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DEN 2027 - Disease Mechanisms > Oral Ecology 2 > Flashcards

Oral Ecology 2 Flashcards

1
Q

What 2 external factors have a role on whether host population of microorganisms can colonize on tooth surface?

A
  1. Saliva

2. Environment

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2
Q

Describe dental plaque interactions between bacteria

A
  • Acquired pellicle on tooth surface made up of components of saliva and bacterial fragments
  • Layer of bacteria on top of pellicle made up of streptococcus species
  • F. nucleatum bridges early and late colonizers
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3
Q

What are the 2 ways dental plaque can form with regards to species interaction?

A
  1. Interaction between bacteria and bacteria

2. Interaction between bacteria and fungi

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4
Q

What is the bacterial composition of the climax community of dental plaque at the fissure site?

A

Gram positive facultative anaerobes e.g. streptococcus, acitnomyces

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5
Q

What is the bacterial composition of the climax community of dental plaque at the approximal site?

A

Gram positive and gram negative facultative and obligate anaerobes e.g. neisseria, prevotella, veillonella

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6
Q

What is the bacterial composition of the climax community of dental plaque at the gingival crevice?

A

Gram positive and gram negative facultative and obligate anaerobes e.g. eubacterium, prevotella, treponema

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7
Q

What 4 things affect oral flora?

A
  1. Saliva
  2. Chewing
  3. Oral hygiene
  4. Diet
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8
Q

Describe the ecological stages in establishment of a microbial community

A
  1. Transmission
  2. Acquisition and colonization
  3. Pioneer species
  4. Microbial succession
  5. Increasing species diversity
  6. Climax community / Environment modification (return to pioneer species)
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9
Q

Give an example of gram positive cocci found in dental plaque

A

Streptococcus salvaris

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10
Q

Give an example of gram positive rod found in dental plaque

A

Lactobacillus acidophilus

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11
Q

Where are streptococci spp. found in the oral cavity?

A

Isolated from all sites in the oral cavity

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12
Q

Give 3 examples of streptococci spp. which are early colonisers of tooth surface

A
  1. S. sanguinis
  2. S. oralis
  3. S. gordonii
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13
Q

What is the primary pathogen in the aetiology of enamel caries in children and young adults?

A

S. mutans

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14
Q

Name another gram positive cocci found in dental plaque

A

Peptostreptococcus spp.

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15
Q

Name 3 types of gram positive rods and filaments found in dental plaque

A
  1. Actinomyces spp.
  2. Lactobacillus spp.
  3. Propionibacterium spp.
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16
Q

What is most commonly associated with lactobacillus spp.?

A

Advanced caries

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17
Q

Name 2 gram negative cocci found in dental plaque

A
  1. Neisseria spp.

2. Veillonella spp.

18
Q

Describe neisseria spp. and how they contribute to the formation of dental plaque

A
  • Facultatively anaerobic or aerobic bacteria isolated in fairly low numbers from most sites in oral cavity
  • Contribute to plaque by consuming oxygen and creating conditions necessary for obligate anaerobes
19
Q

Describe veillonella spp. and how they contribute to the formation of dental plaque

A
  • Strictly anaerobic isolated from most sites in oral cavity but in high numbers in dental plaque
  • Cannot metabolise carbohydrates so utilise intermediate metabolites e.g. lactic acid
  • Reduce potentially harmful effects of lactic acid on dissolution of enamel
20
Q

Name 4 gram negative rods found in dental plaque

A
  1. Aggregatibacter spp.
  2. Prevotella spp.
  3. Porphyromonas spp.
  4. Fusobacterium spp.
21
Q

Describe aggregatibacter spp.

A
  • Facultative anaerobes

- Implicated in particular aggressive form of periodontal disease in adolescents

22
Q

Describe prevotella spp.

A
  • Strictly anaerobes
  • P. intermedia associated with periodontal disease
  • P. nigrescens isolated more often from healthy sites
23
Q

Describe porphyromonas spp.

A
  • P. gingivalis strictly anaerobic

- Isolated mainly from subgingival sites especially in advanced periodontitis

24
Q

Describe fusobacterium spp.

A
  • F. nucleatum is obligate anaerobe
  • Able to aggregate with most oral bacteria so believed to be important bridging organism between early and late colonisers during plaque formation
25
Q

What 5 categories can salivary proteins belong to?

A
  1. Enzymes
  2. Proline rich proteins (PRPs)
  3. Immunoglobulins
  4. Mucins
  5. Other proteins
26
Q

What is saliva’s role in the oral cavity with regard to pH?

A

Act as a buffer to stabilise pH in the mouth

27
Q

Name 4 ways in which saliva is adapted for its ability to buffer pH in the oral cavity

A
  1. Bicarbonate
  2. pH
  3. Calcium and phosphate ions
  4. Proteins and peptides
28
Q

What is the function of bicarbonate in saliva in terms of buffering?

A
  • Most important buffering system in stimulated saliva

- Effective buffer system against acid at high salivary flow rates

29
Q

What is the function of pH in saliva in terms of buffering?

A
  • pH dependent on bicarbonate concentration

- Can range between 5.3 and 7.8

30
Q

What is the function of calcium and phosphate ions in saliva in terms of buffering?

A
  • Maintain saturation of saliva with respect to tooth mineral
  • Important in calculus formation and protection against caries
  • Higher salivary flow reduces demineralisation but increases potential of calculus formation
31
Q

What is the function of proteins and peptides in saliva in terms of buffering?

A
  • Salivary peptide sialin tends to raise salivary pH to neutral
32
Q

What is a potential problem with saliva buffering capacity in individuals affected by xerostomia?

A

Low salivary flow which results in low buffering capacity

33
Q

What is The Stephan Curve?

A

Describes the change in pH occurring within dental plaque when its subjected to challenge, typically within food stuff

34
Q

Why is a high starch diet less likely to cause low pH than a high glucose diet?

A
  • Slow metabolism of starch by heterofermentation
  • Fast metabolism of glucose by homofermentation
  • Lots more of acids including lactic acid are produced by homofermentation
  • Lactic acid can damage enamel due to low pH
35
Q

Below what pH is there demineralisation of enamel?

A

5.4

36
Q

Name 4 direct effects of ageing on the oral microflora

A
  1. Cell mediated immunity wears
  2. Change in salivary antibodies
  3. Hormonal changes
  4. Altered physiology of oral mucosa
37
Q

Name 4 indirect effects of ageing on the oral microflora

A
  1. Denture wearing
  2. Medication
  3. Cancer therapy
  4. Dietary changes
38
Q

What type of bacteria tends to cause dental caries?

A

Acidogenic / aciduric bacteria

39
Q

What type of bacteria tends to cause periodontal diseases?

A

Gram negative anaerobes

40
Q

What 2 things are necessary for caries to develop from a stable plaque community?

A
  1. Frequent sugar intake (low pH)

2. Low saliva flow

41
Q

What 2 things are necessary for periodontal disease to develop from a stable plaque community?

A
  1. Inflammation (increased GCF flow)

2. Immune suppression

DEN 2027 - Disease Mechanisms (20 decks)

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