Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Extra Stage 2 > MFD SSA > Flashcards

MFD SSA Flashcards

1
Q

what is the stephan curve

A

• Plaque pH drops when challenged
- Food
• Oral pH drops with acidic food and drinks
• Measure at the point of dental plaque touches enamel
• Rise is much slower than drop
• Enamel dissolves more quickly below ‘critical pH’ (~5.5)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is Ksp

A

total no. Ions - allows understanding of the solubility of a salt; smaller the number the lower the solubility. Calcium hydroxyapaptite has a very low Ksp - very sparingly soluble.
If Ionic product < Ksp - dissolution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Koch’s postulates: (modern day?)

A

Suspected pathogen must be present in all cases of the disease and absent from healthy animals

The suspected pathogen must be grown in pure culture

Cells from a pure culture of the suspected pathogen must cause disease in a healthy animal model

The suspected pathogen must be re isolated and shown to be the same as the original

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

When Koch’s postulates cannot be applied precisely

A

f no infecting organism can be detected

If the bacteria cannot be grown in culture

If no suitable animal model is available

If more than one species of bacteria is involved

If it is the level rather than just the presence of the infecting bacterium that is important

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the difference between specificity and sensitivity

A

Specificity - how close it is to selecting/producing results for the attribute it is looking for; the quality or state of being specific or precise. True positives. True negatives/( true negatives+ False positives)x100

Sensitivity - reduced likelihood of false positives; all positive results are true positives. Detect low levels of particles. True positives/ (true positives+false negatives)x 100

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

If 250 were in the test, the test predicted 14 would get periodontitis
In fact 10 got perio, 8 of those who were predicted. Fill in the table:

A

Disease ND

+test 8 . 6

  • test . 2 . 234
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Two molecular components that contribute to fighting off a fungal infection?

A

Azoles - block 14 alpha demethylase cytochrome p450 mediated step in the synthesis of ergosterol

Polyenes - binds to sterols in membranes forming an ion channel

Mitotic inhibitors - disrupt microtubules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How can dental clinicians avoid the spread of antibiotic resistance?

A

Consider drainage for dental infections rather than the use of antibiotics

Discuss methods of controlling symptoms rather than prescribing antibiotics

Encourage and enforce patients to complete their antibiotic course and follow dose and duration guidelines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Two advantages of amoxicillin over penicillin G

A

Looks for antigens, used to find group A streptococcus e.g. S. Pyogenes

Carbohydrate agar is non selective

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why do people have different critical pH?

A

It is when the saliva and plaque fluid cease to be saturated with calcium and phosphate, thereby permitting the hydroxyapatite in dental enamel to dissolve

It is dependent upon calcium and phosphate concentrations and these are dependent upon salivary flow rate. Their concentrations will vary from person to person

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

If HAP was left in water at pH 7.0 why would the temperature rise?

A

ond breaking, pH of the mouth is greater than 7, slightly alkaline so if hydroxyapatite is within a solution less than this then this encourages bond breaking (reaction to the right)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Ecological plaque hypothesis

A

Dysbiosis in microbiota in the oral cavity leads to plaque and therefore caries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Specific plaque hypothesis

A

One organism e.g. S.mutans leads to plaque and therefore caries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Non-specific plaque hypothesis

A

Amount of plaque rather than what is present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Function of peptidoglycan:

A

Forms a cell wall outside the membranes of bacteria consisting of NAG and NAM

Structural role in bacterial cell wall as well as resisting osmotic effects of cytoplasm

Binary fission during cell reproduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is an opportunistic pathogen?

A

An organism which requires the host to have a pre existing defect in its immune defences in order for it to cause disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is a pathogen?

A

An organism that can cause disease in an otherwise healthy individual

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is a virulence factor?

A

Properties of a pathogen that contribute to virulence e.g. adhesins, toxins and tissue degrading enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is virulence?

A

A measure of the capacity of an organism to cause disease. Used to measure lethal dose

20
Q

What agents are not killed by sterilisation?

A

Prions

21
Q

Why is saliva hypotonic?

A

To prevent loss of water from oral mucosa into oral cavity

The final product is hypotonic because duct cells are impermeable to water

22
Q

Why do beta lactam antibiotics only work on growing bacteria?

A

Prevents the action of transpeptidase which forms the cross links in peptidoglycan.
Only growing cells are building new cell wall components

23
Q

Why does the concentration of salivary sodium change when saliva stimulation is increased?

A

Sodium is removed from secretion in striated ducts by Na/H pumps. If flow rate is increased, less time for it diffuse across since it spends less time in the striated ducts and so overall output is higher in concentration of sodium than resting

24
Q

3 factors which affect the Dawes model of clearance?

A

Flow rate of saliva
Volume of saliva held in the mouth
Sucrose concentration

25
Q

Best sterilisation for hand pieces?

A

Best sterilisation for handpieces is autoclave, 134 C for 3 minutes or 121 C for 15 minutes. High pressure steam

26
Q

What does Maconkey agar show?

A

Contains bile salts which inhibit G +ve growth; lactose in the agar medium differentiates bacteria that can ferment it (red indicator)

It is selective and indicative - Enteric gram negative bacteria

27
Q

Why does the number of CFU not equal the total number of bacteria?

A

Some bacteria form staphylococcal bunches/streptococci chains which is lots of bacteria, but only forms on CFU and therefore more bacteria than CFU. The viable count method does not directly count the number of bacteria in the sample. Only the microbes (‘units’) that give rise to a single colony are counted.

Colony forming units are an estimate of the number of cells in a population

It makes the assumption that all cells in the population will grow when cultured on agar or will give rise to distinct colonies that can then be counted

28
Q

Saliva pH

Critical pH

A

Saliva pH - 7.1-7.5

Critical pH - 5.5

29
Q

Red group bacteria

A

annerella forysthia, Treponoma denticola, Porphorymonas gingivalis

30
Q

Where are the subgingival environments in the mouth and why do obligate anaerobes live here?

A

Obligate anaerobes are killed by oxygen and so must live in low oxygen environments e.g. subgingivally

31
Q

2 bacteria in mutans streptococci

A

Streptococci mutans and Streptococcus sanguinis

32
Q

Alpha haemolysis
Beta haemolysis -
Gamma haemolysis

A

Alpha haemolysis - agar under the colony is dark and greenish - streptococci

Beta haemolysis - sometimes called complete haemolysis, is a complete lysis of red cells in the media around and under the colonies: the area appears lightened (yellow) and transparent.

Gamma haemolysis - a lack of haemolysis in the area around a bacterial colony - streptococcus mutans

33
Q

curve of batch bacteria

A
  1. lag phase- no increase in number of living bacterial cells
  2. log phase- exponential increase in number of living cells of bacteria

3- stationary phase- plateay in number of living bacterial cells: rate of cell division and death roughly equal

4- death of decline phase: exponential decrease in number of living bacterial cells

34
Q

what are 2 compounds that make halitosis

A 
hydrogen sulphide and sulphur containing compounds; 
skatole
 cadaverine
putrescine
isovaleric acid
35
Q

What is a plasmid

A

A genetic structure in a cell that can replicate independently of the chromosomes, typically a small circular DNA strand in the cytoplasm of a bacterium or protozoan.

36
Q

What is an endotoxin

A

Part of the outer membrane of gram negative bacteria e.g. LPS or O-antigen or Lipid A

37
Q

Neurotoxin produced by bacteria

A

botulinium

38
Q

Frisee perio test

A

Healthy: 0.5 - 2 mm
Diseased: >3 mm (periodontal pocket)

39
Q

Autochtonous flora and

Allochthonous microbiota -

A

Autochtonous flora - Microorganisms characteristically found at a particular site

Allochthonous microbiota - Microorganisms transiently present at a site

40
Q

Facultative anaerobes

A

an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation or anaerobic respiration if oxygen is absent

41
Q

Synder test

A

The Snyder Test is used to determine a person’s susceptibility to dental caries (cavities).The susceptibility is correlated with acid production that is assumed to result from fermentation by cariogenic Lactobacillus species on the teeth or in other areas of the mouth. lactobacillus

It tests for aciduric and acidogenic bacteria - key virulence factors in order to cause caries (pH-5)

42
Q

How does the polymer mutan help plaque:

A

70% of plaque extracellular polysacchardie
Prevents acid leaching from the enamel surface -> cariogenesis
Aids in adherence and aggregation; glucan binding proteins

43
Q

Fluoride effect on critical ph and graph of ph after fizzy drink

A

Fluoride reduces the critical pH

Fizzy drink lowers the pH considerably (has a ph level of 1-3)

44
Q

Non selective agar

A

Grow most bacterium; non selective or indicative

45
Q

Main virulence factors of aggregatibacter actinomuycetemomitans?

A 
Adhesins, bacteriocins, invasins
Proteases
Immunosuppression factors
Surface antigens
Heat shock proteins
Antimicrobial resistance
Localised aggressive PD

Extra Stage 2 (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions