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Exam 2: DHHD 5001 > Role of Oral Biofilm (Amaechi 5) > Flashcards

Role of Oral Biofilm (Amaechi 5) Flashcards

1
Q

Caries is a _____ dependent oral disease.

A

Biofilm

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2
Q

The acquired salivary pellicle is a layer of structureless, homogeneous biofilm
formed post-eruptively, on the surface of dental
mineral, by the _____ adsorption of
_______ salivary glycoprotein.

A
  • selective

- hydroxyapatite-reactive

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3
Q

Pellicle composition:

  1. ___% amino acids (___% acidic)
  2. ___% Carbohydrates
  3. ___% Lipids
A
  1. 45-50%, 20%
  2. 10-15%
  3. 23%
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4
Q

Functions of the pellicle include:

  1. _____ of microorganisms
  2. _____ – by selective permeability
  3. ______ for microorganisms
A
  1. Attachment
  2. Protection
  3. Substrate/nutrient
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5
Q

_______ is a population of microorganisms growing on a surface, firmly attached to and enmeshed in an extracellular polysaccharide matrix.

A

Plaque Biofilm

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6
Q

Bacterial plaque is soft, densely packed mass consisting by dry weight of:
___% bacteria
___% intercellular matrix

A
  • 70%

- 30%

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7
Q

The intercellular matrix is composed of:

  • Carbohydrate ____%
  • Protein ____%
  • Lipid ____%
  • Inorganic elements (including ____, ____, and ____)
A
  • Carbohydrate 13-18%
  • Protein 40-50%
  • Lipid 10-14%
  • Inorganic elements (including calcium, phosphate, and fluoride)
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8
Q

Plaque is not removed by mouth rinsing, but is easily removed by ______.

A

Mechanical means (prophylaxis)

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9
Q

Classifications of plaque

A
  1. Supragingival

2. Subgingival

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10
Q

Supragingival plaque

A
  • located above the gingivae

- bacteria population predominantly Streptococcus spp. and Actinomyces spp.

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11
Q

Subgingival plaque

A
  • located underneath the gingivae

- predominantly anaerobic organisms

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12
Q

Part of dental plaque formation is expression of _____, _____, _____, and _____ by S. mutans.

A
  • Adhesin (Antigen I/II)
  • Glucosyltransferase (gtf B,C, D)
  • Fructosyltransferase (ftf)
  • Glucan binding protein (GBP)
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13
Q

_______ phase is characterized by rapid bacterial growth mediated by extracellular glucans and streptococcal glucan receptors.

A

Colonization (Accumulation)

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14
Q

______ phase: early dominance by Streptococci followed by a shift towards more anaerobic and filamentous flora.

A

Remodeling

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15
Q

3 stages of plaque formation

A
  1. Initial attachment phase
  2. Colonization (Accumulation) phase
  3. Plaque biofilm formation phase
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16
Q

Plaque composition:

  1. Total bacteria count
  2. Streptococci %
A
  1. ≈ 2 x 1011 bacteria/g

2. 17-38%

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17
Q

____ and ____ are present in high proportions on all sites on tooth surface.

A

Streptococcus and Actinomyces

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18
Q

Carbohydrates of plaque composition exist mainly as extra-cellular polymers…

A
  • Glucans (dextrans and mutans)
  • Fructans (levans)
  • Heteropolysaccharides
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19
Q

Glucan-producers

A

Strep. mutans
L. casei
L. acidophilus

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20
Q

Fructan-producers

A

Actinomyces viscosus

Strep. mutans

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21
Q

Heteropolysaccharides-producers

A

Actinomyces viscosus

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22
Q

Proteins of plaque composition have contributions from the following components of bacteria…

A 
glucosyl transferase
glucanhydrolase
hyaluronidase
phosphatase
Protease
amylase
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23
Q

Proteins of plaque composition have contributions from the following components of saliva and gingival fluid…

A 
amylase
lysozyme
IgA
IgG
IgM
Albumin
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24
Q

Lipids of plaque composition are mainly a component of bacterial ______.

A

Cell membrane

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25
Q

Inorganic components of plaque composition are _____, _____, and _____.

A

Fluoride, Ca, and PO4

26
Q

______ is present in high concentration (14-20 ppm) and mainly bound to other inorganic components and bacteria.

A

Fluoride

27
Q

____ and ____ are also in high concentration and bound to saliva-derived proteins e.g. statherin.

A

Ca and PO4

28
Q

Plaque can be separated by centrifugation into

liquid (______) and solid (_______) phases.

A

-plaque fluid
-bacteria/insoluble
Matrix components

29
Q

Plaque fluid composition

A

Fluoride, Ca, PO4, sodium, potassium, calcium,
Chloride as well as the acids and bases produced by
bacterial metabolism.

30
Q

Plaque fluid anions vary according to the availability of ______.

A

Fermentable carbohydrate

31
Q

At resting plaque pH the dominant acid species is _____; following exposure to fermentable carbohydrate there is a rise in _____ concentrations and a synchronous fall in _____ concentrations.

A
  • acetate
  • lactate
  • acetate
32
Q

Factors affecting the extent and rate pH changes in plaque:

  • Bacteria composition (_____ and ____)
  • the _____ and _____ of the plaque
  • _____: flow rate/ access/ composition
  • the frequency of _____
  • type and consistency of ______ ingested
A
  • type and quantity
  • thickness and age
  • saliva
  • ingestion
  • carbohydrate
33
Q

_______ utilize more environmental
substrate to produce acid at higher rate per
unit time than other microorganisms

A

Strept. mutans

34
Q

Individuals with poor oral hygiene (caries-prone individuals) harbors higher proportion of ______ which produce _______ that cause the fall in plaque pH.

A
  • Strept. mutans

- Stronger acid (lactate)

35
Q

The 3D community of bacteria attached to a surface includes…

A
  • Fluid interaction
  • Channels/pores
  • Complex structure
36
Q

Caries-prone individuals also harbor higher proportion of bacteria capable of synthesizing and storing _________ and ________, which serve as CHO storage compound for extended period of acid production.

A

Intracellular polysaccharides (ICP) and extracellular polysaccharides (ECP)

37
Q

All the factors that determine the extent and rate of pH changes in plaque are risk indicators of dental caries, such as…

A
  • Oral Hygiene
  • Frequency of eating
  • Type of food
38
Q

Bacterial organic acids

A

Formic acid
Acetic acid
Lactic acid
Propionic acid

39
Q

As pH falls…
-Trivalent phosphate ions (PO4-3) become ______
-PO4-3 converted to _________
-HPO4-2 weakens the calcium-phosphate bond
thereby allowing _____ to be released

A
  • protonated
  • divalent phosphate ions (HPO4-2)
  • calcium
40
Q

Remineralization is the delivery of calcium and phosphate, from outside the tooth, into the enamel lesion, effecting deposition of mineral onto the _______ enamel within.

A

demineralized

41
Q

Fall in pH is _______.

A

Reversible

42
Q

Biochemical events leading to recovery of plaque pH back to neutrality:

  • ______ by the salivary components
  • Proton-binding by the products of _______
  • Proton-binding with ________
  • Decreased ______ by the bacteria
  • Diffusion of acid products away into the _____
  • Washing away of acid by _____
A
  • Buffering
  • Mineral dissolution (OH- & PO43-)
  • Elements on bacterial cell wall
  • Acid production
  • Saliva
  • Saliva
43
Q

The _______ provides about 85% of the total buffer capacity of saliva.

A

bicarbonate system

44
Q

____ and ____ in saliva constitute the other buffering system, but their concentrations are too low to be of significance

A

PO4 and Proteins

45
Q

Ammonia production from hydrolysis of urea by the enzyme urease in bacteria, such as ______ and ______.

A

S. gordonii and S. sanguinis

46
Q

Ammonia production from deamination of amino acids by some oral bacteria by means of the arginine deiminase system (ADS) e.g. ______, ______, and ______.

A

S. sanguis, S. milleri & b serotype of S. mutans.

47
Q

Ammonia production from coupled oxidation-reduction of pairs of amino acids (_______).

A

Stickland Reaction

48
Q

Ammonia is highly _____ and causes a rise in ____.

A
  • Alkaline

- pH

49
Q

Decarboxylation of amino acids resulting to the
production ____ with the loss of ____ leading to
a rise in pH.

A
  • amines

- CO2

50
Q

Ammonia production and decarboxylation of amino acids are only effective in plaque under _________.

A

Moderate sugar intake

51
Q

Conversion of the stronger lactic acid to weaker
acids e.g.
-_______ convert lactate to propionate, acetate and ethanol
-_______ degrade lactate to acetate and CO2

A
  • Veillonella sp.

- Neisseria sp.

52
Q

When the plaque pH returns to neutrality, ______ of dissolved calcium phosphate occurs.

A

redeposition

53
Q

Fluoride in solution during de- and remineralization can react with the outer surfaces of dissolving HA crystals thereby forming a shell (of CaF2 nature) that has solubility properties of _______.

A

fluorapatite

54
Q

Cycles of de- and re- mineralization result to a mineral of ______. A remineralized surface is more resistant to subsequent acid attack than the original apatite.

A

better quality

55
Q
  • During remineralization process different phases of calcium phosphate are formed, such as…
  • These intermediate products can transform to ______
A

CaHPO4
CaHPO4.2H2O
Ca3(PO4)2
Ca8H2(PO4)6.5H2O

HA or FA

56
Q

At least 3 credible fluoride reservoir mechanisms have been proposed:

  • Deposition of ________ in plaque , tooth surfaces and early lesions
  • Association of calcium and fluoride with bacteria, particularly ________
  • Deposition of _______ in the plaque matrix
A
  • ‘Calcium fluoride-like’ material
  • Bacterial Lipoteichoic acid (LTA)
  • Crystalline calcium salts
57
Q

The first reason the rate of formation of FA is relatively slow at resting oral pH values, reducing the pH from 7.0 to ≈ 5.0 increases the rate considerably because….

A

Low pH may prolong mineral ions’ access to the lesion body by preventing surface-blocking and arrest

58
Q

The second reason the rate of formation of FA is relatively slow at resting oral pH values, reducing the pH from 7.0 to ≈ 5.0 increases the rate considerably because….

A

Both calcium and fluoride, associated with LTA, are likely to be released during acidogenesis via protonation of anionic binding sites

59
Q

The third reason the rate of formation of FA is relatively slow at resting oral pH values, reducing the pH from 7.0 to ≈ 5.0 increases the rate considerably because….

A

Calcium-fluoride-like deposits and other calcium salts may dissolve, releasing calcium and/or fluoride at the site of action when needed most, potentiating such effects as laid out above

60
Q

The porous demineralized surface may absorb ______ so that following remineralization the lesion remains dark brown in color.

A

extrinsic stains

Exam 2: DHHD 5001 (14 decks)

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