Researchers study what happens to teeth as we age by looking at individual atoms in tooth enamel.

Teeth are essential for breaking down the food we eat and are protected by enamel, which allows them to withstand the high stress they undergo when chewing. Unlike other materials in the body, enamel has no way to repair damage. This means that as you get older, you run the risk of becoming weaker over time.

Researchers are interested in understanding how enamel changes as we age so they can begin to develop ways to keep teeth healthy and happy for longer.

Researchers from the University of Washington and Pacific Northwest National Laboratory examined the atomic composition of enamel samples taken from two human teeth, one from a 22-year-old and one from a 56-year-old. . Samples from elderly people contained high concentrations of fluoride ions, which are commonly found in drinking water and toothpaste, and fluoride is added to protect enamel. (It’s been a hot topic in the news lately). .

The team published these findings in Communications Materials. Although this is a proof-of-concept study, the researchers said these results have implications for how fluoride is taken up and integrated into enamel as we age.

“We know that teeth become more brittle as we age, especially near the top surface where cracks begin,” said lead author and doctoral student in the Wisconsin Department of Materials Science and Engineering, PNNL. said Jack Grimm, who is also a doctoral intern. “There are many factors behind this, one of which is the composition of the mineral content. We are interested in understanding exactly how the mineral content is changing. , if you want to see that, you have to look at the scale of the atoms. ”

Enamel is primarily composed of minerals, arranged in a repeating structure 1/10,000 times the width of a human hair.

“Everything we’ve done in my lab so far has been on a much larger scale, probably about one-tenth the size of a human hair,” said co-senior author and University of Wisconsin Materials Science and Engineering Professor Dwayne Arora said. “At that scale, it is impossible to see the distribution of the relative mineral and organic parts of the enamel crystal structure.”

To investigate the atomic composition of these structures, Grimm is collaborating with PNNL materials scientist Arun Devaraj to develop an atom probe tomography system that allows researchers to obtain 3D maps of each atom in space within a sample. We used a technique called “.

The research team created three samples from each of the two teeth studied and determined the elemental composition in three different regions of the small repeating structure: the core of the structure, the “shell” surrounding the core, and the space between the structures. I compared the differences. shell.

Older tooth samples had higher fluoride levels in most areas. However, they were particularly high in shell areas.

“We are exposed to fluoride through toothpaste and drinking water, but no one has been able to track it in real teeth at this scale. That fluoride is actually taken up over time. “Now we’re starting to be able to paint it,” said co-author Cameron Renteria, a postdoctoral fellow in the Department of Oral Health Sciences and Materials Science and Engineering at the University of California. said. “Of course, the ideal sample would be the teeth of a person who recorded how much acidic food and drink they consumed, each time they drank fluoridated and non-fluoridated water. But that’s not realistic. So , this is the starting point.

Key to the study, the researchers say, is the interdisciplinary nature of the study.

“I am a metallurgist by training and did not begin researching biomaterials until 2015, when I met Dwayne. We began discussing potential synergies between our specialties. We started talking about how we can look at these small scales to understand how biomaterials work,” Devaraj said. “Then in 2019, Jack joined the group as a PhD student and helped us investigate this issue in depth. Interdisciplinary science can foster innovation, and hopefully I We hope that we can continue to address the really interesting question of what happens to our teeth as we age.”

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

“We started trying to determine the distribution of organic matter in enamel and whether the trace proteins present in enamel actually disappear with age. But after seeing these results, , one of the most obvious things was that this is actually a distribution of fluoride around the crystal structure,” Arora said.

“I don’t think there’s any public word yet on how aging affects teeth in general. The jury is still out on that. The message from dentistry is very strong. Next You should try to utilize fluoride or fluoridated products to enable you to fight the possibility of cavities. ”