Pulp Oral Biology PDF

Oral Biology Pulp Professor Name : Prof. Dr. Hala Zaatar And Prof. Dr. Sahar Shawkat The dental pulp is the loose delicate connective tissue occupying the cavity lying in the center of dentin.  Morphology 1- The coronal pulp: present in the pulp chamber. 2- The radicular pulp: ext...

Oral Biology Pulp Professor Name : Prof. Dr. Hala Zaatar And Prof. Dr. Sahar Shawkat The dental pulp is the loose delicate connective tissue occupying the cavity lying in the center of dentin.  Morphology 1- The coronal pulp: present in the pulp chamber. 2- The radicular pulp: extends from the cervical region of the crown to the root apex. ☻Apical foramen: The pulp tissue is continuous with the periapical tissue through the apical foramen. ☻ The average size of the apical foramen: maxillary teeth : 0.4 mm mandibular teeth : 0.3mm Accessory root canals: ☻This means that the pulp cavity is connected with the periodontal tissue Accessory with an opening rather canals than the apical foramen. ☻They are numerous in the apical third of the root. Mechanism of formation of accessory root canals 1- Early degeneration of the epithelial root sheath of Hertwig before the differentiation of the odontoblasts. 2- It occurs in areas, where the developing root meets a large blood vessel, where dentin will be formed around it. 3-Lack of complete union of the tongue like extension at the floor of the pulp chamber.  Histological Structure Of The Pulp Blood vessels Cells Intercellular substance Nerves Lymph vessels Fibers Ground substance ☻Collagen I&III ☻Acid mucopolysaccharides ☻ Elastic fibers ☻ (wall of B.V.) Glycoprotein.  Zones of the pulp Central zone (pulp core) peripheral zone (odontogenic zone) peripheral zone (odontogenic zone)  peripheral zone Central zone (odontogenic (pulp core) zone) Dentin  Dentin Odontoblasts layer Predentin Cell rich zone Pulp core Cell free zone  Odontogenic zone a- odontoblasts: Location: Adjacent to the Dentin predentin with the cell bodies in the pulp and cell processes in the dentinal tubules. B- cell free zone (the zone of Weil) It is present beneath the odontoblastic layer. It is suggested to be the area of mobilization and replacement of odontoblasts. C- cell rich zone It is present beneath the cell free zone. It is composed of fibroblasts and undifferentiated mesenchymal Odontogeni c zone Odontoblastic Predentin process Cell bodies Odontoblasts Cell-free zone Cell-rich zone  Microscopic Zones in Pulp Zones-from outer to inner Description zone Odontoblastic layer Lines the outer pulpal wall and consists of the cell bodies of odontoblast. Secondary dentin may form in this area.from the apposition of odontoblast Cell-free zone Few cells. Fibers and ground substance.Nerve and capillary plexus located here Cell-rich zone Increased density of cells (fibroblasts,UMC) as compared to cell- free zone and also a more extensive vascular system Pulpal-core Located in the center of the pulp chamber, which has many cells and an extensive vascular supply, similar to cell-rich zone  Cells of the pulp A- Synthetic cells 1- The odontoblasts. Origin: UMC of dental papilla Site: The cells line the pulpal surface of the dentine. A layer of predentine is always present between the odontoblasts and the dentine. Function: dentine (primary and secondary) formation. ◙ The odontoblasts are arranged in a single layer ◙ In the pulp chamber the cells are crowded and appear psudostratefied columnar. ◙ Near the beginning of the root canal they become columnar in shape. ◙ In the mid portion of the root canal they become cuboidal in shape. ◙In the apical area of the root canal they become flat cells.  2- Fibroblasts Origin: UMC of the pulp Site: in cell rich zone and pulp core. Function: formation of fibers and ground substance. Morphology: They are star shape cells; their body has rounded deeply stained nucleus and their process join with other fibroblasts.  B- Progenitor cells ◙ Undifferentiated mesenchymal cells (UMC). Site: in the cell rich zone and pulp core around the blood vessels.. Morphology They are similar to the fibroblasts but smaller. Function: They have the potentiality to form other types of formative or defensive cells.  C- Defensive cells 1- Histiocyte (macrophage). Origin :bone marrow. Morphology: Their cytoplasm is granular, especially during inflammation and also the nucleus becomes large. Site: Associated with the blood vessels in the pulp core Function: Engulfs foreign bodies 2- Lymphocytes.Origin: from blood Morphology: Agranular cell with clear pale blue cytoplasm. Its nucleus is very large and stains dark purple Function: These cells play an important role in our immune.response Site: in the pulp core 3-Esinophils..Origin: from blood Morphology: Have large granules which are acidophilic and appear pink.The.nucleus often has two lobes Function: They phagocytoze antigen-.antibody complexes Site: in the pulp core  4- Mast cells Morphology: Their cytoplasm is granular (histamine granules )with round nucleus. Stained with toloudine blue. Origin: from blood. Site: in the pulp core. Function: produce histamine that initiate allergic reactions in inflammation.  5- Plasma cells Function: These cells produce antibodies and are seen during inflammation. Morphology: The nucleus is eccentric with cart wheel appearance. Site: in the pulp core Origin: from blood. D- Rouget's cells (pericytes). ◘ They are seen on the wall of the blood capillaries. ◘ They have round or oval nucleus and considered as modified muscular cell that control BV contraction.. Fibers  In young pulp the fine fibers predominate.  By age the bundle increase in size and have 2 arrangements: 1- Diffuse collagen network. 2- Collagen bundles.  The ground substances of the pulp ☻The ground substances consists of acid mucopolysaccharides and neutral glycoprotein. ☻These substances are the environment that promotes life of the cells.  The blood vessels The pulp is highly vascularized. It is supplied by the inferior and superior alveolar arteries. As the vessels enter the D tooth, their walls become considerably thinner than those surrounding the tooth. Along their course they give numerous branches in the radicular pulp that pass peripherally to form ☻The capillaries adjacent to the odontoblasts are fenestrated. Such capillaries are found in areas of rapid exchange. Lymph vessels  They are thin walled endothelial tubes.  The pulp and the periodontal ligament of the teeth are drained into a common outlet : ☼ The anterior teeth are drained into the submental lymph node. ☼ The posterior teeth are drained into the submandibular and the deep cervical lymph nodes.  Nerves of the pulp ☻The pulp has an abundant nerve supply which follows the distribution of the blood vessels. Two types of nerve fibers are present: 1-Unmyelinated nerves: Sympathetic in nature. They control the contraction of the smooth muscles of the blood vessels. 2-Myelinated fibers which are *The peripheral myelinated axons form a network of nerves located adjacent to the cell-rich zone. This is termed the parietal layer of nerves or plexus of Raschkow. *More nerve endings are found in the pulp horns than in other peripheral areas of the coronal or radicular pulp. Nerves in pulp ☻ Sensory response in the pulp cannot differentiate between heat, touch, pressure or chemicals. This is because the pulp organs lack those types of receptors. ☻The Only type of the nerve receptors is FREE NERVE ENDING. ◙ Heat, ◙ Touch, ◙ Pressure, ◙ Chemicals Pai  Functions of the pulp 1- Inductive: a-Dental papilla induces the enamel organ formation. b- Determines the morphology of the tooth. 2- Formative : Pulp organ produces dentine. Odontoblasts develop the organic matrix and function in its calcification. 3- Nutritive : The pulp nourishes the dentine. Nutrition is mediated through the odontoblasts and their processes. Denti B Vs n 4- Protective: The sensory nerves in the tooth respond with pain to all stimuli, Pain sensation is a useful alarm system of the pulp. 5- Defensive or reparative: ☻The pulp responds to irritation by producing reparative dentine and mineralizing any affected dentinal tubules (sclerotic D). These reparative reactions are an attempt to wall off the pulp from the source of irritation. ☻The presence of macrophages, lymphocytes and leucocytes aid in the process of repair of the pulp.  Age changes in the pulp The size of the pulp The apical foramen The cellular elements decrease The b.v & n. Vitality d Reticular atrophy: The total effect is the production of a lessened vitality of the pulp tissue and a lessened response to stimulation.  Pulp clacification localized diffuse (pulp stone or denticle ) True denticle False denticle  True denticles odontoblast predentine dentinal tubules  1-Occurance: rare 2-Size: small in size 3-Site: found near the apical foramen. 4-Cause: remnants of the epithelial root sheath invade the pulp tissues causing UMC of the pulp to differentiate into odontoblasts that form this irregular type of dentine. 5-Histology: They consist of irregular dentine containing traces of dentinal tubules and few odontoblasts. False denticles  1-Occurance: more commen. Overdoses of vit. D, may favor the formation of numerous denticles. 2-Size: larger in size 3-Site: found mainly in the pulp chamber. 4-Cause: dystrophic calcification of the pulp tissue. Formed of degenerated cells or areas of hemorrhage which act as a central nidus for calcification. 5-Histology: They contain no dentinal tubules but concentric rings of  False denticles True denticles.It is more to happen.It is rare to happen.It is large.It is small Found in the Pulp Found near the apical foramen. chamber. Cause: Cause: They are formed of Remnants of Malassez invade the degenerated cells or pulp tissues causing UMC of the pulp areas of hemorrhage to form this irregular type of dentin. which act as a central nidus for calcification. Histology: Histology: They consist of irregular dentin They contain no containing traces of dentinal dentinal tubules but tubules and few odontoblasts. concentric rings. ☻Pulp stones are classified according to their location into Free Free Embedded Attached ☻They continue to increase in size and in certain cases they fill up the pulp chamber completely. ☻If pulp stones come close enough to a nerve bundle pain may be elicited. ☻The close proximity of pulp stones to Attache blood vessels may cause atrophy of it. d  Diffuse pulp calcification ☻ Commonly occurs on top of hyaline degeneration in the root canal and not common in the pulp chamber. ☻They are irregular calcific deposition in the pulp tissue following the course of blood vessels or collagen bundle. ☻Advancing age favors their development.