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BDS2 Oral Biology > Dental Plaque and Biofilms (2) > Flashcards

Dental Plaque and Biofilms (2) Flashcards

1
Q

What is an example of an oral reservoir?

A

tongue

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2
Q

What are the 6 stages of plaque formation?

A
  1. Acquired Pellicle Formation
  2. Transport of Microorganisms and Reversible Attachment
  3. Pioneer Microbial Colonisers and Irreversible Attachment
  4. Co-aggregation/Co-adhesion and Microbial Succession
  5. Mature Biofilm Formation
  6. Detachment From Surfaces
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3
Q

What protein are absorbed onto the surface of teeth (enamel)?

A

salivary glycoproteins

e.g. salivary agglutinin glycoprotein for s. mutants

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4
Q

What are the different substances which cover the crown region of the tooth and the root region of the tooth?

A

crown - saliva

root - gingival crevicular fluid

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5
Q

How are microorganisms transported to the tooth surface?

A

passively through saliva

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6
Q

What forces attract bacteria to the dental pellicle?

A

Van der Waals forces

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7
Q

Are van der waals forces weak?

A

yes

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8
Q

Why is the attachment of bacteria to teeth (stage 2) reversible?

A

As the attraction is weak this stage and is reversible

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9
Q

Where are motile organisms usually found?

A

subgingival

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10
Q

What is stage 3 of plaque formation?

A

Pioneer Microbial Colonisers and Irreversible Attachment

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11
Q

How do the physiological interactions of bacteria to teeth become irreversible?

A

adhesin

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12
Q

Does the tooth or bacteria have the receptor for adhesins?

A

tooth has receptor

bacteria has adhesins

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13
Q

What stage and bacteria are show here?

A

Pioneer Microbial Colonisers and Irreversible Attachment

pioneering bacteria

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14
Q

What is the pioneer microbial colonisers?

A

The initial colonisers constitute a highly selected part of the oral microflora

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15
Q

What genus of bacteria are usually the pioneering colonisers?

A

cocci

usually streptococcus

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16
Q

What group of streptococci appear first?

A

mitis group

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17
Q

What are example of the Streptococcus mitis group?

A

S. sanguinis
S. oralis
S. mitis bioval 1

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18
Q

What happens and forms when after the pioneering bacteria adhere to the dental pellicle?

A

Once attached, these pioneer microorganisms start to divide and form microcolonies

19
Q

What forms the ECM of the biofilm

A

They become embedded in bacterial extracellular slimes and polysaccharides together with additional layers of adsorbed salivary proteins and glycoproteins

20
Q

What is the stage which bacterial division is fastest?

A

The fastest rate of multiplication occurs during these early stages of plaque formation

(stage 3)

after the pioneering bacteria colonise

21
Q

What is stage 4 of plaque formation?

A

Co-aggregation/Co-adhesion and Microbial Succession

22
Q

What happens to the plaque microflora over time?

A

becomes more diverse

23
Q

What bacteria shift occurs when co-aggregation occurs during stage 4?

A

Shift away from streptococci to an increased proportion of Actinomyces and other G+ve bacilli

24
Q

What stage of plaque formation is shown here?

A

stage 4

Co-aggregation/Co-adhesion and Microbial Succession

25
Q

At what stage do secondary colonisers attach to primary colonisers?

A

stage 4

Co-aggregation/Co-adhesion and Microbial Succession

26
Q

How do secondary colonisers adhere/co-aggregate with primary colonisers?

A

by intra- and inter-genetic Co-adhesion/Co-aggregation (lectin mediated)

27
Q

What is a type of co-aggregation?

A

lectin-mediated

28
Q

Why is adhesion and attachment of bacteria essential?

A

Essential for colonisation and to resist the washing effect of saliva and GCF

29
Q

What can adhesions and attachment occur between? (5)

A

Bacteria and the tooth surface

Bacteria and the matrix

Bacteria and the same species

Bacteria and different species

Bacteria and the pellicle

30
Q

What are mechanisms of adhesion and attachment?

A

Electrostatic attraction

Hydrophobic interaction

Surface enzymes and receptors

Adhesion structures e.g. fimbriae

31
Q

What is microbial succession?

A

Due to a series of complex interactions e.g. reduction in redox potential (Eh), changes in pH, nutrient availability, development of food chains etc. the composition of the plaque microflora changes with time

can be more favourable or unfavourable to bacteria in the colony

32
Q

What can cause growth rates of bacteria to slow down as the biofilm matures?

A

microbial succession, possible less nutrients in the middle so these cells reproduce slower

makes them more resistant to bacteria

33
Q

Does the biofilm have 3D structure?

A

yes

34
Q

What are examples of extracellular polymers produced by bacteria?

A

soluble and insoluble glucans, fructans and heteropolymers

add to the plaque matrix

35
Q

What host products contribute to the plaque matrix?

A

Salivary glycoprotein
Dead cells
Serum proteins

36
Q

What bacteria products contribute to the plaque matrix?

A

Polysaccharides

37
Q

What percent of supragingival plaque is the plaque matrix?

A

50%

38
Q

What percent of subgingival plaque is the plaque matrix?

A

Almost none found in deep subgingival plaque

39
Q

What is the role of the plaque matrix?

A
  • Source of nutrients for other microorganisms
  • Chemical scaffold to maintain the shape of the biofilm and structural integrity of the biofilm
  • Tolerance to environmental factors e.g. desiccation
  • Biologically active and can retain water, nutrients and enzymes within the biofilm
  • Can help to restrict or exclude the penetration of other molecules e.g. antimicrobial agents
40
Q

What is stage 5 of plaque formation?

A

biofilm maturation

41
Q

What is the climax community of a biofilm?

A

all the bacteria working together

common goods

division of labour

different species may be localised in 1 area as it is the best environment for it to reproduce etc

42
Q

What is stage 6 of plaque formation?

A

detachment from surface

43
Q

What can cause microorganisms to detach from surface?

A

Shear forces can remove microorganisms from the tooth surface

However some microorganisms can detach themselves from the surface so that they can colonise elsewhere

BDS2 Oral Biology (27 decks)

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