooth of the person: globular deposits of crystals of hydrooxyapatite in dentine of a crown; x 200.
Fig. 17. Microdrug of a shlif of a fang: 1 — cement; 2 — a granular layer (Toms's layer); 3 — dentine; x 100.
Fig. 18. Microdrug of a shlif of tooth of the person: interglobular dentine is specified by shooters; x 200.

Dentine makes ground mass 3. Contains in it apprx. 72% of mineral salts, 28% are made by organic matters and water. An inorganic part of dentine is presented to hl. obr. calcium phosphate, and also small amount of calcium fluoride, calcium carbonate, magnesium and sodium; an organic basis collagen and a nek-swarm represents amount of mucopolysaccharides. The main substance of dentine is penetrated by a set of thin tubules, or dentinal tubules. In these tubules there are cytoplasmatic shoots of fibrilloblasts (Toms's shoots). Dentinal tubules disperse in the radial direction from a pulp 3., diameter them fluctuates from 1 to 3 microns. From within they are covered by the membrane seen under a supermicroscope. Dentinal tubules branch and give the side shoots anastomosing among themselves (fig. 15). The reinforced ends of dentinal tubules get into substance of enamel and carry the name of enamel spindles. The quantity of dentinal tubules fluctuates from 30 000 to 75 000 by 1 mm 2 dentine. More densely they are located about a pulp less often in periblasts, in dentine of their crown it is more, than in dentine of a root. Dentinal tubules can be isolated by maceration in strong solutions to - t or alkalis; the wall of a dentinal tubule remaining at the same time received the name of a cover of Neymann. Tubules are surrounded by the so-called peritubulyarny zone containing bigger amount of inorganic matters, than other sites of dentine.

In dentine distinguish the outside zone formed by so-called cover dentine, and internal, including okolopulparny dentine. These zones differ in various arrangement of collagenic fibers. In cover dentine collagenic fibers go radially, and in okolopulparny — they are directed tangentsialno. In the site where one zone of dentine passes into another, radial and tangential fibers intertwine. Hardness of dentine is provided with availability of salts of calcium in it in the form of crystals of hydrooxyapatite. According to a submicroscopy, the form of crystals in dentine happens needle, lamellar and granular. Crystals of a needle form meet preferential in interfibrillar main substance, crystals of platelet shape — along collagenic fibers, granular — around dentinal tubules: Crystals of hydrooxyapatite are postponed in dentine in the form of the .sharovidny complexes visible: under the ordinary light microscope. These spheres, or globul and, can be various sizes. Large spheres meet in dentine of a crown (fig. 16), small — in dentine of a root where they form a so-called granular layer of dentine of Toms (fig. 17). Between spheres sites of not calciphied main substance of dentine which are called interglobular dentine (fig. 18), or interglobular space (the outdated name) are located.

Interglobular dentine on shlifa 3. under the light microscope has an appearance of dark semi-arches or the wrong rhombuses. Quite often on gistol, drugs in dentine are visible chereduyushchyesya the arc-shaped lines which received the name of planimetric lines of Owen; they are reflection of rhythmic growth and layered adjournment of dentine. In dentine created 3., as a rule, there is a zone, the edge is not exposed to calcification. It is the layer of dentine directly adjacent to a pulp 3.; on gistol, the drugs painted hematoxylin-eosine it has an appearance of a pink strip and is called predentin.

Fig. 3. Microdrug of tooth of the person: 1 — primary dentine; 2 — the border separating replaceable dentine from primary; 3 — secondary (replaceable) dentine; 4 — predentin; 5 — a layer of fibrilloblasts; 6 — a subadentoblastichesky layer. Coloring hematoxylin-eosine

Formation of dentine does not stop also in completely created 3. adult. The dentine which is again formed in created 3., is called secondary, or replaceable. It differs from primary dentine created in the course of an embryogenesis, the wrong arrangement of collagenic fibers and dentinal tubules (tsvetn. 480, fig. 3). Adjournment of secondary dentine amplifies at the raised combustibility of enamel, developing of caries and some other states. It is characteristic that at caries adjournment of secondary dentine happens in that site of a tooth cavity which corresponds to the site of caries. At dystrophic processes in a pulp sometimes are found various amount and a form of education, consisting of dentine and received the name of denticles; they can adjoin to a wall of the camera 3. (pristenochny denticles) or freely to lie in a pulp (free denticles) (tsvetn. fig. 4). A source of their development are fibrilloblasts.

Fig. 19. A horizontal cut of a mandible through a root of a cutter (in the center the root channel): 1 — an opening in a wall of a bone alveolus; 2 — a wall of a bone alveolus; 3 — a periodontium.

Cement covers dentine of a root on all its extent, and in a neck 3. it contacts to enamel. On structure cement very reminds a coarse-fibered bone. It consists of the main substance impregnated with salts of calcium, in Krom are located going in different on: boards collagenic fibers, Part of them crosses all thickness of cement in the radial direction and proceeds in fibers of a periodontium which are in turn interwoven into a bone of an alveolus. Mineral substances in cement make apprx. 70%. Distinguish two types of cement: acellular, or primary, and cellular, or secondary. Acellular cement is on side surfaces of a root; cellular cement — at a top of a root, and in multi-rooted teeth — in interroot department, i.e. at bifurcation of roots. Cellular cement contains otrostchaty cells — tsementotsita. Unlike a bone, cement does not contain blood vessels. Its food occurs by diffusion from outside periodontium (see), representing the sheaf strengthening 3. in a bone alveolus (fig. 19).

The pulp occupies a cavity of a tooth crown and channels of roots. At top of a root through an apical opening it is reported from periodontomas; through this opening from a periodontium in a pulp 3. blood vessels and nerves get. A pulp — multifabric part 3. It consists preferential of the friable connecting fabric containing a significant amount of jellylike intercellular substance where fibrous structures and cellular elements are located. Fibrous structures are presented by collagenic and prekollagenovy argyrophil fibers; elastic fibers are not found in a pulp. Collagenic fibers are located diversely, forming a condensation in the center near a neurovascular bunch. The pulp of root channels differs from a coronal pulp in high content of bunches of collagenic fibers. Cellular elements of a pulp are various: in addition to odontobdast, there are fibroblasts, macrophages, plasmocytes.

Fig. 5. Microdrug of a dentinogenny zone of a pulp of tooth of the adult: 1 — dentinal tubules in a layer of calciphied dentine; 2 — dentinal spheres; 3 — predentin; 4 — membranes between a layer of fibrilloblasts and predentin; 5 — fibrilloblasts; 6 — a subadentoblastichesky layer. Coloring hematoxylin-eosine

Fibrilloblasts take part in exchange, processes of dentine and enamel. They are located in the periblast of a pulp, directly adjoining to a layer of predentin (tsvetn. fig. 5). Fibrilloblasts have basphilic cytoplasm and an oval kernel. Shoots which get into dentinal tubules depart from top of fibrilloblasts and go on all their extent. Under a supermicroscope in cytoplasm of fibrilloblasts created 3. the advanced cytoplasmic reticulum, a lamellar complex and numerous mitochondrions is found. These organellas are oriented parallel to a longitudinal axis of fibrilloblasts. The cytoplasmic reticulum and mitochondrions come to light also in shoots of fibrilloblasts. Connection between fibrilloblasts is carried out as desmosomes. Between fibrilloblasts and predentin in intervals between inlet openings of dentinal tubules the thin membrane which received the name of a film of Kelliker — Fdeyshmanna is located.

Behind a layer of fibrilloblasts in a pulp the layer poor in cells, a so-called layer of Veyl is located; on drugs it has an appearance of the light strip located between fibrilloblasts and the third layer of a pulp, a subodontoblastichesky layer which is presented by a large number of star-shaped cells — pulpocytes with thin long shoots. In the center of a pulp cells like fibroblasts, and also a significant amount of macrophages are located.

Fig. 20. Microdrug of an odontoblastichesky layer of a pulp of tooth of the person with the sensitive nerve termination passing in it like a bush (it is specified by an arrow); x 600.

The lateral branches going to the periphery of a pulp depart from the central bunch of the nerve fibrils getting into a pulp through an apical opening; here they form a dense texture (Rashkov's texture), a cut consists of preterminal branches nervous volonon. Especially dense texture is found in the field of so-called horns of a pulp (ledges of a pulp according to hillocks of a chewing surface). L. I. Falin (1956) found out that the receptor terminations of nerves of a pulp preferential belong to the category of branched trailer bushes (fig. 20). Besides, in a pulp 3. special vascular and fabric receptors which terminal branches come to an end in connecting fabric and on vessels of a pulp are found.

Concerning an innervation of solid fabrics 3. there are various opinions. By means of a submicroscopy it is established that some trailer branches of nerve fibrils get into predentin, however in the most calciphied dentine nerve fibrils are not found. At the same time it is known that at preparation of a cavity in dentine there can be severe pain. Concerning an origin of such pain various hypotheses express. Most the informed opinion was stated by Brennstrem (M. to Brannstrom, 1962). According to its theory developing of pain during the processing of dentine depends on change of hydrodynamic conditions in dentinal tubules in this connection there is a moving of a part of cytoplasm of fibrilloblasts (dentinal liquid) to dentinal tubules that is transferred to nervous elements of a pulp. At a research of shoots of the fibrilloblasts passing in tubules of a zone of predentin, Frank (R. Frank, 1966) found near them fine amyelenic nerve fibrils; these fibers were revealed also in dentinal tubules of calciphied dentine.

Teething

One of the first theories of eruption 3. belongs to J. Gunter (1770) who believed that growth of roots is the reason of eruption. In his opinion, the growing roots milk 3. rest against a bottom of a bone alveolus and as if push out 3. from it.

G. V. Yasvoin (1929, 1936) put forward the theory, according to a cut not the growth of a root defines eruption 3., and on the contrary — development of a root happens in connection with eruption 3. The reason of eruption consists in processes of a differentiation of fabric of a tooth nipple at its transformation into fabric of a pulp 3. This differentiation is followed by formation of a large amount of intercellular substance therefore fabric of a pulp gets bigger volume in comparison with initial. Increase in volume of a pulp creates pressure in a dental germ, a cut forces it to move to a gingiva. Moment of full eruption 3. matches that stage of development of a pulp when all undifferentiated elements in it are spent.

Among other reasons which could explain eruption 3., many authors pointed to adjournment of again formed bone at the bottom of a tooth socket. Proliferation of a bone at the bottom of a tooth socket, and also increase in intra papillary pressure are the important factors promoting the movement cutting through 3. in the vertical direction. However also processes of reorganization of the bone tissue surrounding growing 3 are not less important. This point of view received the most finished expression in A. Ya. Katts's theory (1940). In his opinion, process of reorganization of a bone tissue ahead of and behind a dental germ at simultaneous development of tension in its basal part due to increase in intra papillary pressure offers an explanation for the movement 3. at its eruption.

L. I. Falin (1963), attaching significance to the mechanical factors stated above, considered that eruption 3. represents difficult biol, process, to-rogo processes of formation and growth of fabrics and which proceeds as a result of neurohumoral influences from all organism and conditions of the environment are the cornerstone. Diseases of a hypophysis, a thyroid gland and other closed glands cause deep disturbances in development and eruption 3.

Fig. 21. Roentgenogram of teeth of an upper jaw: the remains of the resolving roots of milk teeth (1) and the cutting-through second teeth (2).

Rassasyvaniye of a root milk 3. begins with that site where to it prilezhit a rudiment constant 3. (fig. 21). First of all cement and dentine in the field of bifurcation of roots at painters or at a top of a root of cutters and canines are exposed to a rassasyvaniye; rassasyvaniye of roots milk 3. begins in 2 — 3 after they were created.

Eruption 3. occurs in certain terms and in the strict sequence. Milk medial cutters are cut through aged from 6 up to 8 months, side cutters — from 8 to 12; the first painters — from 12 to 16; canines — from 16 to 20; the second painters — from 20 to 30 months. Considerable derogations from the specified terms of eruption in this or that party are possible. Extremely seldom cases of eruption of cutters till the birth of the child meet.

Eruption of constants 3. begins at the age of 5 — 6 years when the first painter is cut through; medial cutters are cut through in 6 — 8 years; side cutters — in 8 — 9, canines — in 10 — 11; premolar tooths — in the 9 — 12, second painters — in 12 — 13 years, the third painters (wisdom teeth) — in 18 — 25-year age.

Due to the general acceleration physical. development of children (acceleration) eruption 3 is observed. at earlier age. Full formation of roots of constants 3. comes to an end on average in the following terms: medial and side cutters and the first painters — on the 10th year of life, canines and small radical — in 12 — 14 years, the second painters — in 14 — 16 years.

Age changes

Enamel just cut through 3. it is covered with a cuticle (a nasmitovy cover) very steady against influence to - t. Cuticle 3. it is quickly erased during the chewing and in enamel of the adult it remains only on side surfaces of a crown. After eruption 3. it is gradually enameled a cover — a so-called pellicle — the thin acquired organic film consisting of proteinaceous and carbohydrate complexes (glycoproteins) which drop out in a deposit of saliva. From a deposit glycoproteins are selectively adsorbed by the surface of enamel. The pellicle, according to a number of authors, is a structural element of a surface layer of enamel, as if a medine between enamel and fluid medium of an oral cavity and represents the semipermeable membrane participating in processes of regulation of permeability of enamel; it is possible to remove a pellicle only with abrasive means or solution divorced salt to - you.

The pellicle always becomes covered by the soft dental plaque representing the whitish viscous not mineralized bacterial deposits (so-called tooth plaques) consisting of bacterial cells, intercellular substance and the specific liquid which is formed of saliva or the liquid of a dentogingival pocket containing to - you and the alkalis produced by microbes. The dental plaque formed during 24 hours after careful cleaning 3. (with single bacterial bodies), call unripe, in 72 hours — mature (established).

Mechanism of formation of a dental plaque: adhesion of the desquamated epithelial cells infested by bacteria to a pellicle and precipitation of extracellular polysaccharides and glycoproteins of saliva at destruction of bacteria.

Under certain conditions the soft dental plaque becomes impregnated with mineral substances and is formed dental calculus (see).

In the course of functioning 3. there is a gradual deleting of enamel, dentine. Intensity of deleting 3. it is various and depends on age, character of food, and also specific features of people. On degree of a stertost 3. it is possible to judge age of people, though not absolutely precisely. There is a special gradation of degree of a stertost 3., expressed in points from 0 to 6: 0 — lack of a stertost; 1 — emergence of a soshlifovannost, smoothness of hillocks (16 — 20 years); 2 — deleting of enamel with an exposure of sites of dentine on cutting edges and hillocks 3. (20 — 30 years); 3 — an exposure of big sites of dentine with deleting of all speakers of sites of a chewing surface of a crown, enamel remains only in the depth of grooves and poles (30 — 50 years); 4 — full deleting of enamel on a chewing surface (50 — 60 years); 5 — partial deleting of a crown 3. (60 — 70 years); 6 — full deleting of a crown 3. to the level of a neck (70 and more years).

With age in solid fabrics 3. content of mineral components increases, the amount of organic matters decreases, enamel and dentinal liquid, the gleam of dentinal tubules decreases; gradually there comes the obliteration of pulp cavities and root channels.

There are age changes and in a pulp 3., in it the number of fibrous structures increases, the quantity of cellular elements decreases, the layer of fibrilloblasts is rarefied, petrifikata often are found. In a periodontium 3. at aged people of 40 — 60 years sclerous changes of vessels often come to light.

Biochemistry

Studying of chemical structure and biochemical, processes in solid fabrics and a pulp 3. it is closely connected with problems of prevention and treatment of caries, a hypoplasia, a fluorosis, occupational and other not carious diseases 3.

Density of enamel makes from 2,90 to 3,05 g/cm 3 , density of dentine — 2,2 g/cm 3 . Enamel generally consists of inorganic fraction (95% for dry weight) in the form of the small crystals found by means of a supermicroscope and called by crystallites. Mineral component of dentine — 70% for dry weight. On chemical structure and a structure crystals remind minerals like a hydroxyapatite, however in hydroxyapatites 3. there can be a deficit (vacant positions) of calcium. The observed low ratio of calcium and phosphorus in surface layers 3 is explained by it sometimes. Contains in enamel apprx. 2% of neapatitny crystals: oktakaltsiyfosfat, dicalcium phosphate and calcium phosphate. Generally mineral fraction of enamel is presented by calcium phosphate and ions of a hydroxyl, and each crystal cell consists of 18 ions located in the form of a hydroxyapatite — Ca10(PO4)6(OH)2. A reactive part of structure of a hydroxyapatite represents the column of an ion of a hydroxyl located parallel to a longitudinal crystalline axis. Some ions of a hydroxyl collapse that strengthens the movement of ions in a column, increases its chemical reactivity. Other ions of a hydroxyl can be replaced with fluorine that limits mobility of ions of a hydroxyl in a column, leading to strengthening of communication with the subject calcium ions, and does a crystal steadier, promotes its formation in processes of a mineralization, - and remineralization. Calcium ions and phosphorus can be also replaced.

Enamel contains traces of sodium, magnesium, zinc, potassium, lead, strontium, iron, fluorine and other small ionic components, including carbonates most of which exists as a part of structure of a crystal of apatite, others — as the remains on sites of a surface of crystals or as a separate phase. Carbonates collect in a crystal lattice, replacing phosphates and to a lesser extent ions of a hydroxyl. Magnesium and other ions, including citrate, are too big easily to get into lattice structure and therefore are at the edges of a crystal.

The maintenance of usual ions in enamel depends on their concentration in the fabrics surrounding a dental germ during formation of crystals before eruption 3., to a lesser extent from their concentration in drinking water and foodstuff after eruption, and also from the speed of absorption of ions on a surface 3., edges it is regulated physical. a condition of enamel, degree of its mineralization, pH on border saliva — enamel.

The relation of calcium to phosphorus is slightly lower in carious, than in healthy enamel; in intact 3. at persons of young age this ratio is equal 2,07, at persons 30 years — 1,97 are more senior. Content of calcium and phosphorus increases in the direction from enamel and dentinal border to the surface of enamel.

Carbonates in surface layers of enamel contain in quantity apprx. 1,5%, and in a zone of enamel and dentinal border — apprx. 2,9%, and is established that with age the person the maintenance of carbonates in surface layers of enamel decreases; in the thickness of enamel of such changes it is not revealed. Magnesium in surface layers makes 30 — 60 µmol/g, in the thickness — 60 — 74 µmol/g.

Chlorides in surface layers of enamel make 0,6% and decrease to 0,1% in the depth of fabric. Chlorides are capable to exchange with hydroxylic group of a hydroxyapatite, but they are not fixed in calciphied fabrics. Strontium is found in 3. before eruption, and contents it in number of 90 — 150 mg/g constantly and in direct ratio to contents it in bones of an organism. It can easily collect in 3. by absorption.

Concentration of fluorine in enamel and dentine is closely connected with receipt it in an organism with drinking water and food. The following pattern in distribution of fluorine in enamel is noted. Its greatest concentration is found in 3. before eruption in the period of their mineralization, fluorine quickly joins in not completely mineralized enamel; in cut through 3. the most high level of fluorine is found in a surface layer of enamel. The zone of okolopulparny dentine contains 3 — 4 times more fluorine, than on enamel and dentinal border. Level of fluorine in coronal dentine in the field of a pulp reaches considerable sizes with increase in age; in dentine and in cement 3. content of fluorine also high.

Enamel contains 3 — 4% of the water occupying free spaces in a crystal lattice and an organic matrix of an enamel column, and also connected in structure of crystals; a part of water is presented in the form of the hydrated cover surrounding crystallites. The ions which are on a surface of crystals are connected with water molecules of hydrated covers. Besides, a part of water in enamel is connected with a small amount of proteic matters.

Organic matter of enamel (less than 4%) and dentine (apprx. 20%) is presented generally by proteins; besides, it contains carbohydrates, citrate, a lactate, lipids.

Proteins of an organic matrix of enamel on amino-acid structure belong to kollageno-and to keratinopodobny proteins. At recalculation on protein enamel contains 1,3% of proteic matters; proteinaceous components consist of soluble protein (0,3%), insoluble protein (0,9%), free amino acids (0,1%) and high-molecular polypeptides.

Most part of protein of enamel (70%) 3. the person is made by insoluble fraction at pH 5,5; the fraction of free amino acids makes 10%. In enamel 3. a fruit the prolinecontaining proteins prevail. After eruption 3. enamel loses 90% of protein. At adults the ground mass of protein of enamel consists of low-molecular weight compounds with a large amount of serine, generally in the form of serinephosphate. In protein a significant amount of oxyproline is revealed that allows to carry it to collagen. The proteinaceous matrix of dentine and cement consists of collagen. In dentine acid serusoderzhashchy mucopolysaccharides, glycoproteins are found.

Collagen of dentine contains 0,6% of a hondroitinsulfat (a hexosemine and hexuronic to - that).

The carbohydrate composition of enamel and dentine is presented by a glycogen; from carbohydrate components in enamel the galactose, glucose, mannose, a fukoza, xylose, rhamnose are found. The glycogen provides energy for processes of formation of crystallization nuclei. Monosaccharides (glucose) are a part of an uglevodnobelkovy complex of soluble and insoluble protein of enamel. In the surface of enamel contains in 10 times more of carbohydrates, than in deep layers. Among chemical components is enamel and dentine in rather large number citrates are found (enamel — 0,1%, dentine — 0,8 — 0,9%). Citrates take part in processes of a mineralization and demineralization of solid fabrics 3., forming a soluble transport form with calcium phosphate. Lactates (0,01 — 0,03%) also participate in processes of a mineralization. The maintenance of lipids in enamel 3. makes 0,6% for dry weight, in dentine — 0,2%.

Exchange processes in enamel, dentine and a pulp 3. are carried out by means of the circulating liquid. Dentinal liquid protein content makes from 0,45 to 1,2% in comparison with 6,6% in a blood plasma, the reducing substances (sugar) — 45 mg of %. Content of calcium and inorganic phosphorus in dentinal liquid is lower, than in a blood plasma.

Availability of liquid in enamel was established by Bergman (G. Bergman, 1963); he established that between enamel and dentine there is close connection since from dentine to enamel liquid is transported. On structure enamel liquid differs from dentinal? too small time in enamel does not pass the large molecules which are contained in dentinal liquid. Enamel liquid serves as the transport environment for ions and small molecules.

Extracellular matrix of a pulp 3. it is characterized by existence of the glycoproteins, acid mucopolysaccharides and proteins containing amino groups, characteristic of collagen. Basal membrane of vessels of a pulp 3. it is rich with glycoproteins.

Macromolecules of fabric of a pulp 3. have amphoteric properties (i.e. acid and alkaline). At fiziol, pH values carboxyl groups of collagen, glycoproteins and acid mucopolysaccharides give a negative charge to an extracellular matrix. It causes not only absorption of alien substances, but also and the cations having fiziol, value. Extracellular matrix of a pulp 3. consists from easily water soluble and isotonic solution of sodium chloride of the fraction and insoluble fraction steady against neutral and acid buffers. Protein content in a pulp 3. equally to 52+-3 mg/g, a glycogen — 42,4 mg of %.

Pulp 3. differs in activity of oxidation-reduction processes, rather high in comparison with other body tissues, and respectively a high level of oxygen consumption. Regulation of the energy balance of a pulp 3. it is carried out by means of the interfaced phosphorylation. Existence of a pentozomonofosfatny cycle testifies to a high level of exchange processes in a pulp, the most high level to-rogo is defined in the period of active products by fibrilloblasts of dentine, napr, at formation of secondary dentine. By means of radio isotope techniques (including radio of autography) in a pulp found active processes of synthesis of RNA and consequently, and proteins, patterns of proteinaceous and synthetic function of fibrilloblasts normal are revealed and deciphered and at pathology.

Pulp 3. it is rich with enzymes, the carbohydrate metabolism which is especially dominating in a pulp, namely, enzymes of glycolysis: zymohexase, lactate dehydrogenase, malate dehydrogenase, etc. The pulp also contains respiratory enzymes: cytochrome oxydase and catalase, various forms of esterases, alkaline and acid phosphatases, glyukozo-6-phosphatase, adenozintrifosfataza, aminopolypeptidase, cholinesterase, etc. The found complex of enzymes allows to characterize a pulp as fabric with high fermental activity that causes a high level of a trophicity, reactivity and protective mechanisms. Increase in fermental activity of a pulp at pathology testifies to it (see. Caries of tooth , Pulpitis ).

Researches under a supermicroscope revealed also complex structure of the soft dental plaque always covering 3. and playing an essential role in biochemical, the processes proceeding in enamel. The colonies of different types of microorganisms making the ground mass of a dental plaque are put into the organic matrix consisting of precipitated calcium superphosphates of glycoproteins of saliva, its proteins and partially of extracellular microbic polysaccharides. Bacteria of a dental plaque and saliva, first of all synthesize streptococci, and also some strains of lactobacilli and actinomycetes from biopolymers of the glucose and fructose (a dextran glucan and lavan-fruktan) coming to an oral cavity with food of sucrose with high (5 — 20 million) pier. it is powerful. The mutant streptococcus of a dental plaque produces water-insoluble biopolymer — the muton consisting of the glucosic units connected by alfa1-1-3-bonds in addition to the water soluble dextran connected by alfa1-1-6-bonds. Mutan makes up to 1,35% of dry weight of a dental plaque. The dextran of a dental plaque contains up to 95% of all hexoses extracted from it, 5% fall to the share of lavan.

Extracellular polysaccharides of bacteria influence microbic structure of a dental plaque, promoting increase in its acid potential, thus as if increasing solubility of enamel, lowering its resistance. Porosity and permeability of a soft dental plaque depend on a specific arrangement of bacterial cells and speed, about a cut of space between them are filled with the polysaccharides produced by bacteria. At destruction by microbes of carbohydrates of food or nitrogenous substances collecting in a soft dental plaque to - you and alkalis diffuse in saliva. Diffusion rate to - t and alkalis from a plaque is less, than the speed of their education therefore they accumulate. Excess accumulation to - t can promote dissolution of enamel, dentine. Accumulation of alkalis leads to adjournment in an organic matrix of a dental plaque of phosphates and calcium from saliva and liquid of a gingival pocket and to education dental calculus (see).

Apprx. 80% on the weight of a dental plaque the water which is in bacteria and connected with protein makes. Calcium, phosphorus, potassium and sodium are a part it. The first two macrocells come to a soft dental plaque from saliva, however phosphorus can pass into a plaque from enamel. Much more, than in saliva, sodium and potassium — it is less calcium and phosphorus in a dental plaque. From microelements in a dental plaque as well as in enamel, high concentration of fluorine, iron, zinc are noted.

Concentration of fluorine in a dental plaque in tens — hundreds times more, than in saliva (from 6 to 180 mg/kg); it joins in a plaque from saliva, food and can arrive from enamel at decrease in pH of a plaque, to 2 — 3% of fluorine is in the ionized form; it actively influences metabolism of a plaque. Level of fluorine in a plaque depends on its concentration in drinking water.

The dental plaque contains phosphatases, proteases, collagenases, hyaluronidases and other enzymes of generally bacterial origin, and also it is a lot of enzymes of carbohydrate metabolism; pH of a dental plaque is, as a rule, higher at persons with the high speed of salivation.

Physiology

Enamel, dentine and pulp 3. possess a row fiziol, features. Enamel 3. — avascular fabric, free of and nerve fibrils; its trophicity and transport of various substances are carried out on a basis fiziol, mechanisms: permeability, circulation of enamel liquid, solubility and ion exchange. These processes provide also constancy of composition of enamel at the expense of a dynamic equilibrium between processes of demineralization and remineralization (recrystallization). Dentine 3. it is penetrated by a set of dentinal tubules with the shoots of fibrilloblasts passing in them and the circulating dentinal liquid.

Enamel 3. has high resistance to influence of considerable mechanical loading, temperature variations (+50 C), to acid and alkaline products, enzymes, various physiologically active agents of oral liquid and bacteria of an oral cavity.

Level of resistance of enamel 3. it is very high: after influence of the strong demineralizing solutions remineralization of enamel occurs in several days. As expression of protective function at influence of pathogenic agents, napr, at caries, enamel reacts formation of the zones of a hyper mineralization delimiting the damaged enamel from intact. Dentine 3. also reacts to influence of the damaging agents formation of replaceable dentine at the expense of synthetic (hl. obr. proteinaceous and synthetic) functions of fibrilloblasts of a pulp 3. Fibrilloblasts participate in formation of dentinal liquid.

Trophicity of solid fabrics 3. and its regulation pulps and a parodonta are carried out by interaction of sialadens, saliva, oral liquid, a dental plaque, pellicle, enamel and dentinal liquids. This system which is expression of adaptable and compensatory mechanisms of regulation provides function 3. normal and at some patol, states, napr, in pulpless 3., at the raised loadings on 3., used as a support for dentures, etc.

The main source of intake of substances in dentine are vessels of a pulp 3. Surface layer of enamel 3. the hl is supplied. obr. substances from saliva; the substances arriving from saliva can get into a pulp 3. and vice versa.

Important property of enamel 3., providing transport of various substances and a trophicity, is permeability (see). Enamel, as well as dentine, a pronitsayema in both directions: from the surface of enamel to dentine and a pulp (tsentrostremitelno) and in the opposite direction — from a pulp and dentine to the surface of enamel (tsentrobezhno). Level of permeability of enamel is rather high: through enamel 3. not only ions and mineral elements, but also substances of high molecular weight, with big sizes of molecules — amino acids, vitamins, enzymes, carbohydrates, etc. get. Speed of penetration of various substances into enamel is also relatively high: from several micrometers to 1 mm an hour depending on chemical properties, molecular weight, etc. Especially quickly carbohydrates, first of all glucose get into enamel; rather quickly get lemon to - that, bacterial toxins, urea and thiourea, niacinamide and acetamide, a lysine, glycine, methionine, polyneuramin 1 etc. Permeability of enamel 3. decreases with age, and also at influence of alkaline products, lime hydrates, etc. raises under the influence of various organic and inorganic to - t, urea, at deficit of salts of phosphorus in food. Thyrocalcitonin (hormone of a thyroid gland) raises, and parathormone (parathyroid) lowers permeability of enamel. Increases permeability of enamel and drug parotin (an extract from a parotid sialaden). The substances applied to treatment 3. (alcohol, phenol, salt to - that, solutions of silver nitrate and calcium chloride, clove-stems oil, etc.), increase permeability of enamel. Keratino-and kollagenopodobny soluble proteins of enamel, and also the lipids which are contained in a small amount participate in regulation of permeability of fabrics 3.

At damage of a pellicle resistance of enamel sharply decreases due to increase in permeability and solubility. Permeability of enamel 3. it is possible to raise impact on it some physical. (electro-and fonoforez), chemical and biologically active factors (hyaluronidase, acetylcholine, phosphatases, etc.) or to lower by influence of fluorine, adrenaline, etc. The mechanism of impact on permeability of enamel of the specified mediators and enzymes is not clear.

Transport of substances and a trophicity of solid tissues of tooth are carried out by means of enamel and dentinal liquids. Enamel liquid is distributed in enamel 3. unevenly: it is more of it in a deep layer of enamel, especially at enamel and dentinal border. The movement of enamel liquid happens generally in intercrystal spaces and in enamel plates, and dentinal liquid — on dentinal tubules. Circulation of dentinal liquid provides a trophicity of dentine and partially enamel, adjacent to dentine (on enamel and dentinal border).

Circulation of enamel and dentinal liquids happens generally due to hydrostatic and thermodynamic effects, osmotic and electroosmotic currents, and also the mechanisms regulating permeability of solid fabrics 3. The hydrostatic effect is caused by pressure of blood and an intercellular lymph of a pulp, and also secretory function of fibrilloblasts. The thermodynamic effect is caused by the heat drops arising in an oral cavity at breath, a conversation, from cold or hot food and causing expansion of liquid in enamel and dentine and its movement towards smaller temperature. Osmotic currents in solid fabrics 3. arise owing to a difference of osmotic pressure in an intercellular lymph of a pulp 3., dentinal, enamel and oral liquids. The phenomena of electroosmosis in enamel and dentine are caused by the electrokinetic processes arising on border firm (a surface of crystals of a hydroxyapatite) and liquid (hydrated and absorbing layers of crystals) phases. Electrokinetic potentials of solid fabrics 3. can arise on border of hydrated and absorbing layers of crystals of a hydroxyapatite owing to preferential adsorption of ions of one sign, ionization of a surface of crystals (on border with an absorbing layer) or the piezoelectric effect described by the Basset (A. Basset, 1967), arising in crystal structures.

Solubility and remineralization of enamel — two dynamic processes (dissolution of crystals of a hydroxyapatite and their education again — recrystallization) which provide updating and constancy of components of enamel. These processes are caused by ions and hydroxyls macro - both microelements and change of pH of oral liquid. Normal oral liquid represents peresyshchenny solution of a hydroxyapatite that at optimum pH interferes with dissolution in it of enamel and causes receipt in enamel of calcium ions and phosphorus, providing its remineralization (recrystallization). At pathology, napr, at caries, when concentration of a hydroxyapatite in oral liquid and pH on the surface of enamel 3. go down, solubility of enamel 3. raises, demineralization prevails over remineralization with disturbance of structure of crystals of a hydroxyapatite. The optimum ratio between calcium and phosphorus of saliva since crystals of a hydroxyapatite are dynamically steady (elektroneytralna) at a ratio calcium — phosphorus 1:1,67 is important for processes of recrystallization.

In processes of remineralization of enamel 3. the essential role belongs to organic matrixes of the enamel columns which are in direct chemical communication with crystals of a hydroxyapatite. Important property of proteins of enamel 3. their expressed ability to a mineralization at the expense of a large amount of the phosphoserine which is their part through which chemical communication with a hydroxyapatite is also carried out is. Essential role in dynamic stability of solid fabrics 3. play glycoproteins (glikozaminoglikan) which are carrying out chemical bonds between proteins, carbohydrates and mineral elements of solid fabrics 3., closely connected and in many respects the defining processes of remineralization of enamel. The lipids which are contained in enamel in a small amount also participate in processes of a mineralization and remineralization. Remineralization of enamel 3. (including at influence of pathogenic agents, napr, at caries) it is possible only at preservation of function of organic matrixes of enamel.

Exchange processes in solid fabrics 3. are made very slowly in comparison with other fabrics. However it was experimentally shown that, e.g., the marked 14C amino acid entered vnutriserdechno glycine is found in solid fabrics 3. in 10 — 15 min.; even quicker mineral salts (macro - and microelements), slightly more slowly carbohydrates, then proteins, lipids arrive; rather quickly carbonates arrive. Speed of updating of solid fabrics 3. (determined for body tissues by an elimination half-life of substances) inorganic and organic components it is also small. E.g., if speeds of semi-removal of mineral and proteinaceous components from tissues of a liver, muscular and other metabolic active fabrics the elimination half-life of calcium of enamel 3 makes hours and days, then. the person, according to different data, equals on average apprx. 500 days. Intensity of exchange processes in enamel is much lower, than in dentine.

Exchange of mineral elements is carried out at the level of ion exchange with participation of catalysts like microelements (first of all fluorine, molybdenum, etc.), hormones (thyrocalcitonin, parathormone, somatotropic hormone of a hypophysis, etc.), mediators of a metabolic row (adrenaline, acetylcholine) and physiologically active agents of saliva and a dental plaque. Exchange of proteins of solid fabrics 3., especially enamels, occurs extremely slowly. Experiences with marked 14C oxyproline showed a possibility of inclusion of free amino acids in molecules of proteins of enamel.

Enamel and dentine have low electroconductive and respectively high dielectric properties (resistance of solid fabrics 3. makes apprx. 2 Megohms). These fiziol, properties have essential value at researches (a reografiya, an electric pulp test, etc.) and treatment 3. (electro-, fonoforez). Solid fabrics 3. pronitsayema for light in visible and invisible (infrared) parts of a range that allows to carry out raying (a trance illumination) and a fotoodontografiya 3.

A surface layer of enamel together with a pellicle 3. and a dental plaque, being boundary with oral liquid, according to a number of authors, performs protective function as a multilayer semipermeable membrane.

Pulp 3. possesses a number of adaptation and compensatory opportunities. Because blood circulation of a pulp happens in the closed space limited to walls of a cavity 3., its vascular network has effective anticongestive properties: the total gleam of veins of a coronal pulp is more, than in the field of an apical opening, i.e. peripheral speed of a blood-groove in an apical opening of a root 3. above, than in a coronal pulp; the nature of pulse fluctuations of veins is similar to veins of a brain. Mechanisms of regulation of microcirculation are very perfect: a difference of a pressure gradient (on an arterial part of capillaries — 25 — 30 mm of mercury., on venous — 8 — 10 mm of mercury.); konstriktorny sympathetic (adrenergic) innervation; the arteriovenous anastomosis shunting blood at influence of temperature irritants, chewing pressure, etc.; own myogenetic tone of vessels as fiziol, mechanism of protection of fabric of a pulp against hypostasis; the humoral factors (metabolites, kinina, a histamine, etc.) operating on well-cared and adrenoceptors of vessels of a pulp and directly on smooth muscles of vessels.

At penetration into a cavity 3. alien substances, infectious agents, etc. the pulp actively reacts in the form of an inflammation, is more often with formation of the connective tissue capsule delimiting a zone of damage, and at perforation of a cavity 3. the dentinal bridge at the expense of active products is quite often formed by fibrilloblasts of secondary dentine.

Solid fabrics 3. under certain conditions pronitsayema for infectious and toxic agents, but a pulp 3. possesses the expressed barrier function: existence of gistogematichesky barriers, phagocytal activity of macrophages and other cells. One of features of a pulp 3. very high absorbing capacity of cells of an endothelium of vessels as one of reserve fiziol, mechanisms of fabric protection is, especially at an inflammation of a pulp.

With age functional properties 3 change. In its solid fabrics the level of permeability, solubility and exchange processes decreases. In a pulp the level of microcirculation and exchange processes sharply decreases, the tone and reactivity of walls of vessels goes down, their gleam decreases, walls of vessels are sclerosed, dehydration of a pulp develops; there occur destructive changes of cellular elements; barrier and protective properties decrease. Therefore at a research intact 3. and at various patol, processes, and also at treatment it is necessary to consider age changes 3.

Methods of a research

For definition of a state 3. conduct survey and survey of the patient, percussion, a thermodiagnostic and special tool researches. At poll of the patient it is important to establish not only the anamnesis of a disease, but also a working condition; professional harm, able to promote the increased erasability of fabrics 3., possibility of an acid necrosis (couple to - t), caries (e.g., during the work at the confectionery enterprises); reveal addictions (smoking, chewing of tobacco, disturbance of food, etc.).

The main subjective symptom at diseases 3. pain is, different character and duration can have edges. Pain arising under the influence of mechanical, physical. and chemical irritants, it is characteristic of caries. The continuous pulling or throbbing pains with strict localization amplifying during the pressing on

3., are typical for periodontitis; the pristupoobrazny pains with irradiation on the course of a trifacial arising spontaneously, especially in the evening or at night are characteristic of an inflammation of a pulp.

Examine 3. with the help stomatol. a mirror and the probe, the Crimea define an integrity of enamel, a softened dentine, depth of a carious cavity, its message with a cavity 3.

Percussion — easy percussion on 3. — apply to definition of a condition of a periodontium. Distinguish vertical (on axis 3.) and horizontal (in the side direction) percussion. If the periodontium is not changed, percussion 3. it is painless; at inflammatory process from blows of the same force in it there is pain.

Normal 3. irritants in the form of short-term weak pain react on temperature (hot and cold). At a pulpitis note inadequate feeling: from cold and warm there is severe long pain. At a nekrotization of a pulp 3. do not react to temperature irritants.

Fiziol, the condition of a pulp and a periodontium can be defined by an electric pulp test (see. Elektrodiagnostika ).

Healthy 3. react to irritation electric current with a force of 2 — 6 mk. Decrease in sensitivity to irritation indicates by electric current to 20 — 40 mk inflammatory process in a pulp. At a necrosis of a pulp the periodontium reacts to irritation electric current 100 — 200 mk.

At radiological the revealed changes in a periodontium reaction to influence of electric current arises with the force of 250 mk and above.

Apply the following special researches.

Definition of resistance of enamel is based on properties of a mineralization, permeability and solubility. The Colour Reaction Time test (CRT test) offered by Myulemann and Volgenzinger (H. R. Muhlemann, F. Wolgensinger, 1959), is based on use of the demineralizing solution (1 N solution salt to - you) with an acid base indicator (0,02% water solution of a crystal violet) and the staining reaction, on discoloration of the indicator showing degree of solubility of enamel. The surface of enamel is carefully cleared cotton plugs of a dental plaque, dried up warm air and place on it a disk from filter paper to dia. 3 mm, impregnated during 30 sec. with the indicator, also apply on it with an automatic micropipet 1.5 mkl 1 N solution salt to - you. Time in seconds from the moment of drawing to - you before full transition of coloring of a paper disk from light green to pink-violet characterize the size of the CRT test. This indicator depends on a number not always of comparable conditions (different thickness of paper disks, density of their prileganiye, etc.) therefore the size of the CRT test normal can fluctuate over a wide range — from 20 to 120 sec.

More exact way of definition of resistance of enamel 3. it is offered by V. K. Leontyev (1975); this way is also based on influence of the demineralizing solution with the subsequent definition in it of calcium, to-rogo determine degree of solubility by quantity and, respectively, resistance of enamel 3. The demineralizing solution — 1.5 mkl the muriatic pH 0,37 buffer (97 ml 1 N solution salt to - you, 50 ml 1 N solution of potassium chloride, 200 ml a dist, waters with addition of glycerin — 1 part) — a semi-automatic micropipet apply on 1 part of the specified solution on previously processed (see above) enamel. In 1 min. the same micropipet the drop of the demineralizing solution is removed and determine the content of calcium by Karakashev's technique — Vicheva in V. K. Leontyev's modification (1972).

Raying of teeth (transillumination) gained distribution in connection with development of small-size powerful electrolamps, especially such sources of radiation as lasers (e.g., helium - neon, helium - cadmium, etc.), and also the flexible fiber light guides allowing to bring a light flux to any 3. At raying 3. well microcracks, an initial stage of caries, defects of enamel of not carious origin, recurrent caries sealed up 3 are found., inflammation, necrosis of a pulp, subdingival dental calculus, etc. Sometimes raying possible to define extent of development or a rassasyvaniye of roots milk 3., what allows to avoid an undesirable X-ray analysis at children's age.

Functional methods of a research of teeth give the chance to conduct a research by means of functional loads (heat, cold, vasoactive substances, napr, nicotinic to - that, the dosed chewing tests, etc.) for definition of adaptation and compensatory opportunities of a pulp 3., and also to reveal hidden patol, process. For a research funkts, conditions of a pulp 3. use ways of a reodentografiya and a fotoodontografiya. Reodentografiya is based on registration of a krovenapolneniye of a pulp 3. on change of electric resistance of its fabrics at a transmission of electric current of high frequency (600 — 800 kHz). Fotoodontografiya is based on registration of a krovenapolneniye of a pulp 3. on change of its optical density at raying 3. with use of light sources (including the semiconductor laser), using electronic (reopletizmograf) and the electron-optical (photoplethysmograph) devices allowing to register graphically a krovenapolneniye and blood circulation of fabrics 3. with the subsequent mathematical interpretation of results of a research. These methods help to control influence of some pharmaceuticals used at treatment of caries, a pulpitis, etc., a condition of a pulp at an inflammation, damage, after preparation 3. under artificial crowns, etc.

X-ray inspection sometimes is the only method allowing to reveal patol, process in solid fabrics 3. and a parodonta, a change of a root, a hypercementosis, lack of dental germs at an inborn edentia, etc.

The main method rentgenol, researches is X-ray analysis (see). Special value has contrast and clearness of the shadow image of roots 3. and bone structure of a jaw. That size and form 3. in pictures corresponded valid, a X-ray analysis produce not less than 50 — 60 cm at focal length. In the same purposes it is necessary to aim to arrange a film parallel to a dischargeable object, and to direct the central beam, whenever possible, perpendicularly to a film. Pictures 3. make usually in one (direct) projection under various corners from top to down or from below up. The X-ray analysis is carried out intra oral and extraoral by ways.

Fig. 22. The roentgenograms of teeth made in the intra oral contact way: and — a curvature of roots of the 4th and 5th upper small molars (1), an osteoporosis at tops of roots of the 4th and 5th teeth (2); — carious cavities in the 5th, 6th and 7th teeth (1); fragment of the tool in the 5th tooth (2) and an osteoporosis at roots of the lower 5th and 6th teeth (3); in — the hanging edges of seals of the lower 6th and 7th teeth.
Fig. 23. Position of the head investigated at an intra oral contact X-ray analysis of foreteeth: 1 — an upper jaw (at the left above — the provision of a film in a mouth), 2 — a mandible. The arrow specified the direction of the central bunch of x-ray emission.

The intra oral X-ray analysis is carried out by means of contact pictures and pictures vprikus. Contact pictures give the chance to receive more sharp image (fig. 22). At an intra oral contact X-ray analysis of lobbies 3. the x-ray film is entered into an oral cavity and have under this or that corner to 3., pressing it to roots so that it formed with axis 3. acute angle (fig. 23). At an intra oral research of a parallel prileganiye of a film to 3. and okoloverkhushechny fabrics do not manage to receive. For the minimum deformation, lengthening or shortening 3. on roentgenograms the central bunch of x-ray emission should be directed so that it fell perpendicularly to a bisector, formed by axis 3. and plane of a film.

The sitting position of the patient at a research is more convenient since at it it is easier to enter a film into an oral cavity, to fix it, to center a bunch of radiations, and it is easier for patient to swallow the collecting saliva. At a X-ray analysis the comfortable and steady position of a body, fixing of the head in the necessary situation on a head restraint, a pillow, the roller or sacks with sand shall be provided.

At a X-ray analysis 3. an upper jaw in a sitting position the head of the patient shall be a little inclined forward, and for a X-ray analysis of side departments of a jaw the head is as much as possible turned to the opposite side. The patient densely presses a x-ray film to a hard palate and an alveolar shoot a thumb of a hand opposite to a picture. The central beam is directed ortoradialno, from top to down through a top of the root investigated 3. At a research 3. the mandible in a sitting position of the patient should throw back the head a little back, the film is also pressed to alveolar edge a big or index finger. The bunch of radiation is directed from below up and ortoradialno through a top investigated 3. At this method apply films of 3x4 or 4x5 cm in size, their corners are rounded off. Films turn in black paper, outside wrap a wax paper. Before introduction to a mouth corners of a wrapped up film are a little folded and have it in a mouth so that investigated 3. was in the center, and the free edge of a film supported on 0,5 cm edge of crowns 3. Films in factory packing are more convenient.

The correct centration of a X-ray tube at an intra oral X-ray analysis can be carried out by means of the special centralizer which is available on a X-ray apparatus and an inclination of a X-ray tube according to the table offered by S. L. Kopelman and L. G. Berman.

Table. Tilt angles of a X-ray tube at a X-ray analysis of teeth


At good skill the doctor and the X-ray laboratory assistant give to a tube a necessary inclination, without resorting to a goniometer.

Pictures of all upper cutters, as well as lower, usually do on one film. The clear image of a root of a canine sometimes manages to be received on one film together with cutters or premolar tooths, however more often the picture of a canine should be done separately. Pictures of premolar tooths and painters (top and bottom) should be done separately. To receive the separate image of a palatal and buccal root of upper premolar tooths, the X-ray tube should give a small inclination in the medial or lateral party, having provided these passing of radiation through interroot space. The same way sometimes it is possible to receive the separate image of roots of upper painters. For assignment of a shadow of a malar from tops of roots of painters the central beam is directed to a film under more acute angle. Sometimes it is not possible to make an intra oral picture upper 3. wisdom, then resort to a X-ray analysis vprikus.

Fig. 24. Position of the head investigated at an intra oral X-ray analysis of foreteeth vprikus: 1 — an upper jaw, 2 — a mandible. The arrow specified the direction of the central bunch of x-ray emission.
Fig. 25. The scheme of an arrangement of a film (black color) and the direction of a beam of x-ray emission (dashed lines) at an intra oral X-ray analysis vprikus an upper tooth of wisdom.

vprikus resort to an intra oral X-ray analysis in cases, when there is no an opportunity to make the intra oral contact roentgenogram — at the complicated dehiscence of a mouth, at hypersensitivity of a mucous membrane of an oral cavity, wounded in a jaw, and also at a research of small children. The film of 6 X 8 pieces in size is entered to the sitting or lying patient into an oral cavity in horizontal position, and the patient holds her close teeth (fig. 24). The head of the patient is given the same situation, as well as at a contact X-ray analysis. At pictures upper 3. the inclination of a tube in relation to the horizontal plane of a film does not exceed +60 °, and for lower — 20 °. For a picture upper 3. wisdom the x-ray film is advanced deeply in an oral cavity, and the central beam is directed to a film from above and in front through bottom edge of an eye-socket at an angle in 60 ° (fig. 25). For a X-ray analysis vprikus lower 3. to wisdom the central beam is sent from below up according to a corner of a jaw, it is perpendicular to a film. On roentgenograms vprikus the image turns out less accurate, than on contact, but there is an opportunity on rather big films to receive the image of a large number 3.

An extraoral X-ray analysis for a research 3. it is applied extremely seldom since the image small patol, the centers, roots 3., a periodontium and bone structure it turns out much less accurate, the sizes of roots are proyektsionno increased; it is explained by a considerable distance of roots 3. and jaws in general from a film. At an extraoral X-ray analysis 3. are guided by the general rules of shooting of a jaw (see. Jaws, X-ray inspection ).

Fig. 26. Panoramic roentgenogram of teeth top and bottom jaws.

The panoramic X-ray analysis which is carried out by the special device gives the chance to receive the simultaneous image of top and bottom ranks 3. (fig. 26). The picture, as a rule, does not differ in clearness, but gives a general idea about a condition of roots and periapical tissues of all 3. On the basis of these data it is possible to make additional aim intra oral pictures 3. for detailed studying. The panoramic X-ray analysis is effective during the carrying out medical examination of the population, especially children and teenagers.

At rentgenol, a research 3. strict observance of «Rules of the device, operation and safety of work in X-ray departments» is obligatory (see. X-ray department ). During obtaining the intra oral roentgenogram it is impossible to resort to the help of personnel for fixing of a film in a mouth of the patient.

Pathology

To patol, to processes anomalies of development separate 3 belong., dentitions, anomaly of a bite, dystrophic processes in 3., caries 3. and its complication — a pulpitis, and also acute and hron, injuries.

Anomalies of teeth, dentitions, anomalies of a bite

Anomalies of teeth have unequal value. One anomalies are not followed by functional disturbances and have only a nek-swarm cosmetic value (deviations in shape, the size, color); others lead to functional frustration, napr, anomalies of situation, a retention 3., inborn absence 3. Some deformations distort a ratio of dentitions, break a configuration of the person, napr, sharply expressed prognathism, a progeny, an open bite (see. Bite ); such anomalies are subject to correction with the help orthodontic methods of treatment (see).

The various factors influencing dentoalveolar system during its formation, especially during formation of constants 3 can be the cause of anomalies. So, at a lack of vitamin A formation of organic matrixes of solid fabrics 3 is broken. At insufficiency of function of parathyroids the mineralization 3 is broken., at hypofunction of a hypophysis 3. are early cut through, but quickly collapse. At insufficiency of function of a thyroid gland overdue eruption milk and constant 3 is observed., partial edentia, underdevelopment of fabrics 3.

Fig. 27. Model from a mold of an upper jaw with anomaly of an arrangement, form and number of foreteeth.

Refer anomalies of situation 3 to anomalies of development. and their numbers, terms of eruption, size, form, color. As anomaly of number observe surplus 3. this or that group — a so-called supradentia, or a giperdentiya (fig. 27), inborn lack of all or some 3. (see. Edentia ), connected more often with death of rudiments in development. It is necessary to distinguish a retention from an edentia or a gipodentiya 3., when in a jaw 3. were created, but were not cut through. Quite often there are no 3. wisdom or owing to lack of laying of their rudiments, or owing to a retention. Retention 3. more often happens it is connected about a nek-swarm by a growth inhibition of a jaw, in connection with premature removal milk 3. Death of a dental germ constant 3. it is most often connected with inflammatory process in a periodontium milk 3. At a supradentia accessory 3. can have either normal, or irregular shape; they are located more often out of a tooth arch. Accessory 3., causing cosmetic defect, are subject to removal.

Premature or overdue eruption 3 belongs to anomalies of eruption. Premature eruption is observed rather seldom; however cases of eruption of one or several 3 are known. at the newborn. Overdue eruption is often expressed in a deviation from average terms for 4 — 8 months. Eruption 3., as a rule, proceeds without the general complications. Diseases of children during eruption 3. most often it is necessary to consider as coincidence, but not as a result of this process. However at the children weakened napr, at anemia, rickets, at diseases of a nervous system, frustration escalate went. - kish. a path, respiratory tracts, sometimes at the children inclined to a spasmophilia, spasms (can be observed more often at eruption of canines and painters). To complications at eruption milk 3. it is possible to refer morbidity and an inflammation of a gingiva, as a rule, not demanding special treatment. At eruption of painters between hillocks of a chewing surface sometimes a nek-swarm time remains a crossing point of a gingiva, edges is injured and inflames that can be followed by fervescence, a sleep disorder. In such cases the section of this crossing point, antiseptic processing of a gingiva is shown.

A frequent complication — the so-called complicated teething of wisdom of a mandible at that age when growth and formation of jawbones are already complete. At the same time the gingiva covering a crown cutting through 3., inflames (pericoronitis), in the started cases the periostitis and even osteomyelitis of a jaw can develop (see. Jaws, pathology ).

Fig. 28. The roentgenograms revealing anomaly of position of not cut through wisdom teeth (are specified by shooters).

Anomalies of situation 3 are most widespread., which can be cut through out of dentition, to be turned around a vertical axis (torsiversion), a chewing surface 3. can be higher or lower than a chewing surface of the others 3. this row. Wide intervals between 3 belong to anomaly of situation. (see. Diastem , Trema ) and a transposition — inborn movement 3. to the place of 3. other group, napr, a premolar tooth to the place of a canine; 3. it can be cut through in a nasal cavity, a genyantrum, an eye-socket. Also the anomalies which are shown a close arrangement 3 meet., which as if approach at each other. Reason of a close arrangement 3. the heterotopy of dental germs, an underdevelopment of jaws is. Sometimes anomalies of situation 3. are caused by the fact that constants 3. take the place prematurely remote next milk 3., and corresponding constant 3. remains impacted. The wrong situation 3 is quite often observed. wisdom; features of their arrangement come to light on the roentgenogram (fig. 28).

Fig. 29. Abnormal shapes of teeth: 1 — Fournier's tooth; 2 and 3 — Getchinson's teeth; 4 — Pflyuger's tooth.

Anomalies of a form 3. meet in each group (fig. 29). 3 treat anomalies of a form of medial upper cutters. an otvertkoobrazny or barrel-shaped form (cross sectional dimension of a crown at a cutting edge is less, than at a neck), on a cutting edge defect of a semi-lunar form is defined. This form of anomaly was described by J. Getchinson, observing it is exclusive at the children having inborn syphilis. A. Fournier observed at inborn syphilis medial upper cutters of an otvertkoobrazny form, but without semi-lunar dredging. This defect is not considered specific to inborn syphilis since it arises also as a result of other diseases of the child during development 3.; only in the presence of Getchinson's triad — all three symptoms of inborn syphilis — 3. an otvertkoobrazny form can be a pathognomonic sign (see. Syphilis, inborn ).

Anomaly of upper medial cutters which are similar to a wedge or a thorn (aculeiform tooth) is described — side surfaces of a crown meet at a cutting edge at an acute angle. Anomaly of the first upper painter, shaped kidneys meets. — width of a crown at a neck is more, than at a chewing surface; chewing hillocks are underdeveloped and converge. E. Pflyuger observed this anomaly only at inborn syphilis, however afterwards this anomaly was established also at other diseases. Rare anomaly of the lower medial and side cutters in the form of their turn around an axis — so-called overwound 3 meets. Anomaly of size of crowns can be expressed in their sharp reduction — a mikrodentizm or in increase in comparison with the average sizes — a macrodontia that it is necessary to distinguish from dual 3., which are formed from merge of rudiments 3. or from splitting of enamel body and formation of two crowns at one root. In case of cosmetic defect form of a crown 3. recover a metal or plastic crown.

Changes of a form of roots are observed in the form of their bifurcation, sometimes roots can be strongly bent.

Treatment of anomalies of development of teeth — is more detailed see. Edentia , Diastem , Trema etc. See also Orthodontic methods of treatment .

Fig. 30. Teeth with a hypoplasia of enamel.

Hypoplasia — anomaly of structure 3. (fig. 30). The underdevelopment of enamel (more often) and dentine occurs in connection with disbolism in an organism of the child during formation 3 (less often). and mineralizations of enamel and dentine that can be caused by an acute children's infection, went. - kish. diseases, hypovitaminosis, especially vitamin D, insufficiency of function of closed glands; disturbance of development of enamel can have a hereditary origin. Hypoplasia of solid fabrics 3. it is caused by change of a ratio of organic and mineral fractions of solid fabrics: increase in amount of organic matter and an insufficient mineralization (but sometimes there are sites of a hyper mineralization of enamel).

At all forms of a hypoplasia reduction of an enamel layer histologically comes to light, increase in interprismatic spaces, expansion of strips of Rettsius, borders of enamel columns are indistinct, in prisms and interprismatic substance inclusions in the form of black grains and glybok are defined, sites of homogeneous transparency are observed. At a dot form with formation of erosion destruction of enamel is expressed stronger. In dentine interglobular spaces are increased, the wide zone of predentin is formed; in a pulp reduction of cellular elements, fibrilloblasts lose usual orientation.

The hypoplasia is shown more often on cutters and the first constant painters, is rare — on canines, is even more rare on premolar tooths and the second painters. Such pattern is explained with the fact that these disturbances arise in the first years of life of the child when cutters and the first constant painters at the same time develop. If the child is ill on the first year of life, then process of a mineralization of one sites of a crown specified 3 suffers., on the second year — other sites.

Clinically distinguish several forms of a hypoplasia: spotty and wavy enamel, a dot and furrowed hypoplasia, partial or total absence of enamel on cutting edges of cutters and on hillocks chewing 3. and the combined form having a so-called ladder appearance. Spotty enamel differs from normal in spots of gray and nacreous or light brown color. Disturbance of structure is found only at microscopic examination. Wavy enamel is not always found, it becomes noticeable only at attentive survey. The dot hypoplasia is characterized by a set of small dimples of yellowish color. The furrowed hypoplasia is expressed as a horizontal strip of defect. Lack of enamel on cutting edges of lobbies 3 is observed., very seldom enamel completely is absent. Sometimes strips of defect alternate with strips of normal structure of enamel that is called a hypoplasia of ladder type (it is observed at insufficiency of function of parathyroids).

Cavity and root channels such 3. very narrow since process of their obliteration begins even during formation. Excitability of a pulp at irritation is lowered by its current, usually does not react to other irritants. After eruption enamel such 3. it is quickly chopped off, dentine is erased.

Patients with a hypoplasia of enamel do not need special treatment. In cases of a skalyvaniye and strong deleting of enamel 3 get into condition. artificial crowns (see. Dentures ).

Damages

carry dislocation To an acute injury 3., a vkolachivaniye in a hole, in a bone of a jaw, otly a part or all crown, a change of a root. Dislocation 3. is followed by damage of a parodont and gingiva, the sharp pain amplifying at touch; at considerable shift 3. there can be a rupture of a neurovascular bunch. Treatment comes down to establishment 3. in the correct situation and fixings by the wire tire; at a rupture of a gingiva put a stitch. For identification of a condition of a pulp determine her excitability at irritation by electric current after subsiding of the acute phenomena (in 5 — 7 days); decrease in excitability of a pulp to 100 mk indicates a rupture of a neurovascular bunch. In such cases 3. trepan, delete a pulp with the subsequent sealing of the channel (see. Sealing of teeth ). If at an injury there was a vkolachivaniye 3. (that is always followed by a rupture of a neurovascular bunch), together with establishment 3. in the correct situation delete a nekrotizirovanny pulp and seal up the channel.

Fig. 31. A fracture of tooth through a crown and a root.

At an acute injury can occur otly crowns 3. (fig. 31) with an exposure of a pulp. In these cases the pulp is deleted, seal up the channel and 3 get into condition. artificial crown.

If otly the crown is not followed by opening of a pulp, then 3 get into condition. by sealing, tooth tabs (see. Tabs tooth ). At a change of a root 3. in the beginning there is a sharp morbidity in connection with disturbance of an integrity of fabrics of a parodont and neurovascular bunch; further gradually color of a crown changes. The change of a root is established by a X-ray analysis. If the change of a root occurs in a cervical part of lobbies 3., the crown is deleted, and the root is kept, using it for bayonet 3. At a change of a root in a middle or apical part the pulp is deleted, the channel is sealed up, and 3. it can be kept.

Fig. 32. The defects of cutters of a top and bottom jaw formed as a result of a habit to hold a pencil (1) in a mouth and constantly to bite off threads (2).

Refer education to a chronic injury uzur, deleting of cutting edges, wedge-shaped defects and an erosion of solid fabrics 3. Hron, an injury can be connected with the prof. factors or harmful household habits. E.g., emergence uzur on lobbies 3. at the shoemakers holding teeth of a nail at the smokers using a tube or a mouthpiece at glass blowers, musicians, tailors who are biting off with teeth of a thread, etc. (fig. 32). Malocclusion, reception of a gastric juice or the means replacing it leads to premature deleting 3. Education uzur or nek-swarm deleting 3. does not cause pain; treatment consists in elimination of the injuring factors and a soshlifovyvaniya of keen edges 3. At considerable deleting 3. deformation can follow temporal and mandibular joint (see). Treatment 3. during the deleting comes down to elimination of the reasons and recovery of normal bite (see); sometimes there is a need for a denture.

Wedge-shaped defect of solid fabrics 3. it is formed on average and advanced age is, as a rule, closer to a neck 3. hron, the mechanical injury, decrease in microhardness and the degree of a mineralization of enamel arising owing to the postponed diseases, improper feeding, etc. are the reasons of formation of wedge-shaped defects. Defect begins on the limited site with a decrease of enamel, and then dentine, usually on cutters, canines and premolar tooths, gradually defect becomes deeper and wider. Process proceeds very slowly that promotes adjournment of replaceable dentine in this connection a bottom of defect firm, smooth, the complication caries usually does not occur. Usually is not subject to treatment, at big deep defects 3 get into condition. sealing or artificial crowns (see. Dentures ).

Fig. 33. Erosion of solid tissues of upper teeth.

Erosion of solid fabrics 3. it can be formed under the influence of food to - t, and also from friction by a rigid toothbrush. The erosion is characterized by defect of enamel, and sometimes and dentine; it has the rounded, oval or irregular form, the surface to-rogo dense, smooth is formed in a middle part of a vestibular surface of cutters, canines and premolar tooths (fig. 33) in the form of bowl-shaped deepening. The erosion often is followed by a hyperesthesia, can be complicated by caries; in this case at the bottom of it the softened dentine appears. Treatment of an erosion of enamel consists in processing of the site of defeat of 10% solution of a gluconate of calcium and 4% solution of sodium fluoride. Erosion of dentine treat sealing.

Chemical injuries of teeth occur at the persons working at the chemical enterprises in laboratories, and belong to professional more often, but can arise at long reception divorced salt to - you, napr, at anacid gastritis. At long influence to - the t (a so-called acid necrosis) and alkalis changes color of enamel 3., mottling and the separate hyper pigmented spots, then a roughness, destruction of a crown 3 appears. (necrosis). One of the first signs of chemical defeat 3. the feeling of a soreness of the mouth, hypersensitivity to temperature and mechanical irritants is. Solubility of enamel increases, it collapses gradually, bared and softened dentine; as a rule, at the same time there is no pulpitis owing to adjournment of replaceable dentine, is frequent with an obliteration of a cavity 3. and dystrophy of a pulp. For differentiation of acid and alkaline defeats 3. essential value has poll since clinically it is difficult to distinguish them.

Treatment carry out by way systematic (in 1 — 2 hour) rinsings by neutralized solutions (1 — 2% solution of sodium borate, 3 — 5% solution of hydrosodium carbonate at acid defeats and 2% solutions boric or lemon to - you at alkaline defeats). In cases of destruction 3. they are recovered prostheses.

Prevention of chemical damages 3. consists in elimination of their reasons. Due to the improvement of labor protection, the organization of systematic surveys and sanitation of an oral cavity (see) at the enterprises of the USSR of chemical defeat 3. began to meet seldom. In working conditions when acid defeats are possible, suction of the tablets containing hydrosodium carbonate, neutralizing to - you is recommended. Covering 3 is recommended. protective varnishes on an epoxy basis.

Beam injuries of teeth arise at radiation therapy of tumors of lips, persons, sometimes at radiation of other parts of a body. Similarity wedge. - morfol, pictures of radiation injuries 3. with caries allowed many authors to consider them as «beam» caries 3. Histologically changes of a pulp begin with a hyperemia and increase in permeability of walls of vessels that leads to hypostasis, increase in interstitial pressure and numerous dot hemorrhages. Then develops hyalinizations of vessels with the subsequent obliteration of a gleam, denticles are quite often formed and there occur sharply expressed dystrophic changes of fibrilloblasts (wrinkling, a chaotic arrangement, a razvolokneniye and a rupture of their shoots).

Clinically radiation injuries 3. are shown in remote (4 — 6 months) terms after beam influences also proceed without serious consequences. Contrary to caries at first there is a defeat of a pulp 3., and then solid fabrics. Sensitivity of a pulp to irritation electric current goes down that is one of diagnostic characters of radiation injury 3. Destruction of enamel and dentine happens quickly as acute cervical circular caries 3. with distribution of process on cement; quite often there are changes 3. in a neck.

Changes of a pulp 3. develop quickly as a necrosis with distribution patol, process on a periodontium and a periosteum of a jaw therefore clinically more often at first find periodontitis or a periostitis of a jaw. At emergence of pulpitises and periodontitis carry out an extirpation of a pulp 3. and sealing of root channels with use of the sparing techniques.

Prevention of radiation injuries 3. consists in careful sanitation of an oral cavity before radiation; the sites of the maxillofacial area which are not subject to radiation shield lead slips, use protective tubes localizers. On 3. in the form of applications impose 75% fluoric paste, fluorinated varnishes or gels. Inside appoint the means stimulating reactivity of an organism.

Damage by electric current consists in defeat of a pulp more often. Solid fabrics 3. are damaged under the influence of electric current of big force or high tension; at the same time the oplavleniye and a carbonization of enamel with formation of the pigmented cone-shaped deepenings or cracks is noted. The phenomena of a pulpitis develop gradually, pains arise not at once, color 3 can change. The condition of a pulp is defined by an electric pulp test, by raying, reo-and fotopletizmografiya. Treatment consists in trepanation of a cavity 3., extirpation of a pulp and sealing; sometimes damaged 3. it is necessary to delete.

Damage by ultrasound of solid fabrics 3. can arise as a complication during the use stomatol, ultrasonic installations like Ultrastom or Kavitron for removal of a dental calculus (see. Ultrasonic therapy, equipment ). At insufficient experience on these installations the surface layer of enamel, hl can be damaged. obr. in cervical area therefore work shall be carried out with use of the optimum modes, at constant control of a surface of enamel; in case of detection of small defect enamel is polished and polished, deeper defect is sealed up.

Light damages of teeth as all body tissues, can be caused by optical quantum generators — lasers (see). At impact on an organism of radiations ruby, garnet and others a similar type of lasers there is a complex thermal, thermohydraulic, mechanical, electric, acoustic and biochemical, processes that defines biol, effect of the generated radiation. As a result macro - and micro cracks of enamel and dentine, damage of a pulp can be formed, and also to occur fusion, burning and evaporation. However the garnet laser is used in therapeutic stomatol, installations for bystry preparation of solid fabrics 3., including opening of a cavity, removal of a dental calculus, etc. Power deceleration in an impulse and increase in frequency (so-called modulation of good quality of radiation) allows to avoid the undesirable by-effects stated above.

Diseases

the Most widespread disease 3. caries is.

To diseases 3. not carious origin the fluorosis, a necrosis of solid fabrics 3 belongs., patol, deleting 3., a hyperesthesia of solid fabrics and dystrophic processes in a pulp.

Caries of tooth — patol, the process which is developing as a result of disturbances of functions of an oral cavity and systems of an organism and shown gradual destruction of enamel and dentine with formation of defect in the form of a cavity (see. Caries of tooth ). Destruction of solid fabrics 3. proceeds with participation of microorganisms, gradually leads to an inflammation of a pulp 3. and to its necrosis (see. Pulpitis ), and then, if 3. do not treat, to a further complication — an inflammation of the fabrics surrounding a root 3. (see. Periodontitis ). At decrease in protective forces of an organism periodontitis can be complicated by a periostitis and osteomyelitis of a jaw (see. Jaws , pathology). Caries not only constants, but also milk 3 are surprised., at which destruction and their premature removal development of a jaw is broken that results in anomaly of a bite, a retention of separate constants 3.; at inflammatory process around milk 3. often rudiments of constants 3 are surprised.

A fluorosis of teeth — one of the first manifestations hron, intoxication fluorine resulting from the increased content of fluorine in drinking water (see. Fluorosis ). The fluorine a lot of coming to an organism breaks exchange processes. During formation of fabrics 3. fluorine toxic affects enameloblasta, causing their destruction and suspension of formation of enamel columns and formation of enamel. At excess intake of fluorine in the forming solid fabrics 3. almost insoluble fluorapatite is formed. For a fluorosis 3. stratification hypo - and hyper mineralizations of enamel and dentine is characteristic; in a pulp the centers of calcification are formed, it is frequent in the form of denticles.

A fluorosis are surprised generally constant 3. the children (milk — is rare) living with the birth in the center of a local fluorosis or who lodged there at the age of 3 — 4 years. At small increase in concentration of fluorine only cutters are surprised, at big — all 3.

Fig. 34. Microdrug of a cut of enamel of tooth at a fluorosis: enamel has the moire drawing; x 135.

Patogistologiya: the surface layer of enamel at an initial form of a disease is presented in the form of a pretty strip; at melovidno-speckled and erosive forms the periblast of enamel considerably differs on color, width reaches it 1/2 or 2/3 thickness of enamel; enamel has the moire drawing (fig. 34) that is caused by increase in interprismatic spaces, a partial resorption of enamel columns, zones hypo - and hyper mineralizations. The deep layer of enamel is rather seldom pigmented.

Fig. 35. Pigmentation of enamel of teeth at a fluorosis.

The following forms of defeat 3 are clinically observed. at a fluorosis. A shaped form — emergence on the vestibular surface of enamel of the small pretty strips inclined to merge. A spotty form — pretty spots and light yellow pigmentation of certain sites of a crown 3. (fig. 35); the surface of enamel even in sites of spots smooth, brilliant. Melovidno-krapchataya a form — pretty color of a crown with sites of light yellow and dark brown pigmentation; on a lip and buccal surface there can be a defect of a surface layer of enamel in the form of specks.

The erosive and deforming forms are expression of heavy degree of intoxication. Erosion can be in the form of limited defects of enamel or surround with a continuous strip a crown 3.; separate spots are sharply pigmented (dark brown and even black color). Many are struck 3., which are deformed by the most part, on cutting edges and a chewing surface enamel and dentine are erased.

The most efficient preventive and to lay down. a measure is change of a water source or defluorination of water; it is reasonable to recommend to replace to children water with milk, to enter polyneuramins with food 1 and Page. For elimination of pigmentation a surface 3. process the cotton plug moistened 20 — 30% with solution milk to - you or 5 — 10% solution divorced hydrochloric to - you, then paste from hydrosodium carbonate. At deformation a form 3. recover sealing or an artificial crown, a tooth tab.

The necrosis — a peculiar form of a disease of enamel, and sometimes and dentine, is usually observed at hyperfunction of a thyroid gland.

Fig. 36. Teeth with the broken-off sites of enamel on cutting edges as a result of a necrosis.

In the beginning there is a tarnishing, tarnishing of enamel, emergence of pretty spots which become further opaque, then dark brown. Enamel loses hardness, becomes brittle, sites of enamel and dentine are broken off, is more often on a cutting edge and a chewing surface 3. (fig. 36). Treatment — identification of a causative factor, inside — drugs of calcium; the cervical sites of a necrosis which are especially complicated by caries are subject to sealing; crowns undergone a necrosis 3. cover with artificial crowns.

Pathological dental abrasion is shown by the accelerated process of deleting, more often observed at anomalies of a bite owing to a considerable overload of some groups 3. Sometimes and at the correct bite by 20 — 25 years the considerable stertost 3 is found. At the same time in a pathogeny functional and structural insufficiency of tooth fabrics, especially enamels, caused by various disturbances in an organism during development and eruption 3 matters. Usually happens orthodontic treatment or a denture is necessary.

Hyperesthesia of solid fabrics 3. it is expressed by emergence of sharp morbidity from different irritants. Patients address usually with the complaint to pain in 3. from a hot or cold water, sometimes morbidity arises during the carrying out stomatol, the tool on a neck or a crown 3. The etiology and a pathogeny of this phenomenon are not clear. Some authors connect a hyperesthesia with decrease in a mineralization and increase in permeability of enamel, sensitization of receptors of a pulp, change of electrokinetic processes, etc. The hyperesthesia can be observed at an erosion, wedge-shaped defect, deleting 3., an exposure of a neck and a root as a result of retraction of a gingiva. However the hyperesthesia can arise also at clinically healthy 3. Treatment: sites of a hyperesthesia process 75% fluoric paste, 1,5 — 2% a fluoric tooth varnish (or gel), 10% solution of a gluconate of calcium; inside appoint glycerophosphate, a gluconate of calcium.

Dystrophic processes in a pulp clinically usually proceed asymptomatically and are found accidentally at gistol. researches. However in some cases there are unpleasant feelings or spontaneous painful attacks similar to pain at the beginning pulpitis. Disturbance of a functional condition of a pulp can be established on her excitability (at irritation by electric current), edges it is often lowered, or with the help reo-and the fotoodontografiya showing decrease in degree of a krovenapolneniye, tone and reactivity of vessels, change of their walls and other signs of functional or organic changes of a pulp. Specific manifestations of changes in a pulp 3. vacuolation of fibrilloblasts, a reticular atrophy of a pulp and petrification are.

Vacuolation of fibrilloblasts is expressed in emergence of small single cavities or vacuoles in fibrilloblasts of a coronal pulp. Cavities, or vacuoles, are formed both in cytoplasm of fibrilloblasts, and between them. In the subsequent these cavities increase in sizes, fibrilloblasts are deformed and perish; on their place there are various size cystous cavities. Sometimes vacuolation takes only a layer of fibrilloblasts, but quite often extends also to the central department of a pulp, squeezing its cells and giving a mesh look to all pulp 3. This phenomenon received the name mesh, or reticular, atrophies of a pulp. Most of authors considers these changes in a pulp as pathological; some authors are inclined to regard these changes as fiziol, the phenomenon connected with age and functional activity of a pulp; vacuolation of fibrilloblasts is as if one of forms biol, existence of these cells and the beginning of their destruction and death.

Fig. 4. Microdrug of a pulp of tooth of the person: sites of dentinopodobny fabric (denticles) are specified by shooters. Coloring hematoxylin-eosine

Petrification of a pulp 3. it is shown by adjournment of salts of lime in fabric of a pulp, usually along blood vessels, is more often in a root pulp. Some authors explain this process with local disturbances of mineral metabolism; adjournment of salts can happen in the form of unstructured educations — petrifikat or in the form of the denticles consisting of dentinopodobny fabric (tsvetn. fig. 4). The most expressed petrification of a pulp is observed at periodontosis (see), the increased erasability 3.

Operations

At various diseases 3. sometimes it is necessary to resort to an operative measure, a cut, as a rule, carry out under local anesthesia (see. Anesthesia local ). To operation exodontias (see) resort at certain indications taking into account the general condition of an organism. The absolute indication to removal 3. strong destruction of a crown is 3. with increase of the inflammatory phenomena in a periodontium, despite conservative treatment, especially in multi-rooted 3. Removal sealed up 3 can be shown. in the presence of fistula and recuring of inflammatory process, etc. A number of contraindications to removal 3 is established.: nervous diseases, epilepsy, pregnancy, diseases of cardiovascular system and blood (hemophilia, thrombocytopenia, leukoses, etc.), acute systemic infections, ulcer and necrotic processes in an oral cavity. In many of the specified cases at improvement of a condition of the patient and acceptance of the appropriate measures of precaution to carry out removal 3. happens perhaps, and sometimes and it is necessary as sanitation of an oral cavity and elimination of the center of a dontogenous infection.

Milk 3. it is necessary to keep before eruption of constants in order to avoid the subsequent disturbances of a bite; however at eruption constant not dropped out milk 3. is subject to removal.

Operation of a resection of a top of a root 3. it is shown when want to keep 3. at impossibility to eliminate hron, inflammatory process in a periodontium (a granuloma, a cyst) with therapeutic methods, at an oncotomy, located at a top of a root. More often the resection of a root is done in the presence of a cyst in the field of cutters. In the course of enucleating of a cyst (see. Odontocele ) the bared top of a root is deleted with boron.

Replantation of tooth — the room of the extracted tooth in own hole — is applied quite widely at dislocation, full pushing out 3. from a hole, at anomalies of situation 3., etc. — see. Replantation of teeth .

Hemisection — division of roots at painters and premolar tooths with the subsequent removal of the destroyed root and preservation of the root which is subject to treatment.

Teeth in the medicolegal relation

3. often are objects of examination at an injury 3., drawing damages or establishment of age, court. - stomatol, identification of the personality, investigation of the defects or offenses which arose during the rendering stomatol, the help, aspiration remote 3. or its parts, etc. Also cases of obturation of upper respiratory tracts dentures in unconsciousness have expert value, at alcoholic or drug intoxication therefore there comes death from asphyxia.

At an injury 3., as a rule, examination installs the mechanism of its emergence and severity, edges is defined according to acting court. - medical rules.

The damages caused 3., can be single in the form of the fragmentary hurt wounds or a nibble, napr, parts of a nose, an auricle, a finger etc., but are more often the multiple, combining grazes, bruises and superficial wounds which are located on an arch or an oval and divided by intervals of the unimpaired skin; specific features of a bite can be reflected in the nature of damage. Localization of signs of the injuries done 3., is able to allow the expert to state judgment of conditions and circumstances of drawing damages or to critically estimate the anamnestic data reported by the victim.

Often it is necessary to differentiate the damages put 3. the person, from the damages put 3. animals; it is established on the nature of a wound.

At establishment of age matter: existence 3., their quantity, character of a bite, extent of age changes (stertost of edges, exposure of dentine, change of enamel), loss 3. in connection with age, and the processes which led to loss 3 shall be excluded patol., or absence 3. in connection with an injury of a jaw.

Considerable stability of solid fabrics 3. in relation to different external influences the court provides their long structural keeping and an opportunity. - stomatol. identifications of the personality (see). Such need arises at a research gnilostno of the changed corpse of the unknown person, skeletirovanny corpses or their parts, in particular for determination of prescription of burial (on dynamics of ultrastructure 3.); for identification of the charred corpses at the fires, plane crashes etc. At the same time surely pay attention to height 3., intervals between them, their amount, the color of enamel, localization which is absent, existence artificial, sealed up and carious 3., and also on character and features of a bite; during the carrying the removable dentures which are absent at examination the condition of fabrics, adjacent to a prosthesis, in particular a relief of folds of a hard palate matters. At identification of the personality can be objects of examination not only 3., but also the marks of their influence left on a body of victims or on various objects.



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E. V. Borovsky; V. V. Gemonov, BB. H. Ko shares (An., gist.), G. A. Zedgenidze (rents.), M. M. Persits (biochemical), A. A. Prokhonchukov, (physical.), V. M. Smolyaninov (court.).

Яндекс.Метрика