Water fluoridation and tooth decay: the latest research

Water fluoridation is a widely used dental prevention method in many countries around the world. However, for decades, there has been an ongoing debate about its effectiveness and potential side effects. In light of the latest research published in the Cochrane Library, it’s worth revisiting the impact of fluoride on our health.

Tooth decay as a global public health problem

Tooth decay remains one of the most common public health issues globally, affecting 60% to 90% of school-aged children. If left untreated, it can lead to pain, infections, and even tooth loss, which negatively affects quality of life and overall health. Despite advances in dentistry and the availability of fluoride-containing toothpaste, tooth decay continues to pose a serious threat, especially in communities with limited access to dental care.

Water fluoridation as a preventive strategy

Community water fluoridation (CWF) is practiced in about 25 countries and is recognized by numerous health organizations, including the World Health Organization (WHO), as an effective preventive strategy for tooth decay. This process involves the controlled addition of fluoride to drinking water, aimed at strengthening tooth enamel, increasing resistance to acids, and reducing the risk of cavities. Fluoride, a naturally occurring mineral, can significantly improve oral health across entire populations when present in appropriate concentrations in water.

Cochrane review methodology

The latest Cochrane systematic review focused on evaluating the impact of water fluoridation on preventing tooth decay. A total of 157 studies were analyzed, including 21 studies assessing the initiation of fluoridation and one study regarding its cessation. The studies involved populations of different ages, although most focused on children. The review included both pre-1975 and post-1975 studies, allowing for an assessment of how the widespread use of fluoride toothpaste has influenced the effectiveness of CWF.

What was established?

An analysis of contemporary studies (post-1975) found that the initiation of water fluoridation may lead to a slight reduction in tooth decay in children’s primary teeth. On average, the difference amounted to about a quarter of a tooth in favor of CWF. Additionally, a small increase in the percentage of children free from cavities was observed. The findings regarding the effectiveness of fluoridation in permanent teeth were less conclusive, with the certainty of the evidence rated as low or very low. Methodological limitations, such as insufficient control of variables and discrepancies in study results, contributed to this uncertainty. In many cases, studies showed varying effects depending on the population, duration of observation, and fluoride concentrations in water, making it difficult to draw clear conclusions and limiting the overall reliability of the available evidence.

Older studies, especially those conducted before 1975, showed a more pronounced effect of community water fluoridation (CWF) in reducing tooth decay, which may be related to the limited availability of other fluoride sources during that period. At that time, fluoride in toothpaste and other products was not widely available, making CWF a key source of fluoride for the population. Modern studies show a reduced effect of CWF, which may be attributed to the broader availability of alternative preventive measures, such as fluoride-containing toothpaste and other fluoride-enriched products.

Dental fluorosis

One of the main concerns regarding water fluoridation is the risk of dental fluorosis, which manifests as staining on tooth enamel. The Cochrane review found that at the fluoride concentrations used in fluoridation programs (typically 0.7–1.2 mg/l), the risk of severe fluorosis is minimal. Milder forms of fluorosis occurred more frequently, but these were mainly aesthetic in nature and did not affect the functionality of the teeth.

The Cochrane review also did not find credible evidence to suggest that water fluoridation at recommended concentrations has negative effects on other aspects of health, such as damage to the kidneys, bones, or nervous system. In countries where long-term studies have been conducted, such as Ireland and the UK, no increased risk of serious conditions has been noted in people consuming fluoridated water.

Health policy and dental practice

The results of the review indicate that community water fluoridation (CWF) can be an effective tool in preventing tooth decay, though its effectiveness appears to be less clear than previously thought, particularly in communities with broad access to other fluoride sources, such as toothpaste. Nevertheless, in communities with limited access to such products, CWF can still play a key role in improving oral health.

Decisions regarding the implementation or continuation of water fluoridation should be based on local conditions, including the level of tooth decay in the population, access to dental care, and societal acceptance of this form of prevention. It is also important to regularly monitor fluoride levels in drinking water to ensure its optimal concentration and to educate the public about both the benefits and potential risks associated with CWF.