Dental Pulp PDF

Dental Pulp By dr. Sally Sakr  Dental pulp It is a specialized loose connective tissue surrounded by hard dental tissue.  Anatomy of the dental pulp 1. Pulp cavity: It lies within the tooth and is enclosed by dentin all around, except at the apical foramen. Coronal...

Dental Pulp By dr. Sally Sakr  Dental pulp It is a specialized loose connective tissue surrounded by hard dental tissue.  Anatomy of the dental pulp 1. Pulp cavity: It lies within the tooth and is enclosed by dentin all around, except at the apical foramen. Coronal pulp It is divided into two parts; coronal Radicular pulp and radicular. 2. Pulp chamber: It occupies the coronal portion of the pulp cavity. It acquires its shape according to  Anatomy of the denta The roof of pulp chamber consists of dentin covering the pulp chamber occlusally or incisally. The floor of pulp chamber merges into the root canal at the orifices. 3. Pulp horn: They are landmarks present Canal orific occlusal to pulp chamber. es They may vary in height and location. Their number is determined according to number of the cusps. Canal Orifice: They are openings in the floor of Root canal orifice the pulp chamber leading into root canals. Root Canal: It is the radicular part of the pulp cavity. The root canal extends from the canal orifice to the apical foramen. Apical root anatomy Apical Constriction (Minor Diameter): It is an apical part of root canal having the narrowest diameter. It may or may not coincide with cemento-dentinal junction.  Apical root anatom Apical Foramen (Major Diameter): It is the main apical opening on the surface of the root canal through which the blood vessels and nerves enter the canal. Its diameter is almost double the apical constriction giving it a funnel shape appearance. Average distance between minor and major diameter in person is 0.5 mm.  Apical root anato Accessory root canal: It is a communication between the main root canal and periodontal ligament.  Apical root anato Apical Delta: It is a triangular area of root surrounded by main canal, accessory canals and peri-radicular tissue.  Apical root anato Isthmus: Isthmus is defined as narrow passage or anatomic part connecting two larger structures. It is commonly found in teeth with multiple canals. An isthmus is a narrow, ribbon shaped communication between two root canals which can be complete or incomplete. Histology of the dental pulp When pulp is examined histologically, it can be cell- distinguished into four distinct rich zone zones from the periphery to the center of the pulp. Zones of pulp are: a. Odontoblastic layer at the pulp periphery. b. Cell free zone of Weil.  Histology of the denta A, Cell-rich zone; C, Cell-free zone; B, Odontoblastic layer; D, Dentin E, pulp core E  Histology of the denta a. Odontoblastic layer: Odontoblasts consists of cell bodies and cytoplasmic processes. The odontoblastic cell bodies form the odontoblastic zone whereas the odontoblastic processes are located within predentin matrix. Capillaries, nerve fibers (unmyelinated) and dendritic cells may be found around the odontoblasts in this zone.  Histology of the denta b. Cell free zone of Weil: Central to odontoblasts is sub-odontoblastic layer, termed cell free zone of Weil. It contains plexuses of capillaries and small nerve fiber ramifications.  Histology of the denta c. Cell rich zone: This zone lies next to sub- odontoblastic layer. It contains fibroblasts, undifferentiated cells which maintain number of odontoblasts by proliferation and differentiation.  Histology of the denta d. Pulp core: It is circumscribed by cell rich zone. It contains large vessels and nerves from which branches extend to peripheral layers. Principal cells are fibroblasts with collagen and ground substance. Contents of the pulp A. Cells (odontoblasts, fibroblast, undifferentiated mesenchymal cells, inflammatory cells). B. Fibers. C. Ground substance.  A. Cells 1) Odontoblasts. 2) Fibroblast. 3) Undifferentiated mesenchymal cells. 4) Inflammatory cells.  1) Odontoblasts They occupy odontoblastic zone. They are columnar in shape at the coronal part, pseudostratified at the cusp area (pulp horn region) and cuboidal in the radicular region. is columnar in the coronal region It is pseudostratified in the cusp region It is cuboidal in the radicular reg  Odontoblasts A = pseudostratified odontoblast layer; B = Cell-free zone; C = cell-rich zone; D = dentine (Toluidine blue stain)  2) Fibroblast Fibroblasts are the most prominent cells of the pulp. They are numerous in the coronal portion of the pulp, where they form the cell-rich zone. Typical fibroblasts of pulp are stellate in shape with long processes. Fibroblasts secrete extracellular components like collagen and ground substance. Fibroblasts eliminate excess collagen by action of lysosomal enzymes.  3) Undifferentiated Mesenchymal Cells They are undifferentiated cells that may transform into odontoblast or fibroblast. These cells are found throughout the cell rich zone and the pulp core and often are related to blood vessels (perivascular). When examined under light microscope, these cells appear as large polyhedral cells. In older pulps, the number of undifferentiated mesenchymal Undifferentiated Mesenchymal Cel cells decreases and so reduces  4) defence cells a) Macrophages: They originate from undifferentiated mesenchymal cells or monocytes. They appear as large oval or spindle shaped cells which are involved in the elimination of dead cells, debris, bacteria and foreign bodies by phagocytosis. It is the main defensive cell  defence cel b) Polymorphonuclear leukocytes “PMNL” Neutrophil (neutrophiles): The most common form of leukocyte is neutrophil, though it is not present in healthy pulp. However, they are major cell type in inflamed pulp. Lymphocyte c) Lymphocytes: In normal pulps, mainly T-lymphocytes are found but B lymphocytes are absent. T-lymphocytes present in small numbers in the normal dental pulp.  defence cel d) Dendritic antigen-presenting cells: Dendritic cells are important component of the normal dental pulp. They are present in odontoblastic zone. They initiate the primary immune response and may migrate with trapped antigen, to regional lymph nodes and induce T-lymphocyte division and differentiation. These cells are non-phagocytic and their number increase in carious teeth. defence cel  defence cel Their dendritic process sometimes extended into the dentinal tubules and contact the odontoblastic process. B. Fibers of the pulp The fibers are principally type I and type III Collagen. Their arrangement in the pulp is irregular. The greatest concentration of collagen occurs in the most apical portion of the pulp. There are no elastic fibers in the pulp except for those in the walls of the larger blood vessels.  Fibers of the pu Dental pulp with collagen fibers arranged in bundles with different orientation (HE staining, ×200).  C. Ground substance: It is composed of glycosaminoglycans (GAG) & glycoproteins. The ground substance supports the cells & acts as the medium for transport of: 1. nutrients from the blood vessels to the cells. 2. metabolites from the cells to blood vessels. Blood supply of the pulp Blood supply of the pulp Blood vessels which are branches of dental arteries enter the dental pulp through apical and accessory foramina. The arterioles course up through radicular pulp and give off branches which spread laterally towards the odontoblasts layer and form capillary plexus. As they pass into coronal pulp, they diverge towards dentin, diminish in size and give rise to capillary network in sub- Capillary plexus in the odontogenic reg  Blood supply of the pu Blood passes from capillary plexus into venules which constitute the efferent (exit) side of the pulpal circulation and are slightly larger than corresponding arterioles. Venules enlarge as they merge and advance toward the apical foramen. Efferent vessels are thin walled and show only scanty smooth muscle.  Blood supply of the pu Numerous arterio-venous and venous-venous anastomoses are found between peripheral pulpal vessels. “arterio-venous shunt” Anastomosis is points of direct communication between the arterial and venous sides of the circulation and serves to divert blood away from the capillaries.  Blood capillaries in the pulp Capillaries are present both within and below the odontoblast layer and between the odontoblasts and the predentin. Capillaries do not enter the dentinal tubules. The capillary network provides odontoblasts with rich source of metabolites.  Blood capillaries in th Capillary plexus penetrate the odontoblastic cell layer and loop back to join venules of central pulp The dental pulp showing branching capillaries below the  Blood capillaries in th Two kinds of capillaries are found in the pulp: Fenestrated capillaries as well as capillaries with a continuous Fenestrated endothelial lining. Fenestrated capillaries are least common, and they are required during dentinogenesis to allow Continuous rapid movement of nutrients out of capillaries. Nerve supply of the pulp  Nerve supply of the pulp The dental pulp is richly innervated. Nerve enter the pulp through the apical foramen, along with afferent blood vessels, and together form the neurovascular bundle.  Nerve supply of the The nerve fibers enter the pulp and divide into many branches till reaching the cell-free zone where they lose their myelin sheath, and form plexus of nerves called subodontoblastic plexus or plexus of Raschkow.  Nerve supply of the Plexus of Rashcow  Nerve supply of the Some nerve fibers pass between the odontoblast cell bodies and enter the dentinal tubules. Such intratubular nerves are found only in about one to ten tubules or less in human coronal dentin and are fewer in root dentin. These nerve endings are presumed to function in pain reception. The only sensation of the dental pulp is pain.  Nerve supply of the Nerve fibril arising from the plexus of Raschkow is shown passing between the odontoblasts and looping within the predentin.  Types of nerve fibers in the pulp The nerve fibers are classified according to their diameter, velocity of conduction and function. The fibers having largest diameter are classified as A delta fibers while those having smallest diameter are classified as C fibers. 80% percent of nerves of the pulp are C fibers and remaining are A-delta fibers.  Types of nerve fibers in the pulp A-delta nerve fibers C nerve fibers Most of myelinated nerve They are small fibers are A-delta fibers. unmyelinated and fine At the odontoblastic layer, they lose their myelin sensory afferent nerves. sheath and anastomose They have slow forming network of nerves conduction velocities and called "Plexuses of Raschkow”. high threshold. They send free nerve They are found at the endings into dentinal centre of the pulp. tubules. Age changes of the pulp 1- Decrease in cellularity and vascularity of the pulp. 2- Increase in the fibers (Pulp fibrosis). “↑CollagenPulp fibers” stones 3-Pulp Pulpstones stones.or denticles are nodular, calcified masses appearing in either or both the coronal and root portions of the pulp organ. They are usually asymptomatic  Pulp stones They are classified according to their location into: 1. Free denticle (surrounded by pulp tissue) 2. Attached denticle (attached to dentinal wall) 3. Embedded denticles (totally surrounded by dentin)  Pulp stones They are also classified according to their structure into: True and false pulp stone. 1.True denticle Composed of dentinal tubules and lined by odontoblasts. (it is rare)  Pulp stones 2. False denticle Formed of concentric calcification.  Pulp stones Diffuse calcifications Diffuse calcifications appear as irregular calcific deposits in the pulp tissue, usually following collagenous fiber bundles or blood vessels.