What is tooth pulp: histological structure, layers, functions

The structure of a tooth on a cross-cut is very similar to the structure of a tree trunk. The role of the cortex is fulfilled here tooth enamel, the layers of dentin are similar to the wood of the middle part of the trunk with annual rings, and the role of the core belongs to the central cavity, which contains the dental pulp, or pulp.

It is called pulp because it is really softer compared to other, really hard fabrics.

And just as the core of the trunk is the source of its emergence, existence and thickening, the dental pulp is the source of life for the tooth as an organ.

Pulp functions

Due to its presence and structure, it is possible to perform four main functions:

• sensory;
• protective;
• trophic;
• plastic.

Thanks to the pulp, the growth and development of both the initial tooth germ and its subsequent evolution take place. Almost completely formed by the time of eruption from the gums, it continues to increase the thickness and mass of its tissues throughout the entire period of development of the human body.

But even after its approval in the hole, the work does not end: the pulp sensitively reacts with pain to organ damage (especially when fracture with the opening of the central chamber), on a change in the temperature and chemical composition of saliva and processed in the mouth food.

The protective properties of tooth pulp consist in the production of antitoxin substances and compounds responsible for the strength of hard tissues. Extremely acute sensations appear when inflammation of the substance of the dental pulp begins in the pulp cavity (chamber). For it contains not only cells and fibers, but also nerves.

The histological structure of the dental core

Like any body tissue in general, the pulp consists of a stroma (a framework of connective tissue fibers), between the structures of which cavities remain - free spaces.

Nerves and blood vessels pass through them, in the remaining unoccupied volumes, the most energetic and active component of the tooth pulp is distributed - its cellular part.

The main substance, consisting of mucopolysaccharides, muco- and glycoproteins, hyaluronidases and hyaluronic acid, acts as a component that binds all parts of the pulp into a single whole.

The vascular network of the dental pulp represents the end segments of arterioles - arteries of the smallest diameter with a minimally thin wall, smoothly transforming into capillaries.

The wall thickness of the capillaries is so negligible that it allows free exchange between surfaces erythrocytes literally squeezing through the narrow lumen of the capillaries, and the fluid filling the intercellular space. At this stage, there is an exchange between arterial blood, which carries oxygen and nutrition to the cells, and the interstitial fluid, where the final products - the waste of cellular activity - enter.

Capillaries are the limit of the subtlety of branching of the arterial part of the vascular bed. From their level, the process of increasing the diameter of the vessels taking blood away from the organ begins - venules, on the way to the heart, uniting with formations of a similar diameter, form veins. Veins carry blood with cellular waste to the heart, which sends it to the purification organs: kidneys, lungs, liver.

In addition to removing waste with blood flowing through the venules, they are removed from the intercellular spaces with using the end sections of the network of lymphatic vessels located between dense formations pulp.

The nervous system of the tooth is represented by the processes of nerve cells (whose bodies are located outside pulp chamber), which are part of the nerves into the cavity of the tooth through the apical foramen of each tooth root.

The branching neural network is not only located in the spaces of the stroma, but also penetrates the entire thickness of the dental wall, reaching its surface inside the dentinal tubules.

From the processes of nerve cells, an uninterrupted network of conductors begins from the tooth to the brain and back. Through them, sensations (temperature, pressure, pain) are transmitted to the conscious centers of the brain - and almost immediately through the reverse system communication, a signal is received that prompts action to stop irritation (for example, to release the mouth from too hot food).

Cellular composition of the pulp

The existence of nervous and vascular structures would be impossible without the functioning of the cellular framework and cells that move freely.

Cellular "armature" is formed by three layers of cells:

• peripheral;
• intermediate;
• central.

The peripheral is formed by odontoblasts located in several tiers - pear-shaped cells with two processes: central (within the pulp) and peripheral, reaching the dentin layer along the dentin tubules.

The intermediate layer is composed of stellate cells and perhodontoblasts.

The central layer is represented by:

• fibroblasts;
• macrophages;
• lymphocytes;
• histiocytes;
• mast cells;
• plasma cells.

The cells listed above are free to move (especially during inflammation) and transform into other types (for example, histiocytes are transformed into macrophages, and mesenchymal cells, called undifferentiated ones, in general into any of species).

Changes with age

Each class of cells has a specific function in the life of the pulp.

Responsible for protection:

• fibroblasts that synthesize collagen;
• macrophages that carry out antitoxic work and remove dead cells from spaces;
• lymphocytes responsible for the production of immunoglobulins.

Odontoblasts are busy performing the plastic function of the pulp - the production of primary dentin before the eruption of the tooth and the formation of secondary dentin after the completion of the process. Moreover, secondary dentin is constantly synthesized, leading with age to a decrease in the volume of the dental chamber.

Pulp inflammation

Despite the clear coherence of biochemical processes occurring in the pulp cavity, it can begin an inflammatory process caused by the failure of protective mechanisms during penetration of the microbial flora into the cavity and her toxins.

Since the cavity of the tooth is not tightly closed, invasion into it is possible from the side of the mouth of the apical canals of the roots.

The second option is the opening of the pulp chamber in the event of a tooth fracture or after an unsuccessful filling procedure.

Another reason may be the thinning of the tissues of the teeth due to their pathological abrasion.

But the most common development option pulpitis - This is a slow diffusion of microbial toxins through the thinned bottom of the carious cavity, leading to irritation, and then to damage to the pulp structures.

In the absence of dynamics, the pulp is in a state of chronic sluggish inflammation, but in a critical situation, the death of its fragments begins, leading to a picture of acute pulpitis and the need to open the dental chamber.

Treatment

For the treatment of acute or primary chronic pulpitis 3 different approaches are applied.

After opening the tooth cavity, the following method is used:

• biological;
• amputation;
• extirpation.

Biological method

The application of a biological (or conservative) method involves an attempt to restore a healthy state tooth pulp only at the very initial stage of inflammation by treating its structures with anti-inflammatory means.

Inside the opened cavity, a tampon soaked in a solution of an antibiotic or other antimicrobial composition is left for one or two days. The tooth is sealed with a temporary filling.

After the expiration of the prescribed period, the newly opened cavity is washed with a disinfectant solution, and a paste with calcium hydroxide in the recipe is left inside. The stage, ending with the imposition of a new temporary filling, lasts from 5 to 7 days.

After the required time has elapsed, the final filling of the tooth is performed.

Extirpation method

The extirpation technique has options that are used depending on the degree of viability of the pulp.

At pulpitis chronic gangrenous cost by vital extirpation, chronic fibrous - requires preliminary devitalization, with acute diffuse - the choice depends on the specific case.

Devitalization the process of killing the pulp is called, preceding its possible complete removal from the cavity of the crown and root canals.

With devital extirpation, the opened pulp chamber is treated with an antiseptic, followed by its drying and leaving the arsenic-containing paste inside. The exposure period depends on the number of roots: in the case of a single-rooted tooth, it is one day, with a larger number of them, the period is twice as long.

At the second visit, the remains of the paste are removed, as well as the extraction of the entire sacrificed mass of both root and coronal pulp.

After driving the root canals to the maximum possible depth with their cleaning and sterilization, the cavity is sealed with a temporary filling.

The third visit to the dentist ends with a permanent (final) filling, provided the tooth is healthy.

The method of vital extirpation is an operation on pulp removal without first killing her.

Amputation method

The amputation technique is used when the complete release of the dental cavity from the dental core occupying it is impossible for one reason or another.

It is pertinent to recall that in addition to the coronal pulp, there is also its root part, which is its continuation in the cavities of the dental roots. Since, due to the tortuosity, narrowness, curvature of the root canals, their passage through the entire length (depth) is not always a feasible measure, full-scale extraction of root pulp from them is also not always possible. In such cases, they resort to partial removal of the pulp mass - amputation.

The method has two modifications - amputation:

• vital;
• devital.

The first is used in cases with children's dental roots, the complete extraction of the pulp from which can disrupt their growth and development. After amputation at the level of the root canals, the dental cavity after its sanitation is sealed with a temporary filling for up to six months, after which the filling is changed to a permanent one.

With the devital version of amputation, the entire mass of the coronal pulp is removed, which is not subject to extraction from the root canals, after killing it, it is preserved and left in place. It is mummified (turns into a sterile strand of fibrous structure that does not contain living structures) under the influence of the dehydrating effect of devitalizing paste.

Subsequent observation reveals either the need for subsequent extirpation of the pulp (with the development of inflammation in periodontal tissues), or states a successful outcome of the intervention, when the continuation of treatment is not required.

Considering that the state of the dental core depends not only on unthinkable suffering when it is damaged, but also on the aesthetic perception of the face and the ability to fully chew food, both patients and dentists need to do everything possible to keep it healthy condition.