Biology
Tooth Enamel
Quick fact
Tooth enamel is the hardest tissue in the human body, yet it is only about 2.5 mm thick at its thickest point, and it cannot repair itself once damaged.
Why this is interesting
Think of your teeth as tools you use every day—but what makes them strong enough to bite through an apple without shattering? The secret lies in a single, remarkable substance: enamel.