Mechanisms of Action Fluoride Flashcards by Dennis Zhu

How much ppm of F- is in water? How does that compare to toothpaste?

1 ppm in water

1000-5000 ppm in toothpaste

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How much fluoride is in flouride tray applcations?

9000-12300 ppm

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What are 2 reasons why fluoride is important in dentistry?

Promote formation of fluorapatite

Fluorapatite is more stable than HA

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What are the two theories surrounding the caries preventive effects of fluoride?

Systemic theory

Topical action theory

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What is the systemic theory?

F- is incorporated into teeth as FA and protects against dental caries.

It’s known as the bound-only theory

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What is the topical action theory?

F- ions that bathe the teeth throughout life prevent caries

also known as free-ion theory

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What are the limitations of the systemic theory?

need high amounts of F- in tooth structure to affect solubility

studies that show increased caries risk in populations that move from fluoridated to non-fluoridated regions

potential fluorosis risk

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1) Enamel Surface
2) DEJ
3) Dentine-pulp interface

Order the numbers above from highest fluoride concentration to lowest.

3, 1, 2

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Deep dentine has more fluoride than surface enamel. True or false?

True

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What does this graph show?

Sharks nearly have pure FA in their teeth

Humans do not have pure FA in their teeth

pure FA = 34000

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This graph shows the depth of demineralization in enamel. What does this graph demonstrate?

Why is it interesting?

Rinsing with a F- solution almost had the lesion reducing effect as pure HF in sharks.

Interesting because it shows that F- does not need to be chemically bound to teeth to elicit effect (supports free-ion theory)

Second graph to prove the point

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What are the conclusions of the shark enamel - human enamel study?

look at slide

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What are the products of HA dissociation?

OH- , Ca2+, PO43-

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What is this diagram showing?

Write out the chemical formula associated with this diagram

Showing that calcium deficient apatite reprecipitates into HA, and HA reprecipitates into FA at the surface layer, where F concentration is high

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The journey is more important than the destination
- James Fernando

Explain what this means and what theory it applies to

topical application theory (2)

Continued supply of F- ions allow products of dissoluted HA to be redeposited into FA, preventing net demineralization. The resulting formation of FA is more stable and less soluble.

Essentially F- intercepts Ca2+ and phosphate ions, before it leaves the tooth.

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What is this?

What does it demonstrate?

at 0.1 ppm of F-, what is the white band?

Microradiograph

Demonstrates the dose dependent effect of fluoride
- less mineral loss = higher concentration of flouride

At 2 ppm, no net change in mineral

white band is fluroapatite surface layer

This microradiograph shows a fluoride’s ability to help remineralize teeth. True or False?

False, this is an example of redistribution of calcium phosphate; deposition/mineralization.

Why does dentine require more fluoride than enamel to prevent demineralization?

Smaller crystals
More soluble
Dentine tubules

Why do dentists prescribe higher concentrations of fluoride for patients with Frank Cavitation? Why don’t all patients use prescription (high -) toothpastes if it’s better?

Exposed dentine requires higher than normal F- to prevent demin

reduction of Demin effect of enamel doesn’t change much after 1 ppm

How do the forms of fluoride differ from inside your enamel compared to inside your plaque?

Free F-, CaF2, or FA in enamel

CAF2, bacterial-surface bound F-, or F- within bacteria in plaque

Gingival fluid has less F- compared to saliva. True or false?

False, it has more F-

Why is it important to ingest fluoride?

Fluoride become present in saliva although it returns to basline after 3-6 hours

NAF vs NA2FPO3

Name them and explain which one you would prefer to use

Sodium Fluoride and Sodium Monofluorophosphate

Prefer NaF because NA2FPO3 requires alkaline phosphatase to hydrolyze P-F bond to free fluoride

NaF vs SnF2

Name them and explain which one you would prefer to use

Sodium fluoride and Stannous fluoride

Prefer SnF2 because tin ion also has antibacteiral and demin-inhibiting effects

Name this compound: AgF(NH3)2 What cases would you use it and why?

Silver Diammine Fluoride It's strong and potent so it's good for spot applications to arrest dental caries. However I would only use it on posterior teeth as it can cause tooth to stain black due to the silver ions

What are the 3 most important reactions of F-? Write them out.

What is HF and what can it do?

Neutral ion pair diffuse through charged membranes and dissociate into F- and H+ access bacteria and cause damage (enzyme disruptor) Access subsurface lesions

What is CaF and what can it do?

Crystal in enamel or plaque relatively high solubility product -- typically phosphate and protein coat wrap around this crystal making it insoluble. Upon exposure to acid, protonation of proteins and phosphate allow for the release and dissolving of CaF2

Compare FA to HA (4 pts)

FA - less soluble FA - higher crystallinity FA- easier to form FA- forms faster

What are fluorides 3 mechanisms of action?

Inhibit net demineralisation Promote net remineralisation Bacterial effects

How does fluoride inhibit net demin?

Intercepts calcium and phosphate and prevens them from diffusing out the tooth. Fluoroapatite is more resistant to dissolution being more stable

How does fluoride promote net remineralisation?

It has greater thermodynamic driving force for FA formaton DS is more easily over one and can form FA from saliva ions FA has low solubility

How is fluoride anti bacterial? What are the limitations?

Inhibit enzymes in oral bacteria Inhibit carb metabolism Acidify bacteria --> disrupt cellular function need high concentrations for this to occur

How does enamel fluorosis occur?

During enamel maturation, proteases degrade amelogenin to allow for crystal maturation Calcium required for protease function high conc of fluoride bind to calcium and protease activity decreases Amelogenin and its by products are not adequetley removed and the result is flouride rich enamel but mineral poor

Try review Questions

Open ended