Dental pulp refers to the interior of the tooth. It also bears the name dental pulp.
What is the dental pulp?
Dental pulp refers to the soft tissue inside the tooth. It is also known as dental pulp and fills the pulp cavity (cavum dentis) as well as the root canals. Composed largely of gelatinous connective tissue, the pulp is equipped with sensitive nerve fibers. Also part of the dental pulp are the blood and lymph vessels. In common parlance, the dental pulp is also called the dental nerve, but this is not correct. It is surrounded by the dental hard tissues in the pulp cavity. The pulp cavity extends from the tooth crown to the tooth root tips. The course of all inflows and outflows of veins, arteries and lymphatic vessels passes through the apical foramen. In endodontics, dental pulp and the adjacent dentin are referred to as the pulp-dentin complex. This is to emphasize the functional unity of these structures.
Anatomy and structure
From a macroscopic perspective, a subdivision of the dental pulp into root pulp and crown pulp occurs. This differentiation can be quite important clinically, as in the context of a pulpotomy. In this procedure, the dentist removes the infected crown pulp while preserving the root pulp. In the region of the crown pulp, there is a buildup in several layers. Towards the tip, it loses its circumference to an increasing extent. Basically, the pulp can be divided into several sections. These are the odontoblast margin, the subodontoblast layer, the Weil zone as well as the bipolar zone and the core zone. The odontoblast seam acts as the first layer. It is superimposed on the predentin and has a palisade arrangement. The odontoblasts send out the tomes fibers, elongated cell processes, into the dentinal tubules. The fibers have a tight connection among themselves. At the crown pulp, there is a columnar arrangement of odontoblasts. In the central region of the root pulp, they exhibit a cube shape, while in the apical root region they are flattened and ultimately completely absent. Attached to the odontoblasts are the so-called cave cells, which mark the subodontoblast layer. These bipolar preodontoblasts serve as stem cells for the replenishment of cells for the odontoblast layer. The pulp tissue adjacent to the odontoblast layer is called the Weil zone. This has fewer cells than the other pulp zones. Instead, it contains cytoplasmic extensions derived from fibroblasts. In addition, some terminal branches of nerve fibers are present. The nucleus-poor zone is followed by the bipolar zone. There, there are a large number of cells that are densely attached and equipped with a spindle-shaped nucleus. Since the cells visually give the impression of being equipped with two poles, their section was given the name “bipolar zone”. In this zone, replacement cells of pulp and fibroblasts are abundant. Collagen is produced by the fibroblasts. In this way, they ensure the emergence of a fiber network. There the cells as well as the extracellular matrix embed themselves. The pulp core area is demarcated from the bipolar zone. This refers to a connective tissue strand with a gelatinous structure. Blood vessels, nerves, and various cell types occur in the strand. These include lymphocytes, macrophages, fibroblasts, and mesenchymal cells.
Function and tasks
The dental pulp performs several important tasks. Among these is the synthesis of dentin. It is important to distinguish between several types of dentin. Until the growth of the root is complete, the production of primary dentin takes place. Once the tooth has fully matured, production switches to secondary dentin. The synthesis of secondary dentin progresses continuously. This in turn leads to a slow reduction in the size of the pulp cavity. Furthermore, the formation of stimulus dentin close to the pulp in response to stimuli of a mechanical, thermal or chemical nature is possible. The vascular system of the pulp has the task of supplying the dentin with nutrients. Furthermore, the dental pulp has a sensory function. It is thus able to register mechanical, thermal, chemical and osmotic stimuli. How the transmission of pain stimuli from the dentin to the pulp takes place has not yet been precisely clarified. It is assumed that the transmission of the stimuli is taken over by the odontoblast processes.Another important task of the dental pulp represents the defense against harmful microorganisms.
Diseases
The pulp is susceptible to various pathological changes. First and foremost among these is pulpitis, which is an inflammation of the dental pulp. Pulpitis is noticeable by toothache and feelings of pressure. Inflammation of the pulp causes pressure to build up within the pulp cavity. This radiates to the adjacent tissue and the tooth nerve. Unlike other areas of the body, it is not possible to redirect the pressure to the neighboring soft tissues. Pulpitis can occur in milk teeth as well as in permanent teeth. It is caused by caries, which leads to infestation of the pulp with harmful bacteria. The caries in turn is caused by bacterial plaque. In case of deep decay of the tooth substance, the bacteria are able to penetrate into the pulp and cause inflammation. Sometimes, however, acidic food residues, injuries, dental fillings or crowns can also be the reason for pulpitis. Other damage to the dental pulp includes apical periodontitis at the tooth root tip, odontogenic infection with an abscess, or pulp gangrene, which leads to pulp tissue death.
