ZME Science
No Result
View All Result
ZME Science
No Result
View All Result
ZME Science

Home → Science

Nanoscale look at tooth enamel reveals its ‘mis-orientation’ that makes it so strong

Chomp!

Alexandru MicubyAlexandru Micu
September 30, 2019
in Biology, News, Science
A A
Share on FacebookShare on TwitterSubmit to Reddit

A first-of-its-kind look at the nanostructure of tooth enamel helps uncover the secret of the hardest substance in the human body.

PIC mapping of tooth enamel, with colors representing degrees of nanocrystal mis-orientation.
Image credits Pupa Gilbert.

While the enamel on our teeth looks pretty much like bone, it’s not actually living tissue (while bones are). Enamel grows while teeth are developing to encase all the other material in our teeth and provides protection. Once the teeth are fully developed, they lose the ability to repair or grow new enamel. It’s not so bad, though: enamel is incredibly tough and harder, pound for zpound, than steel.

The skin of our teeth

“We apply huge pressure on tooth enamel every time we chew, hundreds of times a day,” says biophysicist Pupa Gilbert from the University of Wisconsin-Madison. “Tooth enamel is unique in that it has to last our entire lifetime. How does it prevent catastrophic failure?”

The new study reports it all comes down to enamel’s “hidden structure”. The outer layer of our teeth, they explain, is constructed out of a complex weave of hydroxyapatite nanocrystals. Hydroxyapatite is a phosphate mineral from the apatite family that contains calcium and makes up to 70% of our bones by weight.

In tooth enamel, hydroxyapatite takes the shape of crystals one-thousandth the thickness of human hair. They’re so small, the team explains, that nobody has been able to get a proper look at them until now.

“Prior to this study, we just didn’t have the methods to look at the structure of enamel,” Gilbert says. “But with a technique that I previously invented, called polarisation-dependent imaging contrast (PIC) mapping, you can measure and visualise in colour the orientation of individual nanocrystals and see many millions of them at once.”

Using the PIC technique on human tooth enamel, the team spotted that the hydroxyapatite nanocrystals were not oriented in as we had previously assumed. Instead, they’re bundled up into ‘rods’ and ‘interrods’. The team further describes a gradual change in the orientation between adjacent nanocrystals that was similarly unexpected. Differences in orientation between adjacent crystals ranged between 1 and 30 degrees, they report.

“We propose that mis-orientation of adjacent enamel nanocrystals provides a toughening mechanism,” the study reads. “If all crystals are co-oriented, a transverse crack can propagate across crystal interfaces, whereas if the crystals are mis-oriented a crack primarily propagates along the crystal interfaces.”

While testing their hypothesis in real life would be very difficult, computer modeling of the enamel’s structure and its behavior supports the team’s view. These models showed that cracks could spread through enamel’s crystal structure through pressure and how, also revealing that cracks propagated more quickly through perfectly-aligned crystal networks. The researchers therefore believe that the angles of mis-orientation they found in enamel is the best at deflecting cracks, selected for over the course of millions of years of natural evolution.

“Crack deflection is a well-established toughening [mechanism], we therefore conclude that in enamel the observed mis-orientations play a key mechanical role: they increase the toughness of enamel at the nanoscale, which is fundamentally important to withstand the powerful masticatory forces, approaching 1,000 newtons, repeated thousands of times per day.”

The paper “The hidden structure of human enamel” has been published in the journal Nature Communications.

RelatedPosts

These are the 25 happiest US city parks, as ranked by data science
Louisiana’s coastline is sinking much faster than anyone thought, new study finds
What’s the difference between ionic and covalent bonds
Russian scientist admits no new life forms in Vostok lake

ShareTweetShare
Alexandru Micu

Alexandru Micu

Stunningly charming pun connoisseur, I have been fascinated by the world around me since I first laid eyes on it. Always curious, I'm just having a little fun with some very serious science.

Related Posts

Future

A New AI Tool Can Recreate Your Face Using Nothing But Your DNA

byTibi Puiu
1 hour ago
Biology

How Some Flowers Evolved the Grossest Stench — and Why Flies Love It

byMihai Andrei
1 hour ago
Health

People Living Near Golf Courses Face Double the Risk of Parkinson’s

byTibi Puiu
3 hours ago
Health

He Let Snakes Bite Him Over 200 Times and Now Scientists Want His Blood for an Universal Antivenom

byTudor Tarita
5 hours ago

Recent news

A New AI Tool Can Recreate Your Face Using Nothing But Your DNA

May 9, 2025

How Some Flowers Evolved the Grossest Stench — and Why Flies Love It

May 9, 2025

People Living Near Golf Courses Face Double the Risk of Parkinson’s

May 9, 2025
  • About
  • Advertise
  • Editorial Policy
  • Privacy Policy and Terms of Use
  • How we review products
  • Contact

© 2007-2025 ZME Science - Not exactly rocket science. All Rights Reserved.

No Result
View All Result
  • Science News
  • Environment
  • Health
  • Space
  • Future
  • Features
    • Natural Sciences
    • Physics
      • Matter and Energy
      • Quantum Mechanics
      • Thermodynamics
    • Chemistry
      • Periodic Table
      • Applied Chemistry
      • Materials
      • Physical Chemistry
    • Biology
      • Anatomy
      • Biochemistry
      • Ecology
      • Genetics
      • Microbiology
      • Plants and Fungi
    • Geology and Paleontology
      • Planet Earth
      • Earth Dynamics
      • Rocks and Minerals
      • Volcanoes
      • Dinosaurs
      • Fossils
    • Animals
      • Mammals
      • Birds
      • Fish
      • Amphibians
      • Reptiles
      • Invertebrates
      • Pets
      • Conservation
      • Animal facts
    • Climate and Weather
      • Climate change
      • Weather and atmosphere
    • Health
      • Drugs
      • Diseases and Conditions
      • Human Body
      • Mind and Brain
      • Food and Nutrition
      • Wellness
    • History and Humanities
      • Anthropology
      • Archaeology
      • History
      • Economics
      • People
      • Sociology
    • Space & Astronomy
      • The Solar System
      • Sun
      • The Moon
      • Planets
      • Asteroids, meteors & comets
      • Astronomy
      • Astrophysics
      • Cosmology
      • Exoplanets & Alien Life
      • Spaceflight and Exploration
    • Technology
      • Computer Science & IT
      • Engineering
      • Inventions
      • Sustainability
      • Renewable Energy
      • Green Living
    • Culture
    • Resources
  • Videos
  • Reviews
  • About Us
    • About
    • The Team
    • Advertise
    • Contribute
    • Editorial policy
    • Privacy Policy
    • Contact

© 2007-2025 ZME Science - Not exactly rocket science. All Rights Reserved.