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Dental pulp forms the soft tissue nucleus of the tooth; its surface mirrors the outer (larger) shape of the tooth.
It is connected with the body as a whole via both the apical foramen and lateral and inter-radicular ducts connected with the periodontium.
Therefore, pulp diseases often involve the periodontium. Furthermore, medical treatment of the pulp or the pulp cavity always implies systemic distribution of the medical drug or its ingredients, though to a lesser extent.
The pulp and the surrounding dentine are an evolutionary, biological and functional unit referred to as the pulp-dentinal complex.
The odontoblast processes in the dentine tubules are an integral part of dental pulp. The complex of odontoblast processes, pulp and dentine is referred to as endodontium.
Topography of the pulp chamber
The space inside the anatomic crown of the tooth that contains the pulp is referred to as pulp cavity.
The pulp cavity and the root canals form the pulp chamber.
In the course of its functional period, continuous physiological formation of secondary dentine results in a reduced size of the pulp chamber.
Root canal system
The shape of the root canals with the root pulp they contain is usually not easily predictable and may vary; frequently, root canals have a bizarre shape with numerous protrusions and ramifications, with their cross-sections also shaped differently (round or C-shaped root canals are rare; elliptic or flat and elongated root canals occur more often).
This extremely irregular shape of the root canals, particularly those of premolars and molars, frequently results in the use of the term "root canal system" instead of "root canal".
Accessory root canals
The main root canal is often divided like a delta into several smaller, accessory canals in the area of the root tip. Accessory root canals can be distinguished as follows:
They leave the main canal usually horizontally in the coronal or middle third of the root.
They are present in approx. 70 % of all teeth, with anterior teeth having fewer lateral canals than molars.
Approx. 25 - 65 % of all permanent molars and approx. 20 - 35 % of all deciduous molars have patent canals passing from the base of the coronal part of the cavity #pic# to the furcation #pic#.
The pulp is basically responsible for dentine vitality and reaction.
Therefore, part of the mesenchymal pulp cells remain in an undifferentiated state in the course of tooth development. These mesenchymal pulp cells form a reservoir of pulpal replacement cells.
Viable and functional pulp has the following tasks:
Nutrition of odontoblasts
The pulp feeds the odontoblasts and, via their processes, the dentine through the dentinal fluid, or lymph, an intra-tubular, extra-cellular fluid originating from the pulp.
Dentinal fluid is the connecting medium of dentine and the body. The area of pulp distribution is approx. 30 times the size of the actual pulp space.
Formation of primary dentine
During the phase of tooth development, the pulp develops primary dentine.
Formation of secondary dentine
Secondary dentine is permanently developed by the odontoblasts, even after tooth development is complete.
This deposited dentine can be considered a kind of protective layer for the pulp against attrition and caries.
Differentiation of pulp cells into odontoblast-like cells
If some odontoblasts are destroyed because of trauma or iatrogenic damage, differentiation of pulp cells to odontoblast-like cells may occur which are then able to develop repair dentine or irritation dentine.
This restorative potency of the pulp is of great significance for various therapeutic measures.
Formation of irritation dentine
The most important function of the pulp is the formation of irritation dentine #pic# as a protective layer.
Irritation dentine (irregular dentine, irregular secondary dentine, osteodentine, reactive dentine, restorative dentine, tertiary dentine) is dentine developed from primary odontoblasts as a reaction to trauma, e.g. deep caries or restorative measures.
Formation of peritubular dentine
During the physiological aging processes, pulp odontoblasts produce highly mineralized peritubular dentine resulting in a continuous reduction of the lumen size of the dentine tubules with increasing age.
Signalling and warning functions
The pulp signals and warns against thermal, osmotic, toxic, and infectious irritations.
Triggering of an inflammatory reaction
The pulp responds with acute or chronic inflammatory reactions to stronger thermal, mechanical, toxic, or infectious irritation.
Compared to juvenile pulp #pic#, the number of pulp cells decreases continuously with age and a fibre structure develops.
The immediate clinical consequence of this reduced number of cells is a decreasing restorative power of the pulp with increasing age of the tooth.