Salt fluoridation involves adding fluoride, usually sodium or potassium fluoride, to salt during manufacturing to help prevent tooth decay. Fluoride is added at levels of 200-350mg per kg of salt. It was introduced in Switzerland in 1948 and over 75% of salt sold was fluoridated by 1967. Salt fluoridation provides fluoride systemically and is popular in some countries as an alternative to water fluoridation for mass prevention of dental caries. While it has limitations, it can reduce tooth decay by up to 50% and is cheaper than water fluoridation.
2. FLUORIDE & FLUORIDATION
• Fluoride is the ionic form of the element fluorine.
• Fluoride has a high affinity for calcium and hence, is very compatible with
teeth and bone.
• Fluoride’s ability to inhibit or even reverse the initiation and progression of
dental caries is well documented.
• The first use of adjusted fluoride levels in water supplies for caries control
began in 1945 and 1946 in the United States and Canada.
3. • The Anti-Caries activity of Fluoride includes:-
a). Fluoride prevents demineralization.
b). Fluoride enhances remineralization.
c). Fluoride alters the action of plaque bacteria.
d). Fluoride aids in post-eruptive maturation of the enamel.
e). Fluoride reduces enamel solubility.
• The average daily intake of fluoride :-
from dry food substances - 0.2 - 1.8mg
from water containing 1ppm of fluoride - 1.5mg
for adults - 1.7 – 3.3mg
in children - 0.7mg
4.
5. • Fluoridation refers to the addition of fluorides (often as Sodium
Monofluorophosphate) to drinking water, with the purpose of
lowering tooth decay in general population.
• It is a method of fluoride delivery.
• Fluorides are delivered either as –
1. Topical Fluorides (Fluoride pastes, solutions, gels and
varnishers, dentifrices and rinses)
2. Systemic Fluorides (Community Water Fluoridation, Salt
fluoridation, Milk Fluoridation and Fluoride tablets/lozenges)
6. Salt Fluoridation:-
• It is the controlled addition of fluoride, usually sodium or potassium
fluoride, during the manufacture of salt for human consumption.
• It was introduced by Wespi in Switzerland in 1948.
• Fluoridated salt has been on sale in Switzerland since 1955 and by 1967,
more than three quarters of domestic salt sold were fluoridated at 90mg
of fluoride/kg salt.
• Salt is a good vehicle for systemic fluoride introduction.
• Fluoridation of salt is suggested as an alternative method of preventing
dental caries on mass scale.
• It is most popular in Colombia, Hungary and Spain.
7.
8. Ideal Fluoride Concentration in Salt:-
• The concentration of fluoride in salt is largely based on the average salt consumption.
• Level of fluoride can be kept at 200, 250 and 350mg of fluoride/kg of salt.
Production of Fluoridated Salt:-
• For effective caries prevention, fluoride must be present in ionic form when salt (sodium
chloride)
is dissolved in water.
• There are 2 different salt production processes:-
1. Batch processing
2. Continuous processing
9. 1. Batch processing :-
• A fixed amount of fluoride compound (mostly Sodium or Potassium Fluoride) is added to a
fixed amount of refined salt.
Eg:- 765g of potassium fluoride are added to 1 ton of refined salt (765gm of Fluoride salt
contains 250mg of fluoride). This results in a mixture of 1 ton containing 250ppm of
fluoride.
• For batch processing , sodium fluoride can be used, this fluoride salt being much cheaper.
• Powder mixing refutes the assumption that the longer the mixing time , the better the
homogeneity.
• It has been found that the best mixture- i.e. the most homogenous distribution of fluoride
ina ton of salt –was obtained after 20 min of mixing. Beyond this point the fluoride
tended to accumulate selectively at the bottom of mixing cone.
10. 2. Continuous processing of salt:-
• In large production plants where continuous processing of salt is common, the procedure is
often to spray a dosed concentrated fluoride solution through a nozzle onto the salt passing
on a conveyor belt blow.
• The amount of salt passing under the nozzle must be continuously assessed and this
determines the amount of fluoride solution to be sprayed, acc to the fluoride concentration
specified by law or decree.
• Eg:- in 1 sec , 1kg of refined and dried salt passes under the nozzle from which the
concentrated solution is sprayed (1kg salt/sec corresponds to an annual production of 10,000
to 20,000 tons).
• The solution must therefore spray 0.25g of fluoride/sec.
• In continuous production facilities , potassium fluoride is preferred compound because of its
high solubility in water .
• Developing countries may find the cost of potassium fluoride prohibitive and its very strong
hygroscopic properties are likely to pose storage problems.
11. EVALUATION AND SAFETY
• Fluoride ingestion should be studied by monitoring urinary output.
• There is no problem of acute toxicity with fluoridated salt because renal
clearance of fluoride is more rapid than it is for either sodium or chlorine.
• It is found that calcium fluoride and sodium fluoride in salt result in similar
preventive effects.
12. ADVANTAGES
1. It does not require a community water supply as in case of water
fluoridation.
2. It permits individuals to accept or reject it.
3. Non-fluoridated salt, like non-iodized salt, can be made available to the
population.
13. LIMITATIONS
• Large variation in different groups of people.
• The amount of fluoridated salt ingested may decrease with increasing consumption of
processed foods if the processors do not use fluoridated salt.
• Difficulties arise when there are multiple drinking water sources which have a naturally
optimal or excessive fluoride concentration.
• It requires refined salt produced with modern technology and a high level of technical
expertise.
• The current view that a high salt intake may contribute to hypertension.
14.
15. CONCLUSION
Salt fluoridation has cariostatic potential like water fluoridation
(caries reductions up to 50%). In Europe, meaningful percentages of
users have been attained only in Germany (67%) and Switzerland
(85%). In Latin America, there are more than 100 million users, and
several countries have arrived at coverage of 90 to 99%. Salt
fluoridation is by far the cheapest method of caries prevention, and
billions of people throughout the world could benefit from this
method.
