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2ND YR- CSA- Microbiology > Microbiology of dental caries 2 > Flashcards

Microbiology of dental caries 2 Flashcards

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1
Q

Can dental caries/ gingivitis be diagnosed usigmicrobial aetiology?

A

No

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2
Q

Is the pathogen that causes dental caries/ gingivitis presenting health?

A

Yes most of the time

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3
Q

Does the pathogen that causes dental caries/ gingivitis satisfy Kochos postulates?

A

NO

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4
Q

Does the pathogen that causes dental caries/ gingivitis produce specific virulence factors?

A

No

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5
Q

Can dental caries/ gingivitis be transmitted from person to person

A

no

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6
Q

How is dental disease describes?

A

As an example of dysbiosis of a beneficial resident microbiota

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7
Q

Why does dysbiosis occurs in the mouth?

A

Due to a major ecological pressure for example frequent sugar, reduced saliva and acidic pH

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8
Q

What are he key functions that acidogenic bacteria have in common?

A
  1. Produce acid
  2. Tolerate acid
  3. Produce EPS / IPS
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9
Q

Name the 3 hypotheses used to explain the transition from health to disease

A
  1. Specific plaque hypothesis
  2. Non-specific plaque hypothesis
  3. Ecological plaque hypothesis
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10
Q

Which of th 3 plaque hypothesis theories is the most accepted?

A

The ecological plaque hypothesis

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11
Q

What is disease preventability and controllability determined by?

A
  1. Direct inhibition of causative organisms
  2. Promotion of natural balance
  3. Interference with factors driving dysbiosis
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12
Q

What is specificity in disease found in?

A

Microbial function not bacterial name

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13
Q

Give some examples of environmental factors that can drive dysbiosis

A
  1. Low pH in biofilm
  2. Sugar metabolism
  3. low saliva flow
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14
Q

What does an increase in sugar frequency lead to?

A

More frequent acid production
Increases low pH challenges
Conc of mutans-streps, lactobacilli, bifidobacteriaetc increases
This leads to caries

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15
Q

Name a common sweetener?

A

Sucrose

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16
Q

What is sucrose made up of?

A

Glucose and fructose

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17
Q

What can a cariogenic diet or low salivary flow lead to according to the caries ecological plaque hypothesis?

A
  1. Stress due to increase sugar frequency
  2. This leads to an ENVIRONMENTAL SHIFT as the pH decreases
  3. This leads to an ECOLOGICAL SHIFT as the concentration of mutans-streps and lactobacilli
    bifidobacteria increases
  4. This eventually leads to disease in this case caries
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18
Q

Which properties are associated with mutans streptococci?

A
  1. acidogenic

2. Acid tolerating

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19
Q

What drives dysbiosis in dental caries?

A

SUGAR and PH

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20
Q

What can the breakdown of sugar lead to?

A
  1. Organisms can make sticky slime that stops saliva penetrating to the tooth surface
  2. Organisms break sucrose down into lactic acid which reduces the pH of the mouth
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21
Q

What happens in the mouth if theres an excess of sucrose?

A

Organisms will make food reserves using intracellular polymers

22
Q

What is the critical pH?

A

It is the pH at which enamel starts to demineralise faster than saliva remineralises it

23
Q

State the critical pH

A

5.5

24
Q

When should you not have a sugary snack and why?

A

Before bed as salivary flow is reduced so biofilm has time to accumulate on the tooth surface

25
Q

Name some bacteria associated with caries

A
  1. S.mutans

2. L casei

26
Q

Name some bacteria associated with health

A
  1. S. gordonii
  2. S. oralis
  3. A. Naeslundii
  4. N. subflava
  5. V. dispar
27
Q

What happens to cariogenic bacteria as the pH falls

A

The lower the pH is allowed to fall in the biofilm the more competitive the cariogenic bacteria become

28
Q

What does low level of fluoride do in the mouth?

A

It wont kill bacteria but it slows acid production as ti slows down glycolysis

29
Q

Give some approaches for controlling dental caries

A
  1. PLAQUE CONTROL
  2. Fluoride
  3. Sugar substitues
  4. Antimicrobial and anti plaque agents
  5. Modify the microbiota
  6. Vaccination
  7. Passive immunity
30
Q

How does fluoride help control dental caries?

A

It inhibits intra cellular polysaccharides synthesis
It reduces glycolysis and therefor acid production so the pH doesn’t fall bellow the critical level
By eliminating a low ph environment the competitive opportunity for Mutant streptococci is removed

31
Q

When fluoride goes into enamel what does it do?

A

It forms fluorapatite

32
Q

Describe how fluorapatite reacts to acid

A

It is more tolerantof acid and it promotes remineralisation

33
Q

What does H+F- do in the mouth?

A

This whizzes inside the bacteria cell and dissociates into H+ and F-
The F- then inhibits the enzymes
The H+ creates an acidic environment inside the bacteria causing denaturing of enzymes

34
Q

Which enzyme does fluid inhibit when it reduces glycolysis?

A

Enolase

35
Q

Give examples of sugar substitutes

A

Bulking agents: sorbitol, xylitol

Intense sweeteners: saccharin, aspartame

36
Q

How do sugar substitutes help control dental caries?

A
  1. They can not be converted to acid so they dont create an acidic environment
  2. They stimulate saliva flow
  3. They have weak antimicrobial activity
37
Q

Why is it hard to control dental caries using antimicrobial and anti-plaque agents ?

A

As theres a mixed community of good and bad bacteria so you need a concentration of anti plaque agent that will only remove harmful bacteria

38
Q

What have antimicrobial and anti-plaque agents been added to?

A

Toothpaste and mouthwashes

39
Q

Name the gold standard anti-plaque agents

A

chlorhexidine

40
Q

What is the disadvantage of chlorhexidine

A

It is very potent so its only used for short incidents

It may stain the teeth

41
Q

give examples of antimicrobial and anti-plaque substances that can be added yo toothpaste

A

Triclosan, metal salts, plant extracts, enzymes, innate host defences

42
Q

Essentially what are antimicrobial and anti-plaque substances doing in bacteria?

A

They are messing up the bacterias biochemistry but not killing it

43
Q

How can we modify the microbiota?

A

By using probiotics

44
Q

Give examples of probiotics we have tried to use to control dental caries

A
  1. Dairy strains like Lactobacillus

2. Strep salivarius

45
Q

why re probiotics not the most effective way of controlling dental caries?

A

As the probiotics don’t have time to stay in the mouth as they are swallowed so don’t have enough time to work effectively

46
Q

Name some bacteria that have been found in people that are seen to be caries free

A

Streptococcus dentisani

Streptococcus A12

47
Q

What does Streptococcus dentisani do

A

Makes an inhibitor of bacteria that inhibits mutant streptococci and create a more alkali environment

48
Q

Name a more drastic way of modifying a person microbiota

A

By doing replacement therapy

49
Q

What do prebiotics do?

A

They are molecules that stimulate the growth of beneficial bacteria

50
Q

What is the difference between pre and probiotics?

A

Pro bionics are living molecules whereas prebiotics are molecules that living things feed f

51
Q

Give an example of a prebiotic

A

arginine

52
Q

How can we achieve passive immunity for dental caries?

A

We can coat surfaces with antibodies or synthetic antibody fragments

2ND YR- CSA- Microbiology (2 decks)

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