Submitted by :- NESHEENA.V.K 3rd year BDS Roll No:- 9

Community water fluoridation

&Defluoridation

Introductionsystemic fluorides provides a low concentration of fluoride to the teeth over a long period of time.It circulates through the blood stream & is incorporated into developing teeth.After teeth erupt, fluoride contacts teeth directly through salivary secretions.Most systemic fluorides have a topical effect but their primary effect is systemic.

Community water fluoridation

The studies carried out by Dean et al in the U.S.A. showed that a high degree of reduction in caries occurred in temperate climates when the

fluoride content was approximately 1mg/L.

Most common form of systemic fluoride is addition of fluorides to public water supplies. Optimal level of fluoride in water for protection against dental caries is 1ppm.

Definition

Defined as controlled adjustment of the concentration of fluoride in a communal water supply so as to achieve maximum caries reduction and a clinically insignificant level of fluorosis.

Also defined as the upward adjustment of the concentration of fluoride ion in a public water supply in such a way that the concentration of fluoride ion in the water may be consistently maintained at 1ppm by weight to prevent dental caries with minimum possibility of causing dental fluorosis.

CONTROLLED WATER FLUORIDATION STUDIES

Grand Rapids – Muskegon studyNewburgh – Kingston studyBrantford – Sarnia – Stratford fluoridation caries studyEvanston – Oak Park studyTiel – Culemborg fluoridation

1.Grand Rapids – Muskegon study

On January 25th – 1945 Sodium fluoride was added to Grand rapid water supply. Muskegon was the control. Effect of 6 ½ years of fluoridation reported by Arnold et al. Result : The caries experience of 6 year old Grand Rapid children was half that of 6 year old Muskegon children.

2.Newburgh – Kingston study• On may 2nd 1945 Sodium fluoride was

added to the drinking water of Newburg on the Hudson river. Kingston town was the control.After 10 years of fluoridation Ast et al reported that the DMF rate has from 23.4% to 13.9%

3.Brantford-Sarnia-Stratford fluoridation caries study:

In June 1945 Fluoride was added to water supply of Brantford , Ontario Sarnia was the control town. Community of Stratford where fluoride level is 1.3ppm was Auxiliary control.After 17 years caries experience in Brantford & Stratford – 50% less than Sarnia.

4.Evanston – Oak Park study

In January 1946 Fluoridation in Evanston. Oak Park was the control town. After 14 years of fluoridation there was reduction of 49% in DMF value in Evanston.

5.Tiel-Culemborg fluoridation study:

In March 1953Water in Tiel was fluoridated to 1.1ppm.Culemborg with water fluoride level of 0.1ppm was the control.After 13 years of fluoridation the number of dental caries was 58% lower in Tiel than in Culemborg.

Optimal water fluoride concentration

In order to determine the amount of fluoride that should be added to water, Galagan & Vermillion (1957) develop an empiric formula for estimating the amount of daily fluoride based on body weight & climatic condition.ppm F = 0.34/E E = -0.038+0.0062*TT=Temperature of the area in ºFIn 1958, WHO produced the first report committee on water fluoridation and concluded that drinking water containing about 1 ppm fluoride. 1ppm is 1mg fluoride in1liter or 1 mg fluoride in 1 kilogram.

In temperate regions – 1ppmTemp in degree Celsius

Recommended ppm

<18.3 1.1-1.3

18.9-26.6 0.8-1.0

>26.7 0.5-0.7

For colder climates where the mean annual maximum air temperature is lower than 10 degree celcius fluoride concentration in water as high as 1.3 ppm must be considered safe and beneficial.Levels of fluoride used

irrigation water – 10 mg/l aquatic life - 1.5 mg/l industrial water supply – 1.0 mg/l

Before fluoridation , the following factors should be taken into account

Daily fluoride conc. Of water supply Baseline dental caries prevalence Index of enamel fluorosis and post fluoridation data of the same population.

Japanese limit their fluoride content since they eat fish which is rich in fluorosis.

METHODOLOGY OF ESTIMATION OF FLUORIDE CONCENTRATION IN DRINKING WATER:

Sample collection for fluoride estimation

500ml of water is taken in a clean dry polythene container2cc of 6N HCL is added to inhibit growth /enzymatic changeStore at 4ºC for analysis.

Fluoride concentration in the water can be estimated by :

Fluoride electrode coupled with standard рН meter. Scot – Sanchis method.

Fluoride electrode coupled with standard рН meterMost recent & universally accepted method. This method allows fluoride in aqueous solution to be measured quickly, simply, economically & accurately. The reading observed are the electrode potentials of the standard / sample solutions from which fluoride concentration is calculated. 2 рН meters :Orion 901 microprocessor ion analyzer & Orion 407 are used. Unknown concentration of fluoride in the sample can be calculated by

Typical calibration curve.By applying electrode potential difference equation.Direct ppm reading.

Scot – Sanchis method:Test is based on the reaction between fluoride & red Zirconium Alizarin lake.Fluoride forms colorless complex ion & liberates free alzarin sulfuric acid, which is yellow in acid solution.As the amount of fluoride increases color varies from yellow to red.The fluoride level is determined by comparing the color thus produced with the standard

LIMITATIONS OF COMMUNITY WATER FLUORIDATION:It can be implemented only in areas which have central pipe water supply system.

It interferes with personal choice.

People may think of overprotection.

Initial cost for installing fluoridation plant is more.

CHOICE OF EQUIPMENT & CHEMICALS FOR WATER FLUORIDATION:

When planning a fluoridation system, the selection of the chemical product to be used as the source of the fluoride ion will have an important bearing on the final decision as to the type of distribution equipment to be installed. Thus, a saturator is used with granular sodium fluoride , a dry distributor with silicofluoride or sodium fluoride, and a liquid distributor with hydrofluosilicic acid.General characteristics of the system

It must be adapted to local conditions &needs of water network.It should be of standard type , recognized as satisfactory &for which maintenance is easily provided.

It should have well defined precision limits. It must be safe. It should be provided with a safety mechanism that

automatically stops the addition of fluoride if the water flow through the treatment plant is suddenly diminished

Adjustment of the distribution must be easy & rapid.

It should be operate between 20% & 80% of its total capacity.

In each system an anti-siphon mechanism should be installed to avoid a concentrated solution of fluoride entering the distribution system.

Fluoride compounds used in water fluoridation:• Fluorspar• Sodium fluoride• Silicofluoride• Sodium silicofluoride• Hydrofluosilicic acid• Ammonium silicofluoride

Fluorspar It is a mineral containing varying amount of calcium fluoride.

Commercial grades of fluorspar contain from 85 to over 98% calcium fluoride. Sodium fluoride

It is white, odorless, free flowing material available either as a powder or a mixture of various sized crystals. Manufactured from hydrofluoric acid, a by– product of fluorspar .Available in 45 kg bags. Most expensive. Silicofluorides

Most of the commercially available silicofluoride are obtained as by products of the purification of phosphate rocks. The primary products are super phosphates, phosphoric acid, elemental phosphorous, and triple super phosphates.

 Sodium silicofluoride

Hydrofluosilicic acid is the raw material used in the manufacture. Most popular because of Low cost. Solutions of this compounds are corrosive. Hydrofluosilicic acid

More expensive than silicofluoride (transporting liquids).it can be delivered by tanker lorry with a capacity of up to 19,000 liters.Ammonium silicofluoride

Produced by neutralizing fluosilicic acid with either aqueous ammonia or ammonia in gaseous form.Used at those places where ammonia is used to form chloramine with the chlorine added to water for the disinfection purpose.

TYPES OF EQUIPMENT FOR WATER FLUORIDATION:• The saturator system.• The dry-feeder system.• The solution-feeder system.

Saturator system Principle : A 4% saturated solution of sodium fluoride is produced & injected at the desired concentration at the water distribution source with the aid of pump.Factors limiting utilization : A high hard water level , the need to clean the gravel bed used for water filtration.Recommendation : Suitable for small towns with a total requirement of less than 3.8 million liters per day.

Dry feederPrinciple : Sodium fluoride or silicofluoride in the form of powder is introduced into a dissolving basin with the aid of an automatic mechanism to ensure maintenance of the correct supply of fluoride according to the amount of water to be delivered. Factors limiting utilization : The need for care in the handling of fluoride, obstruction of pipes, compacting of fluoride while stocked in a humid atmosphere. Recommendation : Suitable for medium-sized towns with a total requirement of 19 million liters per day.

Solution feederPrinciple : Volumetric pump permitting the addition of given quantity of hydrofluosilicic acid in proportion to the mount of water treated. Factors limiting utilization : All equipment must be resistant to attack by hydrofluosilicic acid, necessitating construction using polyvinyl chloride or any other plastic. Recommendation : Suitable for medium-sized & large towns, with a total requirement of more than 7.6 million liters per day.

School water fluoridation programme

This procedure makes the fluoride available to children, for whom dental caries is a primary problem, as compared to older age groups.The amount of fluoride added to school drinking water must be greater than that used in communal water supplies, i.e.,4.5 times the optimum concentration since children are in school for shorter hours and less water is consumed during that time. For Individuals not served by a public water supply, alternative methods such as fluoridating the individual school water I supply must be considered.A major disadvantage is that children do not receive benefits until they begin school.

Cost of water fluoridationIn India, the approximate per capita cost shall be about Rs0.25/ individual /year & a caries reduction of 50%. If one assumes a caries increment of DMFS /year & the cost of restoring a tooth surface at Rs 40/-. The cost to benefit ratio work out to be 1:160 i.e. for every Rs0.25 spent on water fluoridation , each person shall save Rs40/-

Advantage LIMITATIONSNeed for co-operation from school authorities.Children may not attend all school day.There is intermittent fluoride exposure .Limited pre-eruptive benefits for primary teeth.

Effective public health measureTarget population- school childrenQuite economical

Defluoridation

Defluoridation of water

Defluoridation is the process of removing excess naturally occurring fluoride from drinking water in order to reduce the prevalence & severity dental fluorosis. several method have been suggested from time to time for defluoridation . These divided into two,

Based upon ion exchange process / adsorptionBased upon addition of chemicals to water during treatment(Nalgonda technique)

ION EXCHANGE RESINS

These are commercially produced resins which are expensive & uneconomical in most circumstances

Carbion : it is a cation exchange resin of good durability & can be used on sodium & hydrogen cycles.Defluoron 1: a sulphonated saw dust impregnated with 2% alum solution.Defluoron 2: it is sulphonated coal using aluminium solution as regenerant. it was successful .

Nalgonda technique of defluoridation.

it was developed by NEERI at Nagpur in 1974 & reported by Bulusu in 1988.The process comprises addition in sequence of sodium aluminate (filter lime ), lime & bleaching powder to the fluoride water followed by flocculation, sedmentation, & filtration. MECHANISM The unit holds 22L OF WATER ,which filter into upper chamber.

• Factors that influence sedimentation are

Size, shape, density, nature of the particles.

Viscosity, density, temp of water. Surface over flow rate. Velocity of water. Effective depth of settling water.

Operation & maintenance of Nalgonda technique Fill 22 L of test water in the upper

chamber . Add the required dose of aluminium salt

solution mix it rapidly for a period for 30-60 sec

with a speed of 10-20rpm On chemical rxn tiny floc are formed Then mix for a period of 10-15 min with a

speed of 2-4rpm

Water is allowed to settle and filter through earth candles overnight

Salient features of Nalgonda technique

Indication for AdoptingNalgonda technique

Domestic defluoridation

filter

•Public health dentistry – Soben peter 3rd & 5th edition•www.de-fluoride.net•http://en .wikipedia.org•Text book of pediatric dentistry – Nikhil marwah

BIBLIOGRAPHY