Methods for correcting alveolar process atrophy depending on the pathological condition. Alveolar bone Anatomical histological features of the structure of the alveolar bone

The alveolar process is the part of the upper and lower jaws that extends from their bodies and contains teeth. There is no sharp boundary between the body of the jaw and its alveolar process. The alveolar process appears only after teeth erupt and almost completely disappears with their loss. The alveolar process is divided into two parts: the alveolar bone itself and the supporting alveolar bone.

The alveolar bone itself (alveolar wall) is a thin (0.1-0.4 mm) bone plate that surrounds the tooth root and serves as a site for attachment of periodontal fibers. It consists of lamellar bone tissue, which contains osteons, is penetrated by a large number of perforating (Sharpey's) periodontal fibers, and contains many holes through which blood and lymphatic vessels and nerves penetrate into the periodontal space.
The supporting alveolar bone includes: a) compact bone that forms the outer (buccal or labial) and inner (lingual or oral) walls of the alveolar process, also called the cortical plates of the alveolar process;
b) spongy bone, filling the spaces between the walls of the alveolar process and the alveolar bone itself.
The cortical plates of the alveolar process continue into the corresponding plates of the body of the upper and lower jaw. They are thickest in the area of the lower premolars and molars, especially on the buccal surface; in the alveolar process of the upper jaw they are much thinner than in the lower jaw (Fig. 1, 2). Their thickness is always less on the vestibular side in the area of the front teeth, in the area of molars - thinner on the lingual side. Cortical plates are formed by longitudinal plates and osteons; in the lower jaw, the surrounding plates from the body of the jaw penetrate into the cortical plates.

Rice. 1. Thickness of the walls of the alveoli of the upper jaw

Rice. 2. Thickness of the walls of the alveoli of the lower jaw

Spongy bone is formed by anastomosing trabeculae, the distribution of which usually corresponds to the direction of forces acting on the alveolus during chewing movements (Fig. 3). The lower jaw bone has a fine-mesh structure with a predominantly horizontal direction of trabeculae. In the bone of the upper jaw there is more spongy substance, the cells are large-loop, and the bone trabeculae are located vertically (Fig. 4). Spongy bone forms interradicular and interdental septa, which contain vertical feeding canals, bearing nerves, blood and lymphatic vessels. Between the bone trabeculae there are bone marrow spaces, filled with red bone marrow in children, and yellow bone marrow in adults. In general, the bone of the alveolar processes contains 30-40% organic substances (mainly collagen) and 60-70% mineral salts and water.

Rice. 3. Structure of the spongy substance of the alveoli of the anterior (A) and lateral (B) teeth

Rice. 4. The direction of the trabeculae of the cancellous bone of the alveolar part on the transverse (A) and longitudinal (B) sections

The roots of the teeth are fixed in special recesses of the jaws - alveoli. The alveoli have 5 walls: vestibular, lingual (palatal), medial, distal and floor. The outer and inner walls of the alveoli consist of two layers of compact substance, which merge at different levels in different groups of teeth. The linear size of the alveolus is somewhat shorter than the length of the corresponding tooth, and therefore the edge of the alveolus does not reach the level of the enamel-cement junction, and the apex of the root, due to the periodontium, does not adhere tightly to the bottom of the alveolus (Fig. 5).

Rice. 5. The relationship between the gums, the apex of the interalveolar septum and the crown of the tooth:
A - central incisor; B - canine (side view)

The human dental system is complex in its structure and very important in its functions. As a rule, every person pays special attention to their teeth, since they are always in sight, and at the same time often ignores problems associated with the jaw. In this article we will talk to you about the alveolar process and find out what function it performs in the dental system, what injuries it is susceptible to, and how correction is carried out.

Anatomical structure

The alveolar process is an anatomical part of the human jaw. The processes are located on the upper and lower parts of the jaws, to which the teeth are attached, and consist of the following components.

Alveolar bone with osteons, i.e. walls of the dental alveoli.
The alveolar bone is of a supporting nature, filled with a spongy, rather compact substance.

The alveolar process is subject to tissue osteogenesis or resorption processes. All these changes must be balanced and balanced with each other. But pathologies may also arise due to constant restructuring of the alveolar process of the lower jaw. Changes in the alveolar processes are associated with the plasticity and adaptation of bone to the fact that teeth change their position due to development, eruption, loads and function.

The alveolar processes have different heights, which depends on the age of the person, dental diseases, and the presence of defects in the dentition. If the process is small in height, then dental implantation cannot be performed. Before such an operation, special bone grafting is performed, after which the implant becomes real.

Injuries and fractures

Sometimes people experience alveolar bone fractures. The alveolus often breaks as a result of various injuries or pathological processes. A fracture of this area of the jaw means a violation of the integrity of the process structure. Among the main symptoms that help a doctor determine a fracture of the alveolar process of the upper jaw in a patient are factors such as:

pronounced pain in the jaw area;
soreness that can be transmitted to the palate, especially when trying to close the teeth;
pain that gets worse when trying to swallow.

During a visual examination, the doctor may detect wounds in the area around the mouth, abrasions, and swelling. There are also signs of lacerations and bruises of varying degrees. Fractures in the area of the alveolar process of both the upper and lower jaws come in several types.

Fractures in the alveolar region may be accompanied by simultaneous fracture and dislocation of teeth. Most often, such fractures have an arched shape. The crack runs from the ridge in the interdental space, rising up the lower or upper jaw, and then in a horizontal direction along the dentition. At the end it descends between the teeth to the crest of the process.

How is the correction carried out?

Treatment of this pathology involves the following procedures.

Gradual relief of pain using conduction anesthesia.
Antiseptic treatment of fabrics using herbal decoctions or preparations based on chlorhexidine bigluconate.
Manual reduction of fragments that were formed as a result of a fracture.
Immobilization.

Operation of the alveolar process involves revision of the injury, smoothing of sharp corners of bones and fragments, suturing of mucous tissue or closing the wound with a special iodoform bandage. In the area where the displacement occurred, the required fragment must be identified. For fixation, a bracket splint is used, which is made of aluminum. A bracket is attached to the teeth on either side of the fracture. To ensure immobilization is stable and strong, a chin sling is used.

If the patient has been diagnosed with an impacted dislocation of the anterior maxilla, then doctors use a single-jaw steel brace. It is needed to immobilize the damaged process. The bracket is attached to the teeth with ligatures using a splint with elastic bands. This allows you to connect and put in place a fragment that has moved. If there are no teeth in the required area for fastening, the splint is made of plastic, which hardens quickly. After installing the splint, the patient is prescribed antibiotic therapy and special hypothermia.

If the patient has atrophy of the alveolar process of the upper jaw, treatment must be carried out. Restructuring processes may be observed in the alveolar area, especially if a tooth has been removed. This provokes the development of atrophy, a cleft palate is formed, and new bone grows, which completely fills the bottom of the socket and its edges. Such pathologies require immediate correction both in the area of the extracted tooth and on the palate, near the socket or at the site of former fractures and old injuries.

Atrophy can also develop in the case of dysfunction of the alveolar process. A cleft palate caused by this process may have varying degrees of severity of the pathological development processes and the reasons that led to it. In particular, periodontal disease has a pronounced atrophy, which is associated with tooth extraction, loss of alveolar function, the development of the disease and its negative impact on the jaw: palate, dentition, gums.

Often after tooth extraction, the reasons that caused this operation continue to affect the process. As a result of this, general atrophy of the process occurs, which is irreversible, which manifests itself in the fact that the bone decreases. If prosthetics are performed at the site of an extracted tooth, this does not stop the atrophic processes, but, on the contrary, intensifies them. This is due to the fact that the bone begins to react negatively to tension, rejecting the prosthesis. It puts pressure on the ligaments and tendons, which increases atrophy.

The situation can be worsened by improper prosthetics, which results in incorrect distribution of chewing movements. The alveolar process also takes part in this, and continues to deteriorate further. With extreme atrophy of the upper jaw, the palate becomes hard. Such processes practically do not affect the palatine eminence and the tubercle of the alveoli.

The lower jaw is more affected. Here the process may disappear altogether. When atrophy has strong manifestations, it reaches the mucosa. This causes pinching of blood vessels and nerves. Pathology can be detected using x-rays. Cleft palate does not only occur in adults. In children aged 8-11 years, such problems may arise at the time of formation of a mixed dentition.

Correction of the alveolar process in children does not require major surgical intervention. It is enough to perform bone grafting by transplanting a piece of bone to the desired location. Within 1 year, the patient must undergo regular examinations by a doctor in order for bone tissue to appear. In conclusion, we present to your attention a video where the maxillofacial surgeon will demonstrate to you how bone grafting of the alveolar process is performed.

The alveolar process appears only after teeth erupt and almost completely disappears with their loss.

Dental alveoli, or sockets - separate cells of the alveolar process in which the teeth are located. The dental alveoli are separated from each other by bony interdental septa. Inside the alveoli of multi-rooted teeth there are also internal interradicular septa that extend from the bottom of the alveoli. The depth of the dental alveoli is slightly less than the length of the tooth root.

In the alveolar process there are
two parts: the alveolar proper
bone and supporting alveolar
new bone (Fig. 9-7).
1) Alveolar proper
(alveolar wall) represents
thin (0.1 - 0.4 mm) bone plate -	Rice. 9-7. The structure of the alveolar
ku, which surrounds the root of the tooth and	process.
SERVES AS AN ATTACHMENT POINT FOR FIBERS	SAC - alveolar proper
Periodont. IT CONSISTS OF PLATES -	bone (wall of tooth)	alveoli);
THIS BONE TISSUE, IN WHICH THEY HAVE-	™ K - supporting	alveolar-
	naya bone; CAO - alveolar wall -
XIA OSTEONS, PERMEATED WITH A LARGE COLLECTION	leg process (cortical plate-
HONOR THE PERFORMING (SHARPEES)	ka);/7C - spongy bone; D - gums;
FIBERS PERIODONTE, CONTAINS MUCH-	/70 - periodontium.
number of holes through which periodically

The dontal space is penetrated by blood and lymphatic vessels and nerves."

2) The supporting alveolar bone includes:

a) compact bone that forms the outer (buccal or labial) and inner (lingual or oral) walls of the alveolar process, also called cortical plates of the alveolar process;

b) spongy bone, filling the spaces between the walls of the alveolar process and the alveolar bone itself.

The cortical plates of the alveolar process continue into the corresponding plates of the body of the upper and lower jaw. They are much thinner in the alveolar process of the upper jaw than in the lower jaw; They reach their greatest thickness in the area of the lower premolars and molars, especially on the buccal surface. Corti-

the cal plates of the alveolar process are formed by longitudinal plates and osteons; in the lower jaw, the surrounding plates from the body of the jaw penetrate into the cortical plates.

Spongy bone is formed by anastomosing trabeculae, the distribution of which usually corresponds to the direction of forces acting on the alveolus during chewing movements. Trabeculae distribute the forces acting on the alveolar bone itself to the cortical plates. In the area of the lateral walls of the alveoli, they are located predominantly horizontally; at their bottom they have a more vertical course. Their number varies in different parts of the alveolar process and decreases with age and in the absence of tooth function. Spongy bone forms both interradicular and interdental septa, which contain vertical feeding canals, bearing nerves, blood and lymphatic vessels. Between the bone trabeculae there are bone marrow spaces, filled in childhood with red bone marrow, and in adults - with yellow bone marrow. Sometimes certain areas of red bone marrow can persist throughout life.

RESTRUCTURING THE ALVEOLAR PROCESS

The bone tissue of the alveolar process, like any other bone tissue, has high plasticity and is in a state of constant restructuring. The latter includes balanced processes of bone resorption by osteoclasts and its new formation by osteoblasts. Processes of continuous restructuring ensure the adaptation of bone tissue to changing functional loads and occur both in the walls of the dental alveolus and in the supporting bone of the alveolar process. They are especially clearly manifested during physiological and orthodontic movement of teeth.

Under physiological conditions, after teeth erupt, two types of movement occur: associated with abrasion of approximal (facing each other) surfaces and compensating occlusal abrasion. When the approximal (contacting) surfaces of the teeth are worn away, they become less convex, but the contact between them is not disrupted, since at the same time the interdental septa become thinner (Fig. 9-8). This compensatory process is known as approximal, or medial, displacement of teeth. It is assumed that its driving factors are occlusal forces (in particular, their component directed anteriorly), as well as the influence of transseptal periodontal fibers that bring the teeth together. The main mechanism providing medial displacement is the restructuring of the alveolar wall. At

Rice. 9-8. Abrasion of proximal (contacting) surfaces of teeth

And age-related periodontal changes.

A - appearance of the periodontium of molars shortly after eruption; b - age-related changes in teeth and periodontium: abrasion of the occlusal and proximal surfaces of the teeth, a decrease in the volume of the tooth cavity, narrowing of the root canals, thinning of the interdental bone septum, cement deposition, vertical displacement of the teeth and an increase in the clinical crown (according to G. H. Schumacher et al., 1990 ).

In this case, on its medial side (in the direction of tooth movement), a narrowing of the periodontal space and subsequent resorption of bone tissue occur. On the lateral side, the periodontal space expands, and on the alveolar wall, coarse fibrous bone tissue is deposited, which is subsequently replaced by lamellar tissue.

The abrasion of the tooth is compensated by its gradual advancement from the bone alveolus. An important mechanism of this process is the deposition of cement in the region of the root apex (see above). In this case, however, the walls of the alveoli are also reconstructed, at the bottom of which and in the area of the interradicular septa, bone tissue is deposited. This process reaches particular intensity with the loss of tooth function due to the loss of the antagonist.

During orthodontic displacement of teeth, thanks to the use of special devices, it is possible to provide effects on the alveolar wall (mediated, obviously, by the periodontium), which lead to resorption of bone tissue in the area of pressure and its new formation in the area of tension (Fig. 9-9). Excessively large forces acting on a tooth for a long time during orthodontic reshaping143

Rice. 9-9. Restructuring of the alveolar process during orthodontic horizontal movement of teeth.

a - normal position of the tooth in the alveolus; b - inclined position of the tooth after exposure to force; c - oblique-rotational movement of the tooth. Arrows indicate the direction of force and movement of the tooth. In pressure zones, resorption of the alveolar bone wall occurs, and in traction zones, bone deposition occurs. ZD - pressure zones; ZT - traction zones (according to D. A. Kalvelis, 1961, from L. I. Falin, 1963, with modifications).

placement, can cause a number of unfavorable phenomena: compression of the periodontium with damage to its fibers, disruption of its vascularization and damage to the vessels supplying the tooth pulp, focal root resorption.

The cancellous bone surrounding the alveolar bone itself also undergoes constant restructuring in accordance with the load acting on it. So, around the alveolus of a non-functioning tooth (after the loss of its antagonist), it undergoes atrophy -

bone trabeculae become thin and their number decreases.

The bone tissue of the alveolar process has a high potential for regeneration not only under physiological conditions and under orthodontic influences, but also after damage. A typical example of its reparative regeneration is the restoration of bone tissue and the reconstruction of a section of the dental alveolus after tooth extraction. Immediately after tooth extraction, the alveolar defect is filled with a blood clot. The free gum, mobile and not connected to the alveolar bone, bends towards the cavity, thereby not only reducing the size of the defect, but also helping to protect the blood clot.

As a result of active proliferation and migration of the epithelium, which begins after 24 hours, the integrity of its cover is restored within 10-14 days. Inflammatory infiltration in the area of the clot is replaced by migration of fibroblasts into the alveoli and the development of fibrous connective tissue in it. Osteogenic precursor cells also migrate into the alveolus, differentiate into osteoblasts and, starting from the 10th day, actively form bone tissue that gradually fills the alveolus; At the same time, partial resorption of its walls occurs. As a result of the described changes, after 10-12 weeks the first, reparative phase of tissue changes after tooth extraction is completed. The second phase of changes (reorganization phase) lasts for many months and includes the restructuring of all tissues involved in reparative processes (epithelium, fibrous connective tissue, bone tissue) in accordance with the changed conditions of their functioning.

DENTAL JOINT

The dentogingival junction performs a barrier function and includes: gingival epithelium, sulcus epithelium And attachment epithelium(see Fig. 2-2; 9-10, a).

The gingival epithelium is a multilayered squamous keratinized epithelium, into which the high connective tissue papillae of the lamina propria of the mucous membrane are embedded (described in Chapter 2).

Furrow epithelium forms the lateral wall of the gingival sulcus, at the apex of the gingival papilla it passes into the gingival epithelium, and towards the neck of the tooth it borders on the attachment epithelium.

Gingival sulcus(cleft) - a narrow slit-like space between the tooth and the gum, located from the edge of the free gum to the attachment epithelium (see Fig. 2-2; 9-10, a). The depth of the gingival sulcus varies between 0.5-3 mm, averaging 1.8 mm. When the groove depth is more than 3 mm, it is considered pathological, and it is often called a gingival pocket. After the tooth erupts and begins to function, the bottom of the gingival sulcus usually corresponds to the cervical part of the anatomical crown, but with age it gradually moves, and ultimately the bottom of the sulcus may be located at the level of the cementum (Fig. 9-11). The gingival sulcus contains fluid that is secreted through the attachment epithelium, desquamated cells of the sulcus and attachment epithelium, and leukocytes (mainly neutrophil granulocytes) that have migrated into the sulcus through the attachment epithelium.

Rice. 9-10. Attachment epithelium. Migration of leukocytes from the lamina propria of the gingival mucosa into the attachment epithelium.

a - topography; b - microscopic structure of the area shown in fragment a. E - enamel; C - cement; DB - gingival sulcus; EB - sulcal epithelium; GD - gingival epithelium; EP - attachment epithelium; SChD - free part of the gum; G - gingival groove; PSD - attached part of the gum; SA - proper lamina of the mucous membrane; KRS - blood vessel; IBM - internal basement membrane; EBM - outer basement membrane; L - leukocytes.

The sulcus epithelium is similar to the gingival epithelium, but is thinner and does not undergo keratinization (see Fig. 2-2). Its cells are relatively small in size and contain a significant amount of tonofilaments. The border between this epithelium and the lamina propria of the mucous membrane is smooth, since there are no connective tissue papillae here. Both the epithelium and connective tissue are infiltrated with neutrophilic granulocytes and monocytes, which migrate from the vessels of the lamina propria towards the lumen of the gingival sulcus. The number of intraepithelial leukocytes here is not as high as in the attachment epithelium (see below).

Attachment epithelium- multilayer flat, is a continuation of the epithelium of the groove, lining its bottom and forming a cuff around the tooth, firmly connected to the surface of the enamel, which is covered with the primary cuticle (see Fig. 2-2; 9-10, b). The thickness of the layer of attachment epithelium in the area of the bottom of the gingival sulcus is 15-30 layers of cells, decreasing in the direction of the neck to 3-4.

Rice. 9-11. Displacement of the periodontal junction area with age (passive tooth eruption).

Stage I (in temporary teeth and in permanent teeth during the period from the eruption of permanent teeth to 20-30 years of age) - the bottom of the gingival sulcus is at the level of the enamel; Stage II (from 0 to 40 years and later) - the beginning of growth of the attachment epithelium along the surface of the cement, displacement of the bottom of the gingival sulcus to the cement-enamel boundary; Stage III - transition of the epithelial attachment area from the crown to the cement; Stage IV - exposure of part of the root, complete movement of the epithelium to the surface of the cement. At stages I and II, the anatomical crown is larger than the clinical one, at I"IY they are equal, and at (V) the anatomical crown is smaller than the clinical one." Some authors with All 4 stages are considered physiological, the other is only the first two. on the right with a black arrow.

The attachment epithelium is unusual morphologically and functionally. Its cells, with the exception of the basal ones, lying on the basement membrane, which is a continuation of the basement membrane of the sulcus epithelium, regardless of their location in the layer, have a flattened shape and are oriented parallel to the surface of the tooth. The surface cells of this epithelium provide attachment of the gum to the tooth surface using hemidesmosomes associated with the second (inner) basement membrane. As a result, they are not subject to descalation, which is unusual for cells of the surface

layer of stratified epithelium. Desquamation is experienced by cells lying under the surface layer of the attachment epithelium, which are displaced towards the gingival sulcus and sloughed into its lumen. Thus, epithelial cells from the basal layer are displaced simultaneously towards the enamel and the gingival sulcus. The intensity of desquamation of the attachment epithelium is very high and is 50-100 times higher than that in the gingival epithelium. The loss of cells is balanced by their constant new formation in the basal layer of the epithelium, where epithelial cells are characterized by very high mitotic activity. The rate of renewal of the attachment epithelium under physiological conditions is 4-10 days in humans. After its damage, complete restoration of the epithelial layer is achieved within 5 days.

In their ultrastructure, the cells of the attachment epithelium differ from the epithelial cells of the rest of the gum. They contain more developed GES and the Golgi complex, while tonofilaments occupy a significantly smaller volume in them. The cytokeratin intermediate filaments of these cells are biochemically different from those in the gingival and sulcus epithelial cells, indicating differences in the differentiation of these epithelia. Moreover, the attachment epithelium is characterized by a set of cytokeratins that is generally not characteristic of multilayered epithelia. Analysis of surface membrane carbohydrates, which serve as a marker for the level of differentiation of epithelial cells, shows that in the attachment epithelium there is a single class of carbohydrates, which is typical for poorly differentiated cells, for example, basal cells of the gingival and sulcus epithelium. It has been suggested that maintaining attachment epithelial cells in a relatively undifferentiated state is important for preserving their ability to form hemidesmosomes, which ensure the connection of the epithelium with the tooth surface.

The intercellular spaces in the attachment epithelium are widened and occupy about 20% of its volume, and the content of desmosomes connecting epithelial cells is reduced four times compared to that in the sulcal epithelium. Due to these features, the attachment epithelium has a very high permeability, ensuring the transport of substances through it in both directions. Thus, from saliva and from the surface of the mucous membrane there is a massive supply of antigens into the tissues of the internal environment, which may be necessary for adequate stimulation of the function of the immune system. At the same time, many substances are transferred in the opposite direction - from the blood circulating in the vessels of the lamina propria of the mucous membrane, into the epithelium and further into the lumen of the gingival sulcus and saliva as part of the so-called gingival liquid

you. In this way, for example, electrolytes, immunoglobulins, complement components, and antibacterial substances are transported from the blood. Antibiotics of some groups (in particular, the tetracycline series) are not simply transferred from the blood, but accumulate in the gums in concentrations 2-10 times higher than their levels in the serum. The volume of gingival fluid containing proteins and electrolytes and constantly secreted into the lumen of the gingival sulcus is negligible under physiological conditions; it increases sharply with inflammation.

In the expanded intercellular spaces of the epithelium, numerous neutrophil granulocytes and monocytes are constantly detected, which migrate from the connective tissue of the gingival lamina propria into the gingival sulcus (see Fig. 9-10, b). The relative volume they occupy in the epithelium in clinically healthy gums can exceed 60%. Their movement within the epithelial layer is facilitated by the presence of expanded intercellular spaces and a reduced number of connections between epithelial cells. The attachment epithelium lacks melanocytes, Langerhans and Merkel cells.

In periodontitis, under the influence of metabolites secreted by microorganisms, the attachment epithelium can grow and migrate in the apical direction, ending with the formation of a deep gingival (periodontal) pocket.

lamina propria of the mucous membrane in the area of the periodontal junction it is formed by loose fibrous tissue with a high content of small vessels, which are branches of the gingival plexus located here. Granulocytes (mainly neutrophils) and, in smaller numbers, monocytes and lymphocytes, which move through the intercellular substance of the connective tissue, are continuously evicted from the lumen of the vessels in the direction epithelium. Next, these cells penetrate into the attachment epithelium (partly into the sulcus epithelium), where they move between epithelial cells and, ultimately, move into the lumen of the gingival sulcus, from where they enter the saliva. The gums, in particular the gingival sulcus, serve as the main source of leukocytes, which are found in saliva and turn into salivary corpuscles. The number of leukocytes migrating in this way into the oral cavity is normally, according to some estimates, about 3000 per minute, according to others - an order of magnitude higher. Most(70-99%) In the initial period after migration, these cells not only remain viable, but also have high functional activity. With pathology, the number of migrating leukocytes can increase significantly.

Factors determining the migration of leukocytes from the vessels of the lamina propria of the mucous membrane through the epithelium of the region

the dentogingival junction into the gingival sulcus, and the mechanisms that control the intensity of this process have not been fully determined. It is assumed that the movement of leukocytes reflects their response to chemotactic factors secreted by bacteria that are located in and around the furrow. It is also possible that such a high number of leukocytes is necessary to prevent the penetration of microorganisms into the relatively thin and non-keratinizing epithelium of the sulcus and attachment and underlying tissues.

It has been suggested that cells in individual areas of the lamina propria have different effects on the epithelium, mediated by cytokines and growth factors. This is precisely what determines the differences in the nature of its differentiation described above.

Alveolar process- the anatomical part of the jaw that bears teeth. Available on both the upper and lower jaws. A distinction is made between the alveolar bone itself with osteons (the walls of the dental alveoli) and the supporting alveolar bone with compact and spongy substance.

The alveolar processes consist of two walls: the outer - buccal, or labial, and the inner - oral, or lingual, which are located in the form of arcs along the edges of the jaws. On the upper jaw, the walls converge behind the third large molar, and on the lower jaw they pass into the ramus of the jaw.

In the space between the outer and inner walls of the alveolar processes there are cells - dental sockets, or alveoli (alveolus dentalis), in which the teeth are placed. The alveolar processes, which appear only after teeth erupt, almost completely disappear with their loss.

The alveolar process is part of the upper and lower jaws, covered with a thin cortical layer. The outer compact lamina forms the vestibular and oral surfaces of the alveolar bone. The thickness of the outer cortical plate varies between the upper and lower jaws, as well as in different areas of each of them. The internal compact lamina forms the inner wall of the alveoli.

On an x-ray, the cortical plate of the alveolus appears as a dense line, in contrast to the surrounding layer of cancellous bone tissue. Along the edge of the alveoli, the inner and outer plates close together, forming the crest of the alveoli. The alveolar crest is located 1–2 mm below the enamel-cement junction of the tooth.

Bone tissue between adjacent alveoli forms interalveolar septa. The interalveolar septa of the anterior teeth have a pyramidal shape, in the area of the lateral teeth they are trapezoidal.

Alveolar bone consists of inorganic and organic substances, among which collagen predominates. Bone tissue cells are represented by osteoblasts, osteoclasts, and osteocytes. These cells participate in the continuous process of tissue resorption and osteogenesis.

Normally, these processes are balanced, and they underlie the continuously occurring restructuring of the alveolar bone, which characterizes pronounced plasticity and adaptation of the bone to changes in the position of the tooth during its development, eruption and the entire period of functioning.

To assess the degree of bone resorption, it is necessary to take into account:
– difference in the thickness of the cortical plate;
– microhardness of the jaw bone;
– looping structure;
– direction of bone beams.

There are several parts of the alveolar process:
- external– facing the vestibule of the oral cavity, towards the lips and cheeks;
- internal– facing the hard palate and tongue;
- Part, on which the alveolar openings (sockets) and the teeth themselves are located.

The upper part of the alveolar process is called the alveolar ridge, which can be clearly observed after tooth loss and overgrowth of the alveolar sockets. In the absence of load on the alveolar ridge, its height gradually decreases.

The bone tissue of the alveolar process undergoes changes throughout a person’s life, as the functional load on the teeth changes. The height of the process varies and depends on many factors - age, dental diseases, and the presence of defects in the dentition.

Low height, that is, insufficient volume of bone tissue of the alveolar process, is a contraindication for dental implantation. In order for the implant to be secured, bone grafting is performed.

It is possible to diagnose the alveolar process using an x-ray examination.

Let's continue our conversation about the structure of other periodontal tissues. Let's first remember what they are. Periodontal tissues - periodontal structure (highlighted in red in the figure):

gum;
periodontal ligament;
tooth root cement;
alveolar bone.

It is important that the gums and other periodontal tissues have different functions. The main role of the gums is protection. Protection of underlying tissues from external influences. Cementum, alveolar bone and periodontal ligament together form the so-called “supporting apparatus of the tooth.” Thanks to these tissues, the main function of the periodontium is performed - to hold the tooth in its rightful place, in the socket.

Periodontal ligament

The periodontal ligament is the connective tissue that surrounds the tooth and connects it to the inner wall of the alveolar bone.

It begins 1-1.5 mm below the enamel-cement junction.

It's hard to believe, but its width (on average) is only 0.2 mm. 0.2 millimeters, Karl! The clarification “on average” is explained not only by the individual characteristics of the periodontal ligament in different people, but also by changes in the load on the tooth. The relationship is direct: the greater the load, the wider the ligament.

The main components of the periodontal ligament are

periodontal fibers;
cells;
intercellular (ground) substance;
vessels, nerves.

Reminds me of something, doesn’t it? The connective tissue of the gums has a similar composition:

The similarity is not without reason, because the periodontal ligament is a continuation of the connective tissue of the gums with its own characteristics, thanks to which its unique function is realized.

A few words about each of the components of the periodontal ligament.

Periodontal fibers

The bulk of periodontal fibers consists of type I collagen. It is synthesized in fibroblasts. Next, tropocollagen molecules are formed, which form microfibrils, then fibrils, threads and bundles:

This structure of collagen fibers allows them to be both strong and flexible. In longitudinal section they have a wavy shape:

As with gingival fibers, many classifications of periodontal fibers have been proposed. According to one, there are 6 groups of periodontal fibers:

transseptal;
alveolar ridge fibers;
horizontal;
oblique;
apical;
intraradicular (interradicular).

The term is also often found in the literature "Sharpey fibers", but this is not another group. These are the terminal, partially or completely calcified parts of periodontal fibers of all 6 groups, which intertwine and perforate the cement and alveolar bone. Plus, Sharpey's fibers are associated with non-collagenous proteins (osteopontin, bone sialoprotein) in bone and cement (red arrow in the figure), which ensures such a strong connection.

Transseptal fibers

Transseptal fibers (F) pass over the alveolar ridge (A) and connect two adjacent teeth (T). They are often classified as gingival fibers because they are not woven into the bone.

Alveolar ridge fibers

They originate in the area of cementum of the tooth root immediately below the attachment epithelium, go in an oblique direction and attach to the alveolar ridge or periosteum.

Horizontal, oblique and apical fibers also go from cement to bone. The only difference is in the angle at which they are directed and in which part of the periodontal ligament they are located. The horizontal ones are located at right angles closer to the edge of the tooth socket, the apical ones in the area of the root apex. There are more oblique fibers between them. They are the ones who take on the vertical load that occurs during chewing and “transfer” it to the bone.

Interroot fibers(as the name itself says) pass between the roots of a multi-rooted tooth (from the furcation) to the bone.

In addition to the main groups, the periodontal ligament also contains other, less ordered collagen and elastic fibers. Elastic fibers are mainly located parallel to the tooth in the cervical third of the root. They regulate blood flow in the vessels of the ligament.

Periodontal fibers are constantly renewed due to the work cellular elements of periodontium.

Periodontal cells

Periodontal cells are

connective tissue cells;
epithelial islets of Malasse;
protective cells (neutrophils, lymphocytes, macrophages, eosinophils, mast cells);
cellular elements of nerves and blood vessels.

Connective tissue cells- These are mainly fibroblasts that synthesize collagen. They are also capable, if necessary, of protective reactions - phagocytosis, hydrolysis.

Closer to the bone, osteoblasts and osteoclasts, cementoclasts, -blasts, and odontoclasts are found near the tooth.

Epithelial islets of Malasse– remnants of epithelium walled up next to cement, which collapsed during tooth eruption. In general, their role has not yet been studied. It is only known that with age they can either disappear without a trace or turn into cementicles or cysts.

Main substance fills the space between cells and fibers. Its main difference from the intercellular substance of the adjacent connective tissue of the gums is the possible presence of cementicles. They can be attached to the tooth (1) or freely in a ligament (2):

We already know that they can be formed from the epithelial islands of Malasse. But there are other sources of their development, for example:

particles of cement or bone;
Sharpey fibers;
calcified blood vessels.

The periodontal ligament is a key component of the periodontium. It is she who is responsible for most of its functions. We'll talk about functions a little later, but for now let's move on.

Tooth cement

Cement covers the outside of the tooth root. It consists of

collagen fibers and
calcified intercellular substance.
(+ cells).

(there are no vessels in cement)

Highlight outer fibers- Sharpey's, from the periodontal ligament. AND internal, which are directly formed in the cement by cementoblasts, like the intercellular substance.

Cells are not present everywhere in the cement. Where there is - there cellular cement (CC). Where not - acellular(BC).

Acellular cementum

Acellular cementum also called primary. It is formed before the cellular one and until the moment the tooth reaches its antagonist, it does not become occluded. It covers the root up to half (in the direction from the crown to the apex). In the figure, AC is an acellular cementum that lies between dentin (D) and periodontal ligament (PL). You can notice that it is “striped”. These stripes, like rings on a cut tree trunk, indicate periods of cement formation:

Cell cement

Cell cement formed after the tooth reaches the occlusal plane. It is found in the apical third of the root and in the bifurcation area. Cell cement is less mineralized and contains fewer Sharpey fibers. In it (SS) separate spaces (lacunae) with cementocytes inside are found. Cementocytes are connected to each other through special tubules. Note the accumulation of cells in the ligament (PL). These are nothing more than cementoblasts:

It is noticeable from the figures that the width of the cement is greater towards the apical part of the root (approximately from 0.1 to 1 mm). An interesting age pattern: a 70-year-old has cement three times wider than an 11-year-old child.

Cement binds to enamel in different ways:

there is a gap between them (sensitivity may bother you);
butt connected;
covers the enamel.

By the way, since we are talking about enamel, cement is much less mineralized in comparison with it. Cement is, in principle, the “softest” among the hard tissues of the dental system: it contains only about 50% hydroxyapatite. The figure is small compared to bone (65%), dentin (70%) and enamel (97%).

Speaking of bones.

Alveolar bone

Alveolar bone is part of the alveolar process of the upper and alveolar parts of the lower jaw. It is located just below the enamel-cement junction (1-1.5 mm).

Alveolar bone consists of:

alveolar bone itself - forms the wall of the dental alveolus and surrounds the tooth. This is a kind of support for the periodontal ligament; Sharpey fibers are woven into it. It has numerous openings - Volkmann canals, through which nerves and blood vessels pass.
supporting alveolar bone - spongy substance covered with an outer plate of compact substance. Outer cortical plate covers the outside of the bone. It consists of osteons and is connected to the periosteum.

In spongy substance First, in childhood, there is red bone marrow: many blood vessels needed for jaw growth. As we age, it is replaced by inactive yellow bone marrow. There is very little spongy substance on the oral and vestibular surfaces; the main mass is located near the apexes and between the roots:

Below the alveolar is the basal bone, which is no longer connected with the teeth:

Alveolar bone consists of

2/3 inorganic substance (hydroxyapatite)
1/3 organic (collagen fibers, proteins, growth factors)

Basic cells: osteoblasts, -cytes, -clasts.

Osteocytes immured in lacunae like cementocytes.

Osteoblasts create osteoid – non-mineralized bone, which “ripes” and mineralizes over time.

Osteoclasts are responsible for bone resorption. With the help of enzymes, they cause the breakdown of the organic matrix, and after it sequester mineral ions.

Bone is a “tooth-dependent” structure. It forms when a tooth erupts and disappears when it is gone:

Also, a separate topographic zone is distinguished interdental septa. In essence, it is spongy bone, which is bounded on both sides by the cortical plates of the dental alveoli. Depending on the distance between the teeth, their shape varies: from pointed (white arrow) to trapezoidal (red arrow).

It is also interesting that in some areas next to the tooth, normally or with pathology, there may be no bone. The defect sometimes reaches the edge of the bone:

Well, the story about the components of a huge complex called “periodontium” has come to an end. Their structure determines the important tasks they perform. functions, to which each of the components contributes. Violation of the integrity of such a complex leads to periodontal diseases, conversely, diseases destroy periodontal tissue.

We’ll try to figure out both of these in the following articles.

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The article was written by O. Titenkova. Please, when copying material, do not forget to provide a link to the current page.

Periodontal tissue-Structure updated: April 5, 2018 by: Valeria Zelinskaya