Fluoride was first added to water in 1945, with Grand Rapids, Michigan, being the pioneer city for the newest public health trend.
At the end of the 20th century, the CDC officially recognized the fluoridation of water as one of the ten greatest public health achievements for its role in dental care. However, the new century ushered in more extensive research and better testing tools, casting fresh doubts on the safety and effectiveness of fluoride for tooth decay.
Learn more here about the relationship between fluoride and tooth decay, as well as associated risks.
What Is the Relationship Between Fluoride and Tooth Decay?
Fluoride helps prevent and repair tooth decay, as different studies have confirmed. Decay usually results from a loss of minerals in the enamel (demineralization) without adequate replacement of these minerals (remineralization). In other words, a tooth will decay if the rate of demineralization exceeds that of remineralization.
The primary cause of demineralization is an attack on the enamel (the hard surface of the teeth) by the acid produced by cavity-causing bacteria, which stick to the surface of the teeth. Minerals in the enamel provide hardness and durability, which protect the teeth from cavities and wear and tear.
Fluoride helps to replace lost minerals from the enamel (remineralization), reduce acid production by cavity-causing bacteria, and make the teeth more resistant to bacteria sticking.
This teeth-protecting ability of fluoride was first observed in the early 1900s, with the fluoridation of community water first gaining approval in 1945 in Grand Rapids, Michigan. Essentially, scientists found that people living in areas that relied on water with high-fluoride content were more resistant to tooth decay.
Further research determined that 0.7 parts per million of fluoride was the recommended level for safely preventing tooth decay. Over time, fluoride products gained popularity, including toothpaste, mouthwash, varnish, gel, and supplements.
Will Your Teeth Rot Without Fluoride?
The chances of your teeth rotting are increased without fluoride. While you will not immediately notice rotting if you stop using fluoridated water and fluoride products, the teeth become more prone to damage as the enamel becomes less protected against demineralization.
Acidic and sugary foods (usually ultraprocessed foods, like sweets and chocolates) and drinks (such as sodas, beers, and carbonated drinks) can increase the rate at which the teeth rot [2].
Other factors such as low family income, inflation, unemployment, low level of health awareness, and poor sanitation can also contribute to an increased rate of tooth decay.
Some cities have discontinued the addition of fluoride to their water systems in the past. Notably, Juneau (Alaska, US) and Calgary and Windsor (Canada) discontinued fluoride in the late 2000s to early 2010s.
These cities noticed a spike in the number of children and adolescents with tooth decay and emergency dental care needs, prompting them to reintroduce water fluoridation. This further reinforces the relationship between fluoride and tooth decay.
Currently, it is recommended to take fluoridated water to prevent tooth decay for all ages. Fluoridated toothpastes can also contribute to the fight against tooth decay. Different fluoride concentrations in toothpastes may be needed for people with worse decay progression or living in areas with poor water fluoridation [6].
What Are the Risks of Fluoride?
The beneficial relationship between fluoride and tooth decay does not come without some risks. Here are some of the risks of fluoride to the teeth:
Deteriorating Teeth
Excess fluoride exposure during tooth development, typically between birth and eight years, can cause a condition known as dental fluorosis. This condition is typically characterized by white or brown discoloration, in addition to faint white lines or streaks on the teeth.
Dental fluorosis is dose-dependent, implying that higher fluoride amounts and for extended periods will correlate to more severe symptoms.
Interestingly, what initially caught the attention of researchers was the discoloration of teeth in certain regions, with further studies finding that these regions had high fluoride content. Dental fluorosis usually occurs with fluoride levels greater than 1.5 parts per million, which is more than double the recommended dose (0.7 ppm).
The most typical route of fluoride ingestion is through drinking water. However, it is unlikely for community water systems in areas with proper regulations to reach these high fluoride levels.
Therefore, alternative sources of fluoride, such as fluoride toothpastes, mouth rinses, supplements, and foods, often contribute to the development of dental fluorosis.
Neurodevelopmental Disorders
Fluoride exposure has been linked to neurodevelopmental disorders, such as autism and attention deficit-hyperactivity disorder, or ADHD [1]. Similar to the relationship between fluoride and dental fluorosis, higher doses and longer exposures increase the severity and risk of these neurodevelopmental disorders.
While researchers have identified a link between fluoride and neurodevelopmental disorders, there is no evidence that fluoride exposure causes these conditions.
Instead, they may worsen symptoms and increase the risk of developing these conditions. Also, there is a slight increase in the risk of developing these neurodevelopmental conditions, even after up to ten years of prolonged exposure after birth.
Aside from neurodevelopmental disorders, some studies have uncovered a link between low IQ (intelligence quotient) in children with high fluoride exposure [5]. Again, the severity of the condition increases with increasing fluoride dose.
However, the results of this study were not replicated in other, more extensive studies. The study also did not sample any United States residents.
Hormonal and Thyroid Disruption
Less discussed—but equally concerning—is fluoride’s potential to disrupt hormonal balance and thyroid function.
Research suggests that fluoride can reduce iodine uptake in the thyroid gland, leading to decreased production of thyroid hormones [3]. This is especially problematic for those with existing thyroid issues or borderline iodine deficiency.
One study conducted in England found that areas with higher fluoride concentrations in water had a 30% higher prevalence of hypothyroidism compared to areas with lower fluoride levels [4].
Hypothyroidism can lead to fatigue, weight gain, depression, menstrual irregularities, and slowed metabolism—symptoms commonly reported by individuals with Adrenal Fatigue.
How Much Fluoride Is Too Much?
The recommended level of fluoride in drinking water is 0.7 parts per million (or 0.7 milligrams of fluoride per liter of water). This level is usually carefully maintained in many community water systems.
Concentrations around 1.5 ppm increase the risk of dental fluorosis and damaged teeth, but only at around 4 ppm could there be severe health risks.
Fluoride concentration in toothpaste is much higher, typically between 1,000 and 1,500 ppm, but this is considered safe because toothpaste is used topically and in small amounts, with minimal ingestion when used properly.
You can contact your healthcare provider and consider making changes if your toothpaste products are higher or lower than the recommended level.
Should You Avoid Fluoride in Toothpaste?
Fluoride does offer protective benefits against cavities, especially in high-risk populations. However, emerging science suggests a more nuanced approach is needed—especially for those with developing brains, thyroid issues, or adrenal dysfunction.
If you or your child falls into one of these higher-risk categories, it may be reasonable to reduce fluoride exposure while maintaining other protective dental habits like brushing, flossing, and minimizing sugar intake.
Studies have found a slight risk between fluoride and dental fluorosis, as well as mental disorders, like autism and ADHD. While this risk is largely negligible, it may be worth some consideration in people who are already at a high risk of having these disorders.
These are mostly people with a family history of autism and ADHD. Another group of interest is people with Adrenal Fatigue or thyroid disorders.
Adrenal Fatigue is a condition where the body cannot cope with daily life stressors, typically due to the effects of chronic stress on the adrenal glands. Normally, the adrenal glands produce the hormone cortisol to combat stress.
However, when there are high stress levels for extended periods, the adrenal glands may fatigue, and cortisol production eventually falls. This then leads to symptoms like fatigue, weight gain, PMS, and insomnia.
A major contributor to Adrenal Fatigue is the dysregulation of one of the NeuroEndoMetabolic (NEM) Stress Response circuits. The NEM system spans several organs and systems in the body, grouped into six circuits.
One of these circuits is the Neuroaffect circuit, which covers the brain and nervous system. People with a dysregulated Neuroaffect circuit are at a high risk of mental disorders, and excess use of fluoride products may further raise the risk of these disorders.
Therefore, people with Adrenal Fatigue or thyroid disorder may need to contact a functional health practitioner about the toothpaste and other fluoride products they use.
Conclusion
There is a link between fluoride and tooth decay, as fluoride can help remineralize teeth and prevent tooth decay. However, concerns such as dental fluorosis have long persisted. Newer research has also identified other concerns, such as increased risk of neurodevelopmental disorders and a potential for lower IQ.
Despite these risks and concerns, there is far from sufficient evidence to prove a direct correlation between fluoride and these disorders.
Also, the risk of dental fluorosis is only a concern at extremely elevated amounts of fluoride. Therefore, the recommendation of fluoride toothpaste in oral health management is still founded on the link between fluoride and tooth decay.
However, people with conditions like Adrenal Fatigue or at high risk for autism or ADHD may want to consult a functional health professional.
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