The current state of affairs and the rapid development of dentistry and plastic maxillofacial surgery require detailed knowledge of the blood supply to the face, including the upper and lower jaws (HF, LF). In the literature over the past 40 years, we have not found any works devoted to the study of blood supply to the HF and LF. Meanwhile, this knowledge is necessary for various surgical interventions on the jaws, fractures, wounds, to interpret the paths of spread of purulent-inflammatory processes on the face.
The HF is supplied with blood by a large number of large arteries, which widely anastomose with each other [2, 4]. As for the sources of blood supply to the NP, expert opinions differ. Some authors [5] consider the inferior alveolar artery to be the main and only source of blood supply to the NP. According to others [1-3], in addition to the inferior alveolar artery, additional arteries are involved in the blood supply to the NP.
The LF is supplied with blood from a number of additional extraosseous (extraosseous) arteries: the temporal, arteries of the pterygoid muscles, masticatory, facial, lingual and mylohyoid. The main arteries supplying blood to the NP are considered to be 6 intraosseous (intraosseous) arteries: maxillary, inferior alveolar, lingual, transverse facial artery, masticatory and facial.
The purpose of the study is to study the main and additional sources of blood supply to the HF and LF - extraosseous and intraosseous arteries, to study their participation in the blood supply of the jaws and their relationship with facial tissues.
Material and methods
The work is based on the study of 130 isolated NP preparations removed from corpses in Tver morgues, and 20 embalmed corpses of people aged 20 to 70 years, studied at the Department of Topographic Anatomy and Operative Surgery of the TSMA.
The following methods were used: morphometric measurements, contrast radiography, decalcification, preparation, recording and photography. Using 16 NP preparations, experimental ligations of the inferior alveolar artery in the initial part of the mandibular canal were performed to identify additional intraosseous arteries involved in the blood supply to the NP.
For contrast angiography, injections were made through the external carotid or inferior alveolar artery of lead, diluted in petroleum jelly and turpentine in the following ratio: lead - 60 g, petroleum jelly - 15 g, turpentine - 15 g.
The structure of the dental pulp –
Speaking about the structure of the dental pulp, we will first analyze its structural elements - after which we will move on to a description of its layers, which you could see in Fig. 2. You can see the appearance of the pulp removed from the tooth (wound on a pulp extractor) in the photo below.
Video of tooth pulp removal (pulpectomy) –
1) Structural elements of pulp –
The pulp consists of loose fibrous connective tissue (with a large number of nerve endings, blood and lymphatic vessels). Accordingly, its structure will consist of collagen fibers, the main amorphous substance, as well as a large number of various cellular elements. The total collagen content is from 25 to 30% of the dry mass of the dental pulp, and it is mainly collagen types I and III. In the coronal part of the pulp, collagen fibers are located more loosely, but in its root part they form denser clusters.
As for the main amorphous substance located between the collagen fibers, it consists of water, glycosaminoglycans, as well as glycoproteins and proteoglycans. The intercellular substance has a high ability to diffusion, which allows nutrients from the blood to enter the cellular elements, and metabolic products to be excreted into the venous circulatory system. There is also a wide variety of cellular elements in the pulp - primarily odontoblasts and fibroblasts (fibroblasts are responsible for the formation of intercellular substance and the synthesis of collagen fibrils), as well as dendritic cells, macrophages, lymphocytes, mast cells, etc.
Cellular elements of the pulp -
| Cells | Odontoblasts – form dentin and provide its trophism. Neighboring odontoblasts are interconnected by intercellular connections, which allows the layer of odontoblasts to also perform a barrier function (regulating the movement of molecules and ions between the pulp and predentin). Some authors call these cells “dentinoblasts.” |
| Fibroblasts are the most numerous cells in the pulp (their number decreases with age). Their function is to produce and maintain the composition of the intercellular substance of the pulp, as well as to absorb and digest the components of the intercellular substance. | |
| Macrophages - participate in the renewal of the cellular composition of the pulp, capturing and digesting dead cells and components of the intercellular substance. They phagocytose microorganisms and participate in the development of immune reactions as antigen-presenting effector cells. | |
| Dendritic cells – they are antigen-presenting cells whose function is to absorb various antigens, process them and present them to lymphocytes. They also induce the proliferation of T lymphocytes. The content of dendritic cells increases as the pulp matures, as well as with antigenic stimulation. | |
| T-lymphocytes are contained in the pulp in small quantities, but during inflammation their number increases sharply (of all types of this population of lymphocytes, T-suppressors predominate in the pulp). B-lymphocytes are not normally found in the pulp, and appear only when it is inflamed (they synthesize IgG immunoglobulins and provide humoral immune responses). | |
| Mast cells – they are located around blood vessels; are characterized by the presence in the cytoplasm of a large number of granules with biologically active substances (histamine, heparin, eosinophilic chemotactic factor, etc.). The release of these components causes an increase in vascular permeability. | |
| Poorly differentiated cells - can give rise to odontoblasts and fibroblasts. The content of these cells decreases markedly with age. | |
| Fibers and glycoproteins | Type I and III collagen fibers, reticular fibers, fibronectin. |
| Basic intercellular substance | Glycosaminoglycans, chondroitin, proteoglycan. |
Architectonics of dental pulp layers –
In the coronal part of the pulp, there are several layers that differ in their structure and functions - 1) the outer layer, consisting of odontoblasts, 2) the subodontoblastic layer, which in turn consists of several zones, including the Weil and Rinaggio zones, as well as the Rashkov plexus, 3) central pulp zone. Below we will analyze in detail the structural components of each layer.
Architectonics of dental pulp layers (diagram) –
- The outer layer (peripheral) - consists of several layers of odontoblasts, which are elongated cells with basophilic cytoplasm (24stoma.ru). In “young teeth” the pulp may contain 6-8 layers of odontoblasts, but the older a person gets, the fewer the number of layers will be (at least one layer). Odontoblasts are highly differentiated cells that are specific to the dental pulp.
Long processes (the so-called “Toms fibers”) extend from the odontoblasts, which penetrate the dentinal tubules to the entire depth of the dentin. Odontoblasts and their processes play a very important role in the nutrition of the tooth and the delivery of mineral salts to the dentin and to the enamel-dentin border. In addition, they perform the function of dentin synthesis both during the period of tooth development and throughout a person’s life (we are talking about the synthesis of secondary and tertiary dentin). In the root part of the pulp, a layer of odontoblasts is also present, but it is thinner than in the coronal part of the pulp.Odontoblasts are closely connected to each other by strong intercellular connections, but capillary loops penetrate through their layer, as well as the finest nerve fibers (branches from the Rashkov plexus). These nerve fibers form tree-like branches around the odontoblasts - they are often called the “superodontoblastic nerve plexus”. It is interesting that part of the nerve fibers will end around the odontoblasts, but the other part will be directed along with the processes of the odontoblasts into the dentinal tubules.
- Subodontoblastic layer - morphologically it is usually divided into 2 zones.
The first zone is the more superficially located “light Weil zone” (a layer poor in cell nuclei). This zone mainly consists of collagen fibers, as well as cell processes penetrating from the inner zone of the subodontoblastic layer. This layer contains a large number of capillaries, which form an extensive capillary plexus that nourishes both odontoblasts and the pulp as a whole. Also in this layer there are many myelinated and unmyelinated nerve fibers, forming the so-called Rashkov nerve plexus. The deeper zone of the subodontoblastic layer is the Rinagio zone (a zone rich in cellular elements). This zone consists of a large number of diverse cellular elements, for example, poorly differentiated cells are located here, which can give rise to odontoblasts and fibroblasts. In addition, fibroblasts themselves, lymphocytes, as well as capillaries and nerve fibers are located in this layer.
- The central zone of the pulp is a loose fibrous connective tissue rich in cells (primarily fibroblasts and macrophages). Also contains larger blood and lymphatic vessels, and larger bundles of nerve fibers. In the central zone of the pulp, dendritic cells, lymphocytes, plasma cells, mast cells, and blood granulocytes are constantly present in small quantities.
Summary: below, for convenience, we have arranged the structural elements of the pulp layers - in the form of a single table. Once again, we draw your attention to the fact that the intermediate (subodontoblastic) layer is well developed only in the coronal part of the pulp.
| Peripheral layer | Intermediate layer | Central layer | |
| outer zone (Reil) | inner zone (Rinagio) | ||
| – odontoblasts, – Toms’ processes, – capillary loops, – nerve fibers. | – processes of cells of the inner zone of the intermediate layer, – collagen and reticular fibers, – Rashkov’s nerve plexus. | – fibroblasts, – lymphocytes, – preodontoblasts, – poorly differentiated cells, – capillaries, – myelinated and non-myelinated fibers. | – PBST *, – large blood and lymphatic vessels, – bundles of nerve fibers. |
* PBCT is loose fibrous connective tissue.
Histological specimen (dental pulp and peripulpal dentin) –
Where 1 is dentin (where 1a is calcospherites, 1b is predentin). Where 2 is the dental pulp (where 2a is the peripheral layer consisting of odontoblasts, 2b is a cell-poor zone in the intermediate pulp layer, 2c is a cell-rich zone in the intermediate pulp layer, 2d is the central pulp layer).
Ultramicroscopic structure of odontoblast –
Above you can see what an odontoblast looks like with a branched process, which will be located in dentin and predentin (where 1 is dentin, 2 is predentin, 3 is an odontoblast process located in the dentinal tubule, 4 is the Golgi complex, 5 is the nucleus, 6 is mitochondria, 7 – endoplasmic reticulum.).
Differences between the coronal and root parts of the pulp -
The root part of the pulp has significantly weaker vascularization and innervation compared to the coronal part of the pulp. In addition, the cellular composition of the root part of the pulp is much poorer, and the odontoblast layer, even in the “young pulp,” has only 1-2 rows of cells. Apparently, such differences in structure depend on the characteristics (differences) in the supply of nutrients and calcium salts - in the crown and root parts of the tooth.
In the coronal part, dentin and enamel receive nutrients and calcium salts - almost exclusively from the dental pulp. As for the nutrition of the hard tissues of the tooth root, it occurs not only through the pulp, but also due to the process of diffusion of nutrients from the pericement. Therefore, evolutionarily, a decrease in the importance of root pulp in the nutrition of hard tissues of the tooth root has been formed, and its structure has changed.
| Coronal pulp: | Root pulp: |
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Pulp histology: video
Below in video 1 you can see the histology of tooth tissue in stunning resolution. Video 2 is the best lecture on pulp histology you will ever hear. The video is in English, but if you wish, you can turn on subtitles and select translation from English into Russian in the settings.
Features of the structure of the pulp of temporary teeth -
The structure of the pulp in baby teeth differs little from permanent ones. For example, in baby teeth there are fewer differences in the structure of the coronal and root parts of the pulp, and in addition, the pulp in baby teeth is more abundantly supplied with blood. There are also slight differences in the composition of cellular elements and the number of collagen fibers (Fig. 3).
Functions of dental pulp –
The functions of the dental pulp stem from its morphology (structure). Below we list its main functions:
- Trophic function - we have already said that the pulp has a well-developed network of blood and lymphatic capillaries.
The main intercellular substance of the pulp serves as an intermediate medium through which metabolism occurs. Thus, oxygen and nutrients from the blood enter the cellular elements of the pulp precisely through the intercellular substance, and metabolic products are excreted through it into the venous or lymphatic systems. But the trophic function of the pulp is not only to nourish its own structures. The dentin and enamel of the crown part of the tooth receive nutrients and calcium salts - almost exclusively from the dental pulp (the processes of odontoblasts play a major role here). But as for the nutrition of the hard tissues of the tooth root, it occurs not only through the pulp, but also due to the process of diffusion of nutrients from the pericementum.
- Plastic function is realized thanks to odontoblasts, which throughout a person’s life participate in the formation of secondary and tertiary dentin. For example, in teeth there is a constant deposition of secondary dentin on the side of the pulp chamber, which leads to a gradual decrease in its volume. The deposition of denser tertiary dentin, as well as the obliteration of dentinal tubules, also occurs due to odontoblasts, and protects the pulp from external irritants and the penetration of bacteria into it.
- The protective function - the function of phagocytosis and disposal of dead cells is provided by neutrophil granulocytes and macrophages. Lymphocytes (plasma cells) - participate in the synthesis of antibodies. Fibroblasts participate in the formation of a fibrous capsule around the inflammatory focus. In addition, the pulp is also a biological barrier that prevents the penetration of pathogenic bacteria from the carious cavity into the periodontium. The protective function also includes the processes of formation of tertiary dentin and obliteration of dentinal tubules that we have voiced.
- Sensory function - carried out due to the presence of a large number of nerve endings.
