
How hard is tooth enamel compared to other materials?
Tooth enamel is harder than steel, but breaks much easier.
Asked by: Ron Pirani, Massachusetts, US
Tooth enamel is mostly hydroxyapatite, which is a mineral form of calcium phosphate. The apatite group of minerals scores a five on the Mohs hardness scale; which makes enamel the hardest biological material.
Tooth enamel is harder than steel, but a lot more brittle. So you can’t scratch your enamel on metal cutlery but you can chip it by trying to open a beer bottle with your teeth.
Read more:
- Why does toothpaste make everything taste horrible?
- Does flossing your teeth really make a difference?
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.
Authors

Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.
Sponsored Deals

May Half Price Sale
- Save up to 52% when you subscribe to BBC Science Focus Magazine.
- Risk - free offer! Cancel at any time when you subscribe via Direct Debit.
- FREE UK delivery.
- Stay up to date with the latest developments in the worlds of science and technology.