Tooth A tooth is a hard structure, set in the upper or lower jaw, that is used for chewing food.
Teeth also give shape to the face and aid in the process of speaking clearly.
To prevent decay, good oral hygiene, consisting of daily brushing and flossing, is necessary. The hardest substance in the human body is one of the four kinds of tissue which make up the tooth. When a person gets a toothache, the pulp is what hurts.