Defence mechanism of gingiva


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Defence mechanism of gingiva

  2. 2. INTRODUCTION <ul><li>The gingival tissue is constantly subjected to mechanical & bacterial aggressions. </li></ul><ul><li>Resistance to these action is provided by: </li></ul><ul><li>1. Epithelium </li></ul><ul><li>2. gingival crevicular fluid </li></ul><ul><li>3. saliva </li></ul>
  3. 3. <ul><li>THE ROLE OF THE GINGIVAL EPITHELIUM </li></ul><ul><li>The role of gingival epithelium in defence by its degree of keratinization & turn over rate. </li></ul><ul><li>Epithelium constitutes a continuous lining of stratified squamous epithelium. </li></ul><ul><li>Principle cells of this epithelium is keratinocytes. </li></ul><ul><li>Other cells are non keratinocytes which includes langerhan’s cells,merkel cells & melanocytes. </li></ul>
  4. 4. <ul><li>The main function of the epithelium is to protect the deep structure while allowing selective intechange with oral environment. This is achived by proliferation & differtiation of the keratinocytes. </li></ul><ul><li>Differentiation of keratinocytes by keratinization process which leads to production of an orthokeratinized superficial horny layer which is made up of mainly keratin protein. </li></ul><ul><li>This layer makes intact barrier between the oral environment & deep layers. </li></ul>
  5. 5. <ul><li>Other protein keratolinin & involucrin forms a chemically resistant structure (envelop) located below the cell membrane. </li></ul><ul><li>The upper most cells of the stratum spinosum contains dense granules known as keratinosomes or odland bodies which are modified lysosomes. They contain large amount of acid phosphatase. </li></ul><ul><li>Acid phosphatase activity is related to the degree of keratinization. </li></ul>
  6. 6. <ul><li>Langerhans cells located among keratinocytes at supra basal levels. They belong to the mononuclear phagocyte system as modified monoctes. </li></ul><ul><li>They have an important role in immune reaction as antigen presenting cells for lymphocytes. </li></ul>
  7. 7. GINGIVAL CREVICULAR FLUID <ul><li>GCF is secreted by sulcular epithelium in gingival sulcus. </li></ul><ul><li>The presence of crevicular fluid has been known since the 19 th century. </li></ul><ul><li>Its composition & possible role in oral defence mechanism were elucidated by WAERHANG,BRILL & KRASSE in 1950. </li></ul>
  8. 8. <ul><li>Studies of BRILL considered that GCF is a continuous transudate. </li></ul><ul><li>LOE,HOLM- PEDESEN, WEINSTEIN, MANDEL ID & SALKIND demonstrated that GCF is a inflammatory exudate. </li></ul>
  9. 9. METHODS OF COLLECTION <ul><li>These includes: </li></ul><ul><li>1. Use of absorbing paper strips </li></ul><ul><li>2.Twisteel threads </li></ul><ul><li>3.Micropipettes </li></ul><ul><li>4.Intra crevicular washing </li></ul>
  10. 10. <ul><li>1. Use of absorbing paper strips: </li></ul><ul><li>Paper strips are placed into the sulcus or pocket. </li></ul><ul><li>This method causes the irritation of the sulcular epithelium that can oozing of fluid. </li></ul><ul><li>2. Extra sulcular method: </li></ul><ul><li>Paper strips are placed at the entrance or over the sulcus or pocket. </li></ul><ul><li>The fluid seeping out is picked up by the strip. </li></ul>
  11. 11. <ul><li>3. Twisted threads: </li></ul><ul><li>Preweighed twisted threads are placed in the sulcus around the tooth & the amount of fluid collected is estimated by weighing the thread. </li></ul><ul><li>4. Micropipettes: </li></ul><ul><li>Micropipettes (capillary tubes) of standerized length & diameter are placed in the pocket & their content is centrifuged & analyzed. </li></ul>
  12. 12. <ul><li>4. Intra crevicular washing: </li></ul><ul><li>A acrylic plate appliance is used in this method. </li></ul><ul><li>Plate covering the maxilla with soft border & groove following the gingival margins. </li></ul><ul><li>This appliance is connected by 4 collection tubes ,2 on palatal sides & 2 on buccal side. </li></ul><ul><li>The washing is obtained by rinsing the crevicular area from 1 side to the other using a peristaltic pump. </li></ul>
  13. 13. AMOUNT OF GCF <ul><li>The amount of fluid collected on paper strip is evaluated by: </li></ul><ul><li>1. Staining </li></ul><ul><li>2. Electronic method </li></ul>
  14. 14. <ul><li>1. Staining: </li></ul><ul><li>Wetted paper strips is stain by ninhydrin. </li></ul><ul><li>It is than measured planimetrically on an enlarged photograph or a with help of magnifing glass or a microscope. </li></ul>
  15. 15. <ul><li>2.Electronic method: </li></ul><ul><li>Fluid collected on a ‘blotter’ (periopaper) employing an electronic transducer (periotron). </li></ul><ul><li>Wettners of strip affects flow of current & a digital read out. </li></ul><ul><li>Measurement performed by CIMASONI showed that a 1.5 mm wide strip paper inserted 1mm within the sulcus of inflammed gingiva absorbs about 0.1mg of fluid. </li></ul>
  16. 16. <ul><li>CHALLACOMBE used an isotope dilution method to measure the amount of GCF present in particular space at any given time. </li></ul><ul><li>His calculation in human with mean gingival index of less than 1 showed that mean GCF volume in proximal spce of molar teeth ranged from 0.43 to 1.56 microlitre. </li></ul>
  17. 17. COMPOSITION OF GCF <ul><li>It contains: </li></ul><ul><li>Cellular elements </li></ul><ul><li>Electrolytes </li></ul><ul><li>Organic compounds </li></ul><ul><li>Metabolic & bacterial products </li></ul><ul><li>Enzymes & enzymes inhibitors </li></ul>
  18. 18. A. Cellular elements <ul><li>1. Epithelial cells: </li></ul><ul><li>Oral sulcular epithelium & junctional epithelium are constantly renewing & shed cells will be found in GCF. </li></ul><ul><li>Krekelar & ochs showed that fluid originated from area with more severe gingivitis contains a much higher proportion of these cells thus conferming the possible stimulating effect of inflammation upon the renewal of sulcular or junctional epithelium . </li></ul>
  19. 19. 2. Leukocytes <ul><li>The major site of entrance of leukocytes in oral cavity is the gingival sulcus. </li></ul><ul><li>In sulcus the differential leukocytes count are present in following relative proportion. </li></ul><ul><li>95-97% neutrophils </li></ul><ul><li>1-2% lymphocytes </li></ul><ul><li>2-2% monocytes </li></ul><ul><li>Among lymphocytes – </li></ul><ul><li>58% B lymphocytes </li></ul><ul><li>24% T lymphocytes </li></ul>
  20. 20. <ul><li>Number of leukocytes increase with the intensity of inflammatory process. </li></ul><ul><li>Their main function is phagocytic & killing of bacteria therefore they constitute a major protective mechanism. </li></ul>
  21. 21. 3.Bacteria <ul><li>Bacteria cultured from GCF is similar those grown from adjacent dental plaque. </li></ul><ul><li>Eg. Strepto sanguis </li></ul><ul><li>Actinomyces viscosus </li></ul><ul><li>Porphyromonas gingivalis </li></ul><ul><li>Porphyromonas endodentalis </li></ul><ul><li>Camphylobacter rectus </li></ul><ul><li>Prevotella intermedia </li></ul>
  22. 22. B. Electrolytes <ul><li>Na, k, Ca, F have been studied in GCF. </li></ul><ul><li>1. Na concentration: </li></ul><ul><li>The investigation of GCF in inflammed gingiva by matsue (1967) show an average concentration of Na is 207- 222 meq Na litre. </li></ul><ul><li>While normal gingival fluid contains 158 meq Na/litre. </li></ul>
  23. 23. <ul><li>2. K concentration: </li></ul><ul><li>Matsue reported that K concentration is 69 meq K / litre in inflammed area. </li></ul><ul><li>Normal GCF contains K conc. is 9.54 meq k / litre. </li></ul>
  24. 24. <ul><li>3.Na: k ratio: </li></ul><ul><li>Study of krasse & egelberg (1962) showed that GCF of inflammed gingiva contain Na:k ratio is 3:9. </li></ul><ul><li>While normal GCF shows Na:k ratio is 28:1. </li></ul>
  25. 25. <ul><li>4.concentration of other ions: </li></ul><ul><li>Ca, Mg, phosphate ion, chlorine ion have also been determined in known amount in GCF. </li></ul><ul><li>Krasse & egelburg (1962) reported Na:Ca ratio average about 10 in normally healthy gingiva. </li></ul><ul><li>In inflammed gingiva this ratio is 18. </li></ul><ul><li>Weinstein et al (1967) reported that ca: protein ratio much higher in gingival fluid than serum this ratio tended to decrease in fluid from more inflammed areas. </li></ul>
  26. 26. C. Organic compounds <ul><li>Mainly 3 substances reported in crevicular exudate. </li></ul><ul><li>1. Carbohydrates </li></ul><ul><li>Glucose </li></ul><ul><li>Hexasamine </li></ul><ul><li>Hexuronic acid </li></ul><ul><li>Exudate glucose content is higher in inflammed gingiva than normal gingiva. </li></ul><ul><li>This is interpreted not only as a result of metabolic activity of tissues but also as a function of local microbial flora. </li></ul>
  27. 27. <ul><li>2.proteins </li></ul><ul><li>5 proteins alpha,beta,alpha 1,alpha 2 globulin & albumin were reported in GCF. </li></ul><ul><li>Holmberg & killander confirmed that IgG,IgA & IgM immunoglobulin are present in GCF. </li></ul><ul><li>These immunoglobulins might significantly contribute the oral defence mechanism. </li></ul>
  28. 28. <ul><li>3.Lipids: </li></ul><ul><li>Gingival fluid contains many classes of phospholipids as well as neutral lipids. </li></ul>
  29. 29. D. Metabolic & bacterial products <ul><li>1. Lactic acid: </li></ul><ul><li>Lactic acid present in gingival fluid was reported positively correlation to both the degree of inflammation & intensity of gingival fluid flow. </li></ul><ul><li>Its origin considered mainly tissue origin. </li></ul>
  30. 30. <ul><li>2. Hydroxyproline: </li></ul><ul><li>Hydroxyproline is a major break down products of collagen. </li></ul><ul><li>Its presence in gingival fluid is on indicator of the rate of progression of periodontal disease. </li></ul>
  31. 31. <ul><li>3.Prostaglandins: </li></ul><ul><li>It is a component of inflammatory reaction. </li></ul><ul><li>Inflammed gingiva show more concentration of prostaglandins. </li></ul><ul><li>It causes vasodilatation, bone deposition & inhibition of collagen synthesis. </li></ul>
  32. 32. <ul><li>4. Endotoxins: </li></ul><ul><li>Endotoxins released from gram negative bacteria are highly toxic to gingival tissue & pathogenic factor in periodontal disease. </li></ul>
  33. 33. <ul><li>5.Cytotoxic substance: </li></ul><ul><li>Cytotoxic substance like hydrogen sulphide which is toxic metabolite of bacteria origin also reported in gingival fluid & causes gingival inflammation. </li></ul>
  34. 34. <ul><li>6. PH of gingival fluid: </li></ul><ul><li>Production of ammonia by microorganism causes elevation of PH. </li></ul><ul><li>Elevated PH increases the severity of gingivitis & periodontitis. </li></ul><ul><li>7. Antibacterial factor: </li></ul><ul><li>Antibacterial factor like leukocytes & flow of crevicular fluid is able to remove various kinds of bacteria from gingival pocket. </li></ul>
  35. 35. E. Enzyme & enzyme inhibitor: <ul><li>1. Acid phosphatase: </li></ul><ul><li>The main source of acid phosphatase in crevicular area are probably the PMNs & desqamating epithelial cells. </li></ul><ul><li>In PMNs the enzyme is confined with in the azurophil granules. </li></ul><ul><li>Acid phosphatase is bacteriocidal. </li></ul><ul><li>It attacks teichoic acid which is 1 of the components of the bacterial all wall. </li></ul>
  36. 36. <ul><li>The enzyme is also found in bacteria including those of the gingival sulcular pocket. </li></ul><ul><li>Eg. Actinobacillus </li></ul><ul><li>Capnocytophaga </li></ul><ul><li>Veilloonella </li></ul>
  37. 37. <ul><li>2. Alkaline phosphatase : </li></ul><ul><li>The concentration of this enzyme is significantly correlated with pocket depth. </li></ul><ul><li>This enzyme present in PMNs, exclusively in specific or secondary granules. </li></ul><ul><li>Some gram negative subgingival plaque bacteria also produces alkaline phosphatase activity. </li></ul>
  38. 38. <ul><li>3. Beta glucuronidase: </li></ul><ul><li>Beta glucuronidase is 1 of the hydrolyses found in the azyrophilic or primary granules of PMNs. </li></ul><ul><li>Beta glucuronidase is probably responsible for the final degradation of the oligosaccharides produced initially by the action of hyaluronidase. </li></ul><ul><li>Beta glucuronidse also found in plaque bacteria. </li></ul>
  39. 39. <ul><li>4. LYSOZYME: </li></ul><ul><li>Lysosome has bactericidal properties. </li></ul><ul><li>Its ability to hydrolyze B-1, 4- glycosidic bond of peptidoglycans of the bacterial cell wall. </li></ul><ul><li>It is found in PMNs. </li></ul><ul><li>The free enzyme may contribute to pocket formation by its detrimental effect upon epithelial cell stickness & lytic activity of connective tissue. </li></ul><ul><li>It also accelerates the local release of intracellulr bacterial enzyme. </li></ul>
  40. 40. <ul><li>5. Hyaluronodase: </li></ul><ul><li>Hyaluronidase splits B-1, 4-N- acetyl glucasaminide link in hyaluronic acid, condroitin 4 – sulphate & condroitin 6- sulphate which is components of bacterial cell wall. </li></ul>
  41. 41. <ul><li>6. Proteolytic enzyme: </li></ul><ul><li>Proteinases might have major role in the destruction of tissue component during inflammation. </li></ul><ul><li>Mammalian proteinase: </li></ul><ul><li>(i) Cathepsin D: </li></ul><ul><li>It is a carboxy endopeptidase 1 of the chief acid enzyme in lysosomes present at high concentration in inflammed tissues. </li></ul><ul><li>It is abundant in mononuclear leukocytes. </li></ul>
  42. 42. <ul><li>(ii) Elastase: </li></ul><ul><li>Elastase found in azurophilic granules of PMNs. </li></ul><ul><li>These are analogus to lysosomes. </li></ul><ul><li>(iii) Cathepsin G: </li></ul><ul><li>It is the serine endopeptidase contained into the azurophilic granules of PMNs. </li></ul><ul><li>It hydrolyze hemoglobin, fibrinogen, casein, collagen & proteoglycan. </li></ul>
  43. 43. <ul><li>(iv) Plasminogen activators: </li></ul><ul><li>It is serine proteinase. </li></ul><ul><li>It activates the components of complement which cause increased vascular permeability & accumulation of PMNs & monocytes. </li></ul><ul><li>It also help in wound healing. </li></ul><ul><li>(v) Collagenase: </li></ul><ul><li>It is found in PMNs. (Specific granules) </li></ul><ul><li>It causes degradation of collagen. </li></ul>
  44. 44. <ul><li>Bacterial proteinase: </li></ul><ul><li>It includes serinr endopeptidase,fibrinolytic enzyme, bacterial collagenase etc. </li></ul><ul><li>Serum proteinase inhibitor: </li></ul><ul><li>These are mainly alpha-2 macroglobulin, alpha-1 anti tyypsin, alpha -1 anti chymotrypsin. </li></ul><ul><li>These inhibits proteinase enzymes. </li></ul><ul><li>Its concentration increased during inflammation. </li></ul>
  45. 45. Cellular & humoral activity in GCF <ul><li>Analysis of GCF has identified cellular & humoral response in both healthy individuals & these with periodontal disease. </li></ul><ul><li>The cellular immune response includes the appearance of cytokines in GCF but there is no clear evidence of a relationship between them & disease. </li></ul><ul><li>Interleukin-1 alpha & -1 beta are known to increase the binding of PMNs & monocytes to endothelial cells, stimulate the production of PGE2 & release of lysosomal enzyme & stimulate bone resorption. </li></ul>
  46. 46. <ul><li>There is also preliminary evidence of the presence of y- interferon in GCF which may have protective role in periodontal disease because of its ability to inhibit the bone resorption activity of interleukin -1B. </li></ul><ul><li>Presence of antibodies in GCF, its role in gingival defence mechanism is Hard to ascertain, there is a consensus indicating that : </li></ul><ul><li>In a patient with periodontal disease a reduction in antibody response is deterimental. </li></ul><ul><li>Antibody response play a protective role in periodontal disease. </li></ul>
  47. 47. Clinical significance of GCF: <ul><li>Gingival fluid is an inflammatory exudate. </li></ul><ul><li>Its presence in clinically normal sulcus can be explained by the fact that gingiva that appears clinically normal exhibits inflammation when examined microscopically. </li></ul>
  48. 48. <ul><li>A. General health & gingival fluid: </li></ul><ul><li>(i) Circadian periodicity: </li></ul><ul><li>There is a gradual increase in gingival fluid amount from 6.00 AM to 10.00 PM & decrease afterwards. </li></ul><ul><li>(ii) Sex hormones: </li></ul><ul><li>Female sex hormones increase the gingival fluid flow, probably they enhance vascular permeability. </li></ul><ul><li>Clinical investigations have been shown an excerbation of gingivitis during pregnancy, menstrual cycle & at puberty. </li></ul>
  49. 49. <ul><li>B. Measurement of gingival inflammation: </li></ul><ul><li>Increased GCF is a sign of inflammation. </li></ul><ul><li>C. Influence of mechanical stimuli: </li></ul><ul><li>Chewing, vigrous gingival brushing, intrasulcular placement of paper strips increased the production of GCF. </li></ul>
  50. 50. <ul><li>D. Periodontal therapy: </li></ul><ul><li>There is a increased in gingival fluid production during the healing period after periodontal therapy. </li></ul><ul><li>E. Smoking: </li></ul><ul><li>Smoking causes marked increase in gingival fluid. </li></ul>
  51. 51. Drugs in GCF: <ul><li>Some antibiotics </li></ul><ul><li>Eg. Tetracyclin, metronidazole, are detected in GCF. </li></ul>
  52. 52. Saliva <ul><li>Salivary secretion are protective in nature because they maintain the oral tissue in a physiologic state. </li></ul><ul><li>Saliva exerts major influences: </li></ul><ul><li>On plaque by mechanically cleansing the expose oral surfaces. </li></ul><ul><li>By buffering acids produced by bacteria. </li></ul><ul><li>By controlling bacterial activity. </li></ul>
  53. 53. <ul><li>Saliva contains: </li></ul><ul><li>(i) Antibacterial factor: </li></ul><ul><li>Saliva contains lysozymes, myeloperoxidase, lactoperoxidase, glucoproteins, mucins & antibodies etc. </li></ul><ul><li>(a) Lysosomes: </li></ul><ul><li>Lysosomes is a hydrolytic enzyme that clevage linkage beta-1, 4- glycosidic bond of peptidoglycans of bacterial cell wall. </li></ul><ul><li>Eg. Veillnell species </li></ul><ul><li>Actinobacillus actinomycetemcomitans </li></ul>
  54. 54. <ul><li>(b) Lacto- peroxidase –thiocyanate: </li></ul><ul><li>Bactericidal is some strains of lactobacillus & streptococcus by preventing accumulation of lysine & glutamia acids both of which are essentials for bacterial growth. </li></ul><ul><li>(c) Myeloperoxidase: </li></ul><ul><li>It is bactericidal for actinobacillus. </li></ul>
  55. 55. <ul><li>( d) Glycoproteins & mucin: </li></ul><ul><li>It forms coating layer over tissue structures & provides lubrication & physical protection. </li></ul><ul><li>(e) Antibodies: </li></ul><ul><li>Saliva contains IgG,IgM & IgA antibodies. </li></ul><ul><li>IgG preponderant immunoglobulin found in saliva. </li></ul><ul><li>Antibodies causes opsonization of bacteria. </li></ul>
  56. 56. <ul><li>(ii) Buffers & coagulation factor: </li></ul><ul><li>Salivary buffer bicarbonate – carbonic acid system maintain the physiologic pH of oral cavity. </li></ul><ul><li>Saliva contains coagulation factor- factor viii, ix, x, PTA & hagman factor that hasten blood coagulation & protect wound from bacterial invasion. </li></ul><ul><li>(iii) Leukocytes: </li></ul><ul><li>Leukocytes reach the oral cavity migrating through the gingival sulcus. </li></ul><ul><li>PMNs leukocytes chiefly found in saliva that causes the phagocytosis. </li></ul>
  57. 57. Summary: <ul><li>As we have seen that various component act in defence of gingiva </li></ul><ul><li>Eg. Sulcular fluid </li></ul><ul><li>Saliva </li></ul><ul><li>Gingival epithelium </li></ul><ul><li>Leukocytes etc. </li></ul><ul><li>In which sulcular fluid is 1 of the most important component of defence mechanism. </li></ul><ul><li>These component through various mechanism & enzymes resist against the mechanical & bacterial aggressions & maintain the gingiva normal healthy state. </li></ul>