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Oral Microbio > Fluoride and Dental caries > Flashcards

Fluoride and Dental caries Flashcards

1
Q

When were the benefits of Fluoride discovered?

A

Paradoxically strong “dark yellow” teeth were noted in 200 ad in Greece

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2
Q

What is the “ideal” concentration of Fluoride in water to maximize caries benefit and minimize fluorosis?

A

1 ppm

Caries is reduced by 50%

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3
Q

How can fluorosis occur?

A

Very high physiologic levels of F during the secretory stage can cause pitting and disturbances in scaffolding (not common)

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4
Q

When does Flurosis occur?

A

To kids when their teeth are forming before they erupt

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5
Q

What occurs during the secretory stage of tooth formation?

A

Ameloblasts lay down the protein matrix for the crystal rod structure and rods begin to form

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6
Q

Chronic moderately high levels of F during the pre-eruptive stage can cause what?

A

Disruptions in crystal formation that appear as a chalky whiteness and weakness of enamel
After eruption, the weakened enamel may fracture and stain

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7
Q

Does fluridated water benefit systemically incorporated or by touching the tooth?

A

Benefits are from F touching the tooth

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8
Q

T/F - there is no benefit of fluoridated water before tooth eruption

A

True

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9
Q

T/F - in order to continue benefits of fluoridated water, fluoridation must continue throughout life

A

True

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10
Q

How do topical F products compare to fluoridated water?

A

They have similar benefits (both touch the tooth)

Topical products are lower risk than systemic products

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11
Q

What is the composition of enamel?

A

87% mineral (HA)
11% water
2% organic matrix

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12
Q

Newly formed crystals in a young tooth usually contains what?

A

Impurities

  • carbonate
  • sodium
  • other ions
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13
Q

What is Post-eruptive Enamel Maturation?

A

After eruption, when bathed in saliva and exposed to F, the HA crystals will tend to perfect itself

  • Phosphate replaces carbonate
  • Ca replaces Na
  • F replaces hydroxyl
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14
Q

What do the mineral replacements in Post-eruptive enamel maturation cause?

A

They make Ha less soluble and therefore stronger

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15
Q

T/F - older teeth are more succeptible to caries

A

False - Younger teeth are more susceptible to caries, because post-eruptive enamel maturation strengthens them over time

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16
Q

HA starts to dissolve below what pH?

A

5.5

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17
Q

How does HA dissolve?

A

Acid continues to dissolve HA crystals because the surrounding solution remains unsaturated due to the removal of component ions from solution under acidic onditions

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18
Q

How does F prevent dissolving?

A

When F ions are present, HA dissolves and re-precipitates as flurohydroxyapatite
FHA is less soluble than HA, so enamel is strengthened

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19
Q

Under what conditions does flurohydroxyapatite form?

A

When pH remains above 4.5 and F ions are avaliable, FHA forms on the surface when HA dissolves

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20
Q

When pH rises above 5.5, F ions do what?

A

Enhance remineralization of enamel and dentin

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21
Q

Which is more beneficial; F at low levels in solution, or F at high concentrations incorporated into enamel?

A

F at low levels in solution

22
Q

Where is enamel the least soluble?

A

The surface, because it has more F (FHA) and less carbonate

23
Q

T/F - F diffuses well into the body of a lesion

A

False - it reacts before it gets there with the outer layers to form FHA
subsurface HA is dissolved while FHA is formed in the surface layers

24
Q

Why do whitespot lesions have very high F concentrations on their surface?

A

Because of demin-remin cycles

25
Q

T/F - Areas covered by plaque have higher F levels

A

True

26
Q

T/F - Worn areas (abrasion, erosion) have high levels of F

A

Falase - low levels of F

27
Q

What occurs when topical fluoride concentrations are above 100 ppm?

A

Calcium Fluoride precipitates - and when acid is around, CaF2 is deposited and F is made available in the acidic conditions
CaF2 provides termporary storage of F and is gradually dissolved

28
Q

CaF2 deposition is increased by what?

A

Increasing concentration of F
Increasing exposure time
Lowering pH
Protecting (limit rinsing or cover with varnish)

29
Q

Saliva is supersaturated with what? Why is this important?

A

Calcium and Phosphate

These help so teeth don’t dissolve

30
Q

Why doesn’t crystal growth occur on the tooth?

A

Pellicle proteins

Pellicles also prevent spontaneous precipitation in salivary ducts

31
Q

What is a negative issue of calcium and phosphate in the saliva?

A

Can lead to calculus formaiton

32
Q

Where is F concentration the highest?

A

Tooth surface - it’s dependent on topical exposure to F, acid exposure, and wear

33
Q

T/F - Exposure during development is a major determinant of F levels in enamel

A

False

34
Q

Extent and severity of fluorosis is increased with what?

A

Exposure to higher levels during tooth development

35
Q

T/F - There is a threshold below which no effect of fluorosis will be seen

A

False - even with low exposure, a certain level of fluorosis can occur

36
Q

T/F - Mild fluorosis is perceived as attractive by most people

A

True

37
Q

What level of F is high risk or cosmetically objectionable fluorosis?

A

0.1 mg/kg

38
Q

T/F - Fluoride is highly concentrated in plaque

A

True

39
Q

Can bacteria develop resistance to F?

A

No

40
Q

What are the methods of Fluoride delivery?

A

Community-based water fluoridation
Self-applied
Profesionally applied

41
Q

Self-applied fluoride delivery

A

High frequency, low concentration (1000 ppm)
Topical products
Systemic suppliments

42
Q

Profesionally applied fluoride

A

Low frequency, high concentration

Topical products

43
Q

What forms of fluoride are most commonly found in toothpaste?

A

NaF2
Monofluorophosphate (MFP)
Stannous fluoride (SnF2)

44
Q

How much fluoride can be in Rx toothpastes?

A

5000 ppm

45
Q

T/F - There is a positive relationship between toothpaste amount and caries

A

False

46
Q

Does frequency matter in F exposure?

A

Yes - brushing twice a day is better than once a day

47
Q

T/F - Rinsing does not effect F exposure

A

False - less rinsing is better

48
Q

What is more effective, Professional gels and rinses? Or Professional fluoride varnish?

A

Fluoride varnish

49
Q

Foam gels and rinses

A

1.23% acidulated phosphate fluoride
0.9% fluoride as NaF2
30% reduction in caries

50
Q

Fluoride varnish

A

2.2% F as NaF

40% reduction in caries

Oral Microbio (11 decks)

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