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Clinical Content > Fluoride in Preventative Dentistry W2 > Flashcards

Fluoride in Preventative Dentistry W2 Flashcards

1
Q

What are the mechanisms of action of fluoride in caries reduction?

A

Pre- eruptive: improves the quality of mineralised tooth tissues (lower conc of fluoride)
Post-eruptive:
1. INTERFERENCE with plaque microorganisms
2. PROTECTS the enamel - physical/chemical barrier increased enamel resistance
3. PREVENTS demineralisation- reduction of enamel solubility
4. PROMOTES remineralisation of incipient lesions (attracts Ca and PO4)
5. INCREASED rate of post-eruptive maturation

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2
Q

What ion does Fluoride act on?

A

OH ions.
Ca10 + (PO4)6 +OH2 +2F —> Ca10 (PO4)6 F2

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3
Q

When pH is low what is in high affinity?

A

H+ ions are high- which react with F
Both ions in form of H+ and F

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4
Q

What enzyme do Fluoride ions interfere with?

A

glycolitic enzyme (enolase)

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5
Q

How does fluoride protect enamel? Physically vs Chemically?

A

Physical barrier:

The tooth pellicle- holds CaF together along with PO4 and increases stability.

Chemically
F ions react with Ca on tooth surface and saliva to form a barrier. CaF resists acid, which helps slow/inhibit demineralisation. F ion are highly electronegative- F can form strongly to the surface of carbonated crystals and protect enamel from acid attack

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6
Q

How does fluoride help in physical protection of enamel?

A

F reduces the solubility of Enamel by increase in FAP via CaF interactions.

When the entire surface of the tooth is covered in F ions it will protect the tooth surface from pH drop caused by bacterial-derived acids.

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7
Q

How does fluoride promote remineralisation of incipient lesions?

A
  1. Fluoride adsorbs to tooth surface and attracts Ca ions to form CaF- which provides resistance to acid attack
  2. CaF forms globule shape with incorporation of PO4 - increases stability- lowers H+ ion concentration
  3. Protein pellicle forms around this CaF + PO4 complex to stabilise surface of the tooth.
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8
Q

Why does fluoride appear as small globules?

A

Due to the incorporation of PO4 ions- and enhances CaF

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9
Q

What is a pH controlled reservoir of fluoride on enamel?

A

CaF

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10
Q

What is acquired resistance with Fluoride?

A

Acid-softened enamel, rehardened by fluoridation, acquired significant secondary resistance to acid attack
Increase resistance of remineralised tooth surface that occurs after the process of demineralisation that promotes remineralisation of HAP

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11
Q

What is the relationship of the ions involved in promoting remineralisation and stabilisation of enamel?

A

CaF and PO4 and protein pellicle in saliva

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12
Q

Why is topical fluoride important over systemic fluoride ions?

A

Fluoride ions are only freely available when demineralisation has began and Ca and PO4 are released. Topical fluoride prevents demineralisation- acts as a catalyst and attracts Ca and PO4 ions in the saliva to further build up the process of acquired resistance.

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13
Q

Describe the process of enolase enzyme

A

Enolase catalyses a reaction of glycolysis- and releases ATP for cell to grow and ferment sugars

Interfering with enolase means bacteria are no longer able to produce ATP and ferment sugars = cell death (apoptosis).

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14
Q

In relation to the caries balance, what are the pathological factors?

A

Pathological: lead to caries

  1. acid-producing bacteria
  2. Frequent eating/drinking of fermentable carbs
  3. Subnormal saliva flow
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15
Q

Systemic vs topical fluorides

A

Systemic: circulate through the blood stream and are incorporated into the developing teeth. Provide a low concentration of fluoride over a long period of time (through salivary secretion)

Topical: are placed directly on the teeth. Provide high and low concentrations of fluoride over a short period of time.

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16
Q

What are the 6 steps leading to caries formation?

A
  1. Dietary sugars in oral cavity
  2. Bacterial enzymatic function
  3. Fermentation
  4. Organic acids
  5. Low pH
  6. Demin and Decalc
  7. Caries formation
17
Q

In the crystal lattice, what ions replace each other?

A

Carbonate ions replace phosphate ions. Na & Mg replace Ca.

Produces defects and Calcium deficient regions.

18
Q

What is the Medical Model of Dental Caries?

A

Clinicians are not expected to view dental caries as just cavities - it is to be treated as a disease process. Identify the factors that contribute to the reversal process.

19
Q

What bacteria are involved in caries and the consequent acids produced?

A

Streptococci, and lactobacilli

Lactic, formic, propionic

20
Q

What is the difference between acidogenic and aciduric bacteria?

Give an example species.

A

Acidogenic are bacteria which produce acid. Aciduric are bacteria that can withstand low pH environments. Streptococci is an example of both.

21
Q

Is caries transmissible? If so, how?

A

Vertical transmission via saliva. From mother/caregiver who has a high amount of cariogenic bacteria in their mouth, can pass on to child by close contact.

22
Q

Is the Hydroxyapatite crystalline structure of the tooth pure?

A

No. It is contaminated with carbonate ions. Which makes the tooth more susceptible to demineralisation.

23
Q
A
24
Q

On a high resolution micrograph of sound enamel crystal, how can you differentiate between the calcium rich and calcium deficient regions?

A

Calcium rich are dark. Calcium deficient are white and high in carbonate.

25
Q

What are the arrows indicating in this micrograph? And how would you describe what is happening?

A

Hexagonal white patches are where acid has dissolved mineral from calcium deficient/carbonate rich regions

26
Q

What is the first stage of demineralisation on an atomic level?

A

Calcium deficient regions have expanded into hexagonal shaped regions where mineral has dissolved during acid attack.

27
Q

Define remineralisation of the tooth

A

Natural repair process for subsurface non-cavitated carious lesions.

28
Q

What does remineralisation occur in the presence of?

A

Remineralisation only occurs in the presence of Calcium and Phosphate ions (present in saliva and tooth surface)

29
Q

What is the concept of remineralisation? (including fluorides catalytic role)

A

Fluoride will stick to the surface of demineralised crystals. Fluoride acts as a catalyst and attracts ions Ca and PO4 (from saliva and tooth surface) to diffuse into the tooth as CaF and PO4 and protein pellicle.. CaF and PO4 speeds up the building on existing crystal remnants, which makes the new minerals less soluble. Hardened by fluoridation. = Acquired resistance

30
Q

Does drinking tea cause caries?

A

No. It is rich in fluoride (without sugar added of course)

31
Q

How does the mechanism of action in fluoride differ in pre-erupted vs post-erupted teeth?

A

Pre-erupted: improves the quality of mineralised tooth tissues (lower concentration of fluoride)

Post-erupted: has the interference of plaque microorganisms. Role is to protect enamel, prevent demineralisation, promotes remineralisation

32
Q

Which ions does fluoride act on and replace in HAP?

A

OH- ions

33
Q

What is systemic fluoride?

A

Circulates through the blood stream. Incorporated into the crystalline structure.

Provides low conc of F through saliva, at low pH when demin is occurring (due to leaching of Ca and PO4) which attracts fluoride.

34
Q

What do CaF crystals serve as?

A

pH controlled reservoirs of F ions on enamel or plaque- and release F in caries challenges

35
Q

What is the role of Hydrogen Fluoride?

A

Interference with plaque microorganisms. HF diffuses into bacteria and then separates into H+ and F- ions. This process accumulates high H+ concentration in the cytoplasm of the bacteria.

High H = acidification of cytoplasm which is the first step to cell death. (apoptosis of the bacteria therefore can’t ferment and make acid in the mouth)

36
Q

What are the protective factors of no caries?

A
  1. Saliva flow and components
  2. fluoride- remineralisation with calcium and phosphate
  3. antibacterials- chlorohexidine xylitol
37
Q

What is the largest cause of the increase in solubility of HAP?

A

Carbonate that substitutes for phosphate which causes defects in the crystals

Clinical Content (7 decks)

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