Fluoride in Preventative Dentistry W2 Flashcards
(37 cards)
What are the mechanisms of action of fluoride in caries reduction?
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
What ion does Fluoride act on?
OH ions.
Ca10 + (PO4)6 +OH2 +2F —> Ca10 (PO4)6 F2
When pH is low what is in high affinity?
H+ ions are high- which react with F
Both ions in form of H+ and F
What enzyme do Fluoride ions interfere with?
glycolitic enzyme (enolase)
How does fluoride protect enamel? Physically vs Chemically?
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
How does fluoride help in physical protection of enamel?
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.
How does fluoride promote remineralisation of incipient lesions?
- Fluoride adsorbs to tooth surface and attracts Ca ions to form CaF- which provides resistance to acid attack
- CaF forms globule shape with incorporation of PO4 - increases stability- lowers H+ ion concentration
- Protein pellicle forms around this CaF + PO4 complex to stabilise surface of the tooth.
Why does fluoride appear as small globules?
Due to the incorporation of PO4 ions- and enhances CaF
What is a pH controlled reservoir of fluoride on enamel?
CaF
What is acquired resistance with Fluoride?
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
What is the relationship of the ions involved in promoting remineralisation and stabilisation of enamel?
CaF and PO4 and protein pellicle in saliva
Why is topical fluoride important over systemic fluoride ions?
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.
Describe the process of enolase enzyme
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).
In relation to the caries balance, what are the pathological factors?
Pathological: lead to caries
- acid-producing bacteria
- Frequent eating/drinking of fermentable carbs
- Subnormal saliva flow
Systemic vs topical fluorides
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.
What are the 6 steps leading to caries formation?
- Dietary sugars in oral cavity
- Bacterial enzymatic function
- Fermentation
- Organic acids
- Low pH
- Demin and Decalc
- Caries formation
In the crystal lattice, what ions replace each other?
Carbonate ions replace phosphate ions. Na & Mg replace Ca.
Produces defects and Calcium deficient regions.
What is the Medical Model of Dental Caries?
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.
What bacteria are involved in caries and the consequent acids produced?
Streptococci, and lactobacilli
Lactic, formic, propionic
What is the difference between acidogenic and aciduric bacteria?
Give an example species.
Acidogenic are bacteria which produce acid. Aciduric are bacteria that can withstand low pH environments. Streptococci is an example of both.
Is caries transmissible? If so, how?
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.
Is the Hydroxyapatite crystalline structure of the tooth pure?
No. It is contaminated with carbonate ions. Which makes the tooth more susceptible to demineralisation.
On a high resolution micrograph of sound enamel crystal, how can you differentiate between the calcium rich and calcium deficient regions?
Calcium rich are dark. Calcium deficient are white and high in carbonate.
