How many teeth do humans have?

Baby teeth, also called primary or milk teeth, usually start to appear at around 6 months, and all 20 are typically in place by age 3. From about age 6, they fall out and are replaced by permanent teeth. A full adult set has 8 incisors, 4 canines, 8 premolars and 12 molars, including the four third molars known as wisdom teeth. Wisdom teeth usually arrive between 17 and 25, and many people have them removed because their jaws are too small; some people never develop them at all. Unlike bones, tooth enamel cannot repair itself, so lost or decayed enamel is gone for good.