How many teeth are there in a full mouth?
Apr 24, 2025
Source: Cainiu Health
Dr. Liu Chao
Introduction
As the first set of teeth in life, primary teeth begin to erupt at about six months after birth and are fully erupted by the age of two to two and a half years. These 20 primary teeth are evenly distributed in four regions of the mouth—upper left, upper right, lower left, and lower right—with five teeth in each region, serving the function of chewing during childhood. Upon entering the permanent dentition stage, the total number of teeth increases, typically ranging between 28 and 32.
Generally, the number of teeth in a full mouth is 20 during the primary dentition stage and ranges between 28 and 32 during the permanent dentition stage, with variations due to individual differences. The detailed explanation is as follows:
Primary teeth, a person's first set of teeth, begin to erupt at about six months after birth and continue until fully erupted between two to two and a half years of age. These 20 primary teeth are evenly distributed across four regions—upper left, upper right, lower left, and lower right—in the mouth, with five teeth in each region. They perform the function of chewing during childhood and guide the proper eruption of permanent teeth.
After entering the permanent dentition stage, the total number of teeth increases, typically ranging from 28 to 32. Permanent teeth, the second and final set of teeth, begin replacing primary teeth at about six years of age and complete the replacement process around twelve years of age. Individual differences in the total number of permanent teeth mainly result from variations in the eruption of third molars. Third molars erupt much later, usually between the ages of 16 and 35, and not everyone develops all four wisdom teeth. Therefore, some individuals may have only 28 permanent teeth, while others may have 32.
It is recommended to maintain good oral hygiene by brushing teeth correctly in the morning and evening, rinsing the mouth after meals, using dental floss to clean between teeth, undergoing regular dental cleanings, and maintaining a healthy diet.
