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PULP

PULP. The dental pulp is that loose delicate connective tissue occupying the cavity lying in the center of dentin. Morphlogy *The coronal pulp : it is present in the pulp chamber.

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PULP

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  1. PULP

  2. The dental pulp is that loose delicate connective tissue occupying the cavity lying in the center of dentin.

  3. Morphlogy *The coronal pulp: it is present in the pulp chamber. *The radicular pulp: it is that part of the pulp extending from the cervical region of the crown to the root apex. *Apical foramen: The pulp organs are continuous with the periapical tissue through the apical foramen. The average size of the apical foramen of the maxillary teeth in the adult is 0.4 mm, while in the mandibular teeth it is 0.3 mm in diameter.

  4. Accessory canals: They are commonly seen to extend from theradicular pulp laterally through the root dentin to the periodontal ligament. They are numerous in the apical third of the root. Accessory canals

  5. Mechanism of accessory canalsformation: 1- it occurs in areas, where the developing root encounters a large blood vessel, where dentin will be formed around it, then making the lateral canal . 2- Early degeneration of the epithelial root sheath of Hertwig before the differentiation of the odontoblasts. 3-Lack of complete union of the epithelial diaphragm at the floor of the pulp chamber.

  6. Histological structure of the pulp The dental pulp is formed of specialize loose connective tissue: cells fibers intercellular substances blood vessels, nerves & lymphatics.

  7. odontogenic zone: a- odontoblasts: Location: Adjacent to the predentin with the cell bodies in the pulp and cell processes in the dentinal tubules.

  8. B- cell free zone: It is present Immediately beneath the odontoblastic layer .The cell free zone is the area of mobilization and replacement of odontoblasts,

  9. C- cell rich zone It is present beneath the cell free zone. It is composed of fibroblasts and undifferentiated mesenchymal cells. odontogenic zone

  10. Cells of the pulp 1- Synthetic cells (formative cells): odontoblasts and fibroblasts. 2- Defensive cells: Macrophages, small lymphocytes, eosinophils, mast cells and plasma cells. 3- Progenitor cells: Undifferentiated mesenchymal cells.

  11. a- odontoblasts: Length: 5-7u in the diameter 25-40u in length. In the early stage of development odontoblasts consist of a single layer of columnar cells . In the later stages of development, the odontoblastic layer appeared pyriform (pear like)where the broadest part of the cell contains the nucleus They are longer in the crown and then become cuboidal rootwise, at the root apex, they may be almost flattened.

  12. The cell membranes of adjacent odontoblasts exhibit junctional complexes. The clear terminal part of the cell body and the adjacent intercellular junction is known as terminal bars. Gap junction desmosome

  13. b- Fibroblasts These are the most numerous type of cells. They are spindle in shape. They have elongated processes which are widely separated and link up with those of other pulpal fibroblasts (stellate appearance). The nucleus stains deep with basic dye and the cytoplasm is highly stained and homogenous.

  14. mitochondria These cells have a dual function: synthesize and degradation of fibers and ground substances in the same cell . In young pulp, they are : *large cells . *with large multiple processes *centrally located oval nucleus, *numerous mitochondria, *well developed Golgi bodies *well developed RER Fibroblast (protein secreting cell).

  15. in periods of less activity and aging these cells appear smaller and round or spindle-shaped with w organelles , they are termed fibrocytes. fibroblast fibrocyte

  16. In case of inflammation, *nuclei, increase in size and exhibit a prominent nucleolus. it exhibits granules and vacuoles in their cytoplasm Invaginations (infold)of plasma membrane are noted ultrastructurally with aggregation of vesicles or phagosomes .

  17. 2- Defensive cells:A- Histiocyte ( macrophage ): In light microscope, the cells appear irregular in shape with short blunt processes. The nucleus is small, more rounded and darker in staining than fibroblast. Their presence is obseved by intra-vital dyes such toluidine blue. These cells are distributed around the odontoblasts and small blood vessels and capillaries.

  18. B- Plasma cells: These cells are seen during inflammation. The arrangement of chromatin gives the nucleus a cart wheel appearance. The mature type exhibits a typical small eccentric nucleus and more abundant cytoplasm. The plasma cells are known to produce antibodies.

  19. C- Lymphocytes They are found in normal pulp and they increase during inflammation.

  20. Eosinophils They are found in normal pulp and they increase during inflammation.

  21. D- Mast cells: *They have a round nucleus and their cytoplasm contains many granules. *They are demonstrated by using specific stains as toluidine blue. *They produce histamin& heparin.

  22. 3- Progenitor cells: (The undifferentiated mesenchymal cells): They are smaller than fibroblasts but have a similar appearance. They are usually found along the walls of blood vessels. These cells have the potentiality of forming other types of formative or defensive connective tissue cells.

  23. Fibers of the pulp In young pulp the fibers are relatively sparse (few) and delicate throughout the pulp and gradually the bundles increase in size with advancing age. In older pulp two patterns of collagen distribution can be seen: one is a diffuse collagen network with no definite orientation, the second is bundles of collagen. There are no elastic fibers in the pulp except those present in the walls of the larger blood vessels.

  24. 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

  25. III-Blood vessels The pulp is highly vascularized. It is supplied by the inferior and superior alveolar arteries As the vessels enter the 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 a plexus in the odontogenic region. The pulpal blood flow is more rapid than in most areas of the body. D

  26. Nerves: The pulp has an abundant nerve supply which follows the distribution of the blood vessels. Two types of nerve fibers are present: The nonmyelinated nerves, are sympathetic in nature, they control the contraction of the smooth muscles of the blood vessels Myelinated fibers which are sensory parasympathetic nerves.

  27. The peripheral non mylinated 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.

  28. More nerve endings are found in the pulp horns than in other peripheral areas of the coronal or radicular pulp. Sensory response in the pulp cannot differentiate between heat, touch, pressure, chemicals. This is because the pulp lacks those types of receptors. So the sensory nerve ending in the pulp are presumed to function in painreception.

  29. Functions of the pulp: 1- Inductive: Dental papilla induces the enamel organ formation and also determines the morphology of the tooth. 2- Formative : Pulp organ produces dentin. Odontoblasts develop the organic matrix and function in its calcification. 3- Nutritive : The pulp nourishes the dentin. Nutrition is mediated through the odontoblasts and their processes.

  30. 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 dentin and mineralizing any affected dentinal tubules. 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.

  31. Age changes in the pulp The size of the pulp The apical foramen The cellular elements The bl. vessels & nerves. The Vitality Reticular atrophy: The total affect is the production of a lessened vitality (power to live) of the pulp tissue and a lessened response to stimulation. decreased

  32. Pulp clacification localized (pulp stones ) diffuse True denticle False denticle

  33. True denticles They consist of irregular dentin containing traces of dentinal tubules and few odontoblasts. Remnants of the epithelial root of Hertwig invade the pulp tissues causing UMC of the pulp to form this irregular type of dentin. True denticles are rareto occur, they are small in size and commonly found in the root canal near the apical foramen. dentinal tubules odontoblast

  34. False denticles *They are evidence of dystrophic calcification of the pulp tissue . *They contain no dential tubules. *They are formed of degenerated cells or areas of hemorrhage which act as a central nidus for calcification. *Overdoses of vit. D, may favor the formation of numerous denticles.

  35. *Pulp stones are classified according to their location into: free, attached and embedded. *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 (bring out). *The close proximity of pulp stones to blood vessels may cause atrophy of it. attached free

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