What are the dietary sources of fluoride exposure
Natural (water supplies, rock and soil), added (water milk and salt)
What are the dental sources of fluoride exposure
Dental products ( toothpaste, mouthwash) and fluoride supplements
Where is the majority of fluoride absorbed
90% of F is absorbed mainly in stomach
Where is the majority of fluoride stored in the body
In calcified tissues
How is fluoride excreted
-Main route of excretion is via kidneys
- enters glomerular filtrate
- reabsorbed as HF via passive diffusion
- excreted in faeces and urine
How is fluoride absorbed into the stomach
Passive absorption as hydrogen fluoride
What are the factors affecting fluoride absorption
- increased absorption with highly soluble forms e.g. NaF with water
- decreased absorption with highly dietary concentration of Ca2+/ other divalent/trivalent cations
- decreased absorption when ingested with milk of baby formula
- stomach pH
- decreased absorption when ingested with dietary fat
- decreased absorption with vegetarian diet
Why are organic sources less readily absorbed
Bound to proteins
How is absorption of fluoride different in the small intestine to the stomach
Small intestine absorption is pH independent
Describe transport and cellular distribution of fluoride
- higher pH of extracellular fluid (pH 7) leads to dissociation of HF to release F-
- distributed throughout extracellular fluid
- bound to proteins as fluorine in blood and tissues e.g. bound to blood albumin in blood
- majority of absorbed F- found in calcified tissue
What are the factors affecting F- excretion
- plasma levels F-
- high F- decreases glomerular filtration rate (GFR)
- urine pH
- flow of urine
What does excess of F cause/ toxicity
Debtal and skeletal Fluorosis
Kidney disease
Liver damage
Why is F beneficial
Decline in dental caries as aids mineralisation, inhibits anaerobic glycolysis and acid production by oral bacteria/ growth of oral microbiome
How can dental caries be reversed or prevented
through the elimination or modification of aetiological factors (dietary, microbial) and/or by enhancing protective factors (fluoride, sealants and salivary stimulation).
Describe acute fluoride toxicity
Acute
sudden ingestion of large dose
causes nausea, vomiting, diarrhoea and abdominal pain
certain lethal dose is ~ 32-64mg/F/kg
What is the safe tolerated dose of fluoride
Safe tolerated dose is 8-16 mg F/kg
Describe chronic fluoride toxicity
Chronic
smaller dose over long time
affects teeth while still forming: up to 6 years, incisors up to 3 years
affects bone continually – skeletal fluorosis
Optimum safe daily dose for dental health benefits is 0.05-0.07 mg/kg body weight per/day in children <12 years of age
What is systemic fluoride therapy
Public water fluoridation School water fluoridation Fluoridised salt Fluoridised milk
Fluoride drops/tablets
What is topical fluoride therapy
Topical application
Fluoride mouth rinse
Fluoride toothpaste
When is water fluoridation most effective
water fluoridation at 1 ppm was the best
balance between caries and fluorosis
What do studies on water fluoridation suggest about it’s effectiveness
Water fluoridation has the most impact in the lower social classes
Water fluoridation offers protection from dental caries even when other forms of F are available e.g. Toothpastes
What does research into fluoridation of milk suggest about its effectiveness
Concluded insufficient studies with good quality evidence to show effectiveness
What % of absorbed fluoride is excreted
50-60%
Describe fluoride ingestion and absorption
Fluoride is soluble and rapidly absorbed
•Passive absorption stomach as HF (non-ionic weak acid)
•Small intestine pH-independent as F-
•50% absorbed within ~30 min
•Potential to absorb 80-90% absorbed in absence high [Ca2+]
•Organic sources of F- (bound to proteins) less readily absorbed
