The pulp cavity is the internal cavity of a dental element that is normally occupied by the pulp tissue. The pulp tissue consists of cells, connective tissue, draining and supplying blood vessels, lymph vessels and nerve fibers. The pulp cavity is subdivided into the pulpa room and the root canal. The walls of the pulp cavity follow roughly the outer contour of the dentine.
The pulp chamber is that part of the pulp cavity, which is for the most part located in the crown of the element. The pulpa room is bounded on the occlusal (incisal) side by the roof of the pulpa room. On the cervical side, it is bordered by the bottom of the pulp chamber. The roof of the pulp chamber follows the course of the occlusal surface of the (pre) molars or the oral surface of front elements. The pulpa runs pointed in every nodule in the pulpa horns. The size of the nodule determines the size of the pulpa horn. The bottom of the pulp chamber is always apical to the glaze-cement boundary.
For single-channel elements, there is usually no clear boundary between pulp chamber and root canal. For elements with more channels, a clear boundary can be specified at the place where the pulpa room changes into the channel entrances. The bottom of the pulp chamber is the area between the root canal entrances.
The root canal is the part of the pulp cavity that is located in the root of the tooth. The root canal could be compared to an oval, round or sometimes eight-shaped tube that tapered from the channel entrance to the root tip. This tube can have smaller branches and bends. The branches can occur over the entire root and are called lateral channels. Usually there is a clear main opening apical, the apical foramen. This causes a lymphatic vessel, a blood vessel and a nerve cord to enter the element. The apex is the root point: a curve often appears in the apical part of the root canal (see images below).
The number of roots and root canals at the teeth varies. A root can also contain several channels. The table below provides a schematic overview of the number of roots and the number of root canals per element. The variation in the number of roots and root canals is great!
Schematic overview of the number of roots and root canals.
|Element||Number of roots||Number of channels||Note|
|Premolars||1||1||The P1 in the upper jaw deviates from this|
|1st Premolar in the upper jaw||2||2||1 Buccal and 1 palatal channel|
|1st Molars in the upper jaw||3||4||2 Buccal roots and 1 palatal root, where the mesiobuccal root has 2 channels|
|2nd Molars in the upper jaw||3||3||2 Buccal roots and 1 palatal root, each with 1 channel|
|Molars in the lower jaw||2||3||1 Mesial root with 2 channels and 1 distal root with 1 channel|
Cells, fibers, and intercellular substances are found in the dental pulp. The most important cells are:
- Fibroblasts, which occur throughout the entire pulp cavity and which produce the intercellular dust and fibers;
- Odontoblasts, which lie against the dentin as a single layer. Their foothills lie in the dentine tubules or channels of Tomes. They specialize in dentin formation;
- Immune cells, macrophages, which lie against the blood vessels and which take action when an inflammation occurs. They play a role in the body’s defenses (see image below).
Blood vessels, lymphatic vessels and a nerve cord from the n. trigeminal, into the pulp. Draining blood and lymphatic vessels leave the pulp again via the same foramen.
Sometimes there are so-called pulp pies or denticles in addition to these structures in the pulp room. These are groups of pulp cells that are calcified. They are often found with an older pulp (see image below).
The dental pulp has a number of functions:
- Formative function. The cells of the pulp form fibers and play a role in dentin formation.
- Nourishing function. The pulp consists of living tissue; the living cells must be supplied with nutrients, as must the shoots of the odontoblasts in the dentin. These nutrients are supplied by the supplying blood vessels.
- Sensory function. The sensation of pain and temperature.
- Defense function. In case of inflammation, macrophages and lymph cells take care of the immune system. The defense function also includes the formation of irritant dentine on the pulp dentin border, for example in the case of a deep carious defect.
Age of the pulp
Upon eruption of a dental element in the oral cavity, the pulp cavity is not yet fully grown. An X-ray shows this in a funnel-shaped apical foramen, wide root canals and a large pulpa room. The odontoblasts ensure further formation by dentine deposit against the walls of the pulp cavity. As an element grows older, the deposition of secondary dentin and general calcification reduces the pulp chamber, and the root canals become narrower or even clog up completely (obliterate) (see image below).