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Anatomical and histological features of the structure of the alveolar bone. Scientific review

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)

This article is aimed at conveying to the reader information about the general structure of the upper and lower jaws of a person; special attention will also be paid to the alveolar processes, an important component of our masticatory and communicative apparatus.

Delving into the upper jaw (HF)

The maxillary part of the human cranial bones is paired. Its location is the central front part. It fuses with other facial bones, and also articulates with the frontal, ethmoid and sphenoid. The upper jaw is involved in the creation of the orbital walls, as well as the oral and nasal cavities, the infratemporal and pterygopalatine fossae.

In the structure of the upper jaw there are 4 multidirectional processes:

  • frontal, going upward;
  • alveolar, looking down;
  • palatal, medially facing;
  • zygomatic, laterally directed.

The weight of the human upper jaw is quite small, it does not seem so upon visual inspection, and this is due to the presence of cavities, for example the sinus (sinus maxillaris).

A number of surfaces are also distinguished in the structure of the upper jaw:

  • front;
  • infratemporal;
  • nasal;
  • orbital.

The anterior surface originates from the level of the infraorbital margin. Just below there is a hole along which nerve fibers and blood vessels run. Below the opening is the pterygopalatine fossa, in which the beginning of the muscle responsible for raising the oral corners is fixed.

The surfaces of the orbits are covered with lacrimal notches. On their areas remote from the anterior edge there are grooves, one on each, called infraorbital.

Most of the nasal surface is occupied by the maxillary cleft.

Alveolar component

The alveolar process of the maxilla is part of the maxillary body of the bone. It is united by an intermaxillary suture with the outgrowths of the jaw located on the opposite side. Without a visible feature from behind, it changes, turning into a tubercle facing the process of the palate of the upper part of the jaw. At the same time, he looks medially. Its shape is similar to an arc that is curved like a bone ridge, which has a forward-facing convexity.

The outer surface turns into the vestibule of the mouth. It is called vestibular. The inner surface faces the sky. It's called palatal. The alveolar process on its arch has 8 alveoli of different size and shape, intended for molars. The alveoli of the incisors and canines include two main walls, labial and lingual. There are also lingual and buccal walls. But they are located in the premolar and molar alveoli.

Functional purpose

The alveolar processes have interalveolar septa made of bone tissue. Alveoli, which are multi-rooted, contain septa that separate the roots of the teeth. Their size is similar to the shape and size of tooth roots. The first and second alveoli include incisal roots, which look like cones. The third, fourth and fifth alveoli are the location of the roots of the canines and premolars. The first premolar is often divided by a septum into two chambers: buccal and lingual. The last three alveoli contain the roots of the molars. They are separated by an interroot partition into 3 root compartments. Two of them address the vestibular surface, and one - the palatine surface.

The anatomy of the alveolar process of the upper jaw is designed in such a way that it is somewhat compressed on the sides. As a result, its size, like the size of any of these processes, is smaller in the direction from front to back than in the buccal-palatal region. The lingual alveoli have a rounded shape. The variable number and shape of the dental roots of the third molar determine its different shape. Behind the 3rd molar there are plates, external and internal, which, converging, form a tubercle.

Features of the parameters of the upper jaw

The individual shapes of the upper jaw in people vary, as do the shapes of its alveolar processes. However, in the structure of the jaw, two extreme forms can be distinguished:

  1. The first is characterized by narrowness and is itself tall.
  2. The second is wide and low.

The shapes of the pits of the alveolar processes, accordingly, may also differ slightly depending on the type of jaw structure.

This jaw has a maxillary sinus, which is considered the largest of the paranasal sinuses. Its shape is usually determined by the shape of the maxillary body.

General data about the lower jaw (LM)

The bone of the lower jaw takes its development from two arches: the branchial and the first cartilaginous. The size of the lower jaw is significantly smaller than that of human predecessors, which is due to the emergence of oral speech in humans. And also the large size of the lower jaw would interfere with modern man when chewing food, due to its location when planting the head.

In the lower jaw there are such structural elements as:

  • alveolar process - the outermost part of the jaw body in which the dental cells are located;
  • mandibular body;
  • chin hole;
  • mandibular canal;
  • mandibular angle;
  • branches of the jaw;
  • a number of articular and coronoid processes;
  • opening of the lower jaw;
  • head.

The resulting shoots

The bone in question has the alveolar process of the mandible. The alveolar composite contains eight dental sockets on both sides. These alveoli are separated by septa (septa interalveolaria), and their walls face the lips and cheeks. They are called vestibular. The walls face the tongue. On the surfaces of the alveolar bodies, a raised formation (juga alveolaria) can be clearly seen. In the place between the protrusion of the chin and the alveolar incisors there is a sub-incisal depression.

The depth and shape of the alveolar process can be varied, in accordance with the shape and structure of NP formation. The alveoli belonging to the canines are round in shape, and the deep alveoli belong to the second premolar. Each molar has bony septa between the root attachment sites. The alveolus of the third molar can vary among individuals in appearance and the presence of the number of septa.

In the LF, the alveolar process has a similar structure to the alveoli of the HF. They have two-thirds walls: lower and upper. The upper third is formed by plates of hard and compact substance, and the lower third is lined with spongy-type tissues.

Summing up

Now, having general information about the structural components of the upper and lower jaw, knowing their location and function, you can characterize them. In addition, the structure of the alveolar processes of these jaws, the presence of special components in them and their functional purpose were examined. We also saw that the alveoli of both jaws are largely similar to each other and can slightly change their shape depending on the type of jaw structure.

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.

  1. Alveolar bone with osteons, i.e. walls of the dental alveoli.
  2. 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.

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

Atrophy can also develop in the case of dysfunction of the alveolar process. A cleft palate provoked 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 bite.

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.

Bone skeleton periodontal tissues are the alveolar process of the upper jaw and the alveolar part of the body of the lower jaw. The external and internal structure of the jaws has been sufficiently studied both at the macroscopic and microscopic levels.

Of particular interest are data on the structure of the bone walls of the alveoli and the ratio of spongy and compact substance. The importance of knowing the structure of the bone tissue of the alveolar walls on the vestibular and oral sides is due to the fact that none of the clinical methods can establish the normal structure of these areas and the changes occurring in them. In works devoted to periodontal diseases, they mainly describe the condition of the bone tissue in the area of ​​the interdental septa. At the same time, based on the biomechanics of the periodontium, as well as on the basis of clinical observations, it can be argued that the vestibular and oral walls of the alveoli undergo the greatest changes. In this regard, let us consider the alveolar part of the dentofacial segments.

Alveolus has five walls: vestibular, oral, medial, distal and fundus. The free edge of the alveolar walls does not reach the enamel border, just as the root does not fit tightly to the bottom of the alveolus. Hence the difference between the parameters of the alveolus depth and the length of the tooth root: the alveolus always has larger linear dimensions than the root.

The outer and inner walls of the alveoli consist of two layers of compact bone substance, which merge at different levels in differently functionally oriented teeth. The study of layer-by-layer vertical sections of the jaws and radiographs obtained from them (Fig. 4, 1, 2, 3) makes it possible to determine the ratio of compact and spongy substance in these areas. The vestibular wall of the alveoli of the lower incisors and canines is thin and consists almost entirely of a compact substance. The spongy substance appears in the lower third of the root length. The teeth of the lower jaw have a thicker oral wall.

The thickness of the outer compact substance varies both at the level of one segment and in different segments. For example, the greatest thickness of the external compact plate is observed on the lower jaw on the vestibular side in the region of the molar-maxillary segments, the smallest in the canine-maxillary and incisor-maxillary segments.

The compact plates of the walls of the alveoli are the main abutments that perceive and transmit, together with the fibrous structure of the periodontium, the pressure acting on the tooth, especially at an angle. A. T. Busygin (1963) identified a pattern: the vestibular or lingual cortical plate of the alveolar process and, accordingly, the internal compact layer of the alveolar wall are thinner on the side of the inclination of the tooth. The greater the inclination of the tooth relative to the vertical plane, the greater the difference in thickness. This can be explained by the nature of the loads and resulting deformations. The thinner the walls of the alveoli, the higher the elastic-strength properties in these areas. As a rule, in all teeth the walls of the alveoli (vestibular and oral) become thinner towards the cervical region; After all, in this zone, the tooth root, as well as in the apical zone, makes the greatest amplitude of movements. The structure of the bone of the alveolar process depends on the functional purpose of groups of teeth, the nature of the loads on the teeth and the axis of inclination of the teeth. The inclination determines the nature of the loads and the appearance of pressure concentration zones for compression or tension in the walls of the alveoli.

Cortical plates of the alveolar process on the vestibular and lingual (palatal) sides, the internal compact plate of the alveolar wall, as well as the bottom of the alveolus, have numerous feeding holes directed towards the tooth root. It is characteristic that on the vestibular and oral walls these holes pass mainly closer to the edge of the alveoli and precisely in those areas where there is no spongy bone substance. Blood and lymphatic vessels, as well as nerve fibers, pass through them. The blood vessels of the pericementum anastomose with the vessels of the gums, bone and medullary spaces. Thanks to these holes, there is a close connection between all the tissues of the marginal periodontium, which can explain the involvement of periodontal tissues in the pathological process, regardless of the localization of the pathogenic origin - in the gums, bone tissue or periodontium. A. T. Busygin points out that the number of holes and their diameter are in accordance with the chewing load. According to his data, the holes occupy from 7 to 14% of the area of ​​the compact plate, vestibular and oral walls of the teeth of the upper and lower jaws.

In various parts of the internal compact plate there are openings (Fig. 5) connecting the pericementum with the medullary spaces of the jaw. From our point of view, these holes, being a bed for larger vessels, help relieve pressure on them, and therefore reduce the phenomena of temporary ischemia when moving teeth under load.

The specific structure of the vestibular and oral walls of the tooth sockets, their functional significance in the perception of chewing loads, force us to focus on the clinical assessment of their condition.

The cortical plate, its thickness and preservation throughout, as well as the spongy substance of the jaws, can be clinically assessed only from the mesial and distal sides of the tooth using radiographs. In these areas, the X-ray characteristics coincide with the microstructure of the bone tissue of the jaws.

The alveolar parts of the jaws in the interdental spaces, like other walls of the alveoli, are covered with a thin compact plate (lamina dura) and have the shape of triangles or truncated pyramids. The identification of these two forms of interdental septa is very important, since in the area of ​​chewing teeth or in the presence of primary teeth and diastemas, this is the norm for the construction of bone tissue, however, provided that the compact plate is preserved.

The cortical plate on the lower jaw is thicker than on the upper jaw. In addition, its thickness varies among individual teeth and it is always somewhat thinner towards the tops of the interdental septa. The width and clarity of the radiological image of the plate changes with age; in children it is looser. Taking into account the variability of thickness and the degree of shadow intensity of the cortical plate, its preservation throughout its entire length should be taken as the norm.

Structure of the bone tissue of the jaws due to the pattern of bone beams of the spongy substance intersecting in different directions. On the lower jaw the trabeculae run mostly horizontally, while on the upper jaw they run vertically. There are small-loop, medium-loop and large-loop patterns of spongy matter. In adults, the pattern of the spongy substance is mixed: in the group of frontal teeth it is small-loop, in the area of ​​the molars it is large-loop. N.A. Rabukhina correctly believes that “the size of the cells is a purely individual feature of the structure of bone tissue and cannot serve as a guide in the diagnosis of periodontal diseases.”

There is more spongy substance in the alveolar process of the upper jaw than in the lower jaw, and it is characterized by a more finely cellular structure. The amount of spongy substance of the lower jaw increases significantly in the area of ​​the body of the jaw. The spaces between the bars of the spongy substance are filled with bone marrow. V. Svrakov and E. Atanasova indicate that “the spongy cavities are lined with endosteum, from which bone regeneration predominantly occurs.”

Alveolar processes are the parts of the face to which teeth are naturally attached. Such formations are located on both the upper and lower jaws.

Structure

The maxillary part of the human skull bones is a pair, located in the central part of the face. In its structure, there are 4 types of processes: frontal (runs upward), alveolar (looks down), palatine and zygomatic. The total weight of the upper jaw is small (although visually it seems that it is heavy), this is due to the presence of many cavities (sinuses) in it.

The alveolar process of the maxilla (depicted in the photo above) consists of two wall coverings - the outer (includes the labial wall) and the inner (lingual cavity). Each of the presented areas is an arch, a sinus in the direction of the jaw endings. AO is a special recess designed for attaching a tooth.

In its upper part, the walls of the alveolar process of the lower jaw begin to touch from the second large molar, and in the lower part they transform into a jaw branch with an opening of several millimeters. In the cavity between the outer and inner coverings there are sinuses, holes, cells (holes). The teeth are located in the alveoli.

Atrophy is caused by a bay of the upper or lower jaw. The alveoli are separated from each other by dental bony septa. In the area of ​​holes with a large number of roots, there are interroot partitions.

Thus, several parts of the joint-stock company are anatomically distinguished:

  • external – it faces the cheeks, lips, and the vestibule of the oral cavity;
  • internal - located closer to the tongue and palate;
  • the segment on which all the alveolar openings (sockets), as well as the dental units themselves, are directly located.

The upper part of the joint is called the alveolar ridge; it becomes clearly visible after teeth have been lost and the alveolar sockets have become overgrown. In the absence of functional loads on the ridge, its height gradually decreases.

Atrophy (destruction) of the joint is understood as pathological changes in the structure of a given anatomical unit, which can subsequently lead to a wide range of dental problems

The alveolar process has other anatomical features. The bone tissues of the upper and lower jaw are subject to constant changes throughout human life. This is explained by the physical and work loads that occur on the teeth.

Such transformations provoke a fracture of the alveolar process of the upper jaw, as a result of which the patient may need correction (plasty) of this anatomical unit. As we age, teeth wear away in the active surface area. In this case, the parties facing each other suffer. Corresponding changes occur in the alveolar covering, which can lead to damage.

Possible injuries

Natural aging, physical stress, fracture and alveolar cancer are all abnormal processes that can affect the upper and lower jaws. Each of them can develop not even as a result of an intense blow or mechanical trauma, but on its own, with a not very strong bite (the duration of pathological changes can be very diverse).

With age, the risk of damage to the alveolar process naturally increases, especially the cleft of this formation (the most fragile part) suffers. To prevent such problems, it is necessary to regularly visit the dentist and resort to appropriate treatment and preventive measures.

AO restoration methods

Jaw fractures and other injuries require subsequent correction of both the alveolar processes and the teeth themselves; this is necessary to preserve the “healthy” functioning of a person.

The list of restoration measures is as follows:

  • group of surgical methods - filling, after removal - prosthetic processes;
  • the use of special preparations that strengthen the enamel, hard tissues of teeth, sinuses;
  • the use of compounds to additionally protect the integrity of teeth - this is necessary for people engaged in active physical labor and athletes.


Surgical intervention is the only therapeutic measure for AO injuries

Correcting the condition of teeth in this case is much more problematic than any other type of prosthetics. Restoration can involve both the root part and the sinuses, other fragments, or even the entire jaw and oral mucosa.

Important! Small height (that is, essentially, a lack of bone tissue volume) is a limitation for dental implantation. To subsequently secure the prosthesis, the patient first undergoes bone grafting.

As you can see, the alveolar processes are important anatomical structural units of the upper and lower jaw, which, in fact, are the basis for the attachment of teeth. AO injuries are a direct indication for bone grafting and dental prosthetics.