Which one among the following is the hardest part of our body?

The hardest part of the human body is the enamel of the teeth. Enamel is a highly mineralized tissue that serves as the protective outer layer of the teeth. It is primarily composed of calcium hydroxyapatite, a crystalline form of calcium phosphate, which accounts for approximately 96% of its weight [1]. This dense, crystalline architecture makes it the hardest and strongest material in the body, surpassing the hardness of all bones, including the skull and spinal vertebrae [1]. While bones are strong and rigid due to a composite of collagen and hydroxyapatite, they possess more organic material and are less mineralized than enamel. Nails, on the other hand, are composed of keratin, a fibrous protein that provides structural support but lacks the mineral-derived hardness found in enamel or bone. Therefore, tooth enamel is the ultimate guardian against mechanical and chemical wear.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 2: Acids, Bases and Salts > pH change as the cause of tooth decay > p. 27