Human teeth do not grow all the time, and after permanent teeth replace milk teeth, they will not be replaced later in life, and most people will develop wisdom teeth in adulthood. Teeth have the roles of biting, chewing, maintaining facial appearance, and aiding in pronunciation. The main structure of teeth consists of enamel, bone, periodontium, and pulp. People only have two chances to erupt teeth, the first eruption is called milk teeth, the second eruption is called permanent teeth, in puberty at the age of 11~14 years old when the permanent teeth will replace all the milk teeth, and the wisdom teeth are generally to be born in adulthood at the age of 20 years old, but some of them will not grow wisdom teeth in their whole life. Therefore, after the permanent teeth, if the teeth are missing due to different reasons, or after extraction, there will be no new teeth formed, so pay attention to oral hygiene, take care of your teeth.