Humans are diphyodonts, meaning they develop two sets of teeth over their lifetime: primary and permanent. This natural progression ensures the mouth is equipped with appropriate dentition for different stages of growth and dietary needs.
Primary Teeth
Children develop a set of 20 primary teeth, often called “baby teeth” or “milk teeth.” These teeth begin to emerge around six months of age, with the lower central incisors typically appearing first. By approximately three years old, a child usually has a complete set, consisting of 10 in the upper jaw and 10 in the lower.
These primary teeth aid in speech development and hold space in the jaw for the upcoming permanent teeth. Between the ages of six and twelve, they gradually loosen and fall out, making way for the adult teeth. The shedding process generally follows the same order as their initial eruption.
Permanent Teeth
Permanent teeth begin to replace primary teeth around age six. Most adults typically have 32 permanent teeth, divided evenly between the upper and lower jaws. This complete set includes four distinct types, each with specialized functions.
- Eight incisors, at the front of the mouth, are for biting and cutting food.
- Four canines are pointed teeth that help in tearing food.
- Eight premolars assist in crushing and grinding food.
- Twelve molars, including wisdom teeth, are positioned at the back for heavy grinding and chewing. The four wisdom teeth, or third molars, typically appear last, between 17 and 25 years of age.
Factors Influencing the Total
While 32 is the typical number of permanent teeth, several factors can influence an individual’s total count. The most common variation relates to wisdom teeth, also known as third molars. Many people have these teeth removed due to impaction, lack of space in the jaw, or other complications, which reduces the total count to 28. Some individuals are born without one or more wisdom teeth, a normal variation.
Beyond wisdom teeth, other variations exist, such as supernumerary teeth (hyperdontia), where extra teeth develop. These can appear anywhere in the mouth and may lead to crowding or affect the eruption of other teeth. Conversely, some individuals experience hypodontia, a condition where one or more teeth are congenitally missing, meaning they never develop. These natural differences mean the actual number of teeth can vary among individuals.