UB dental school expert discusses importance, safety of fluoridated water

BUFFALO, N.Y. ­—  In 1945, Grand Rapids, Michigan, became the first city in the world to add fluoride to its drinking water. Five years later, U.S. federal officials endorsed water fluoridation, with many municipalities adding the mineral to their water supplies to help prevent tooth decay.

Today, three-quarters of Americans receive fluoride through the public water system, as do hundreds of millions of people worldwide. This movement has significantly reduced cavities, according to the Centers for Disease Control and Prevention (CDC) and other scientific organizations.

While a small sliver of opposition to fluoride has always existed, in recent years outspoken opponents have raised health concerns connected to excessive levels in the water supply.

Marcelle Nascimento, DDS, PhD, who joined the University at Buffalo School of Dental Medicine in May as assistant dean of clinical research and director of cariology (the study of tooth decay), recently weighed in on the importance of fluoride, the science behind how fluoride works and concerns with studies touting dangers in fluoridated water.

Nascimento is president of the American Academy of Cariology (AAC) and previously served as the president of the Cariology Research Group of the International Association for Dental Research and as chair and councilor of the American Dental Education Association Cariology section.

How big of a problem is tooth decay today, especially in children?

Untreated dental caries is the most common health condition worldwide, affecting 2 billion people, according to the World Health Organization (WHO). In the United States, nearly one in five children ages 5–11 has at least one untreated cavity. Caries is particularly worrisome for children due to the unique vulnerabilities of baby teeth that have thinner enamel and less mineralized dentin. Once decay compromises the enamel, it can quickly reach the dentin and pulp, causing inflammation, discomfort and pain.

Tooth pain in children can significantly disrupt daily activities, including eating, speaking and socializing, potentially affecting their development, self-esteem and academic performance. Cavities in childhood can have lasting impacts, even after baby teeth are replaced by permanent teeth. Preventing cavities early in life, ideally starting before a child is conceived, is crucial for fostering long-term oral and overall health.

How can you prevent cavities before conception?

Studies have shown that untreated cavities in a mother are strongly associated with a risk of her child having cavities by age 3. Untreated cavities in mothers are often linked to poor oral hygiene practices and frequent sugar consumption, which foster the growth of cavity-causing (cariogenic) bacteria.

These bacteria can be transmitted to the child through saliva during common practices such as kissing and sharing utensils or food. The combination of high levels of cariogenic bacteria, inadequate oral hygiene and unhealthy dietary habits creates the perfect environment for the development of early childhood caries.

However, childhood caries can be prevented if proper guidance is provided during pregnancy. Educating mothers on the importance of oral hygiene, regular dental checkups and reducing sugar intake can result in better oral health. This will reduce the likelihood of early childhood caries and promote long-term oral health for the entire family.

What role does fluoride play in preventing cavities?

Fluoride plays a vital role in preventing cavities by strengthening tooth enamel and making it more resistant to decay. Tooth enamel is composed of hydroxyapatite crystals, which are vulnerable to acids produced by oral bacteria when they metabolize dietary sugars. This acid dissolves enamel minerals in a process called demineralization. However, during periods when an individual isn’t eating, minerals from saliva are redeposited onto the tooth surface in a process known as remineralization. Cavities form when demineralization outweighs remineralization, resulting in a net loss of minerals.

Fluoride helps by interacting with enamel and combining with calcium and phosphate ions from saliva to form fluorapatite, a mineral that is significantly more resistant to acid attacks. By reinforcing the enamel structure, fluoride acts as a protective shield against decay.

The benefits of fluoride are most effective with consistent exposure through fluoridated water and daily brushing with fluoride toothpaste.

Is there an age in which fluoride is most important?

Fluoride is beneficial at all ages, but it is especially critical during childhood as childhood cavities can have a lasting impact on oral health and quality of life.

Other periods of life also provide an increased risk for dental caries. During adolescence, for instance, factors such as frequent consumption of sugary snacks and drinks, poor oral hygiene habits and orthodontic treatments (e.g., braces) significantly raise cavity risk.

In older adults, dry mouth often caused by systemic diseases or medications greatly increases susceptibility to tooth decay, particularly root caries. By ensuring consistent fluoride exposure, individuals can reduce cavity risk and maintain strong, healthy teeth across all stages of life.

What is the right amount of fluoride to consume?

The right amount of fluoride depends on both individual needs and public health guidelines. At the individual level, fluoride requirements vary based on caries risk, which is influenced by factors like oral hygiene, diet and access to dental care. Individuals with poor oral hygiene or frequent sugar consumption are at higher risk for cavities and may benefit from additional fluoride, such as prescription-strength toothpaste or fluoride treatments provided at dental offices.

Even individuals with low caries risk, who maintain good oral hygiene, follow a healthy diet and have access to regular dental care, require some fluoride. This is because no oral hygiene routine can fully eliminate the acid-producing bacteria in the mouth; everyone is exposed to cycles of acid challenges throughout the day.

At the community level, water fluoridation is the most effective and equitable method of delivering fluoride. The optimal concentration of fluoride in community water systems is 0.7 milligrams per liter, as recommended by the U.S. Public Health Service. This level effectively prevents cavities while minimizing the risk of dental fluorosis, a condition caused by excessive fluoride exposure during early childhood.

By following evidence-based guidelines and tailoring fluoride use to individual needs, people can benefit from fluoride’s cavity-preventing properties while ensuring safe consumption levels.

How crucial is it for communities to have fluoride in the water?

Community water fluoridation is a highly effective at preventing cavities, benefiting everyone regardless of socioeconomic status or access to dental care. While earlier studies showed a 25-30% reduction in cavities due to water fluoridation, recent evidence suggests the impact may be slightly reduced in areas where other fluoride sources, like toothpaste, are widely available. However, water fluoridation provides consistent fluoride exposure throughout the day, particularly when brushing is not feasible.

Water fluoridation complements toothpaste by reaching the entire community, ensuring equitable protection against cavities. Together, these measures work synergistically to strengthen enamel, reduce cavities and promote lifelong oral health. Water fluoridation remains a cornerstone of effective, population-wide cavity prevention strategies.

What do you think about the recent studies linking high levels of fluoride exposure to lower IQ in children?

As with any emerging scientific information, it’s important to critically evaluate the evidence, including study design, fluoride exposure levels and the broader context of public health recommendations before drawing conclusions.

Concerns about community water fluoridation and its potential impact on children’s neurodevelopment primarily arise from studies conducted in regions with natural fluoride levels significantly higher than the optimal level of 0.7 mg/liter. These studies demonstrate an association rather than a direct causal relationship and have several methodological limitations. They include unreliable methods for assessing children’s IQ, inadequate control for socioeconomic variables and inconsistent fluoride exposure measurements.

Extensive research affirms the safety and efficacy of water fluoridation at recommended levels with no evidence of adverse neurodevelopmental outcomes. Public health organizations, including the CDC and WHO, continue to endorse community water fluoridation as a safe, essential measure for preventing dental caries. While ongoing research is important to address emerging concerns, the current body of evidence strongly supports the safety and benefits of community water fluoridation when maintained at optimal levels.

If fluoride is removed from public drinking water, are you concerned about a detrimental impact to communities?

Absolutely. Its removal could lead to a dramatic rise in tooth decay. This impact would be especially pronounced among vulnerable populations, such as low-income families, children, and the elderly, who are disproportionately affected by oral diseases. These groups often face barriers to accessing regular dental care or purchasing fluoride-containing products like toothpaste. Without fluoride in drinking water, these populations are left unprotected, leading to an increase in cavities and potentially more severe oral health problems such as infections and tooth loss.

The consequences extend beyond oral health, as poor oral health is closely linked to systemic conditions like diabetes, cardiovascular disease and poor pregnancy outcomes. Removing fluoride from public water supplies would exacerbate health inequities, placing an even greater burden on already underserved communities and health care systems.