Water Fluoridation

Dental caries or tooth decay is one of the most prevalent dental problems that affect both children and adults. There were several preventative measures taken to bring down this widespread dental problem. Out of all the preventative measures, water fluoridation proved to be the most effective.

Fluoride is a naturally occurring mineral which is known for its enamel strengthening property.

Water fluoridation is one of the oldest practices that was developed on a community-based level to reduce the incidence of tooth decay in the United States of America. In this process, a controlled amount of fluoride is added to the public water supply. Although an excess of fluoridation can have adverse effects on the development of the tooth, the severity of the oral effects depends on the total daily intake of fluoridated water.

One of the most common consequences of excess fluoride intake is dental fluorosis. This condition causes changes in the tooth appearance – for example, permanent tooth staining and abnormal texture of the tooth surface. The safety and efficacy of water fluoridation have been supported by many health organizations that include the World Health Organization (WHO) and the FDI World Dental Federation. Today’s article will provide a clear insight into the benefits, safety, and history of water fluoridation.

What is water fluoridation?

Water fluoridation is a process of adding a controlled amount of fluoride in the public water supply. Most of the bottled water does not contain fluoride. Usually, the optimum level of fluoride that should be present in the water for high effectiveness is 0.7 ppm or 0.7 mg of fluoride per liter of water.

However, the World Health Organization has suggested a range of 0.5 – 1.5 mg/L of fluoride as optimal. This range constitutes climate change and local environment that may influence the fluoride resource. (1)

Typically, the optimal levels of fluoride added to the water supply is sufficient to prevent tooth decay in children and adults. On average, the cost of water fluoridation in the United States has come around $1.08 per person per year. At present, around 72% of the total population drinks fluoridated water, and this percentage is likely to increase next year.

What is the purpose of water fluoridation?

The main aim of water fluoridation is to adjust the concentration of fluoride in public water supply to eradicate tooth decay. Tooth decay has become one of the most prevalent chronic dental diseases in the world. Some of the adverse effects of tooth decay include –

  • Pain and discomfort
  • Tooth discoloration
  • Loss of tooth structure
  • Gum disease
  • Impaired eating
  • Change in the appearance of the smile

Moreover, tooth decay and cavity formation can have a substantial socioeconomic effect on an individual. Studies have shown that around 60-90% of the school children in industrialized countries suffer from tooth decay frequently. This rise in incidence is expected to increase in the upcoming years.

The U.S. minorities face a high rate of dental decay and tooth loss. This is the reason why water fluoridation was developed to prevent tooth decay among the children and poor. The second purpose of water fluoridation is to bridge the oral health and care inequalities between the rich and the poor. Moreover, it helps to cut down the healthcare cost spent on dental treatments performed to treat dental caries and tooth cavity.

How does water fluoridation work?

As the name suggests, in this process, fluoride is added to the public water supply in any one of the three forms mentioned below. These three compounds match the solubility, safety, and cost of fluoride products that can be used on an extensive scale water fluoridation plan.

  • Sodium fluoride – sodium fluoride is a standard compound which was earlier used in water fluoridation techniques. This compound is characterized as a white and odorless crystalline powder. Sodium fluoride can be handled manually. (2)

Small utility companies typically use it. Being a standard product, sodium fluoride is a little expensive as compared to other forms. Care should be taken regarding the quantity of sodium fluoride as it can be potentially hazardous when used in gram quantities by ingestion or inhalation. Around 9% of the population receives water fluoridation from this compound.

  • Fluorosilicic acid – fluorosilicic acid is another common additive used for water fluoridation. Fluorosilicic acid comes in the form of a liquid by-product of phosphate fertilizer manufacture. It is economical as compared to sodium fluoride. However, the shipping cost of the material may be high. 63% of the population receives fluoridated water from this compound.
  • Sodium fluorosilicate – sodium fluorosilicate is referred to as the sodium salt of fluorosilicic acid. It comes in the form of a powder or fine crystals. Around 28% of the population receives water fluoridation from this compound.

How does water fluoridation prevent tooth decay?

Tooth decay is typically caused by excessive accumulation of plaque and bacteria in the mouth. Some of the common disease-causing bacteria in the mouth include Streptococcus and lactobacillus. Dietary habits also play a crucial role in increasing the incidence of tooth decay.

Typically, dental plaque acts as a host for the bacteria to grow on the tooth surface. Oral bacteria thrive on a food rich in sugar and carbohydrate. It ferments the food particles and produces acids that initiate the process of demineralization of the enamel.

  • Water fluoridation helps to provide a low level of fluoride in the saliva and gingival fluid. Usually, regular use of fluoridated water can raise the concentration of fluoride in the saliva by 0.4 mg/L multiple times a day. This optimum level of fluoride controls the rate of tooth decay in an individual. (3)
  • Fluoride reacts with the hydroxyapatite crystals in the enamel and forms a uniform layer of fluorapatite. This layer is often acid-resistant and also remineralizes the enamel layer.

There is no clear evidence about the effects of fluoride on the bacterial growth over the tooth surface. However, water fluoridation has proved to provide topical fluoride effects in the erupted teeth along with systemic fluoride benefits to developing or unerupted teeth via plasma or crypt fluid. This helps to prevent the incidence of tooth decay.

Clinical studies have shown that drinking fluoridated water can effectively prevent tooth decay and cavity formation by about 25% in children and adults. Moreover, it is the best economic plan for saving the cost of dental treatments performed to treat tooth decay.

Alternatives to water fluoridation

Typically, three types of fluoride supplements can have similar oral benefits as water fluoridation –

  • Topical fluoride access by using fluoridated toothpaste. The direct contact of fluoridated toothpaste with the enamel allows increased absorption of the fluoride that remineralizes the tooth structure and significantly reduced the incidence of tooth decay. Typically, fluoridated toothpaste has shown to reduce 25% of cavities in the young population.
  • Milk fluoridation is another means of providing fluoride to the community. However, milk fluoridation is mainly practiced in locations that lack sufficient water fluoridation resources. In this process, fluoride is added to milk, powdered milk, or yogurt. (4)
  • Salt fluoridation has similar effects as compared to water fluoridation. Fluoridated salt is widely used in almost every meal of the day. Salt fluoridation first started in the year 1987 to prevent the prevalence of dental caries. Typically, around 90-350 mg/kg of fluoride is added to the salt. Many research studies have proved that the optimum fluoride concentration in salt should be around 250mg/kg. (5)

Is water fluoridation safe?

Fluoride mainly acts on strengthening the teeth and bone. It has shown to reduce the incidence of bone fracture and prevent tooth decay. Some studies revealed a possible link between fluoride and cancer, especially bone cancer and osteosarcoma. However, there is no clear evidence to prove this incidence.

Fluoride is usually considered as a double-edged sword. This is because, at optimum levels, fluoride can have significant benefits to oral health. A rise in the concentration of fluoride can lead to severe dental effects which mainly includes dental and skeletal fluorosis.

  • Fluorosis is a process of enamel hypomineralization which is commonly characterized by visual changes in the enamel structure. Clinically, the teeth become flaky or uneven in the surface associated with bands of white or brownish discolorations. The severity of fluorosis usually depends on the dose, duration, and age of the individual during excess fluoride exposure. (6)
  • Skeletal fluorosis is a bone disorder that occurs due to t excess fluoride absorption in the bones. The bones in this condition often become stiff and less elastic, which makes it more prone to fracture. In severe cases, the joints mobility may also be affected by fluorosis. Moreover, the ligaments can get calcified.
  • Excess fluoride may also damage the parathyroid glands. The parathyroid hormones regulate the calcium levels in the body. An increase in the parathyroid hormone can lead to significant depletion of calcium in the bone. This makes the bone fragile and prone to fracture.
  • Other symptoms of fluorosis may include nausea, vomiting, and diarrhea. Acute fluoride poisoning caused by excessive ingestion of fluoride can even lead to sudden death.

In the past, there have been three such outbreaks of water fluoridation where the concentration of fluoride was 220 mg/L. However, in today’s time, extreme measures are taken regularly to regulate the level of fluoride in community drinking water supply.

The World Health Organization has regulated the optimum levels of fluoride in the public water supply. The organization concluded that around 0.5 – 1.5 mg/L of fluoride concentration is beneficial for the improved oral health of the community. Additionally, the fluoridated water within this range is non-hazardous for the environment as well.

A note on the history of water fluoridation

Typically, the development of water fluoridation can be divided into three periods as follows –

  • From (1801 – 1933) – the research for water fluoridation began from finding a cause for mottled tooth appearance, which was termed as the Colorado brown stain. Although the tooth had an abnormal texture and color, it was resistant to tooth decay. After many research and clinical studies, the Colorado brown stain was first given the name as dental fluorosis. (7)
  • From (1933 – 1945) – the prime focus for water fluoridation was to find out the correct fluoride concentration levels to eliminate fluorosis and tooth decay together.
  • From 1945, fluoride was added to water for the first time to test the efficacy of water fluoridation on oral health.

H. Trendley Dean was the first researcher to establish that an optimum level of 1 mg/L of fluoride can prevent cavities among children in temperate climates. He started a controlled experiment in the Grand Rapids, Michigan, on January 25th, 1945. The results of his study showed a significant reduction of tooth decay among the population who drank fluoridated water.

Water fluoridation became an official U.S Public Health Service policy by 1951. From this day, onwards, water fluoridation has become a broad spread concept that benefits the people of the community. Today, more than 72% of the population in the United States receives fluoridated water regularly through public water supplies.

Community fluoridation has also brought increased awareness about the benefits of fluoride to people of all ages.

Take away message

Water fluoridation is a worldwide concept which is now practiced in around 29 countries in the world. H. Trendley Dean first found it as an experiment at the Grand Rapids, Michigan, U.S.A. The process of water fluoridation mainly involves a controlled addition of fluoride to the public water supply between an optimum range of 0.5 – 1.5 mg/L of water. Fluoride is a naturally occurring mineral which typically strengthens the teeth and bones.

Access to fluoridated water on a community level significantly improved the incidence of tooth decay and cavity formation among the population. Moreover, it bridged the oral health inequalities between the rich and the poor. The World health organization supports the safety and efficacy of water fluoridation. However, failure to maintain the optimum range can lead to excess intake of fluoride. The consequence of excess fluoride intake results in dental and skeletal fluorosis.

Now that you have read this article, you must be aware of the benefits and risks associated with water fluoridation.