O13T.pdf

PULP Dr /Abdel-latif Galal Lecturer of oral Medicine& Periodontology Introduction: Def: Loose connective tissue in the center of the tooth. Development: Dental Papilla Anatomy: 1) Parts of the pulp: Coronal pulp Radicular pulp or root canal  Apical foramen 2) Shape: * Similar t...

PULP Dr /Abdel-latif Galal Lecturer of oral Medicine& Periodontology Introduction: Def: Loose connective tissue in the center of the tooth. Development: Dental Papilla Anatomy: 1) Parts of the pulp: Coronal pulp Radicular pulp or root canal  Apical foramen 2) Shape: * Similar to the tooth outline * Under cusps [pulp horns] 3) Apical Foramen: It is wide (apical opening) during root formation Then narrowed apical foramen * Number: 1 or 2 or more Size: 0.3 to 0.4 mm 4) Accessory root conals: Site: Anywhere but: *Most numerous in apical 1/3 especially in premolars. STRUCTURAL FEATURES The central region of both the coronal and the radicular pulp contains large nerve trunks and blood vessels. Peripherally, the pulp is circumscribed by the specialized odontogenic region composed of (1) The odontoblasts (the dentin-forming cells). (2) The cell-free zone (Weil’s zone):is a space in which the odontoblast may move pulpward during tooth development (3) The cell-rich zone : composed principally of fibroblasts and undifferentiated mesenchymal cells is restricted to the coronal regions. (4) Pulp core :which is characterized by the major vessels and nerves of the pulp  Pulp C.T. consists of: a- cells b- intercellular substance The cells of Pulp 1-Fibroblasts The pulp organ is said to consist of specialized connective tissue because it lacks elastic fibers. Fibroblasts are the most numerous cell type in the pulp. They function in collagen fiber formation throughout the pulp during the life of the tooth.  They have the typical stellate shape and extensive processes that contact and are joined by intercellular junctions to the processes of other fibroblasts. 2-Odontoblasts The second most prominent cell in the pulp, reside adjacent to the predentin with cell bodies in the pulp and cell processes in the dentinal tubules. The cell bodies of the odontoblasts are columnar in appearance with large oval nuclei, which fill the basal part of the cell  Immediately adjacent to the nucleus basally is rough-surfaced endoplasmic reticulum and the Golgi apparatus. Functions : Dentin formation 3-Undifferentiated mesenchymal cells Undifferentiated mesenchymal cells are the primary cells in the very young pulp. They are found in the cell-rich zone and scattered throughout the central pulp. They appear spindle shaped.  They are believed to be a totipotent cell and when need arises they may become odontoblasts, fibroblasts, or macrophages. 4-Defense cells These are histiocytes or macrophages, dendritic cells, mast cells, and plasma cells. In addition, there are the blood vascular elements such as the neutrophils, eosinophils, basophils, lymphocytes, and monocytes. 5-Pulpal stem cells Among the numerous stem cells that have been identified from dental tissues and characterized, those from the pulpal tissues include dental pulp stem cells (DPSCs) and stem cells from human exfoliated deciduous teeth (SHED). The dental pulp stem cells (DPSCs) were shown to undergo proliferation and migrate to the site of injured odontoblasts and produce dentin. Intercellular substance The intercellular substance is dense and gel like in nature, varies in appearance from finely granular to fibrillar. It is composed of both acid mucopolysaccharides and protein polysaccharide compounds (glycosaminoglycans and proteoglycans). Blood vessels The pulp organ is extensively vascularized. It is known that the blood vessels of both the pulp and the periodontium arise from the inferior or superior alveolar artery. The communication of the vessels of the pulp with the periodontium, in addition to the apical connections, is further enhanced by connections through the accessory canals. The infection has a potential to spread through the accessory and apical canals. Nerves: The abundant nerve supply in the pulp follows the distribution of the blood vessels. The majority of the nerves that enter the pulp are nonmyelinated. Many of these gain a myelin sheath later in life. The large myelinated fibers (sensory) mediate the sensation of pain that may be caused by external stimuli. The peripheral axons form a network of nerves located adjacent to the cell-rich zone. This is termed the parietal layer of nerves, also known as the plexus of Raschkow. Functions of Pulp: 1) Inductive The primary role of the pulp is to interact with the oral epithelial cells, which leads to differentiation of the dental lamina and enamel organ formation. 2) Formative: The pulp odontoblasts produce dentin. 3) Nutritive: The nutrition pass from it to the dentin. 4) Sensory: The sensory fibers are responsible for the sensitivity of the pulp & Dentin. 5) Defensive: If pulp is exposed to moderate stimuli, it responds by formation of reparative Dentin. REGRESSIVE CHANGES (AGING) 1-Cell changes In addition to the appearance of fewer cells in the aging pulp, the cells are characterized by a decrease in size and number of cytoplasmic organelles. 2- Increased collagen fiber content. 3-Calcifications in and around vessels especially near apical foramen. Pulp stones (denticles) are nodular, calcified masses appearing in either or both the coronal and root portions of the pulp organ. They usually are asymptomatic unless they impinge on nerves or blood vessels. Classification of Pulp stones According to site: (in relation to surrounding dentin wall) * free from dentin *attached fused with dentin. * Embedded in dentin According to their structure  True denticles  False denticles. 1-True denticles Are similar in structure to dentin in that they have dental tubules and contain the processes of the odontoblasts  A theory has been advanced that the development of the true denticle is caused by the inclusion of remnants of the epithelial root sheath within the pulp, induce the cells of the pulp to differentiate into odontoblasts, which then form the dentin masses called true pulp stones True denticle copy 2-False denticles Do not exhibit dentinal tubules but appear instead as concentric layers of calcified tissue. 3-Diffuse calcifications Appear as irregular calcific deposits in the pulp tissue, usually following collagen fiber bundles or blood vessels (Diffuse calcification surrounds blood vessels). Diffuse calcifications are usually found in the root canal and less often in the coronal area, whereas denticles are seen more frequently in the coronal pulp. Diffuse Calcification