Atom Probe Study Reveals Fluoride Patterns in Aging Teeth

teeth
Study: Stratification of fluoride uptake among enamel crystals with age elucidated by atom probe tomography

Teeth are necessary for breaking down the food we eat, and they are covered by enamel, which allows them to survive the high amount of stress they receive while we chew. Enamel, unlike other elements in the body, cannot repair damage, so it may weaken with age.

Researchers want to understand how enamel changes with age so that they might develop techniques to keep teeth happier and healthier for longer.

A team from the University of Washington and the Pacific Northwest National Laboratory investigated the atomic makeup of enamel samples from two human teeth, one from a 22-year-old and one from a 56-year-old.

Higher amounts of the ion fluoride, which is frequently added to toothpaste and drinking water to help protect enamel (although its addition to drinking water has recently been in the news), were identified in the older person’s sample.

These results were released by the team in Communications Materials on December 19, 2024. Despite being a proof-of-concept study, the researchers noted that these findings have ramifications for the way fluoride is absorbed and incorporated into enamel as people age.

We know that teeth get more brittle as people age, especially near the very outer surface, which is where cracks start. There are a number of factors behind this -; one of which is the composition of the mineral content. We’re interested in understanding exactly how the mineral content is changing. And if you want to see that, you have to look at the scale of atoms.”

Jack Grimm, Study Lead Author and Doctoral Student, University of Washington

Minerals that are grouped in repeated formations ten thousand times smaller than the width of a human hair make up the majority of enamel.

“In the past, everything that we’ve done in my lab is on a much larger scale -; maybe a tenth the size of a human hair,” said co-senior author Dwayne Arola, UW professor of materials science and engineering. “On that scale, it’s impossible to see the distribution of the relative mineral and organic portions of the enamel crystalline structure.”

Grimm collaborated with PNNL materials scientist Arun Devaraj to employ a method known as “atom probe tomography,” which enables scientists to obtain a three-dimensional map of every atom in space within a sample, to investigate the atomic makeup of these structures.

In order to compare variations in element composition in three distinct regions of the small, repeating structures—the core of a structure, a “shell” covering the core, and the space between the shells—the team created three samples from each of the two teeth in the study.

Fluoride levels were higher in the majority of the locations in the samples taken from the older tooth. However, they were particularly high in areas with shells.

“We are getting exposed to fluoride through our toothpaste and drinking water and no one has been able to track that in an actual tooth at this scale. Is that fluoride actually being incorporated over time? Now we’re starting to be able to paint that picture,” said co-author Cameron Renteria, a postdoctoral researcher in both the oral health sciences and the materials science and engineering departments at the UW. “Of course, the ideal sample would be a tooth from someone who had documented every time they drank fluoridated versus non-fluoridated water, as well as how much acidic food and drink they consumed, but that’s not really feasible. So this is a starting point.”

The key to this research, the team said, is the interdisciplinary nature of the work.

“I am a metallurgist by training and didn’t start to study biomaterials until 2015 when I met Dwayne. We started to talk about the potential synergy between our areas of expertise -; how we can look at these small scales to start to understand how biomaterials behave,” Devaraj said. “And then in 2019 Jack joined the group as a doctoral student and helped us look at this problem in depth. Interdisciplinary science can facilitate innovation, and hopefully, we will continue to address really interesting questions surrounding what happens to teeth as we age.”

One thing the researchers are interested in studying is how the protein composition of enamel changes over time.

“We set out trying to identify the distribution of the organic content in enamel, and whether the tiny amount of protein present in enamel actually goes away as we age. But when we looked at these results, one of the things that was most obvious was actually this distribution of fluoride around the crystalline structure,” Arola said. “I don’t think we have a public service announcement yet about how aging affects teeth in general. The jury is still out on that. The message from dentistry is pretty strong: You should try to utilize fluoride or fluoridated products to be able to fight the potential for tooth decay.”

For more information: Grimm, J. R., et al. (2024) Stratification of fluoride uptake among enamel crystals with age elucidated by atom probe tomography. Communications Materialsdoi.org/110.1038/s43246-024-00709-8 

Rachel Paul is a Senior Medical Content Specialist. She has a Masters Degree in Pharmacy from Osmania University. She always has a keen interest in medical and health sciences. She expertly communicates and crafts latest informative and engaging medical and healthcare narratives with precision and clarity. She is proficient in researching, writing, editing, and proofreading medical content and blogs.

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