A person will have two sets of teeth in their lifetime, milk teeth and permanent teeth. The normal number of milk teeth is 20 and the normal number of permanent teeth is 28 to 32. Infants mostly in the sixth to eight months after birth began to erupt the first milk teeth, to 2.5 years to 3 years of age when all the milk teeth erupted, the normal number should be 20, upper, lower, left and right each 5. At the age of 6 years, the first permanent molars start to erupt, and at the same time, the permanent teeth of the same name start to gradually erupt to replace the milk teeth, and at the age of about 12-13 years, all the permanent teeth erupt, and the number of them is 28. The number of permanent teeth is 28. There are 7 upper, 7 lower, 7 left and 7 right. The third permanent molar (wisdom tooth) starts to erupt at the age of 16 to 18 years, and some people can erupt smoothly, with 1 each of upper, lower, left and right, and the number of permanent teeth is 32; some people do not have the third permanent molar or the third permanent molar is ambushed and blocked, so the number of normal permanent molar teeth can be between 28 and 32. If dental and periodontal abnormalities occur, please consult a dental professional.