Aetiology of Dental Caries Flashcards

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1
Q

What is dental caries?

A

a bacterial disease of the calcified tissue of the teeth characterized by the demineralisation of the inorganic and destruction of the organic substance of the tooth

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2
Q

What is the acidogenic theory?

A

dental lesions result from a shift in the metabolic activity accompanied by a gradual change in the ecology of the dental biofilm

an imbalance in the equilibrium between tooth mineral and biofilm fluid develops

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3
Q

What do bacteria ferment to produce acid?

A

carbohydrate

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4
Q

What does bacteria producing acid lead to?

A

decalcification of the hard tissue tooth substance and disintegration of the organic matrix

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5
Q

What are the 4 factors associated with caries development?

A

microorganisms
time
food
tooth
saliva

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6
Q

What are the primary modifying factors?

A

these are modifiable factors, patient can control

saliva
biofilm
pH
fluorides
oral hygiene factors

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7
Q

What are secondary modifying factors?

A

Things the patient cannot control, but have a susceptibility to developing caries

socioeconomic background

age

ethnic group

unemployed

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8
Q

Describe this diagram, caries development

  1. what are the orange circles
  2. what is the oink area
  3. what is the green area
  4. what is the yellow area
A

Orange circles represent teeth covered by microbial deposits

The metabolism in the microbial deposit will have an effect on pH (dependent upon acid attacks)

Overtime may result in caries/ demineralisation in the tooth (pink area)

green area influence demineralisation, patient can influence

yellow circle shows social factors which a patient cant influence

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9
Q

How does saliva influence caries?

A

buffer ability

pH 6.8

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10
Q

Is caries a multifactorial disease?

A

yes

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11
Q

What is the acquired pellicle?

A

absorbed of mainly salivary glycoproteins that forms on clean enamel to which bacteria adheres

amorphous organic film formed of glycoprotein from salivary origin.

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12
Q

Define dental plaque?

A

biofilm of bacteria embedded in a matrix of salivary mucins and extracellular polysaccharide polymers (glucans and fructans)

on all surfaces in the oral cavity

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13
Q

What are the common monomers in dental plaque?

A

glucan and fructans

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14
Q

What is a biofilm?

A

microbial community growing on a tooth’s surface

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15
Q

What are the areas of pink and dark pink?

A

pink = pellicle

dark pink = plaque to the naked eye you would not see

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16
Q

What are the 5stages of dental biofilm formation?

A
  1. pellicle formation
  2. attachment of early colonisers
  3. co-adhesion and growth of of attached bacteria leading to the formation of microcolonies
  4. microbial succession leading to increased species diversity concomitant with continued co-adhesion ad growth of microcolonies (1-7 days)
  5. climax community/ mature biofilm (1 week or older)
17
Q

When does the climax community/ mature biofilm form?

A

1 week

18
Q

When do bacteria attach to pellcile?

A

0-14 hours

19
Q

When do co-adhesion and microcolonies form?

A

4-24hr

20
Q

What are the initial colonisers? (examples)

A

S. sanguis, S. oralis, S. mitis

95% streptococci

There are also actinomyces spp and neiserria spp

21
Q

What binds what, bacteria to pellicle?

A

receptors in pellicle attach to the adhesins in the Bactria

receptors attract bacteria to attach onto them

22
Q

What acts as the primary source of carbohydrates and amino acids in the initial coloniser stage?

A

the salivary glycoproteins and proteins in the acquired pellicle

23
Q

Apart from streptococci, what other spp are in the initial colonisers?

A

Actinomyces and neiserria spp

24
Q

What species dominate the initial colonisers?

A

streptococcus

25
Q

What bacterial spp dominates the plaque community

A

actinomyces (microbial succession)

26
Q

What is the shift called from streptococcus to actinomyces?

A

microbial succession

27
Q

What happens to teh biofilm when actinomyces are presnt?

A

plaque

28
Q

What contributes to the biofilm matrix?

A

polysaccharides

glucans

29
Q

What type of bacteria present in the climax community (mature biofilm)?

A

majority facultative or obligately anaerobic

acid producing gram positive cocci

Also, gram positive rods

30
Q

What specific bacteria are found in the mature biofilm?

A

S. mutans

S. sobrinus

31
Q

What are the gram-positive rod in the mature biofilm?

A

actinomyces and lactobacilli

32
Q

Why can cariogenic bacteria survive but beneficial bacteria not?

A

cariogenic bacteria are acid tolerant