Too much of a good thing can be a bad thing. This old saying goes for many things, but what about fluoride?

A study led by researchers at the New York University’s College of Dentistry shows that while fluoride has proven benefits for the teeth, too much fluoride can negatively impact tooth enamel.

The research, published in the journal Science Signaling, found that too much fluoride impacts calcium signaling, mitochondrial function and how genes are expressed in the cells that form enamel. This situation is now the basis for an explanation for dental fluorosis, a condition that results in fluoride overexposure in children.

Fluoride, a naturally occurring mineral found in water, rocks and dirt, has significant benefits for dental health because it helps to remineralize the teeth against decay and acid erosion.

Fluoride is also added to many public water systems around the country and the world. The addition of fluoride to drinking water has been named as one of the 10 greatest public health achievements by the United States Centers for Disease Control and Prevention because of its role in reducing tooth decay and cavities.

But, the amount of fluoride found in drinking water and most toothpastes is low and regulated. When children are exposed to too much fluoride, dental fluorosis can occur, characterized by tooth discoloration, opaque white marks, mottled enamel and lines. Dental fluorosis develops when children between birth and age 9 are exposed to excessive fluoride when teeth are forming.

Too much fluoride can also mean enamel doesn’t harden, leaving children at risk of tooth decay.

Statistics show that dental fluorosis occurs in one in four people ages 6 to 49 in the U.S.

“The benefits of fluoride for the teeth are considerable, but it is important to understand what happens when there’s too much fluoride exposure, too,” said Dr. Ettienne van Zyl, a Rogers, Arkansas, dentist.

Which is precisely what the NYU researchers set out to do. During their study, the scientists examined the effects of high levels of fluoride on tooth enamel cells. Then, they analyzed the impact of fluoride on calcium signaling in the cells, as calcium is one of the minerals that give tooth enamel its strength.

They noticed that exposing enamel cells taken from rodents to high levels of fluoride resulted in calcium dysregulation, which caused a decrease in the strength of tooth enamel.

“When enamel is weakened, from fluorosis or acid erosion, you are at risk of developing cavities and decay,” van Zyl said.

In most cases, everyday exposure to fluoride has a positive effect on the teeth.

“For optimum enamel health, use a toothpaste that contains fluoride,” van Zyl said.


Source: New York University. “How too much fluoride causes defects in tooth enamel: Changes within enamel cells point to mechanism by which excessive fluoride leads to fluorosis.” ScienceDaily. ScienceDaily, 18 February 2020.