Oral Mucosa


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Oral Mucosa

  2. 2. ORAL MUCOSA The oral cavity is lined with an uninterrupted mucous membrane, which is continuous with the skin near the vermilion border of the lips and with the pharyngeal mucosa in the region of the soft palate and anterior pillars of fauces. The epithelium of the oral mucosa originates partly from the ECTODERM (lips, vestibule, gingiva, cheeks, palate, floor of the mouth), and pertly from the endoderm (tongue).
  3. 3. MASTICATORY MUCOSA – free andattached gingiva and hard palate comes inprimary contact with food during masticationand is keratinized.LINING MUCOSA – the lips cheeks, vestibule,floor of the mouth, interior surface of thetongue and soft palate. It does not function inmastication and therefore has little attrition. Itis soft, pliable and non-keratinized.SPECIALIZED MUCOSA – on the dorsalsurface (dorsum) of the tongue. It is coveredwith cornified epithelial papillae.
  4. 4. Functions of the Oral Mucosa Protection – acts as major barrier to microorganisms Sensation – receptors that respond to temperature, touch, pain, taste; initiates reflexes such as swallowing, gagging and salivation Secretion – saliva, contributes to the maintenance of moist surface Permeability and Absorption – thinnest epithelial regions, floor of the mouth, more permeable than other areas Thermal Regulation – dogs, body heat is dissipated thru the oral mucosa by panting
  5. 5. General Histologic Characteristicsof Oral MucosaTwo main tissue components: Oral epithelium – stratified squamous epithelium Lamina Propia or Corium – undderlying connective tissue layer The oral mucosa is attached to the underlying structures by a layer of loose fatty or granular connective tissue containing major blood vessels and nerves
  6. 6. Basement Membrane – structurelesslayer about 1 – 2 micrometers thick;interface between epithelium andconnective tissueConnective tissue papilla - irregular andupward projections of connective tissueRete Ridges – or rete pegs, epithelialridges or pegs that interdigitate with theconnective tissue papilla
  8. 8. Histologic Characteristics of theSurface EpitheliumKeratinization (types) Orthokeratinization - About 20-30% of the gingiva, the stratum corneum is homogenous and made up of flat, closely packed keratinized cells without nuclei Parakeratinization - Approximately 50-70% of the cases, the stratum corneum is homogeneous and consists of flat keratinized cells with pyknotic nuclei and remnants of cytoplasmic organelles
  9. 9. Incomplete Keratinization - Least commontype, approximately 7-10% of cases and isseen only in the region of the marginalgingiva. Stratum corneum is homogenousand consists of 2 cell types, whichoccasionally form 2 superimposed layers:the first type of cell is the same as cornifiedcell of a parakeratinized stratum corneum;the 2nd type is different from keratinizedcells and seems to reach the stratumcorneum and its surface without beingtransformed into a keratinized cell.
  10. 10. Layers of the Keratinized SurfaceEpithelium Stratum corneum dehydrated and flattened thus more resistant to mechanical damage and chemical solvents assume the form of hexagonal disks called squames do not contain any nuclei up to 20 layers of squames and is thicker than that of most of the skin except the soles and palms
  11. 11. Stratum Granulosum ( granular layer) larger flattened cells containing small granules called keratohyalin granules some regions of the masticatory oral epithelium (e.g. gingiva) it is difficult to see the granules under the light microscope
  12. 12. Stratum spinosum (Prickle-cell layer) several rows of larger elliptical or spherical cells appearance of cells when prepared for histologic examination – shrink away from each other remaining in contact only at point known as intercellular bridges or desmosomesStratum Basale ( Basal layer) cuboidal to columnar cells adjacent to the basement membrane
  13. 13. Layers of Non-Keratinized SurfaceEpithelium Stratum Basale Cuboidal or columnar cells containing separate tonofilaments and other cell organelles Site of most cell divisions Stratum Intermedium Slightly increase in cell size as well as accumulation of glycogen in cells of the surface layer On rare occasion, keratohyalin granules can be seen
  14. 14. Stratum Superficiale ( Superficiallayer) Cells appear slightly flattened than in the preceding layers and contain dispersed tonofilaments and nuclei, the number of other cell organelles having diminished
  15. 15. Layers of Lamina Propia/Corium Papillary layer or Connective tissue papilla Indents and interdigitates with the epithelium (rete ridges/pegs) May be short or absent in some mucosa Reticular Layer Consists of densely arranged connective tissue fibers (reticular)
  16. 16. Subdivisions of the OralMucosa
  17. 17. Lining Mucosa
  18. 18. Lips Lined by a moist, stratified squamous non-keratinized epithelium Non-keratinized mucosa is distinguished by a red border known as vermilion border This area is at the junction between the oral mucosa and the skin of the lips, becoming modified into keratinized epihtelium
  19. 19. Three reasons why vermilion border is red: Epithelium is thin This epithelium contain eleidin, which is transparent The blood vessels are near the surface of the papillary layer
  20. 20. Soft Palate Stratified squamous non-keratinizing epithelium – highly vascularized More pink than the mucosa of the keratinized hard palate – lamina propia contains many small blood vessels Beneath the CT of the lamina propia is the submucosa which contains muscles and mucous glands
  21. 21. Cheeks Mucosa is same as the lips and soft palate, however, the submucosa contains fat cells and mixed glands (seromucous) located within and between the muscle fibers The presence of these glands is a unique feature of the cheeks
  22. 22. Ventral Surface of the Tongue Lining mucosa also contains lamina propia and submucosa In the submucosa, muscle fibers are located under the surface of the tongue The entire area exhibits dense, interlaced muscle and CT fibers
  23. 23. Floor of the Mouth Non-keratinized mucous membrane Covering appears loosely attached to the lamina propia in contrast to the mucosa of the ventral surface of the tongue which is firmly attached Presence of minor salivary glands and right and left major mucous glands, the sublingual glands
  24. 24. Masticatory Mucosa
  25. 25. Gingiva or Marginal Epithelium part of the oral mucosa and at the same time, the most peripheral part of the tooth-supporting apparatus. It covers the coronal part of the alveolar process, passes over the crest of the alveolar bone and interdental septa and encircles the necks of teeth
  26. 26. Gingiva or Marginal EpitheliumHistological Characteristics of a Normal Marginal Periodontium “free” gingiva ends on the enamel surface at a shallow angle Gingival sulcus is less than 0.2 mm depth or is absent The junctional epithelium contains only a few isolated leukocytes Collagen Ct fibers extend directly alongside the junctional epithelium all the way to just under the gingival margin No signs of acute inflammation or chronic cellular infiltration
  27. 27. Clinical Characteristic of Normal Gingiva A pale, pink color A smooth marginal and papillary gingiva Attached gingiva with distinct stipples in varying density. Firm consistency of all the tissues. The papillary gingiva reaches halfway to the incisal edge and fills the interdental space up to contact point. a fine probe without the use of apparent force. Sulcular fluid cannot be obtained on filter paper strips placed into the entrance to the sulcus
  28. 28. Gingiva or Marginal Epithelium
  29. 29. Normal gingiva that satisfiesthese criteria is not identical with“clinically healthy” gingiva
  30. 30. Two topographycally distinct zones: Free gingiva a narrow band of tissue that follows the scalloped contour the necks of the teeth and the cementoenamel junction is referred to as “free” because it can be moved mechanically along tooth surface as well as away from the tooth
  31. 31. has an epithelial attachment maintainedby junctional epithelium along the toothsurfaceSeparated from the attached gingiva bya slight indentation called the FREEGINGIVAL GROOVE, whose levelcorresponds approximately to that of thebottom of the gingival sulcusabout 1.1 mm in the primary dentition,about 1.5 mm, 0.8 – 1.8 mm in youngadults and about 1.6 mm (0.9-2.1 mm) inolder people
  32. 32. Marginal gingiva - that part of the freegingiva that tapers to a knife-like edgeextending along the cervical level of thetooth on labial or buccal and lingualsurfacesInterdental gingival papilla – the bulgesof gingival tissue on al occlusal directionin between teethInterdental col – the constriction inbetween the facial and lingual interdentalgingival papilla
  33. 33. Gingival sulcus – a shallow groove extending around the circumference of the tooth Depth varies from 0.6 mm and has the average depth of 1.8 mmAttached Gingiva Is part attached to the teeth and alveolar bone. It is bounded CORONALLY by the free gingival groove and APICALLY by the mucogingival junction
  34. 34. On the facial surface of both jaws, it isadjacent to the alveolar mucosaOn the lingual surface of the mandible itis adjacent to the floor of the mouthThe is NO attached gingiva on thepalatal side of the maxilla since theimmovable palatal mucosa extends allthe way to the free gingivaExhibits many ovoid or elongatedindentations called STIPPLES – reflectsthe arrangement, thickness andfrequency of the rete ridges
  35. 35. Density varies between individualsEspecially pronounced on the anteriorregion of the maxillaAbsent in children younger that 6 years;and is present only 35% of children aged5 – 13 years
  37. 37. Dentogingival Junction Represents a unique anatomic feature concerned with attachment of the gingiva to the tooth Ectodermal in origin Consist of fundamental 3 compartments: Junctional epithelium Oral sulcular epithelium Oral gingival epithelium
  38. 38. Gingival Ligament or Supra-Alveolar Fiber Apparatus Dentogingival fibers Dentoperiosteal fibers Alveologingival fibers Circular an Semicircular fibers Transeptal fibers Transgingival and Intergingival fibers Interpapillary fibers Periosteogingival fibers Intercircular gibers
  39. 39. 1. Dentogingival fibers The most numerous, consists of three groups: First group extends from the cementum in an obliquely coronal direction Second group streams horizontal from the cementum into the free marginal gingiva Third group, many of which run parallel with the dentoperiosteal fibers, curve from the cementum apically over the alveolar crest
  40. 40. 1. Dentogingival fibers FIRST SECOND THIRD
  41. 41. 2. Dentoperiosteal Fibers Insert into the supra- alveolar cementum at the same level as the transeptal fibers, pass apically over the crest of the alveolar bone into the periosteum of the outer and inner plates of the alveolar process
  42. 42. 3. Alveologingival fibers Insert into the crest of the alveolar bone, course coronally and enter the free and attached sections of the marginal and interdental gingiva
  43. 43. 4. Circular and Semicircular fibers Circular – small group of fibers that forms a band around the neck of the tooth helping to bind the free gingiva into the tooth Semicircular – encircle only the vestibular or oral half of the root; lie apical to the circular fibers
  44. 44. 5. Transeptal Fibers Also called INTERDENTAL FIBERS Bind the supra- alveolar cementum of one tooth to that of the adjacent tooth Implicated as a major cause of post retention relapse of orthodontically positioned teeth
  45. 45. 6. Transgingival and Intergingival fibers– reinforce the circular and semicircular Transgingival – identical with semicircular, insert interdentally into a supra-alveolar cementum, pass obliquely through the interdental tissue stream into the free gingiva of the adjacent tooth where they may unite with the circular fiber
  46. 46. 6. Transgingival and Intergingival fibers– reinforce the circular and semicircular Intergingival – form a continuous series of fibers running under the epithelium along both the vestibular and oral aspects of the dental arch converging distal to the last molar
  47. 47. 7. Interpapillary fibers Cross through the free portion of interdental gingival tissue in an orovestibular direction to tie the oral and vestibular gingival papillae together
  48. 48. Periosteogingival fibers Insert into the periosteum of the outer and inner cortical plates of the alveolar process and pass facially and orally into the section of all attached gingiva lying over itIntercircular fibers Are located on the vestibular and oral sides of the interdental gingiva and connect the circular fiber bundles of neighboring teeth. They form part of the Intergingival fiber bundles
  49. 49. Alveolar Mucosa The gingival mucosa joins the alveolar mucosa at the mucogingival junction It is present only in the vestibular region and extends from the scalloped mucogingival junction to the vestibular fornix, where it is continuous with the mucosa covering the lips and cheeks The alveolar mucosa is movable, can be lifted to a limited extent from its base and exhibits structural deep red in color and has a smooth surface
  50. 50. Hard Palate Is the roof of the mouth and is supported by the palatine processes of the maxillary and horizontal parts of the palatine bone At the level of the alveolar tuberosity, it joins the soft palate The hard palate is pale pink
  51. 51. On the surface of the hard palate, the midline isknown as MEDIAN RAPHE - fusiform mucosalmass and forming the midline of the palate andrepresent the fusion area of the palatineprocessesINCISIVE PAPILLA - oral mass of tissue cappingthe opening of incisive canal containing oral part ofthe nasopalatine ductOn each side of the median raphe are ridges oftissue called TRANSVERSE RIDGES ORPALATINE RUGAE AND RUGAE PALATINI -ridges of mucous membrane with denseconnective tissue core extending laterally from theincisive papillae and the anterior raphe
  52. 52. Specialized Mucosa
  53. 53. Dorsum of the tongue Covered by a stratified squamous keratinizing epithelium Consists of four types pf epithelial structures called papilla: Filiform papilla – most numerous; arranged in rows Fungiform papilla – fewer, distributed along the filiform; numerous near the tips of the tongue; contains taste buds
  54. 54. Circumvallate papilla –distributed along theV-shaped sulcusbetween the body andthe base; 3 mm indiameter; containstaste budsFoliate papilla – 4 – 11vewrtical grooves orfurrows on the lateralposterior sides of thetongue; contains tastebuds
  55. 55. Taste Buds Microscopically visible barrel-shaped bodies Contains the chemical sense of taste Generally associated with the papilla of the tongue – circumvallate, foliate, and fungiform, although some are distributed in the soft palate, epiglottis, larynx, and pharynx
  56. 56. Types of taste cells – found amongthe 10 – 14 cells in the taste bud Supporting or Sustentacular cells Tall columnar cell; lie at the periphery of the taste bud Taste cells/chief cells – tall columnar cells that bear either elongated microvilli that project into the taste pore or ones with shortened villi that open into the base of the pore Each are associated with nerves
  57. 57. Basal cells Are in close proximal contact with the basal laminaRapid turn-over of cells in the tastebud – approximately 10 daysFour taste sensations are sweet,salty, sour and bitter
  58. 58. Location of taste perception on thetongue and soft palate