Medicine
Tooth Enamel Structure
Quick fact
Enamel is about 96% mineral (mostly hydroxyapatite) and less than 1% organic material, making it more brittle than other body tissues. It has no blood supply or nerve endings, which is why drilling doesn't hurt until it reaches deeper layers.
Why this is interesting
You know your tooth enamel is the hardest substance your body produces—even harder than bone. But if it's so tough, why can a simple sugar and bacteria cause a cavity?