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Microbiome > Lecture 9: Oral Cavity as a microbial habitat-dental biofilms > Flashcards

Lecture 9: Oral Cavity as a microbial habitat-dental biofilms Flashcards

1
Q

What is the hardest substance? (according to Puri)

A

Dentin

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2
Q

What is the plaque above the gum line called?

A

Supragingival plaque

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3
Q

What is the plaque below the gum line called?

A

Subgingival plaque

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4
Q

What is the typical temperature range of the healthy oral cavity?

A

35-36C

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5
Q

How does temperature effect microbial growth in the oral cavity?

A

can increase to 39C in periodontal pockets with inflammation

-change can regulate gene expression in bacteria for genes encoding enzymes (proteases, SOD) and Fimbriae

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6
Q

What does SOD (superoxide dismutase) do?

A

removes oxidative stress

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7
Q

What is the oxygen tension on the tongue?

A

varies from 12-16%

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8
Q

What is the oxygen tension on the buccal folds?

A

0.3-0.4%

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9
Q

Which colonizers are more aerotolerant?

A

Early colonizers

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10
Q

How does redox potential affect microbial growth in the oral cavity?

A
  • Redox changes oxygen tension
  • oxygen content varies between location
  • Most oral organisms are facultative or obligate anaerobes
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11
Q

How does the saliva regulate pH?

A

the bicarbonate in saliva acts as a buffer and therefore is responsible for regulating pH

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12
Q

How does sugar intake affect the pH of the oral cavity?

A

sugar will cause a decrease in pH due to the byproducts of bacteria (lactic acid) after it metabolizes the sugar
sugar decreases pH (fermentation)

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13
Q

What is the pH range for a healthy oral cavity?

A

6.75-7.25

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14
Q

What is the pH for the Palate?

A

7.34

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15
Q

What is the pH for the buccal mucosa?

A

6.3

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16
Q

What is the pH of the healthy gingival crevice?

A

6.9

17
Q

What is the pH of diseased gingival crevice?

A

7.4+

18
Q

What disease is related to a decrease in pH?

A

Caries

19
Q

What disease is related to a increase in pH?

A

Periodontitis

20
Q

What pH range are S. mutans able to live/survive in?

A

pH4-8, causes caries

21
Q

What pH range can P. gingivalis live/survive in?

A

pH 6-8.5 causes Periodontitis

22
Q

What are the Endogenous nutrients?

A

Whats already present:
Saliva (amino acids, peptides, proteins)
GCF (albumin, protein)
Bacterial products

23
Q

What are the Exogenous nutrients?

A

stuff you consume:
Dietary (fermentables, carbohydrates, metals)
excess iron can cause bacterial growth

24
Q

What are the Specific Host Defense Factors of the mouth?

A 
Intra-epithelial lymphs (langerhans cells)
slgA
IgA, IgG, IgM
Complement
Neutrophils/macrophages
25
Q

What is the source of IgG, IgA, IgM and complement?

A

GCF

26
Q

What favors Expulsion/Death of bacteria entering the mouth?

A

Mechanical shearing
Antimicrobial properties
Antagonistic bacteria
Agglutination

27
Q

What favors the Colonization of bacteria entering the mouth?

A

Nutritional substrates
Adherence properties
Temp and moisture
Synergistic bacteria

28
Q

What are the antimicrobial agents that affect the microbial growth in the oral cavity?

A

Fluoride
Chlorhexidine
Antibiotics

29
Q

What is Quorum Sensing?

A

Intercellular signalling as a regulatory mechanism that plays a significant role in coordinating various stages of biofilm

  • Responds to population density
  • Controls gene expression
  • Capable of auto-induction
  • self-recognized secreted molecules called auto-inducers
30
Q

What are the stages of dental plaque formation?

A
  1. Pellicle Formation
  2. Association (Reversible binding)
  3. Adhesion (Irreversible binding)
  4. Coadhesion: secondary colonizers that attach to primary colonizers with the help of Lectin
31
Q

What mediates coaggregation/coadhesion of interbacterial interaction?

A

Lectins

32
Q

What are the components of the acquired enamel pellicle?

A 
Salivary proteins & Glycoproteins (Sialic acid, proline-rich proteins -PRP, Mucins, Agglutination, Amylase)
Bacterial Components (glucan, glucosyltransferases)
33
Q

What are the beneficial factors of microbial interactions in dental plaque?

A 
Enzyme complementation
Food Chains
Coadhesion
Cell-cell signalling
Gene transfer
34
Q

What are the antagonistic factors of microbial interactions in dental plaque?

A 
Bacteriocins
Hydrogen Peroxide
Organic acids
Low pH
Nutrient Competition
35
Q

What factors affect microbial growth in the oral cavity?

A 
Temp
Redox potential
pH
Nutrients
Host Defenses
Host Genetics
Antimicrobial agents & inhibitors

Microbiome (6 decks)

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