Water and food fluoridation

Lecture outline Introduction Strengths and weaknesses of delivering fluoride in water or foods Water fluoridation Fluoride in natural water Artificial water fluoridation Evidence for water fluoridation Milk and salt fluoridation

Introduction

Methods for fluoride delivery Fluoride supplements: Drops Tablets Fluoridated water Fluoridated foods (salt, milk) Home applied fluoride: Toothpaste Mouthwash Fluoride in dental materials Professionally applied fluoride Gels Varnish Slow release devices

Ideal fluoride delivery Long-term fluoride in the solution surrounding the enamel (topical effect). Only a minimal amount of fluoride being systemically ingested. Cost-effective.

Strengths and weaknesses of delivering fluoride in water or foods

Strengths of delivering fluoride in water or foods A population-level action that ensures universal fluoride delivery. Does not require conscious action by individuals. Relatively cheap and can save manpower.

Weaknesses of delivering fluoride in water or foods Consumption between individuals in a population might vary (thirst, use of bottled water). Does not eliminate systemic ingestion. Requires continuous quality monitoring. Water fluoridation requires centralized water supply .

Water fluoridation

Fluoride in natural water sources Fluoride is found naturally in seawater in concentrations of 0.8-1.4 ppm. In fresh surface water (Rivers, lakes), it is mostly in low concentrations (less than 0.5 ppm). Highly variable concentration in groundwater (up to 300 ppm). Groundwater is more vulnerable to fluoride enrichment due to the greater impact of water-rock reactions in aquifers (permeable rocks).

Fluoride in natural water sources More than 200 million people around the world drink from sources that have a concentration higher the 1.5 ppm. Groundwaters with high fluoride concentrations occur in many areas of the world. Four “fluoride belts” have been identified East African Rift valley from Eritrea to Malawi. Turkey through Iraq, Iran, Afghanistan, India, northern Thailand and China. Pacific coast of the Americas and Japan. Lake Nakuru in Kenya has the highest measured concentration (2800 ppm)

Fluoride belts

Jordan falls within a fluoride belt Southern rtegions Tafila , Karak, Maan…high fluorosis rates

Is there a way to reduce fluoride concentration in water? Difficult and expensive. Produces toxic sludge.

Desalination Expensive Reduces fluoride in the water Almost all fluoride is removed

Artificial water fluoridation One of the 10 greatest public health achievements of the 20th century. 1931: Dr H.T Dean noticed: Increased fluoride concentration in water lead to higher prevalence of enamel mottling. Reduced caries prevalence in children with access to fluoridated water in comparison to with non-fluoridated water.

What concentration of fluoride is most appropriate? Dean noticed that the risk of enamel mottling increases significantly when the concentration of fluoride rises above 1 ppm. His studies also showed that near maximal reduction in caries experience was at 1 ppm. Based on work of Dean it was decided to fluoridate at 1 ppm in US 1 milligram per litre

Moller (1965) showed similar results in Sweden and Denmark

Rugg-Gunn et al. (1981) noted a similar pattern in the primary teeth of children in England

Impact of climate on recommended concentration People in countries with warmer climate will consume more water. Leads to increased ingestion of fluoride in comparison to colder countries. An association between temperature and incidence of mottling has been noted.

WHO-recommended fluoride concentration In 1984 the World Health Organization (WHO) issued a guideline on water fluoridation. In warm climate: 0.5-1 ppm In cold climate: 0.7-1.2 ppm The permissible upper limit value: 1.5 ppm

Impact of water fluoridation Studies demonstrated the efficiency of artificial water fluoridation using different methodologies: Comparison with non-fluoridated areas Comparison with naturally fluoridated areas Comparison of caries experience in same area before and after fluoridation Comparison of caries experience in the same area after cessation of fluoridation

The Grand Rapids-Muskegon study – first phase The earliest study on artificial water fluoridation. Carried out in the 1940s in the USA. A Three armed trial: 1. Grand rapids – experimental town (added 1 ppm) 2. Muskegon – control (no F) 3. Aurora - naturally fluoridated (1.4 ppm)

The Grand Rapids-Muskegon study – first phase Compared DMFT in children: Caries experience in six-year-olds in the experimental town was half of that in control. Caries experience in experimental town was similar to that in the naturally fluoridated town.

The Grand Rapids-Muskegon study – second phase A longitudinal study. Compared caries experience in children in Grand-rapids before and after fluoridation Reported a reduction of caries experience by 50% Fallen from 12 DMFT to 6.2 – fall of approximately 50%

Wick Study Carried out in the Scottish town of Wick The town water was de-fluoridated in 1979. Stephens et al. (1987) reported that the mean dmft of five-year-olds in the town went from 2.63 to 3.92 following de-fluoridation (50% increase).

Impact of water fluoridation Other studies in the USA (Newburgh-Kingston; Evanston-Oak Park), and in the UK (Kilmarnock-Ayr; Watford-Sutton) solidified the positive findings. 1 ppm F in water reduces caries experience by 40-49% in primary teeth, and 50-59% in permanent teeth. Looking at ersults of 113 worlwide studies of water fluoridation

Possible issues with water fluoridation A type of universal medication that can be considered an infringement of personal rights.

Possible issues with water fluoridation UK – 10% USA – 60% Brazil – 42% Ireland – 67% Scandinavian countries – deactivating fluoridated areas

Possible issues with water fluoridation Some groups are concerned with a possible link to increased risk of cancers and bone fractures. Increased incidence of fluorosis.

York review of water fluoridation (2000) Supported that water fluoridation : Reduces caries risk. Reduces discrepancies between social classes.

York review of water fluoridation (2000) No evidence of increased risk of bone fractures (see figure) No increased risk of bone or thyroid cancers

Cochrane review of water fluoridation (2015) Water fluoridation reduces dmft by 35% and DMFT by 26% in children. Evidence in adults was not available. At 0.7 ppm, 40% of the population showed signs of fluorosis,12% had aesthetic concerns.

Cochrane review of water fluoridation (2015) The majority of studies available are old (prior to 1975). This is an issue since fluoridated toothpaste was introduced in the 1970s. Need new studies to evaluate if water fluoridation still has value.

Milk and salt fluoridation

Fluoridated foods Fluoridated foods were suggested as a substitute for water fluoridation. Salt and milk and, to a lesser extent, sugar, bread, and cereals were proposed. The use of foods, when non-fluoridated alternatives are also available in the market gives individuals more choice than water-fluoridation. Needs to be accompanied by promotion and education.

Fluoridated salt Introduced in the 1960s in Hungary, Switzerland and Colombia. Provided in a concentration of 250 ppm. Caries preventive effect approximates that of fluoridated water. Recommended by WHO as one alternative method to Fluoridated water

Fluoridated salt Measurement of impact was complicated by other fluoride sources (toothpaste, tablets). Impact in 0-3 year olds minimal due to low consumption. Not recommended in countries where water is fluoridated.

Fluoridated milk Bovine and human milk contain 0.03 ppm fluoride. Artificially fluoridated milk usually has the concentration of 2.5 ppm. Introduced in Germany, Austria, Switzerland, and Japan

Fluoridated milk Binding of added fluoride to calcium or milk proteins might reduce the topical effect. A Cochrane review noted that there is low quality evidence that fluoridated milk can reduce caries in primary teeth, but further research is needed.

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