Tag: structure

Tiny built-in cracks stop teeth from shattering

By Ed Yong | April 13, 2009 5:00 pm

Blogging on Peer-Reviewed ResearchOur teeth are a mystery. The set we grow during late childhood stays with us throughout our lives, biting and chewing thousands of times a day. They can withstand forces of up to 1,000 newtons and yet, the material that coats them – enamel – is little tougher than glass. How does this extraordinarily brittle substance not shatter into pieces every time we crunch a nut or chomp on an apple?

Molar.jpgHerzl Chai from Tel Aviv University found the answer, and it’s a surprising one. At a microscopic level, our teeth defend against fractures by developing with cracks already built in. These pre-made defects are known as “tufts” because of their wavy appearance. They are scattered throughout the enamel and share any physical burdens placed on a tooth, so that no one part has to take the full brunt.

By pressing down on individual teeth using a metal rod, Chai found that it’s relatively easy to create a crack in a tooth, but much harder to actually make it grow bigger to the point where the tooth properly breaks. The tufts, together with structures that prevent cracks from growing, are responsible – they allow us to chew without catastrophe. Our teeth aren’t built to avoid damage, but they’re incredibly good at containing it.

Humans aren’t alone in this – Chai compared out teeth to those of sea otters, and found the same adaptive features under a microscope. It may seem like an odd pairing, but we share a fondness for hard-shelled foods with sea otters – we like nuts and seeds, while they can’t get enough of shellfish. These similarities are reflected in our teeth.

Read More

CATEGORIZED UNDER: Animals, Material science
NEW ON DISCOVER
OPEN
CITIZEN SCIENCE
ADVERTISEMENT

Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

Not Exactly Rocket Science

Dive into the awe-inspiring, beautiful and quirky world of science news with award-winning writer Ed Yong. No previous experience required.
ADVERTISEMENT

See More

ADVERTISEMENT
Collapse bottom bar
+

Login to your Account

X
E-mail address:
Password:
Remember me
Forgot your password?
No problem. Click here to have it e-mailed to you.

Not Registered Yet?

Register now for FREE. Registration only takes a few minutes to complete. Register now »