1. FLUORIDE: HUMAN HEALTH & CARIES PREVENTION
CHAPTER 24
FLUORIDE: HUMAN HEALTH & CARIES PREVENTION

2. HISTORY OF DENTAL FLUOROSIS
1900’s - Dr. Frederick McKay - practice in Colorado Springs Noticed “blotching” of enamel in many of his clients “Colorado brown stain” Mckay believed it was caused by an environmental agent that was active during period of enamel formation - Mckay found mottled enamel was “endemic”
1920’s - Mottled enamel was associated with community water supply
1930’s - H. Trendley Dean: a) researched prevalence of mottled enamel b) developed 6(7) point ordinal scale of fluorosis c) concluded that caries declined as fluoride rose toward 1.0 ppm and then plateaued

3. ENVIRONMENTAL FLUORIDE
Fluoride occurs universally in soils and waters
All plants and animals contain fluoride to some extent
Eg: seawater: ppm
Eg: deep well waters in Arizona: 29.5 ppm

4. SOURCES & AMOUNTS OF FLUORIDE INTAKE
Humans absosrb fluoride from air, food, and water
Estimates from “market basket” surveys: eg: infant mg F/day eg: toddler mg F/day eg: adult F/day
Water and other beverages provide 75% of fluoride intake regardless of whether drinking water is fluoridated
HOW?
Fluoride concentration of various beverages available in nonfluoridated and fluoridated communities

5. FLUORIDE INTAKE
Recommended Daily Intake mg/kg/day Probable Toxic Dose 5mg/kg fluoride Certain Lethal Dose mg/kg fluoride

6. DIETARY FLUORIDE SOURCES
Constituent
ppm / fluoride
fruit, milk, eggs
grains, vegetables
meat, poultry, fish fillet
canned fish (in oil w/bones)
tea (brewed)

7. SELF APPLIED FLUORIDE
Recommended for clients who are moderate to high risk for dental caries
Used for patients under active orthodontic treatment to prevent caries and decalcification around brackets and bands that cause permanent white spots and lines on the enamel
Recommended on elderly patients on medications that reduce salivary flow (xerostomia) and thus are prone to root caries

8. SELF APPLIED FLUORIDE
Self applied gels are available by Rx: 1.1% neutral sodium fluoride (5000 ppm fluoride) of 0.4% stannous fluoride (900 ppm fluoride)
Stannous fluoride may cause some staining; it delivers less fluoride ion to the teeth
Delivery of fluoride gels is either by using a toothbrush or custom tray
4 minutes of use in a custom tray is more effective than 1 minute of brushing with the gel since saliva quickly dilutes the gel removing contact with the teeth

9. FLUORIDE SAFETY follow manufactures instruction
judicious use of fluoride products
careful monitoring during treatment
maximize use of suction
never leave a patient unattended while receiving treatment

10. ACUTE POISONING must be initiated immediately
induce vomiting - often occurs spontaneously
protect stomach - milk, milk & raw eggs, lime water
maintain blood calcium - calcium chloride or calcium gluconate administered both intravenously and orally

11. OTC FLUORIDE RINSES
reduce caries by 28% when used in a daily rinse program
0.5% (225 ppm)
rinse for 30 to 60 seconds ; spit out the excess; not eat, drink, or smoke for at least 30 minutes
recommended before bedtime so that a residue of fluoride can remain in the saliva during sleep
Prescription rinses contain 0.2% sodium fluoride or 0.63% stannous fluoride

12. FLUORIDE ABSORPTION, RETENTION & EXCRETION
Ingested fluoride is absorbed primarily from upper gastrointestinal tract
80% of fluoride in food is absorbed
85-97% of fluoride in water is absorbed
Absorbed fluoride is transported in the plasma
Most absorbed fluoride is excreted in the urine (5.0 mg F absorbed and cleared from blood in 8 hours)
Fluoride that is not excreted is deposited in bone and developing teeth
A greater proportion of ingested fluoride is excreted in older population than younger population

13. FLUORIDE ABSORPTION, RETENTION & EXCRETION
Fluoride ingested on an empty stomach produces peak plasma level within 30 minutes
Level of peak is reduced if fluoride is taken with food WHY?
Kidneys are important in maintaining fluoride balance
Individuals with severe renal impairment can consume fluoridated water without ill effects provided they receive regular dialysis treatment
Water used for renal dialysis treated by reverse osmosis
Aluminum, iron, and other minerals create greater technical problems for renal dialysis process than does fluoride

14. FLUORIDE BALANCE
Refers to the net result from: a) accumulated effects of fluoride ingestion b) degree of fluoride deposition in bones and teeth c) mobilization rate of fluoride from bone d) efficiency of kidneys in clearing absorbed fluoride

15. OPTIMUM FLUORIDE INTAKE
Frank McClure (biochemist with Public Health Service) estimated 0.05 to 0.07 mg F/kg body weight/day “optimum” of fluoride intake in eg: infant 22lbs (0.45 to 0.64 mg F/day) eg: adult 154lbs ( 3.5 to mg F/day)
National Research Council: a) establishes recommended dietary allowances b) considers fluoride to be a beneficial element for individuals
It DOES NOT consider it to be an “essential” nutrient since it could not be confirmed as a contribution to human growth because the physiologic mechanisms by which fluoride influences growth is undetermined

16. FLUORIDE & HUMAN HEALTH: EARLY STUDIES
McClure demonstrates close relationships between urinary fluoride and fluoride levels of domestic water
4 to 5 mg fluoride limit that could be ingested without hazard of excessive storage in the body

17. CANCER
Study 1977 Burk and Yiamouyiannis proved that fluoridation led to an increase in cancer deaths in fluoridated American cities regardless of age, sex, or race
Study - Britain and United States - more detailed age-sex race adjustments - proved that there was no link between cancer incidence and consumption of fluoridated water
National Toxicology Program (NTP): year study on several animal species using 4 levels of fluoride concentration (0,11,45,79 ppm)
Conclusions: a) optimal fluoridation of drinking water does not pose a detectable cancer risk to humans b) increase osteosarcoma in males under 20

18. OSTEOPOROSIS
High doses of fluoride (80 mg/day) is no longer recommended and does not prevent fractures resulting from osteoporosis
No relationship between bone fracture experience and water with 1.0 ppm F

19. FLUORIDE TOXICITY
Fluoride is beneficial in small amounts and toxic in higher amounts
There is a big difference between single intake of 5.0 g F and constant intake of 1 to 3 mg F daily
Toxic effects observed in workers in aluminum plants
5 to 10 g of single dose of sodium fluoride by an adult can result in death in 2 to 4 hours
mg F ingested or inhaled daily 10 to 20 years by an adult can cause crippling skeletal fluorosis
DEGREES OF POTENTIALLY TOXIC INGESTION OF FLUORIDE

20. FLUORIDE & CARIES
3 MECHANISMS BY WHICH FLUORIDE INHIBITS DENTAL CARIES: ) promote remineralization and inhibit demineralization of early carious lesions ) inhibit glycolysis ) reduce enamel solubility in acid
NOTE: There is a stronger posteruptive fluoride action on caries inhibition
Greater proportional caries reductions on _____________ surfaces than on pit and fissure surfaces
When DMFS scores are declining in a population, the proportion of all decayed surfaces that are pit and fissure surfaces will increase even as the absolute number diminishes

21. FLUORIDE & PLAQUE
Fluoride introduced in the oral cavity is partly taken up by plaque (95% bound form)
Fluoride is absorbed more readily by demineralized enamel than by sound enamel
Dental plaque contains approx. 10 mg F/kg weight in low fluoride regions and approx. 20 mg F/kg in fluoridated communities
Fluoride in plaque inhibits glycolysis
Fluoride from drinking water and dentifrices is higher in concentration than fluoride in saliva
Higher concentrations of fluoride gels aid in the destruction of cariogenic bacteria in dental plaque

22. FLUORIDE & ENAMEL
Higher concentration of enamel fluoride does not necessarily mean that a client will be caries-free
There is a relatively ______ concentration of fluoride in enamel
Eg: depth of 2 microns - enamel fluoride concentration ppm in non fluoridated community ppm in fluoridated community
Fewer enamel lesions progress to dentinal caries in a fluoridated area compared to a nonfluoridated region
Fluoride does not prevent the initial carious attack
Fluoride in the mouth inhibits further ____________________ of the carious lesion and promotes ________________________

23. FLUORIDE & SALIVA
Salivary fluoride concentrations are 3x higher in fluoridated than nonfluoridated communities
Eg: fluoridated area: salivary fluoride levels: Eg: nonfluoridated area: salivary fluoride levels: ppm
After brushing with fluoridated toothpaste or rinsing with fluorided solution, salivary fluoride levels can escalate 100 to 1000-fold and then return to normal
The fluctuating salivary flow level is normal
The average adult will produce approx liter of saliva/day
When salivary and plaque pH drops below 5.5, demineralization of the enamel is likely to occur