dentin

Our 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? Herzl 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…