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Adult Restorative > Biochemical events in Dental Plaque > Flashcards

Biochemical events in Dental Plaque Flashcards

1
Q

What are risk factors for caries

A
  • Orthodontic appliances
  • Xerostemia (dry mouth)
  • Gum tissue recession
  • Radiation therapy
  • Smokeless tobacco
  • Excessive alcohol consumption (xerostemia)
  • Patients with poor oral hygiene = bacteria
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2
Q

What is the plaque composed of

A

Bacterial and salivary protein - 50%
Carbohydrates and lipids - 20-30% - extra and intracellular polysaccharides synthesised by bacteria
Inorganic components - 25% like Ca, P etc

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3
Q

What is the function of plaque fluid

A

Provides an aqueous medium for diffusion and exchange of substances between saliva and tooth surface

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4
Q

What is the main acid involved in caries formation

A

Lactic acid

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5
Q

What contributes to the extent of oral pH drop after eating glucose

A
  • Type and amount of CHO available
  • Bacteria present
  • Salivary composition and flow
  • Other food ingested
  • Thickness and age of dental plaque
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6
Q

Write down the reaction of the conversion of glucose to lactic acid in yeast i think

A

Glucose –> Lactic acid + CO2 + Ethanol

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7
Q

What is glycolysis also known as

A

Embden-Meyerhof-Parnas Pathway (EMP)

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8
Q

What is the end product of glycolysis

A

Pyruvate

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9
Q

What can pyruvate be converted into

A
  1. Lactate (anaerobic)
  2. Acetaldehyde and then Ethanol
  3. Acetyl CoA and then further oxidation
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10
Q

Name some cariogenic bacteria

A
  • Streptococci (S. mutans)
  • Actinomyces
  • Lactinobacilli spp
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11
Q

What kind of bacteria is S. mutans, what does it metabolise and where is it found in the mouth

A

Gram positive
Sucrose
Fissures

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12
Q

Where is Actinomyces found in the mouth and what disease is it associated with

A

Found in gingival plaque

Gingivitis

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13
Q

How can Lactobacilli produce caries

A

It produces lactic acid and acetate but this requires lactic acid

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14
Q

What is acidogenicity

A

The ability to produce acid rapidly from fermentable carbohydrate

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15
Q

What is aciduricity

A

The ability to survive and continue to produce acid at acidic pH

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16
Q

How do extracellular polysaccharides from cariogenic bacteria aid caries formation

A

Dietary sucrose to facilitate adherence to tooth surfaces and build up of large bacterial deposits

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17
Q

How do intracellular polysaccharides from cariogenic bacteria aid caries formation

A

Storage components to prolong acid formation and acidic pH

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18
Q

Write down the reaction for glucose to lactic acid in anaerobic conditions in humans

A

Glucose –> 2 lactic acid + 2 ATPs

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19
Q

What do homofermentative bacteria produce

A

Almost entirely lactic acid

20
Q

What do heterofermentative bacteria produce

A

A mixture of metabolites - organic acids like acetic, propionic, succinct and formic acid

Ethanol

21
Q

What is the ecologic plaque hypothesis

A
  1. Low level of MS or lactobacilli or other bacteria produce acid
  2. Frequent consumption of fermentable carbohydrate
  3. Best acid adaptated bacteria survive
  4. Increase level of MS and lactobacilli
22
Q

How can bacteria maintain an optimum intracellular pH despite the acidic environment

A
  1. Low proton permeability of the cell membrane: cell wall thickening
  2. Production of bases
  3. Buffering capacity of the cytoplasm
  4. Active transport of proton out of cell
23
Q

What form are intracellular polysaccharides stored as

A

Glycogen-amylopectin

24
Q

When are intracellular polysaccharides used

A

Used as energy production and acid production when dietary CHO is depleted

25
Q

How can Intracellular polysaccharides contribute to aciduricity

A

IPS –> Energy for ATPase –> Drive protons out of cell –> Adapt to low pH environment

26
Q

What is the role of glucans around the plaque

A
  • Major component of inter bacterial matrix

- Barrier to the outward diffusion of acids from plaque

27
Q

Where can alkali generation come from in the mouth

A
  1. Ureolysis
  2. Strickland Reaction
  3. Arginine deiminase system - major source of ammonia, S. gordonii, S. rates, S. sanguinis, lactobacilli and spirochetes use enzyme arginine deaminase to catabolise arginine in diet
28
Q

Describe the process of ureolysis

A

S. salivarius, A. Naeslundii, haemophili use enzyme urease to hydrolyse urea in saliva

29
Q

Describe the strickland reaction

A

Peptostreptococci oxidise proline in amino acids and reduce protons in plaque

30
Q

Describe the mechanism of the Arginine deaminase system

A

Major source of ammonia, S. gordonii, S. rates, S. sanguinis, lactobacilli and spirochetes use enzyme arginine deaminase to catabolise arginine in diet

31
Q

What treatment options are there for cariogenic bacteria

A
  • Specific Bacterial
  • Bacteriocides
  • Pathway inhibiting chemicals
  • Acid neutralising smart materials
  • Inhibiters of IPS formation pathways
32
Q

What is dental plaque

A

An aggregation of bacteria and products onto the tooth surface

33
Q

What is the pellicle

A

Salivary components adsorbed onto the HAP surface, forms rapidly and salivary glycoproteins tend to adhere to the surface well.

34
Q

What about plaque fluid can cause cariogenic conditions

A

Changes in the ionic composition of plaque fluid can cause cariogenic conditions

35
Q

What is rested and starved plaque fluid

A

Rested - one to several hours after eating

Starved - Following overnight fasting

36
Q

What is the rough organic conc. and pH of Rested plaque fluid

A

High organic acid conc

Low pH

37
Q

What is the rough organic conc. and pH of Starvedplaque fluid

A

Low organic acid conc

Higher pH

38
Q

How long does it take bacteria to metabolise sucrose

A

about 5 mins its very quick then lactic acid will die off but won’t disappear as IPS/EPS can still be used

39
Q

How does salivary pH of patients with high caries activity differ to those with low caries activity after a glucose challenge

A
  • pH starts lower
  • pH drops to lower pH
  • pH recovery to resting is much slower

Due to presence of different bacteria

40
Q

What contributes to the different starting pHs of patients with different levels of caries activity

A
  • Bacterial composition affects metabolic properties of plaque, storage form of CHO = energy source when dieting so lactic acid is present in higher cones at rest
41
Q

Even though sucrose consumption in the population hasn’t dropped hugely, why has the caries prevalence decreased largely

A
  • Due to more use of fluoride
  • More knowledge of affects of sugar

Just shows that caries aren’t entirely linked to sugar consumption

42
Q

What sugars are the ones that are the most caries promoting

A

Small sugars - glucose, fructose, galactose etc

43
Q

Are sugar alcohols cariogenic

A

NOPE

44
Q

How do bacteria convert Glucose –> lactic acid

A

Anaerobic respiration

45
Q

What can pyruvate be converted into depending on the type of bacteria

A

Ethanol
Totally to CO2 and H2O
Lactate

46
Q

What is the key thing to remember about glycolysis and why

A

That enzymes catalyse each step, so inhibitors for certain enzymes can be used to prevent lactate production

47
Q

AY BAWS CAN I HAE DE NOTE PLZZ

A

The fate of bacterial pyruvate depends entirely on the type of bacteria present

Adult Restorative (14 decks)

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