Here are some facts about teeth:

Tooth enamel: Tooth enamel is the hardest substance in the human body, even harder than bone. 

Teeth can't heal: Teeth are the only part of the body that can't repair themselves. 

Teeth start developing before birth: Both baby and permanent teeth start developing before birth. 

Number of teeth: Humans have two sets of teeth in their lifetime, with 20 baby teeth and 32 adult teeth. 

Wisdom teeth: Some people have an extra set of molars called wisdom teeth, which develop later in adolescence. 

Saliva: The body produces about a quart of saliva every day, which is enough to fill two swimming pools over a lifetime. 

Chewing: Chewing is a natural reflex that's based on which hand is dominant. 

Incisors: The primary function of incisors is to cut and tear food. 

Toothbrushes: Dentists recommend brushing your teeth for at least two minutes. You should also replace your toothbrush every three months. 

Cavities: Cavities are the second-most common disease in the United States. 

Dentistry: The earliest known dentist was Hesi-Ren, an Egyptian who lived thousands of years ago. 

False teeth: Alexis Duchâteau invented false teeth in 1774 from porcelain and animal bone.