Quick Facts
The dental pulp is the richly vascularized and innervated connective tissue of mesodermal origin contained in the central cavity of a tooth and delimited by the dentin; it has formative, nutritive, sensory, and protective functions. The portion within the tooth chamber proper is the pulpa coronalis, and that within the root is the pulpa radicularis (Dorland, 2011).
Related parts of the anatomy
Structure and/or Key Feature(s)
Dental pulp is the specialized loose connective tissue that resides in the central pulp cavity or chamber of the tooth. Unlike other dental tissues such as enamel, dentin or cement, dental pulp is non-mineralized. The pulp itself is the living entity of the tooth and contains connective tissue, blood vessels, and nerves.
Each pulp cavity opens into the tissue surrounding the tooth through the apical foramen of the root. Some teeth may additionally have an accessory canal or foramen. Dental pulp is continuous with the periodontal ligament via the apical and accessory foramen (Standring, 2016).
Pulp has two distinct zones, namely the central zone and peripheral zone, both of which are observed in the coronal and radicular parts of the tooth. The central zone houses arterioles, veins and nerve trunks that enter the pulp cavity through the apical foramen and travel longitudinally to the coronal pulp chamber. The peripheral zone (also known as the odontogenic zone) is comprised of distinct layers, beginning with the outermost layer which lies on the periphery of the pulp known as the odontoblastic layer. The odontoblastic layer is adjacent to the predentin with the cell bodies of the odontoblasts situated in the pulp and their cell processes extending into the dentinal tubules.
Subjacent to the odontoblast layer is the cell-free zone (also known as the zone of Weil) which contains several bundles of reticular fibers and numerous capillaries and nerves. Subjacent to the cell-free zone is the cell-rich zone that contains numerous fibroblasts and perivascular cells (also known as mesenchymal cells), the latter of which can give rise to odontoblasts, fibroblasts or macrophages. The deep pulp cavity, located medial to the cell-rich zone, contains the subodontoblastic nerve plexus of Raschkow (Chiego, 2014).
Through the apical foramen, a number of thin-walled arterioles enter and travel longitudinally until they reach the pulp cavity in the crown. Here, they ramify forming a dense capillary network beneath the odontoblast layer. After draining the capillary bed, small venules travel downward and exit the pulp cavity via the apical foramen.
Along with the arterioles, sensory and sympathetic nerve fibers enter the pulp cavity via the apical foramen. Specifically, sympathetic nerve fibers extend from the superior cervical ganglion, travel into the pulp cavity and innervate the smooth muscle cells of the arterioles to modulate vasoconstriction.
Additionally, sensory fibers that have arisen from the trigeminal ganglion pass through the apical foramen, travel longitudinally toward the crown and ramify as the nerve plexus of Raschkow. Fibers can extend in an unmyelinated form from this plexus toward the odontoblasts where they lose their Schwann cell sheath. These free nerve endings can sometimes extend up between the odontoblasts and enter the dentinal tubules where they function by transmitting pain stimuli from heat, cold or pressure (Standring, 2016).
Anatomical Relations
Dental pulp is located in the root (radicular part) and crown (coronal part) of the tooth and is entirely surrounded and enclosed by dentin (Standring, 2016).
Function
Dental pulp plays an important role in the defense process of the tooth whereby it houses cellular components necessary for the recognition and processing of antigens. Its sensory fibers additionally allow for the recognition of different stimuli including thermal change, mechanical deformation or trauma. The blood vessels and nerves housed by the pulp cavity provide nutritive support to the odontoblast layer, which facilitates the odontoblasts in their production of dentin (Yu and Abbott, 2007).
List of Clinical Correlates
—Pulpitis
References
Chiego, D. J. (2014) Essentials of Oral Histology and Embryology - E-Book: A Clinical Approach. Elsevier Health Sciences.
Dorland, W. (2011) Dorland's Illustrated Medical Dictionary. 32nd edn. Philadelphia, USA: Elsevier Saunders.
Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41 edn.: Elsevier Limited.
Yu, C. and Abbott, P. V. (2007) 'An overview of the dental pulp: its functions and responses to injury', Aust Dent J, 52(1 Suppl), pp. S4-16.
