The hardest substance in the body that protects teeth from damage and decay.

Tooth enamel is the outermost layer of the tooth crown, composed primarily of hydroxyapatite crystals. It's the hardest substance in the human body, even harder than bone, yet it can be eroded by acids and is not a living tissue—meaning it cannot regenerate. Protecting enamel involves fluoride exposure (strengthens the crystal structure), limiting acid exposure, and avoiding abrasive forces. Once enamel is lost, it's gone permanently.