How do teeth age over time? New study uncovers the truth

‘Aging like a fine wine’ seems to be the mantra of most people, as they tend to navigate their way to old age with a certain grace and aspire to retain good health for a healthier life.

As we grow old, our skin and hair start to show effects on them. As the skin gets a few more fine lines, the hair shows gray strands more. However, unlike other organs of our body, our teeth age a bit differently.

Our teeth, responsible for biting, chewing and breaking down food to gulp it down - contribute to our oral health too. Their outer layer, enamel, is an exceptionally hard substance and the most durable material in the human body. While it provides vital protection, enamel lacks the ability to regenerate or self-repair, unlike other tissues in the body. Unfortunately, this enamel isn’t immune to the test of time. A team of researchers has recently explored how enamel morphs with age.

What does the research say?
Led by the researchers at the University of Washington and the Pacific Northwest National Laboratory, the study scrutinized the atomic makeup of enamel samples taken from the teeth of a 22-year-old and a 56-year-old. The study was published in Communications Materials.

Interestingly, as the study found, the older tooth harbored increased levels of ion fluoride – an element often added to our drinking water and toothpaste as a protective measure for enamel.

The researchers investigated how fluoride integrates into enamel as we journey through life.

What is enamel?
The enamel is the protective, outer covering of your tooth. It shields your tooth crown (the part you can see above your gums) from cavities and damage. Tooth enamel is incredibly durable. Dental enamel is the hardest substance in the human body and serves as the wear-resistant outer layer of the dental crown. It forms an insulating barrier that protects the tooth from physical, thermal, and chemical forces that would otherwise be injurious to the vital tissue in the underlying dental pulp.

Enamel is composed mostly of minerals arranged in microscopic structures ten thousand times tinier than the width of a human hair. which makes it a challenge to study. Grimm collaborated with Arun Devaraj, a materials scientist at the Pacific Northwest National Laboratory (PNNL), to investigate the microscopic structure of enamel more deeply, and together, they used a sophisticated technique called “atom probe tomography.”

This cutting-edge method enabled them to create a 3D map of each atom within a sample, revealing differences in element compositions across three key areas: the nanocrystal core, the shell coating the core, and the space between the shells.

The role of fluoride:
The team found that samples from the older tooth had enhanced fluoride levels, predominantly in the shell regions. Study co-author Cameron Renteria, a postdoctoral researcher in oral health sciences at the University of Washington said, “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.” He added, “Is that fluoride actually being incorporated over time? Now we’re starting to be able to paint that picture.”

According to the researchers, the strength of their work lies in its interdisciplinary nature. By combining the expertise of different scientific fields, they were able to uncover fascinating insights.

How enamel changes over time:
Despite enamel being extremely resilient, it undergoes subtle but impactful transformations as we age.

The study revealed that the mineral composition in older enamel is more compact but also more brittle. Over the years, cycles of demineralization and remineralization, influenced by diet and exposure to fluoride, lead to structural shifts.

Interestingly, these processes primarily affect the outermost shell of enamel’s nanocrystals, where increased fluoride levels were most evident in older teeth. This outer layer, while stronger against acid attacks, becomes more prone to cracks due to its rigid nature.

How fluoride integrates into enamel over time
The study lead author Jack Grimm, a UW doctoral student in materials science and engineering and a doctoral intern at PNNL, said, “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.”

He added, “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.”


How to preserve the strength of teeth:
Changes like those highlight the delicate balance between strengthening enamel and preserving its flexibility, which is a challenge that future dental treatments will have to address. The research highlights a key consideration as we grow older – our teeth may become more brittle, requiring us to chew with greater care. To preserve the strength of your teeth, you can:

Brush and floss: Brush your teeth twice a day with fluoride toothpaste and floss once a day. Use a soft-bristled brush and be gentle, as brushing too hard can damage your enamel.

Eat well: Eat a well-balanced diet that includes calcium-rich foods like dairy, leafy greens, and nuts. Foods rich in vitamin C, like oranges and bell peppers, can also help protect your teeth.

Chew crunchy foods: Chewing crunchy fruits and vegetables like apples and carrots helps scrub away harmful substances from your teeth.

Drink water: Drinking water helps flush away food debris and bacteria from your teeth and gums. It also helps dilute harmful acid caused by bacteria in the mouth.

Use sugar-free gum: Sugar-free gum helps reduce dry mouth and stimulates the flow of saliva, which neutralizes acids and remineralizes the teeth.

Avoid smoking: Smoking increases your risk for gum disease.

Wait before brushing: Wait at least an hour after eating before brushing your teeth. The enamel on your teeth gets softer after eating, and brushing while it's soft can damage it.