fluoride Flashcards
what are hydroxyapatite crystals made up of?
calcium
phosphate
hydroxide
how are the crystals arranged?
tightly packed to form prisms
what occurs as apatite dissolves?
calcium, phosphate and hydroxide ions dissolve into surrounding solution (saliva)
when does dissolution stop?
when surrounding solution is saturated in comparison to apetite
what happens in the presence of fluoride?
hydroxide is replace with fluoride to from fluorapetite.
what two things are required to form fluorapetite?
hydrogen
fluoride
for every 2 fluoride ions, how many calcium and phosphate are required to make a unit of fluorapetite?
10 ca, 6 po4
what proteins do saliva bind to in ssaliva?
CPP- casein phosphopeptide
ACP- amorphous calcium phosphate
what else do these proteins do? CPP, ACP
buffer ca and po ions from plaque, promoting remineralisation
name the three modes of action re. fluoride?
enamel solubility
effect on plaque bacteria
tooth morphology
describe enamel solubility:
after dissolution of apetite crystals, fluoride from the surrounding solution/ saliva takes the places of hydroxide forming fluorapetite.
fluoratpetite is a larger crystal with less imperfection
its critical PH is 4.5 therefore requires a larger fall in PH to demineralise
describe the effects on plaque bacteria
plaque accumulates fluoride
fluoride inhibits enzymes (enolase) involves in glycolysis and therefore less lactic acid is produced
fluoride inhibits storage of intracellular polysachardes and prevents acid production between meals
describe the effect on tooth morphology
rounded cusps
shallower fissures
what studies have been carried out re. plaque bacteria?
Jenkins 1969
Edgar 1970
what is fluorosis?
caused by high fluoride exposure during tooth developement
what indicates mild fluorosis
fine white lines
what indicates moderate fluorosis
opaque discoloured enamel
what indicated severe fluorosis
loss of enamel
how is fluorosis caused?
reduced enamel matrix protein degregation
increased amelogenin retention
incomplete crystal growth
what studies were carried out re. mottling
Frederick mackay- Colorado springs ( brown stain)
mottling linked to water supply
later GV Black noticed absence of decay
what studies have been carried out re. fluoride and caries?
H Trendly Dean
examined caries in 21 cities in over 7000 children
aged 12-14
higher fluoride in water = less caries
Weaver 1944
children evacuated from south shields in WW1 where fluoride in water was 2ppm had lower DMFT scores
To what concentration is water fluoridated?
1ppm
what case caused water fluoridation to cease in many areas?
McColl 1978
where are the fluoridated areas in the UK?
Birmingham Newcastle Bedford durhan Gateshead derby southhamptom
What are systemic approaches to fluoridation?
water milk salt tablets drop
what are home methods of fluoride delivery?
toothpaste
mouthwashes
tablets
what are dental surgery approached to fluoride delivery?
fluoride varnish
what is the concentration of fluoride varnish?
22, 650 ppm
what is the concentration of regular toothpaste?
1450 ppm
what form does fluoride take in toothpastes?
sodium monofluoraphosphate
sodium fluoride
stannous fluoride
what concentrations are prescription toothpastes?
2800- not for under 10s
5000- not for under 16s
what is fatal dose re. fluoride poisoning?
5-10g
32-64 mg/kg
what is toxic dose in children?
5mg/kg
what are the symptoms of fluoride toxicity?
nausea vomiting GI pain muscular weakness spasms
what is the management for fluoride poisoning
milk
A+E
what is the recommended dose re. fluoride varnish?
2-5 years: 0.25mls
6+: 0.4mls
what concentrations should fluorides tablets/drops be given?
6months-3 years: 0.25mg
3-6 years: 0.5mg
6+ 1mg
detail the Strathclyde case. re water fluoridation
1978 a citizen of Glasgow claimed water fluoridation violated informed consent
main grounds:
beyond the powers of the public
nuisance- harmful in relation to cancer
breach of water act
council providing medicinal product without liscence
what does the knox report conclude?
1980 department of health commissioned a report on the links of fluoride to cancer
finding in 1985 proved no effects
fluoridation I a safe and effective measure of reducing decay
what concentration re. fluoride mouthwash?
0.05%
225 ppm
what % fluoride varnisih?
5%
22600 ppm
