Dental Pulp PDF

Dental Pulp PULP Pulp is a delicate, specialized living connective tissue which contains: Thin-walled blood vessels Nerves Nerve endings Cells All enclosed within dentin in a gelatinous matrix or ground substance PULP Each pulp opens into the tissue surrounding the tooth (the...

Dental Pulp PULP Pulp is a delicate, specialized living connective tissue which contains: Thin-walled blood vessels Nerves Nerve endings Cells All enclosed within dentin in a gelatinous matrix or ground substance PULP Each pulp opens into the tissue surrounding the tooth (the periodontium) through the apex of the root canal It is a non-mineralised vascular tissue Responsible for the formation of dentine Remains active throughout life. pulp3 Coronal pulp Radicular pulp  Apical Foramen The apical foramen is the opening of root pulp into the periodontium. This opening varies from 0.3 to 0.6 mm It is slightly larger in the maxillary teeth than in the mandibular teeth. The apical foramen generally is centrally located in the newly formed root apex but becomes more eccentrically located with age Accessory canals  If several apical canals exist, the larger is designated the apical foramen, and the more lateral ones are called the accessory canals  Canals may result from the presence of blood vessels obstructing dentin formation or from a break in the Hertwig’s epithelial root  The incidence of accessory canals is about 33% in permanent teeth. Accessory canals Clinically, accessory canals are important because they represent contact of the pulp with the periodontal tissues If inflammation of the pulp is present, it can spread to the periodontium or vice versa MICROSCOPIC ZONES IN PULP Four zones are evident when pulp tissue is viewed microscopically 1. The Odontoblastic layer/zone 2. Cell free zone 3. Cell rich zone 4. Pulpal core The odontogenic zone It is the outermost zone closest to the dentine. It lines the outer pulpal wall It consists of a layer cell bodies of odontoblasts, whose odontoblastic process are located in the dentinal tubules in the adjacent dentine The cell-free zone The cell-free zone is also known as the zone of Weil or Weil's basal layer. It acts as a buffer between the odontoblastic layer and the cell rich zone This zone appears to be virtually free of cells (under low level microscopic powers) A nerve and capillary plexus is also located in this zone The cell rich zone It has an increased density of cells with a more extensive vascular supply If existing odontoblasts degenerate, cells from the cell-rich zone move through the cell-free layer to the degeneration site and differentiate into new odontoblasts Pulpal Core It is located in the center of the pulp chamber with many cells and an extensive vascular supply General Composition of the Pulp It is a loose connective tissue, which is made up of a combination of cells embedded in an extracellular matrix of fibres in a semi-fluid gel. 75% water, 25% organic material. Composition Fibrous Matrix Non-Fibrous Matrix Cells Fibrous Matrix  Type I collagen is the principal fibrous component.  It is scattered irregularly as thin fibrils which bundles as fibres  It is aligned approximately parallel to the predentine surface.  Type III collagen is also present in large amounts  Type V and VI are also present in small amounts.  The greatest collagen concentration is at the apical portion. Non –Fibrous Matrix Glycosaminoglycans(GAGs) Proteoglycans Fibronectin Laminin Cells Odontoblasts Fibroblasts Defence Cells – T lymphocytes, macrophages, dendritic antigen- presenting cells. Undifferentiated cells – pluripotential, primitive mesenchymal cells Cell –types : Odontoblasts Form a layer of lining on the periphery of the pulp and have a process extending into the dentin. At the coronal portion the cells are columnar, mid-portion is cuboidal and apical is flattened. Morphology of cells relates to its activity Fibroblasts The most common cell found in the pulp Found more in the coronal portion of pulp and the cell rich zone. Function is to form and maintain the pulp matrix (ground matrix) Undifferentiated Ectomesenchymal Cells Represents the pool from which connective tissue cells of the pulp are derived. May give rise to odontoblasts and fibroblasts Found in cell-rich area and pulp core Diminishes with age Macrophages Centrally located in the pulp Involved in elimination of dead cells Lymphocytes Presence of T lymphocytes Dendritic Cells Dendritic cell processes extend between odontoblasts. Capture and present foreign antigen to the T cells. Non phagocytic Functions Nutrition Sensory Inductive Defensive Formative Nutritive function Tooth pulp is a living tissue with a blood supply and receives nutrients from the bloodstream Nutrients most likely enter the dentinal tubules through the odontoblastic processes or around the outside of the odontoblastic process and may be carried as far as the dentino-enamel and dentino- cemental junctions Defensive function Defense reactions of the pulp are expressed in several ways. Pulp may display an inflammatory reaction, change the character of existing dentin (sclerosis), or produce additional dentin (reparative dentin) Sclerosis of the dentin involves the filling in of the dentinal tubules, usually in a restricted area, with calcium salts. Consequently, dentin in this area is a solid mineralized tissue instead of a tissue perforated with tubules that contain odontoblastic processes Formative function The odontoblasts, the cell bodies (nuclear part) of which lie at the periphery of the pulp, are responsible for the formative function They produce the collagen fibrils and, while the pulp is young and healthy, the ground substance (organic matrix) of dentin Naturally, the formative function ceases if the odontoblasts degenerate or if the entire pulp is removed during endodontic therapy. Sensory function Tooth pulp is sensitive to external stimuli, and nerves in the pulp are responsible for some of the sensation experienced by an individual when a stimulus is applied to the tooth The sensation induced by stimuli received by a pulp is a sensation of pain A person cannot differentiate between extremes of heat (hot coffee) and of cold (ice cream) applied to the tooth Slight pressures on a tooth, however, produce a sensation of pressure or touch Most of this sensation is caused by pressure on the periodontal ligament. Inductive function It is inductive because in early development the pulp (papilla) interacts with the oral epithelium and initiates tooth formation. Age Related Changes Dental pulp gets smaller because of secondary dentine deposition. Older pulp is less vascular and more fibrous Innervation is reduced Mineralises in the form of pulp stones Pulp stone Theories of Dentine Sensitivity  Direct Innervation Dentine nerve terminals extend to the DEJ and hence initiate an action potential directly.  Transduction Odontoblast can transduce a mechanical stimulus and transfer that signal to a closely opposed nerve terminal. Cont’d Hydrodynamic Theory Due to the fluid movement in the dentinal tubules in response to external stimuli, the nerve terminals within the dentinal tubule and odontoblast layer initiate an action potential Rapid movement will cause pain. CONCLUSION A fully developed tooth may function for many years after its pulp has been removed and its pulp canal has been filled Although the enamel of the tooth becomes more brittle, its function is not affected by the loss of the pulp The cementum is not affected, nor is the process of continued cementum formation A tooth without a pulp cannot, however, produce reparative dentin or sclerotic dentin THANK YOU FOR YOUR ATTENTION