Human Teeth Are as Hard as Shark Teeth

While a shark's mouth full of razor-sharp points might seem infinitely tougher than our own smile, the core material is surprisingly similar. The secret to this dental parallel lies in their mineral composition. Human tooth enamel, the hardest substance in our bodies, is a crystalline form of calcium phosphate called hydroxyapatite. Shark teeth are composed of a similar, slightly more acid-resistant material called fluoroapatite, which incorporates fluoride into its structure. This chemical makeup is what gives both types of teeth a hardness rating of approximately 5 on the Mohs scale, making them as hard as some forms of steel.

The crucial difference isn't in hardness, but in evolutionary strategy. Human teeth are designed for a lifetime of varied use, from tearing to grinding, and are firmly anchored into our jaws. We only get two sets. Sharks, however, possess a "conveyor belt" system of multiple rows of teeth that are not deeply rooted. Their teeth are treated as disposable weapons (Review). When a tooth breaks or falls out, another one from the row behind simply moves forward to replace it. This constant regeneration ensures a shark's bite is always at its sharpest, allowing a single shark to shed and regrow up to 30,000 teeth throughout its life.