Microbiology of dental caries 2

Question 1

Can dental caries/ gingivitis be diagnosed usigmicrobial aetiology?

Answer 1

No

Question 2

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

Answer 2

Yes most of the time

Question 3

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

Answer 3

NO

Question 4

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

Answer 4

No

Question 5

Can dental caries/ gingivitis be transmitted from person to person

Answer 5

no

Question 6

How is dental disease describes?

Answer 6

As an example of dysbiosis of a beneficial resident microbiota

Question 7

Why does dysbiosis occurs in the mouth?

Answer 7

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

Question 8

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

Answer 8

1. Produce acid
2. Tolerate acid
3. Produce EPS / IPS

Question 9

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

Answer 9

1. Specific plaque hypothesis
2. Non-specific plaque hypothesis
3. Ecological plaque hypothesis

Question 10

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

Answer 10

The ecological plaque hypothesis

Question 11

What is disease preventability and controllability determined by?

Answer 11

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

Question 12

What is specificity in disease found in?

Answer 12

Microbial function not bacterial name

Question 13

Give some examples of environmental factors that can drive dysbiosis

Answer 13

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

Question 14

What does an increase in sugar frequency lead to?

Answer 14

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

Question 15

Name a common sweetener?

Answer 15

Sucrose

Question 16

What is sucrose made up of?

Answer 16

Glucose and fructose

Question 17

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

Answer 17

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

Question 18

Which properties are associated with mutans streptococci?

Answer 18

1. acidogenic

2. Acid tolerating

Question 19

What drives dysbiosis in dental caries?

Answer 19

SUGAR and PH

Question 20

What can the breakdown of sugar lead to?

Answer 20

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

Question 21

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

Answer 21

Organisms will make food reserves using intracellular polymers

Question 22

What is the critical pH?

Answer 22

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

Question 23

State the critical pH

Answer 23

5.5

Question 24

When should you not have a sugary snack and why?

Answer 24

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

Question 25

Name some bacteria associated with caries

Answer 25

1. S.mutans | 2. L casei

Question 26

Name some bacteria associated with health

Answer 26

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

Question 27

What happens to cariogenic bacteria as the pH falls

Answer 27

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

Question 28

What does low level of fluoride do in the mouth?

Answer 28

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

Question 29

Give some approaches for controlling dental caries

Answer 29

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

Question 30

How does fluoride help control dental caries?

Answer 30

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

Question 31

When fluoride goes into enamel what does it do?

Answer 31

It forms fluorapatite

Question 32

Describe how fluorapatite reacts to acid

Answer 32

It is more tolerantof acid and it promotes remineralisation

Question 33

What does H+F- do in the mouth?

Answer 33

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

Question 34

Which enzyme does fluid inhibit when it reduces glycolysis?

Answer 34

Enolase

Question 35

Give examples of sugar substitutes

Answer 35

Bulking agents: sorbitol, xylitol | Intense sweeteners: saccharin, aspartame

Question 36

How do sugar substitutes help control dental caries?

Answer 36

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

Question 37

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

Answer 37

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

Question 38

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

Answer 38

Toothpaste and mouthwashes

Question 39

Name the gold standard anti-plaque agents

Answer 39

chlorhexidine

Question 40

What is the disadvantage of chlorhexidine

Answer 40

It is very potent so its only used for short incidents | It may stain the teeth

Question 41

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

Answer 41

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

Question 42

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

Answer 42

They are messing up the bacterias biochemistry but not killing it

Question 43

How can we modify the microbiota?

Answer 43

By using probiotics

Question 44

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

Answer 44

1. Dairy strains like Lactobacillus | 2. Strep salivarius

Question 45

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

Answer 45

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

Question 46

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

Answer 46

Streptococcus dentisani | Streptococcus A12

Question 47

What does Streptococcus dentisani do

Answer 47

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

Question 48

Name a more drastic way of modifying a person microbiota

Answer 48

By doing replacement therapy

Question 49

What do prebiotics do?

Answer 49

They are molecules that stimulate the growth of beneficial bacteria

Question 50

What is the difference between pre and probiotics?

Answer 50

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

Question 51

Give an example of a prebiotic

Answer 51

arginine

Question 52

How can we achieve passive immunity for dental caries?

Answer 52

We can coat surfaces with antibodies or synthetic antibody fragments