Periodontal Microbiology

  1. what is the only known causes of periodontitis?
    bacterial plaque
  2. how soon does the salivary pedicle form after cleaning?
    2 minutes
  3. what are 2 early colonizers?
    streptococci and actinomyces
  4. define Co-Aggregation
    cell-cell recognition when all cells are suspended in solution. clumps form and then attach to the pedicle
  5. define Co-Adhesion
    interactions between suspended and adhering microbes.
  6. what effect does lactose have on Co-adhesion?
    increased lactose = decreased co-adhesion
  7. which species serves as a bridge between early and late colonizers?
    fusobacterium nucleatum
  8. list 4 results of increased thickness of a biofilm
    • 1. difficulty in diffusion
    • 2. oxygen gradient develops
    • 3. anaerobic deep layers
    • 4. reverse gradients of fermentation products
  9. what is the difference in nutritional needs between supra and subgingival plaque?
    • Supragingival: dietary products are dissolved in saliva
    • Subgingival: periodontal tissues and blood serve dietary needs
  10. The matrix of the biofilm is composed of what 3 things?
    • 1. dead bacterial cells
    • 2. saliva
    • 3. gingival exudates
  11. what is the backbone of the biofilm?
  12. what are 2 characteristics of supragingival plaque structure?
    • 1. mushroom towers: low shear force
    • 2. elongated colonies: high shear force
  13. Describe the Gm+ bacterial matrix
    fibrillar due to dextrans and levans
  14. Describe the Gm- bacterial matrix
    tri-laminar vesicles, endotoxins and proteolytic enzymes
  15. what 2 carbs are involved with the bacterial matrix?
    dextrans and fructans
  16. how are the bacterial layers in subgingival plaque near the sulcular epithelium different from the layers from the tooth attached?
    no interbacterial matrix and more spirocetes and flagellated bacteria
  17. list 3 advantages of living in a biofilm
    • 1. defense: concentrated bacterial enzymes
    • 2. protection from external change: minimal diffusion = antibiotic resistance; protection from friction and shearing forces
    • 3. transfer of genetic material
  18. list 4 examples of antibiotic resistance in biofilms
    • 1. biofilm bacteria more resistant to antibiotics than planktonic
    • 2. grow slower and make more exopolymers
    • 3. exopolymers retard diffusion
    • 4. extracellular enzymes inactivate antibiotics
  19. define dental calculus
    mineralized plaque covered by a layer of visible plaque
  20. how is calculus related to periodontitis?
    represents a secondary product of infection, not a primary cause
  21. describe supragingival calculus
    • 1. coronal to gingival margin
    • 2. easily detached
    • 3. found opposite salivary ducts
  22. describe subgingival calculus
    • 1. hard, dense
    • 2. extends to base of pocket but does not reach JE
    • 3. in recession subgingival calculus becomes supragingival calculus
  23. list/define the 4 components that make up calculus
    • 1. Brushite: basis for supragingival calculus and seen in <2 week old calculus
    • 2. Octa Calcium Phosphate: predominant in exterior layers
    • 3. Hydroxyapatite: predominant in inner layers of old calculus
    • 4. Whitlockite: most common form in subgingival calculus
Card Set
Periodontal Microbiology