How many teeth a human has depends on his or her age; children have fewer teeth than adults, just 20 compared to a full-grown adult who has 32 teeth.
How Many Teeth Do Adults Have?
A complete set of adult teeth will include 8 incisors, 4 canines, 8 premolars, and 12 molars; however, this total assumes that the adult in question has 4 wisdom teeth and has kept all of them. More commonly, adults have 28 teeth as they often have to get their wisdom teeth extracted due to alignment issues or impaction (the mouths of modern humans often do not have enough room to fit in four extra molars). It is believed that in the past most humans lost one or more molars by their early twenties, so ancient humans likely did not keep a complete set of 32 adult teeth either and their wisdom teeth replaced molars already lost due to injury or the rigours of consuming very coarse food.
Adults should do everything they can to take care of the 28 teeth they typically have, dentists advise; loss of any adult tooth can cause the teeth around it to shift and loosen, leading to poor bite alignment and a heightened risk of losing further teeth.
How Many Teeth Do Kids have?
Most children will have about 20 teeth prior to their adult teeth beginning to erupt—10 on the top and 10 on the bottom. These “baby teeth” (the medical term for which is “deciduous teeth,” thus named after the fact that these teeth are destined to fall out) usually begin to come in around six months of age, leading to the discomfort and upset of teething.
These teeth act as “placeholders”, allowing children to consume their food properly and supporting the development of healthy jawbones. As such, it’s important to take very good care of these early teeth despite their temporary status. Likewise, caring for these teeth regularly sets children up to establish proper oral care practices which will become a lifelong habit.
Usually, a child will begin to lose his or her “baby teeth” starting around the age of six. Adult teeth will continue to erupt, replacing these lost teeth and filling in additional spaces in the mouth, until the child is in his or her early teens.