The document provides a comprehensive overview of fluoride, its chemical properties, historical discovery, and its impact on dental health through various phases of research. It details the phases of clinical discovery, epidemiology, demonstration, and technology transfer, highlighting key findings from notable researchers like Dr. Frederick McKay and Dr. Trendley Dean regarding fluoride's role in enamel fluorosis and dental caries prevention. The document also discusses fluoride sources, metabolism, and methods for analyzing fluoride concentration in different environments.

1. FLUORIDE
Sakshat lamichhane
KISTMCTH

2. CONTENTS
HISTORY
SOURCES
DISTRIBUTION
METABOLISM
ESTIMATION OF FLUORIDE CONCENTRATION

3. Fluoride
• Latin “fluor”- flow or flux
• Symbol- “F”
• Atomic no.- 9
• Atomic weight- 18.99
• It is a pale yellow, corrosive gas, which reacts with practically
all organic and inorganic substances
• Most electronegative of all elements
• Fluoride containing minerals-
• Fluorspar (CaF2
• Cryolite (Na3AlF6 ) – rare
• Fluorapetite Ca10(PO4 )6F2
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4. HISTORY
• Four separate periods or phases:
• (1) Clinical discovery phase,
• (2) Epidemiologic phase,
• (3) Demonstration phase, and
• (4) Technology transfer phase
4

5. Clinical discovery phase
1.stains could not be polished away
• intrinsic, or
• incorporated into the enamel structure
2. not everyone’s enamel had these characteristics
• Present in long term residents, individual who had been born there,
• Individual who had come there as babies
• But not present among individuals who had not lived in the vicinity
as young children led McKay to believe that the etiologic or causal
agent was environmental in nature and was incorporated into the
enamel structure at the time of tooth formation.
5
The first period,
1901 to 1933, was characterized by the pursuit of knowledge to determine the cause of developmental enamel defects
present in people in certain western areas of the United States
In 1901, Dr. Frederick McKay, noticed -discolored enamel that sometimes exhibited surfaces that were rough, uneven,
or even pitted. Local residents called this condition “Colorado Brown Stain.”
McKay made two important observations about this enamel defect:

6. McKay named this condition “mottled enamel” and noted 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 entire tooth
surface is of dead paper white like color of china dish
1909 - McKay sought the consultation of Dr. G. V. Black, well‐known and
respected researchers
publishing their observations in Dental Cosmos, the premier national dental
journal
Black’s histological finding – an endemic imperfection of enamel in teeth
Over several decades, McKay examined children in various nearby
communities and other states to determine the extent of the condition in
the population.
Demonstrate that mottled enamel was confined to specific geographic areas
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7. 1920’s McKay noted the etiologic agent had to be a constituent of some community water supplies, despite the fact that
chemical analyses all failed to identify likely constituents (most prevalent where deep artesian wells)
In communities such as Andover and Britton, South Dakota, where he found severe mottling, he advised mothers to
obtain their children’s drinking water from sources other than the community supply.
He advised the citizens of Oakley to abandon their old supply and tap this spring for a new source, which the community did in
1925. McKay was right, for children born in Oakley subsequent to the change were free of mottled enamel.
1927, McKay published an important corollary finding: People who had enamel fluorosis also experienced less dental decay
Early 1930s, H. V. Churchill, a chemist with the Aluminum Company of America, used a new method of spectrographic analysis
Of water McKay contacted Churchill and sent him samples of water from Colorado Springs and other areas he had observed to
have a high prevalence of mottled enamel.
The results showed fluoride concentrations ranging from 2 ppm F to 12 ppm F.
Similar findings were reported by investigators at the University of Arizona161 and by a veterinary group in Morocco, then still
a French colony, that was studying le darmous, the local name given to an extreme degree of mottled enamel found in
Moroccan sheep. 7

8. The role of fluoride in the cause of enamel fluorosis and the prevention of dental caries led to the second period, known as the
epidemiologic phase, which lasted from 1933 to 1945
Appointment of Dr. H. Trendley Dean, a commissioned officer in the U.S. Public Health Service
Dean’s job was to map out the prevalence of mottled enamel across the country and to look for a way to reduce or
eliminate it.
He wrote to dental societies across the country asking for their input regarding fluorosis in their locale;
In 1933, he published his first map showing the prevalence of mottled enamel in the United States
By the mid‐1930s, he began using the term fluorosis to replace mottled enamel.
In 1934, Dean developed the Community Fluorosis Index that allowed collection and mapping of severity data in addition to
prevalence data.
This index assessed not only the location of the condition but also its severity.
Dean later modified the index to classify the full range of enamel conditions from fine, lacy markings to stained, pitted,
damaged enamel
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Epidemiologic phase

9. Researchers began looking at the relationship of fluoride in the water
and tooth decay.
Dean conducted some impressive epidemiologic studies, including
the “4 city study” and “Dean’s 21‐Cities Study.”
The 4 city study highlighted the difference in dental health and
fluorosis among four Illinois cities with differing concentrations of
fluoride in the water supply
In the 21‐city study, Dean examined the data collected by teams of
researchers who had examined the teeth of children residing in 21
different communities that had varying levels of naturally occurring
fluoride in the drinking water.
Study showed that
(1) higher concentrations of fluoride in the water correlated with
fewer teeth affected by dental caries
in children, constituting an inverse relationship between the level of
natural fluoride in the water and the prevalence of
dental caries and
(2) higher levels of fluoride were associated with more children with
fluorosis of the teeth, meaning that
a direct relationship existed between the level of natural fluoride in
the water and the prevalence of enamel fluorosis 9

10. Dean’s results showed that both a reduction of dental caries and an acceptable level of enamel fluorosis could be attained
with water containing fluoride levels at approximately 1 ppm of fluoride.
At this level, substantial reductions in dental caries of up to 60% were observed with approximately 10% of the population
exhibiting very mild enamel fluorosis.
The unattractive form of fluorosis, often called mottling, that was associated with higher levels of fluoride was not
observed to occur at the level of 1 ppm F.
Consequently, 1 ppm F became the benchmark level, and was used by the U.S. Public Health Service in
1962 in establishing the optimal range: 0.7 ppm F to 1.2 ppm F.
The optimal fluoride level seeks to maximize the benefits of dental caries reduction and minimize the probability of enamel
fluorosis
Mottling
Widespread 3ppm
Discrete pitting 4 ppm
Less in case of 2.5 to 3ppm
No mottling in 1 ppm
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11. Demonstration phase
11
• third period
• began in January 1945
• was characterized by a series of community trials in which fluoride levels were adjusted in the public drinking water
supply
• On January 25, 1945, Grand Rapids, Michigan, became the first city in the world to fluoridate its drinking water
• The demonstration phase lasted until about 1954
• at that time, the benefits of the optimal adjustment of fluoride levels in drinking water became so apparent that many
U.S. cities began fluoridation programs for their citizens

12. Technology transfer phase
Fourth phase
began about 1950
characterized by the establishment of a set of national health goals, which include fluoridation
In 1969, WHO advocated that 1 ppm of fluoride in community water supplies was a practical and effective public health
measure
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13. 1901- Dr.
Fredrick Mckay
Colorado stain
Mottled stain 1909- Mckay with G.V. black
An endemic imperfection of
enamel
1912 Dr. JK eager
Denti di chiaie
1918 Mc kay confirmed
mysterious element to
be present in water
1931 spectrographic
analysis
Presence of fluoride
1934
Dean’s index of
fluorosis
1931 Dr. Trendley
Dean
1942 Dean et al
1ppm fluoride
decreases caries 60%
1969 WHO
1ppm fluoride
1945 artificial fluoridationFluoride as
essential
element

14. Fluoride in environment
14
lithosphere
•Fluoride is widely distributed
•300ppm
•Concentration of fluoride is increased in highly siliceous igneous rocks, alkali rock eg. Fluorspar,
fluorapatite
biosphere
•Plants 2-20mg/gm of dry weight
•Leafy vegetable as cabbage, lettuce, brussel 11-26mg
•Tea plant highest fluoride concentration
•Fish 20ppm
hydrosphere
•Water contains varying concentration
•Highest of about 2800ppm lake nakura in kenya
•Surface water has less fluoride compared to ground water
atmosphere
•Fluoride emission heaviest in vicinity of industries- in production of aluminum

15. SOURCES OF FLUOR
From fish by population –fish is diet --- 0.5mg/day
Fish (salmon, sardines) fluoride content 20-40mg/day
Jower, banana, potatoes ----substantial quantities of fluoride
Plants – taro, yams-----high fluoride
Rock salts 40 to 200ppm
Dried tea leaves 100 – 400ppm
Tea drinkers 0.04 to 2.7mg/day
Drugs
diuretics, fluorosteroids, phenothiazine
Mineral water ---- 1.5 to 7ppm
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16. METABOLISM
Absorption
Distribution
Elimination
Blood plasma – central compartment
50% of ingested fluoride will be excreted in urine
Rest 50% will be taken by mineralized tissues
Hard tissue- fluoride is reversibly bound and can be released in remodeling of bone
Soft tissues – steady state distribution between extra and intracellular fluids
Major route of fluoride elimination is kidney
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17. Absorption
Introduction to absorption
Major route is gastrointestinal tract ( stomach and small intestine)
fluoride may be
Water soluble fluorides(most) Less soluble fluorides-
NaF, HF, H2SiF6 , Na2PO3F CaF2 , Ca10(PO4 )6F2
ionic form ( inorganic or free fluoride)
In plasma fluoride is in 2 forms non ionic form ( bound fluoride)
Absorption depend on
Physical and chemical properties of compound
Solubility
Amount of fluoride ingested
Other dietary constitutes such as calcium which form insoluble salts with fluoride
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18. Rate and degree of absorption
NAF- rapidly absorbed
height of plasma peak α fluoride dose
height of plasma peak α rate of absorption
height of plasma peak 1/ α body weight ( volume of distribution)
Time of occurance of plasma peak is independent of amont of fluoride
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19. Mechanism and site of absorption
Passive absorption
Mechanism and rate of gastric absorption
related to
gastric acidity
Ionic fluoride acidic environment converted to HF
H+ + F- HF
These are the uncharged molecule which easily pass via biological membrane (gastric mucosa)
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20. Absorption from food and dental fluoride preparation
dietary fluoride is well absorbed - increase bioavailabilty
Topical fluoride- when swallowed absorbed completely
bioavailability of NaF is 100 %
calcium containing abrasive reduces rate and degree of absorption
Fluoride varnish remain in tooth surface for upto 12 hrs
A thorough rinsing of mouth after toothbrusing will minimize the ingestion of fluoride
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21. Pharmacokinetics of fluoride
An initial increase
Rapid fall for 1 hr ( early phase / distribution absorption of fluoride distribution to soft tissues
Phase- a phase) from gastrointestinal tract
Slower decline( representing elimination elimination phase
Phase – b phase)
Plasma half life of fluoride is 4-10 years (time
For which plasma fluoride concentration fall
By one half)
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22. 22

23. DISTRIBUTION
Fluoride in soft tissues
Determined by blood flow
Steady rate fluoride concentration
Plasma fluoride concentration ratio 0.4 to 0.9 regardless of rate
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24. Bone:
99% of all fluoride in human body is found in calcified tissues
-Total amount-2.6mg
-Most of F in the body retained in the skeleton-
-vary according to the renal clearance
- F enter in mineralized tissue-replacing 0H- , C03 2- and HC03
-Remodeling bones deposit more fluoride than older people
-Fluoride deposition is a reversible process
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25. TEETH
Concentration of fluoride was the highest in the outermost layer of the enamel, and there was a marked decrease in
concentration from the surface to a distance of 100-200μm. In the middle and inner third of the enamel, concentration
tended to level off with a small increase at a distance of 50μm adjacent to the enamel dentine junction (EDJ)
A higher level of fluoride in the coronal dentine than in the enamel was observed at the enameldentine junction (EDJ), and
it continued to a distance of about 300μm from the pulpal surface of the coronal dentine. There was a great increase of
fluoride concentration in the coronal dentine near the pulp. The level of fluoride increased with age.
Fluoride concentration was maximal at or near the surface of the cementum and decreased toward the interior of the
cementum. There were different types of fluoride distribution in the cementum. The level of fluoride concentration
increased with age.
Concentration of fluoride decreased after cementum-dentine junction (CDJ), reached the lowest value in the middle of the
root dentine, and rose again toward the surface of the pulpal dentine.
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26. Although Total Fluoride, Average Fluoride, and Maximum Fluoride in the enamel showed no clear tendency of increase
with age, those of the coronal dentine increased with age until a plateau was reached at about 50 years.
Increases in Total Fluoride, Average Fluoride, and Maximum Fluoride in both root dentine and cementum continued to a
higher age of the tooth than in the coronal dentine. Particularly, Total Fluoride increased in the cementum more than in any
other tissues examined
It was concluded that, although the fluoride concentration in the enamel could have been changed due to its post-eruptive
environment, the coronal dentine takes up fluoride from the pulp until about the age of 50 and the root dentine and the
cementum take up fluoride from both the pulp and the periodontal ligament all during the life of the tooth
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27. • highest fluoride
• decreases by 1/10th
• slight increase
• less as less vascular
• highest fluoride as its vascular

28. Fluoride level
enamel (2200- 3200ppm)
dentin (200- 300 ppm)
cementum (4500ppm)
plaque (15-64ppm)
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29. Excretion of fluoride
Renal clearance of fluoride
Excretion via breast milk and saliva
Excretion via faeces and sweat
Renal clearance of fluoride
chief organ of excretion- kidney
Because ionic fluoride is not bound to plasma proteins, its concentration in the glomerular filtrate is the same as that of
plasma water
After entering the renal tubule, a variable amount of the ion will be reabsorbed and returned in systemic circulation
The reminder will be excreted in urine
Hence the first determinent of fluoride excreted in urine is determined by GFR
Renal clearance of fluoride in adult is 30-50 ml/ min
It depends on
1. urinary pH
2. urinary flow rate
‘
29

30. high urinary flow alkaline urine
rapid clearance chronic renal failure
low urinary flow acidic urine increased plasma and bone fluoride level
slow clearance
Normal kidney excrete 50% about fluoride GFR
30% excreted in 6 hrs
60% of fluoride excreted in 24 hr
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31. Excretion via breast milk and saliva
Fluoride concentration of colostrum and mature breast milk is reported to be same about 0.4 uM
No diurnal variation
Excretion via faeces and sweat
less quantitative importance
Concentration of fluoride in sweat is in range of 0.067 – 0.5 ppm
Faecal excretion 8% to total intake and 10% of urinary output
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32. 32

33. Estimation of fluoride concentration
Collection of sample
Flouride analysis
Method of fluoride analysis in food
flow rate exhibit circadian rhythm
Collection of sample
saliva
mechanical
(chewing inert wax) stimulated unstimulated
or use if citric acid
microorganism and desquamated epithelial cell
separation by centrifugation
Analysis 33

34. Fluoride analysis
fluoride
ionic bound
commonly used method made free to ionic state before final measurement
For estimation of fluoride distillation, wet and dry ashing, acid extraction
Specific ion electrode
Isotachophoresis and ion chromatography
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35. Method of fluoride analysis in food
performed by potentiometric measurement with aid of fluoride ion specific electrodes
Perchloric acid diffusion
Simple diffusion
Silanol extraction
Most reliable is microdiffusion technique
35

36. Micro diffusion technique
One day diffusion at 25 ̊C with hexamethyl-di- siloxane (HMDS)
into
o.1ml of 0.65m NaOH
dried
added to 0.5 ml of 0.66 M acetic acid
Solution applied to fluoride electrode
analysis 36

37. 37

38. References
Essentials of public health dentistry – soben peter
Primary Preventive Dentistry Norman O. Harris
Dentistry, dental practise and the community –brain a. burt
https://www.jstage.jst.go.jp/article/jdh1952/36/3/36_3_276/_article/-char/en
https://www.researchgate.net/figure/Flowchart-of-fluoride-metabolism_fig1_238595692
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