History of Fluoridation

History andMechanism of Fluoride

Year3, IIUM, KOD, Dr. Tin Maw 2

Specific Objectives

6th September 2010

After this session the students will be able to:-

1. Outline the historical background of fluoride in relation to dentistry

2. Understand fluorosis

3. Understand the metabolism of fluoride

4. Explain the mechanism of actions of

fluoride


Fluorosis: -

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Definition Fluorosis is a specific disturbance of

tooth caused by excessive ingestion of high concentration of fluoride in drinking water during the formative period of the dentition.


Prevalence

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Majority of prevalence and severity of dental fluorosis is due to the concentration of fluoride in the water consumed by infants and children during the first five years of life.

Although both primary and permanent teeth may be affected by fluorosis it tends to be greater in permanent teeth than in primary teeth.


Intensity

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The intensity of fluorosis ranges from white striations affecting only a small portion of enamel to confluent pitting of almost the entire enamel surface and dark brown to black staining.

Clinically it is characterized by opaque white patches in the enamel which may become striated, mottled or pitted. The opaque areas may become stained yellow to dark brown or black.

Year3, IIUM, KOD, Dr. Tin Maw 66th September 2010

may become

striated, mottled, and/or pitted, or may be stained yellow to dark brown.

discrete pits and larger areas of (confluent pitting) of enamel appear to such an extent that the normal morphology of the tooth is lost.


Dental fluorosis is of developmental origin, the individual teeth in the dentition are not affected to the same degree,

but the bilateral corresponding teeth are affected in the same degree of severity.

The teeth most affected are usually those mineralized last, such as premolars and second molars, upper incisors and canines,

where as first molars and lower incisors are least affected.


A brief on Fluoride

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Fluorine is derived from latin word “ “Fluore” meaning “ to flow” .

Fluorine is a pale, yellow- green gas.

Atomic Weight : 19 , atomic number : 9 .


Fluoride is the anion F−, the reduced form of fluorine.

Both organic and inorganic compounds containing the element fluorine are sometimes called fluoride.

Structurally, and to some extent chemically, the fluoride ion resembles the hydroxide ion.


Figure : (A) The structure of halite, NaCl. (B) The structure of fluorite, CaF2.

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The mineral fluoride

Many fluoride minerals are known, but paramount in commercial importance are fluoride and fluorapatite.

Fluoride is found naturally in low concentration in drinking water and foods.

Water with underground sources is more likely to have higher levels of fluoride,

http://en.wikipedia.org/wiki/File:USDA_Mineral_Flourite_93c3962.jpg


Historical aspect on dental fluorosis

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First described by Prof. Stefano Chiaie, from the Province of Naples, known as

"denti di Chiaie,“ (which bears his name.)

Reference - Denti di Chiaie (Chiaie teeth), J. M. Eager, U.S.M.H.S. Public Health Reports, Vol. 16 November 1, 1901 No. 44; Reprint May-June 1976, Vol. 91, No. 3, 285.


Historical aspect on dental fluorosis

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In 1901, Dr. Frederick McKay,

He noticed that the teeth of many of his

patients, who had grown up in Colorado Springs, had permanent dark stains on their otherwise healthy teeth.

1908 : McKay presented at the annual meeting of State Association in Boulder.


McKay

terms the condition as

“Colorado Brown Stains”.


“Mottled enamel” by

Dr. Greene Vardiman Black

6th September 2010

National Museum of Dentistry


1912 : McKay came across an article written by Dr. J.M. Eager. He reported that a high proportion of residents in Naples had ugly brown stains on their teeth known as “ Denti di chiaie”.

1916 : McKay & Black reported that an unknown causative factor was possibly present in domestic water during the period of tooth calcification.


Almost 25 years after he first observed the discolorations, McKay urged the U.S. Public Health Service (PHS) to track down the cause of the disorder.

His appeal led to a collaboration with Dr. Grover Kempf, a PHS physician.


In 1928 Kempf and McKay investigated a dental defect in Bauxite, Arkansas, a company town of Aluminum Company of America (ALCOA).

1930 : Kemp & McKay observed no mottling in the people of bauxite prior to 1909, which changed its supply from shallow wells to deep drilled wells.


The investigators found the same kind of stain on the teeth of Bauxite children

but none in the neighboring town of Benton, only 5 miles away.

A routine PHS water analysis at the time produced no explanation.


The staining problem however, had aroused the interest of other investigators one of

Chief chemist H. V. Churchill (ALCOA)

who found the reports of Kempf and McKay disturbing.

Churchill was then combating rumors that aluminum pots and pan were poisonous, and he feared that news of the Bauxite staining might exacerbate his company’s problems.


To determine the cause of the discoloration, Churchill directed his staff to test Bauxite drinking water for traces of rare elements not normally screened in standard water analyses.

1931 : Churchill H.V, chief chemist after thorough spectra graphic analysis noted that fluoride was present in bauxite water at a level of 13.7 ppm and IDENTIFIED THE ELEMENT THE “ FLUORIDE ”.


Meanwhile, three Arizona scientists, Dr. Margaret Cammack Smith, Howard Smith, and Edith Lantz, conducted animal experiments to find out what was causing the browning of children’s teeth in the community


At almost the same time, and independent of each other,

the ALCOA and the Arizona investigations provided what appeared to be the long-sought answer to McKay’s search:

excessive amounts of fluorine in the drinking water coincided with the staining.


Those findings triggered a major research effort by the new Public Health Service’s National Institute of Health.

NIH dental officer,

Dr. Henry Trendley Dean, was assigned to study the mottled enamel

problem and determine its extent in the United States.

Dean conferred with McKay and studied the old scientific literature



Shortly after assuming his new duties, Dean named the condition “fluorosis.”

1934 : Trendley H. Dean introduced the mottling index which is popularly known as Dean’s Index for Fluorosis.

He classified fluorosis into seven degrees of severity.


Dean’s Classification

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The codes and criteria are as follows:

0 – Normal. The enamel surface is smooth, glossy and usually pale creamy white color.

1 – Questionable. The enamel shows slight aberrations from the translucency of normal enamel, which may range from a few white flecks to occasional spots.

2 – Very mild. Small, opaque, paper-white areas scattered irregularly over the tooth but involving less than 25% of the labial tooth surface. White opacity of 1-2 mm appeared at the tip of the summit of the cusps of the premolars.

3 – Mild. The white opacity of the enamel of the teeth is more extensive than for code 2, but covers less than 50% of the tooth surface.

4 – Moderate. The enamel surface of the teeth shows marked wear and brown stain is frequently a disfiguring feature.

5 – Severe. The enamel surfaces are badly affected and hypoplasia is so marked that the general form of the tooth may be affected. There are pitted or worn areas, which may be discrete or confluent pitting and brown stains are widespread, the teeth often have a corroded appearance.

8 – Excluded (e.g. a crowned tooth).

9 – Not recorded.


Normal (0) - The enamel represents usual translucent semi-vitriform type of structure. The surface is smooth , glossy and usually of a pale creamy white colour.


Questionable fluorosis (1) - The enamel discloses a slight aberration from the translucency of normal enamel ranging from a few white flecks to occasional white spots. This classification is used in those instances where a definite diagnosis of the mildest form of fluorosis is not warranted and classification of ‘normal’ not justified.

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Very mild fluorosis (2) - Opaque, paper-white areas scattered irregularly over the tooth but involving less than 25% of the labial tooth surface

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Mild Fluorosis (3) - The white opacity of the enamel of the teeth is more extensive than for code 3, but covers less than 50% of the tooth surface

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Moderate fluorosis (4) - The enamel surfaces of the teeth show marked wear and brown stain is frequently a disfiguring feature.

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Severe fluorosis (5) - The enamel surfaces are badly affected and hypoplasia is so marked that the general form of the tooth may be affected. There are pitted or worn areas and brown stains are widespread; the teeth often have a corroded appearance.

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1931 : Shoe Leather Survey by Trendley H. Dean.

shoe leather survey was conducted among 21 cities in 10 states of U.S.A.

During this survey Trendley Dean visited each and every house in that particular community.

Usually any door to door or house to house survey is also called as shoe leather survey.


He discovered that even in the earliest descriptions of mottled enamel, teeth with this condition not only appeared to be healthy but also seemed to show less decay than normal.

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1942 : Dean et al discovered that 1 ppm F in drinking water & 60% reduction in caries experience was observed .

He demonstrated the existence of an

inverse relationship between the prevalence of dental caries and the fluoride content of the drinking water.



In 1935, upon finding fluorosis especially widespread in Texas, Dean and his colleagues declared the situation in that state “an acute and urgent public health problem”.

Dean hypothesized a link between the ingestion of fluoride and the prevention of tooth decay.


He pursued this hypothesis

Dean compared the rates of tooth decay between cities with and without the mottled enamel condition from data collected in a massive 1933-1934 dental survey of US elementary schoolchildren.

He concluded that the water provided some immunity to caries, even at levels that did not contribute toward fluorosis.


Dean’s research team from the NIH found that children in cities with fluoride-free water had three times as many caries as those in cities with an excess of 1.0 part per million (ppm) fluoride in the drinking water supply.

In 1942, Dean and his coworkers published the classical epidemiological studies carried out by the U.S. Public Health Service on children, 12 to 14 years of age, living in 29 towns, relating caries experience and the fluoride content of the water supply.


By 1942 Dean concluded that

1.0 ppm fluoride level in drinking water reduced the rate of new dental caries without inducing fluorosis in schoolchildren who were examined.


They showed that when the drinking water contained about 1ppm of fluoride the teeth of the lifelong inhabitants of that area had low caries prevalence but no signs of dental fluorosis.

For example, children aged 12-14 years had 30% less caries than those with no fluoride in the water.


The identification of this relationship led to the idea of adjusting the fluoride content in fluoride-deficient drinking-water.

That is called

In 1945 the water supply of Grand Rapids, Michigan, was artificially fluoridates at this level.

WATER FLUORIDATION


1946 : Klein observed teeth in eruption received maximal benefits & teeth were also protected.

Using data from the dental surveys in 1991-1992 and 1993-1994,

a British study demonstrated that children in lower socio-economic groups derive an even greater benefit from water fluoridation with an average 54% reduction in dental decay.

Therefore, children with the greatest dental need benefit the most from water fluoridation.


In 2003, studies on initiation and discontinuation of fluoridation were systematically reviewed.

The best available evidence on cessation of water fluoridation indicates that when fluoridation is discontinued caries prevalence appears to increase at a faster rate in the area that had been fluoridated


Fluoridation has substantial lifelong decay preventive effects and

is a highly cost-effective means of preventing tooth decay in countries with established municipal water systems,

regardless of socioeconomic status


The three primary agents used in drinking water fluoridation are

1. sodium fluoride,

2. sodium fluorosilicate and

3. fluorosilicic acid.


Refrences

6th September 2010

1. Achievements in Public Health, 1900-1999: Fluoridation of Drinking Water to Prevent Dental Caries; CDC Centers for Disease Control and Prevention.

2. Fluoridation Facts. American Dental Association. 2005. p. 6-8.

3. Fluoride in Drinking-Water; J. Fawell, K. Bailey, J. Chilton, E. Dahi,L. Fewtrell and Y. Magara; World Health Organization (WHO) 2006.

4. Oral Health Surveys, Basic Methods, 4TH Edition, WHO, 1997.

5. Denti di Chiaie (Chiaie teeth), J. M. Eager, U.S.M.H.S. Public Health Reports, Vol. 16 November 1, 1901 No. 44; Reprint May-June 1976, Vol. 91, No. 3, 285.

http://web.archive.org/web/20070307065553/http:/www.ada.org.au/media/Fluoridenow/Documents/AmDA+fluoridation_factsRO.pdf


THANK YOU for YOUR ATTENTION

6th September 2010

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