3. CONTENTS
• INTRODUCTION
• HISTORICAL EVOLUTION OF FLUORIDES
• FLUORIDE IN THE ENVIRONMENT
• SOURCES OF FLUORIDE
• METABOLISM OF FLUORIDE
• ESTIMATION OF FLUORIDE CONCENTRATION
• MECHANISM OF ACTION OF FLUORIDES
• CONCLUSION
• REFERENCES
4. INTRODUCTION
• Fluorine is a member of the halogen family with a
relative atomic weight of 19 and an atomic
number of 9.
• The word fluorine is derived from the Latin term
“fluore”, meaning, “to flow”.
• At room temperature, fluorine is a pale, yellow-
green gas.
• It is the most electronegative and reactive of all
elements and thus, in nature, is rarely found in its
elemental state.
5. What is fluoride?
• Fluoride is the ionic form of the element fluorine.
• Fluoride is a mineral found throughout the Earth’s
crust and widely distributed in nature.
• The Federal Register of United States Food and
Drug Administration describes fluoride as an
essential nutrient.
• The WHO expert committee on trace elements
has included fluorine as one among the 14
physiologically essential elements required for
the normal growth and development of the body.
6. HISTORICAL EVOLUTION OF FLUORIDE
• In 1529, Georigius Agricola described the use
of fluospar as a flux and Ferdinand Frederic
Henri Moissan, a French chemist, was the first
to successfully isolate fluorine in 1886.
• In 1901, Dr. Fredrick McKay in Colorado
Springs, Colorado, USA, noticed that many of
his patients, had an apparently permanent
stain on their teeth, which was known to the
local inhabitants as ‘Colorado Stain’ and he
called the stain ‘mottled enamel’.
7. • Stain was characterised by minute white
flecks or yellow or brown spots or areas,
scattered irregularly or streaked over the
surface of a tooth or it may be a condition
where the entire tooth surface is of a dead
paper-white like the color of a china dish.
8. In 1908, El Paso Country Odontological Society, sent
Mckay, together with a patient whose teeth bore
the markings of the stain, to the annual meeting,
(in June) of the State Dental Association in
Boulder.
Mckay approached one of America’s foremost
authorities on dental enamel, Dr. Greene
Vardiman Black, Dean of the Northwestern
University Dental School in Chicago.
G.V black agreed to attend the Colorado State
Dental Association Meeting in 1909.
9. • In preparation for his visit, and as a first step in
mapping out the entire endemic area, Mckay,
Issac Burton and A. Fleming, examined 2945
children in the public schools of Colorado Springs
and discovered that 87.5% of the children native
to the areas had mottled teeth.
• This information was given to Black when he
arrived in Denver, in, June 1909.
• At the State Dental Association meeting, Black
described the histological examination of the
lesion.
10. • Black’s histological findings were published in a
paper entitled, ‘An endemic imperfection of the
enamel of the teeth heretofore unknown in the
literature of dentistry’.
• In 1916, Mckay along with Dr.G.V.Black concluded
that an unidentified factor was responsible for
the mottling of enamel.
• They assumed that this unknown factor might
have been present in the water consumed by the
indivisuals during the period of tooth
calcification.
11. • In 1918, Mckay confirmed the presence of an
unknown element in the water supply to be the
definite causative factor for enamel mottling.
• In the year 1931, Mckay asked Churchill H.V. a
Chemist to analyse water samples collected from
areas with enamel mottling.
• The analysis on the samples indicated a high
level of fluoride content in the water.
• Thus after 30 years in 1931, the element fluoride
was identified as the “mysterious factor”
responsible for mottled enamel.
12. • In 1931,U.S.Public health service appointed
Dr. Trendley H Dean to continue the work of
Mckay in determining the extent and severity
of mottled enamel.
13. • Dean conducted a survey and gave the following
report on mottling of enamel
1. A high concentartion of fluoride in water is directly related to the severity
of enamel mottling.
2. Enamel mottling was widespread in areas with water having fluoride
content of 3ppm
3.Mottling with discrete pitting of enamel was noticed at fluoride levels of 4
ppm
4. Mottling was less in case of fluoride levels of 2.5 ppm-3 ppm, with a dull
chalky white appearance of teeth
5.No mottling or any other enamel changes were observed in areas with water
containing 1 ppm fluoride.
14. • Thus in 1934, Dean developed a Standard System
for Classification of dental fluorosis the “mottling
index”(Dean’s Index for fluorosis).
• In 1942, Dean et al discovered that 1 ppm F in
drinking water , a 60% reduction in caries
experience was observed.
• In 1969, WHO advocated that 1 ppm of fluoride
in community water supplies was a practical and
effective public health measure.
• Thus, fluoride was identified as the essential
element for reducing dental caries and led to the
introduction of various methods of topical
application of fluorides for indivisuals and water
fluoridation projects for communities.
15. FLUORIDE LEVEL IN INDIA
• The main fluoride bearing areas are Gujarat,
Rajasthan and Andhra Pradesh where about
50-100% of the districts are affected.
• According to the National Epidemiological Oral
Health Survey and Fluoride Mapping of the
dental council of india (2002-2003), the
overall fluorosis prevalence in the country was
found to be very low.
16. FLUORIDE IN ENVIRONMENT
• LITHOSPHERE
• Fluoride rarely occurs as such in nature but is
present as inorganic fluoride.
• Fluoride concentration in the first several
inches of soil ranges from 20-500 ppm;
• In deeper soil, the level increases.
17. • Biosphere
• The normal level of fluoride in plants is about
2-20 mg/g of dry weight.
• Leafy vegetables such as cabbages and lettuce
contain about 11-26mg fluoride on a dry
weight basis.
• Animal foods like Sardines, salmon, mackerel
and other fish contain about 20-40 ppm of
fluoride on a dry weight basis.
18. • Hydrosphere
• Due to universal presence of fluorides in the
earth’s curst, all water contains fluorides in
varying concentrations.
• The concentration of fluorides is negligible in
rainwater.
• The fluoride content of water obtained from
rivers, lakes, or artesian wells is below 0.5 mg/kg.
• Sea water contains 1.2-1.4 mg/kg of fluoride.
19. • Atmosphere
• In large cities, 1 cubic meter of air on an
average, contains less than 0.05mg of fluoride
but significantly high values have been
recorded in some industrialized areas.
20. SOURCES OF FLUORIDE
• Fish products, in particular canned fish such as salmon
and sardines have a fluoride content of upto 20-
40mg/kg.
• Jowar,banana, potatoes also conatin substantial
quantities of fluoride.
• The fluoride content of rock salt ranges between 40
and 200 ppm.
• The dried tea leaves contain 100-400 ppm fluoride.
• Mineral water usually contains considerably higher
concentration, from 1.5-7 ppm.
21. ESTIMATED DAILY INTAKE OF
FLUORIDE
• An average daily intake of fluoride from dry food
substances is in the range of 0.2-1.8 mg and the
average daily intake from water containing 1 ppm
fluoride is about 1.5mg.
• The total daily intake for:
Adults= 1.7-3.3 mg.
Children=0.7 mg/day for the younger, bottle fed
group of children and
About 1.3 mg fluoride/day for the 12 year old
group.
22. METABOLISM OF FLUORIDE
• The metabolism of fluoride is through
absorption, distribution and elimination.
• Approximately 50% of the ingested fluoride
will be excreted in the urine and most of the
remaining will be taken up by mineralised
tissues.
23. ABSORPTION
• The absorption of most water-soluble fluoride
compounds is rapid and almost complete and
occurs mainly in the stomach.
• Absorptions from dental preparations:
• The fluoride for topical application, is almost
completely absorbed when swallowed.
• The bioavailability of F from sodium fluoride or
stannous fluoride is close to 100%.
• Fluoride from acidulated phosphate fluoride is
also well absorbed.
24. • Fluoride in blood plasma:
Fluoride in plasma exists in the form of,
• Ionic fluoride(inorganic or free fluoride)
• Non-ionic fluoride(bound fluoride)
The plasma concentration is approximately twice as
high as that associated with the blood cells.
Plasma fluoride level expected in a healthy, fasting,
long-term resident of a community with a water
fluoride level of 1ppm is approximately
1mM(0.019ppm).
25. distribution
Fluorides in soft tissues:
Distribution rate is generally determined by
the blood flow to the tissue.
Fluorides is concentrated to high levels within
the kidney tubules.
The amount of fluoride in the pulp is 100-650
ppm.
26. Fluorides in bone:
• Fluoride is a mineralized tissue seeker.
• Approximately 99% of all the fluorides in the
human body is found in calcified tissues.
Fluorides in saliva:
• There are 2 major sources of salivary fluoride-
1.Secretion from salivary glands-
The level of F secreted by the glands is very low and
in the range of 0.007-0.05 ppm.
2.Introduction into the mouth from food,water and
fluoride preparations such as dentrifices and
topical application procedures have been found
to increase the fluoride concentration of saliva,
more than the ingested fluoride.
27. • Fluoride in enamel:
Amount of fluoride in the outer enamel is 2,200-
3,200 ppm.
• Developing enamel-
• During early stages of development, there is a
small but detectable backgound level of
fluorides.
28. Erupted enamel-
Fluoride distribution is not uniform across the
thickness of enamel.
In incompletely mineralised state, the
accumulation of fluoride by enamel seems
largely restricted to the surface region and the
fluoride concentration is therefore always high
at the enamel surface compared with the
interior.
29. • In newly erupted teeth, the surface fluoride
concentrations were found to be the highest
in the first formed enamel near the incisal
edge and decreased steeply towards the more
recently formed cervical region.
• Fully mineralised enamel has a density of
2.98gm/ml with a porosity as low as 0.1%
space by volume.
30. Fluoride in dentin:
• Amount of fluoride in dentin is 200-300ppm.
• The fluoride concentration is more in dentin than in
enamel.
Fluoride in cementum:
• Amount of fluoride in cementum is 4,500ppm.
• The concentration of fluoride in cementum is higher
than that of any skeletal or dental tissue.
• This is because, the tissue is very thin and all of it is
therefore, near to the tissue surface and so accessible
to the fluoride present in blood.
31. Fluoride and dental plaque:
• Fluoride content in plaque ranges from 15-64
ppm.
• The ionic fluoride activity of neutral plaque is
between 0.08 and 0.8 ppm and is too low to
inhibit the metabolism of plaque bacteria.
32. EXCRETION
• Fluoride is excreted in urine, lost through
sweat, and excreted in the faeces.
• About 10-25% of the daily intake of fluoride is
not absorbed and is excreted in the faeces.
• Renal clearance of fluorides-
• The renal clearance rate of fluoride ranges
from 30-50 ml per minute.
33. Estimation of fluoride concentration
1. Collection of sample-
Both stimulated and unstimulated saliva should be
collected for analysis.
2.Fluorides analysis-
Ionic fluoride: commonly used method for
estimation is the fluoride-specific ion electrode.
Bound fluoride: the bound fluoride should be made
free to ionic state before final measurement.
34. 3. Method of fluoride analysis in food:
The most reliable method for fluoride analysis in
foods, is the microdiffusion technique
described by Taves (1983) .
35. Mechanism of action of fluorides
• The mechanisms by which fluoride increases caries
resistance may arise from both systemic and topical
applications of fluoride.
• A number of proposed mechanisms have been
identified which are assumed to work simultaneously
and can be grouped as follows:
1.Increase enamel resistance or reduction in enamel
solubility.
2.Increased rate of posteruptive maturation.
3.Remineralisation of incipient lesions.
4.Interference with plaque microorganisms.
5.Modification in tooth morphology.
36. 1.Increased enamel resistance (OR)
Reduction in enamel solubility
Dental caries involves dissolution of enamel by acids from
bacterial plaque and that dissolution is inhibited by the
presence of fluoride.
Because fluoride forms fluorapatite , which is a less soluble
mineral.
Carious dissolution of enamel is a cyclic phenomenon
consisting of phases of deminaralisation and re-precipitation.
The presence of fluoride reduces the solubility of enamel by
promoting the precipitation of hydroxyapatite and phosphate
mineral.
38. 2.Increased rate of posteruptive
maturation
Posteruptive maturation involves deposition of minerals
into hypomineralised areas.
Newly erupted teeth often have hypomineralised areas that
are prone to dental caries.
Fluorides increases the rate of mineralisation, or post
eruptive maturation of hypomineralised areas.
Both mineral ions and organic material are deposited from the
saliva.
A less soluble tooth that is more resistant to acid attack and
less prone to caries is formed.
39. 3.Remineralisation of incipient lesions
Remineralisation, the deposition of minerals into previously
damaged areas of the tooth is a dynamic process that results in
reduced enamel solubility.
The most effective remineralizing solution contains fluoride
in combination with calcium and phosphate ions .
Fluoride enhances the rate of remineralisation from
calcium phosphate solutions.
remineralisation of white spots is increased two-fold.
41. 4.Interference with microorganisms
• Fluoride interfere with oral bacteria in 2 ways:
1. In high concentrations, fluoride is
bactericidal.
2. In lower concentrations, fluorides is
bacteriostatic. It helps control the growth of
bacteria without destroying them.
3. Fluoride lodges in plaque and inhibits
bacterial enzymes responsible for acid
metabolism.
44. 5.Modification in tooth morphology
• The fluoride action on morphology of teeth is
entirely through systemic route.
• Studies have shown that children living in
fluoridated communities have shallow
occlusal grooves, lower cuspal height and
smaller size teeth.
45. CONCLUSION
• Fluoride has both beneficial and
detrimental effects on human health,
with a narrow range between the
intakes at which these occur.
• There is a need to improve
knowledge on the accumulation of
fluoride in organisms and how to
monitor and control this.
46. REFERENCES
Essentials of Public Health Dentistry-6th
Edition
Soben Peter
Textbook of Preventive and Community
Dentistry-2nd Edition
S S Hiremath
