UB Dental School Expert Discusses Importance, Safety of Fluorinated Water

In 1945, Grand Rapids, Michigan, became the first city in the world to add f luoride to its drinking water. Five years later, U.S. federal officials endorsed water fluoridation, leading many municipalities to incorporate the mineral into their water supplies to help prevent tooth decay.

Today, three-quarters of Americans receive fluoride through public water systems, along with hundreds of millions of people worldwide. According to the Centers for Disease Control and Prevention (CDC) and other scientific organizations, this movement has significantly reduced cavities.

While fluoride has long faced some opposition, concerns over excessive levels in water supplies have become more vocal in recent years. Addressing these issues, Marcelle Nascimento, DDS, PhD, recently discussed the importance of f luoride, the science behind its effectiveness, and the concerns raised by some studies about fluoridated water.

Nascimento 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). She currently serves as president of the American Academy of Cariology (AAC) and has held leadership roles with the Cariology Research Group of the International Association for Dental Research and the American Dental Education Association Cariology section.

The Growing Concern of Tooth Decay in Children

Untreated dental caries remains 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 concerning in children due to the unique vulnerabilities of baby teeth, which 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," Nascimento explained.

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

Studies indicate that untreated cavities in mothers strongly correlate with the risk of their child developing cavities by age three. Poor maternal oral hygiene and frequent sugar consumption contribute to high levels 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," said Nascimento. "High levels of cariogenic bacteria, inadequate oral hygiene, and unhealthy dietary habits create the perfect environment for early childhood caries."

However, with proper guidance during pregnancy, childhood cavities can be prevented. Educating expectant mothers about oral hygiene, regular dental checkups, and reducing sugar intake can significantly improve their children's oral health outcomes.

Fluoride plays a vital role in preventing cavities by strengthening tooth enamel and making it more resistant to decay. Tooth enamel consists of hydroxyapatite crystals, which are vulnerable to acids produced by oral bacteria when metabolizing 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 interacts with enamel and combines with calcium and phosphate ions from saliva to form fluorapatite, a mineral significantly more resistant to acid attacks. By reinforcing the enamel structure, fluoride acts as a protective shield against decay," Nascimento explained.

Fluoride's benefits are most effective with consistent exposure through fluoridated water and daily brushing with fluoride toothpaste.

While fluoride is beneficial at all ages, it is especially critical during childhood, as cavities in early life can have long-term oral health consequences.

"Other periods of life also present an increased risk for dental caries," said Nascimento. "For instance, during adolescence, frequent consumption of sugary snacks and drinks, poor oral hygiene, and orthodontic treatments, such as braces, significantly raise cavity risk."

In older adults, dry mouth caused by systemic diseases or medications increases susceptibility to tooth decay, particularly root caries. Ensuring consistent fluoride exposure can help individuals maintain strong, healthy teeth throughout all life stages.

The optimal amount of fluoride depends on individual needs and public health guidelines. At the individual level, fluoride requirements vary based on oral hygiene, diet, and access to dental care. People at higher risk for cavities may benefit from additional fluoride sources, such as prescription-strength toothpaste or fluoride treatments at dental offices.

"Even individuals with low caries risk require some fluoride exposure. No oral hygiene routine can fully eliminate acid-producing bacteria in the mouth, meaning everyone is exposed to acid challenges throughout the day," Nascimento said.

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

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

Community water fluoridation is a proven method for preventing cavities, benefiting individuals regardless of socioeconomic status or access to dental care. While earlier studies showed a 25-30% reduction in cavities due to water fluoridation, more recent research suggests the impact may be slightly reduced in areas where other fluoride sources, such as toothpaste, are widely available. However, water fluoridation continues to provide consistent fluoride exposure throughout the day, especially when brushing is not feasible.

Nascimento emphasizes that maintaining fluoride in public water supplies is crucial for public health. "Community-wide access to fluoride helps bridge the gap for those who may not have regular access to dental care or fluoride products. It’s a simple, cost-effective measure that significantly improves oral health outcomes."

As discussions about fluoridation continue, public health officials and researchers like Nascimento remain committed to educating communities about the undeniable benefits of fluoride and its role in cavity prevention for all ages.