An in-depth look at shark teeth has found that they contain fluoride, the active ingredient of most toothpaste and dental care mouthwashes.

It helps to explain why sharks are so effective at either tearing or cutting prey. Their teeth are perfectly designed for such tasks, never suffering from cavities, according to the study, recently published in the Journal of Structural Biology,

While shark teeth contain the mineral fluoroapatite (fluorinated calcium phosphate), the teeth of humans and other mammals contain hydroxyapatite, which is an inorganic constituent also found in bone, explained co-author Matthias Epple. In order to make teeth more acid resistant, toothpaste often contains fluoride. In contrast, the surface of shark teeth contains 100 percent fluoride.

Mechanical measurements and tests on the micro and nano-scales determined that shark teeth are not harder than human teeth.

In addition to the unique structure of their teeth, sharks also have the handy ability to replace their teeth several times during their lives. This is not due to cavities, but rather because their teeth sometimes wind up stuck in prey or are otherwise forced out.