#4 Fluoride and Dental Caries Flashcards
In the U.S, when was the effect of fluoride noted?
1930s’
What is the downside of fluoride?
Fluorosis when swallowed
What causes fluorosis?
Ingesting excess fluoride during the (secretory) pre-eruptive stage of teeth. *concern with children b/c little fluoride is incorporated not the enamel during the pre-eruptive maturation phase.
During the secretory stage, ameloblasts do what?
Lay down the protein matrix fro the rod crystal structurre and the rods begin to form.
During the pre-eruptive maturation stage the ameloblasts do what?
Fill in the crystal structure with mineral.
What are the symptoms of Fluorosis?
- Disruptions in crystal formation that appear chalky white.
- Weak enamel
- Fractures in the weakened enamel
Does fluoride make the body of the tooth strong?
No! It just strengthens the outer layer of enamel.
Why are topical products lower risk than water fluorination?
Because less fluoride is ingested.
What level of Fluoride is safe to ingest?
None technically
What is the percentage composition of enamel?
87% mineral (hydroxyapatite)
11% water
2% organic matrix
What is post-eruptive enamel maturation?
A process in which the impurities in newly formed teeth (Carbonate, sodium, other ions) are perfected as it is exposed to calcium and phosphate in the salvia as well as fluoride.
In post-eruptive enamel maturation what materials are replaced with what?
- Phosphate replaces carbonate
- Calcium replaces sodium
- Fluoride replaces hydroxyl
- These replacements make hydroxyapatite less soluble and therefore, stronger.
Hydroxyapatite dissolves if pH drops below ______.
- 5 * the lower it goes the more it dissolves
- Acids remove component ions from hydroxy apatite and leaves the structure unsaturated and weaker.
What occurs when fluoride is present under acids conditions?
Hydroxyapatite dissolves and re-precipitates as Fluorhydroxyapatite (what doesn’t kill you makes you stronger!)
The pH must be above _____ for fluoride to be available?
above 4.5
When pH rises above ______ Fluoride ions enhance remineralization of enamel and dentin.
above 5.5
_______ causes dissolution of enamel.
Lactic acid
T or F, white spot lesions are always low in fluoride.
False, they can be high in floured because of demin-remin cycles. In fact they usually contain higher surface level of F than surround areas.
How is it possible that you can end up with a hard stable surface layer of enamel and a demineralized subsurface zone?
Subsurface hydroxyapatite is dissolved while fluorhyrdoxyapatite is formed on the surface.
Areas covered by plaque have ______ levels of fluoride.
Higher
Worn area, of abrasion or erosion have ___ levels of Fluoride.
Lower
When topical fluoride concentrations are low (50ppm) where is fluorhydroxyapatite formed?
on the outermost layers of enamel
When topical fluoride conc. are high (above 100ppm) what occurs?
calcium fluoride precipitates and acid helps with he deposition of calcium fluoride, because calcium ions are made available *APF deposits more F than NaF)
CaF2 deposition is increased by what 4 things?
- increasing F concentration
- Increasing exposure time
- lowering pH
- Protecting-limit rinsing or cover with varnish
