What is the hardest substance in the human body?
Tooth enamel is the hardest substance in the human body. It is made mostly of a mineral called hydroxyapatite, a form of calcium phosphate.
Enamel covers the crown of each tooth, the part above the gums. It is about 96 percent mineral, making it harder than bone. Its tough, crystal structure allows teeth to withstand the forces of biting and chewing for a lifetime. Underneath is a softer layer called dentin, and in the center is the pulp, which contains nerves and blood vessels.
Enamel has no living cells, so the body cannot repair it once it is badly damaged. Acids from food, drinks and bacteria can slowly weaken it, leading to cavities and sensitivity. However, minerals in saliva and fluoride can help repair early, small areas of damage.
Protecting enamel
Brushing twice a day with fluoride toothpaste, limiting sugary and acidic foods and drinks, drinking water and regular dental checkups help protect enamel. Brushing too hard or immediately after acidic food can wear enamel away.
Did You Know?
Enamel is translucent, so the color of your teeth comes partly from the yellowish dentin underneath.
This answer is general information, not medical advice. For a personal health question, talk to a doctor.