Opy midterm notes (pulp)

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Opy midterm notes (pulp)

  1. 1. Tooth Pulp Oral Physiology Dr. Maria Eller Isabel T. Collantes
  2. 2. Parts of the tooth <ul><li>Enamel </li></ul><ul><li>Dentine </li></ul><ul><li>Pulp </li></ul>
  3. 3. Periodontal Tissue <ul><li>Gingivae </li></ul><ul><li>Alveolar Bone </li></ul><ul><li>Cementum </li></ul><ul><li>Periodontal Ligament </li></ul>
  4. 4. Enamel <ul><li>Outer most layer of the crown </li></ul><ul><li>The hardest tissue in the body </li></ul>
  5. 5. DENTIN <ul><li>The second layer of the crown </li></ul><ul><li>Generally light yellow in colour </li></ul><ul><li>Its colour determines the overall colour of the tooth </li></ul><ul><li>There are many microscopic tubules inside the dentine which connect to the pulp. </li></ul>Dentin Pulp Fluid Nerve Fibers Odontoblast Cell
  6. 6. Periodontal tissues Gingiva Alveolar bone Cementum Periodontal Ligament
  7. 7. GINGIVA <ul><li>The fibrous investing tissue covered by keratinized epithelium </li></ul><ul><li>The gingiva is one of the soft tissues that line the oral cavity </li></ul><ul><li>All the soft tissue in the mouth are Known as the oral mucosa </li></ul>Gingiva
  8. 8. ALVEOLAR BONE <ul><li>Also called the “alveolar process” </li></ul><ul><li>the thickened ridge of bone containing the tooth sockets in the mandible and maxilla. </li></ul>Alveolar bone
  9. 9. PERIODONTAL LIGAMENT <ul><li>Connects the cementum of the tooth root to the alveolar bone of the socket. </li></ul>Periodontal Ligament
  10. 10. CEMENTUM <ul><li>Bonelike </li></ul><ul><li>rigid connective tissue covering the root of a tooth from the cementoenamel junction to the apex and lining the apex of the root canal </li></ul><ul><li>It also serves as an attachment structure for the periodontal ligament, thus assisting in tooth support . </li></ul>Cementum
  11. 11. <ul><li>Formation of dentine (dentinogenesis) </li></ul><ul><li>Sensation (pain only?) </li></ul><ul><li>First line of defense to injuries and infection of dentin </li></ul><ul><ul><li>Tertiary dentin </li></ul></ul><ul><ul><li>Immuno-competent </li></ul></ul><ul><ul><li>Clearance of toxic substances </li></ul></ul>Functions of dental pulp
  12. 12. PULP <ul><li>Innermost part of the tooth </li></ul><ul><li>Highly vascular and richly-innervated connective tissue forming the soft core of the tooth </li></ul>
  13. 13. Pulp <ul><li>Consist of fibers (collagen), cells (odontoblasts, fibroblasts, undifferentiated mesenchymal cells), and a matrix (proteoglycans and fibronectin) </li></ul><ul><li>Encapsulated and protected by hard tissue walls </li></ul><ul><li>Very low compliance because the surrounding dentin prevents any significant volume changes if the pressure within the pulp chamber changes </li></ul>
  14. 14. Pulp <ul><li>Contains large number of free nerve endings </li></ul><ul><li>Afferent neurons originating from the maxillary or mandibular division of the trigeminal nerve </li></ul>
  15. 15. Pulp <ul><li>four distinct zones </li></ul><ul><ul><li>1. odontoblastic zone at the periphery </li></ul></ul><ul><ul><li>2. cell-free zone of Weil – below the ODs </li></ul></ul><ul><ul><li>3. cell-rich zone </li></ul></ul><ul><ul><li>4. pulp core – major vessels and nerves </li></ul></ul>
  16. 16. Predentin Odontoblasts Cell-free zone Cell-rich zone Cell bodies Odontoblastic process
  17. 17. Dentin Predentin Odontoblasts layer Cell free zone Cell rich zone Pulp core
  18. 18. Odontoblastic layer <ul><li>Lines the outer pulpal wall and consists of the cell bodies of odontoblast </li></ul><ul><li>Secondary dentin may form in this area from the apposition of odontoblast. </li></ul>
  19. 19. Cell Free zone <ul><li>Fewer cells than odontoblastic layer </li></ul><ul><li>Nerve and Capillary plexus is located here </li></ul>
  20. 20. Cell Rich Zone <ul><li>Increased density of as compared to cell free zone </li></ul><ul><li>More extensive vascular system </li></ul>
  21. 21. Pulpal core <ul><li>Center of the pulp chamber </li></ul><ul><li>Many cells </li></ul><ul><li>Extensive vascular supply </li></ul><ul><li>Similar to cell rich zone </li></ul>
  22. 22. Cells in the pulp <ul><li>odontoblast </li></ul><ul><li>Fibroblast </li></ul><ul><li>Mesenchymal cells </li></ul><ul><li>Macrophages </li></ul><ul><li>Lymphocytes </li></ul><ul><li>Dendritic cells </li></ul>
  23. 23. Pulp <ul><li>Odontoblasts </li></ul><ul><ul><li>line the periphery of the pulp chamber </li></ul></ul><ul><ul><li>columnar in the crown region of the fully developed tooth </li></ul></ul><ul><ul><li>more cuboidal at the midpoint of the pulp chamber </li></ul></ul><ul><ul><li>the morphology reflects their activity – the more active the more elongated they are – with more cytoplasm </li></ul></ul>
  24. 24. Odontoblast <ul><ul><li>active ODs within the pulp have prominent organelles with multiple vesicles </li></ul></ul><ul><ul><li>CN pathway is similar to that of the pulp fibroblasts </li></ul></ul><ul><ul><li>CNs and non-CN proteins are packaged into secretory granules for exocytosis </li></ul></ul><ul><ul><li>the non-CN proteins are the same as those found in the dentin </li></ul></ul>
  25. 25. Fibroblasts <ul><ul><li>greatest number </li></ul></ul><ul><ul><li>numerous in the coronal portion of the pulp </li></ul></ul><ul><ul><li>form the cell-rich zone </li></ul></ul><ul><ul><li>form and maintain the pulp matrix – CN fibers and ground substance </li></ul></ul><ul><ul><li>in young pulp the fibroblasts are active and have extensive cytoplasm and organelles </li></ul></ul><ul><ul><li>decrease in size with age and they flatten </li></ul></ul>
  26. 26. Mesenchymal cells <ul><ul><li>undifferentiated cells of the pulp </li></ul></ul><ul><ul><li>from neural crest (ectodermal) </li></ul></ul><ul><ul><li>depending on the stimulus – give rise to the ODs or fibroblasts of the pulp </li></ul></ul>
  27. 27. Vascularity and Nerves of the Pulp <ul><li>The pulp organ is extensively vascular with vessels arising from the external carotids to the superior or inferior alveolar arteries. It drain by the same vein. </li></ul><ul><li>Blood flow is more rapid in the pulp than in most area of the body, and the blood pressure is quite high </li></ul>
  28. 28. <ul><li>The walls of the pulpal vessels become very thin as their enter the pulp. </li></ul><ul><li>Nerves : Several large nerves enter the apical canal of each Molar and Premolar and single ones enter the anterior teeth. This trunks transverse the radicular pulp, proceed to the coronal area and branch peripherally. </li></ul>
  29. 29. Nerves and Vessels of the pulp <ul><li>Blood and vessels enter and exit the dental pulp by way of the apical and accessory foramina </li></ul><ul><li>Pulp is richly innervated; nerves enter the pulp through the apical foramen, along with afferent blood vessels and together form the neuro-vascular bundle </li></ul>
  30. 30. Nerves in pulp
  31. 31. Dental Pulp Nerve Blood vessel
  32. 32. <ul><li>Subodontoblastic zone – is a major site of nutrient and gas exchange within the subodontoblastic plexus </li></ul><ul><li>In a healthy tooth pulp, blood occupies about 5% of the total volume </li></ul><ul><li>High blood flow comparable to the brain and liver </li></ul><ul><li>Blood flow is controlled by autonomic nervous system primarily by sympathetic efferent nerve fibres </li></ul><ul><li>Activity in nociceptive afferents can also influence pulpal blood flow by the release of vasodilatatory substances </li></ul>
  33. 33. <ul><li>Extravasation – it is a leakage of plasma proteins from venules to the insterstitial space and that will be an inflammation, thus increases intrapulpal pressure </li></ul><ul><li>Inflammation of the pulp is induced by bacterial or mechanical trauma and can lead to increases in pressure in the pulp chamber </li></ul><ul><li>Increased pressure will lead to tissue hypoxia then necrosis </li></ul>
  34. 34. Types and properties of pulpal sensory nerve fibers <ul><li>A – beta fibers </li></ul><ul><li>A – delta fibers </li></ul><ul><li>C – fibers </li></ul><ul><li>Non – myelinated sympathetic fibers </li></ul>
  35. 35. A-beta fibers <ul><li>Conduction velocity 30-70 m/s </li></ul><ul><li>Very low threshold , non-noxious sensation </li></ul><ul><li>50% of myelinated fibers in pulp </li></ul><ul><li>Functions not fully known </li></ul>
  36. 36. A – delta fibers <ul><li>Conduction velocity 2-30 m/s </li></ul><ul><li>Lower threshold </li></ul><ul><li>Involved in fast, sharp pain </li></ul><ul><li>Stimulated by hydrodynamic stimuli </li></ul><ul><li>Sensitive to ischemia </li></ul><ul><li>Sharp pain </li></ul>
  37. 37. C - fibers <ul><li>Conduction velocity 0-2 m/s </li></ul><ul><li>Higher threshold </li></ul><ul><li>Involved in slow, dull pain </li></ul><ul><li>Stimulated by direct pulp damage </li></ul><ul><li>Sensitive to anesthetic s </li></ul><ul><li>Dull pain </li></ul>
  38. 38. Non – myelinated sympathetic fibers <ul><li>Conduction velocity 0-2 m/s </li></ul><ul><li>Post-ganglionic fibers of superior cervical ganglion </li></ul><ul><li>Vasoconstriction </li></ul>
  39. 39. Possible mechanisms of dentine sensitivity Hydrodynamic mechanism (Gysi, 1900; Brannstrom, 1963)
  40. 40. Neural Theory <ul><li>Attributes activation to excitation of the nerve endings within the dentinal tubules, leading to action potentials that are conducted along the parent primary afferent nerve fibres in the pulp into the dental nerve branches and then to the brain </li></ul>
  41. 41. Odontoblastic transduction theory <ul><li>Proposes that the stimuli initially excite the odontoblast process or body, the membrane of which may come into close apposition with that of the nerve endings in the pulp or in the dentinal tubule </li></ul><ul><li>The odontoblast then transmits the excitation to the associated nerve endings </li></ul><ul><li>However, lack of evidence for either synapses or neurotransmission between odontoblast and dentinal nerve opposes this theory </li></ul>
  42. 42. Hydrodynamic theory <ul><li>Proposes that the stimuli cause displacement of the fluid within the dentinal tubules </li></ul><ul><li>Stimuli such as drilling of dentin, probing, and air drying of exposed dentin, mechanical irritation of pulp, and application of hyperosmotic solutions promote liquid displacement within the dentinal tubules </li></ul><ul><li>Displacement occurs in either an outward or an inward direction </li></ul><ul><li>Activate mechanoreceptors in the nerve endings in the dentin or pulp </li></ul>
  43. 43. Clinical correlates TOOTHACHE <ul><li>It is a clinical manifestation of tooth pulp physiology </li></ul><ul><li>Perceived only a limited number of forms </li></ul><ul><li>Intensity very close to the threshold of pain can induce a non painful sensation called “pre pain” </li></ul><ul><li>Pre pain or paraesthesia may be due to recruitment of a few nociceptive afferent fibres, but not enough to give the pain sensation </li></ul>

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