Form and position of the baby teeth: Form and position of the permanent teeth: General time of eruption of the baby teeth: Baby incisors 8 months after birth, lower jaw 2 months before the upper jaw Baby lateral incisors 12 months after birth, upper jaw 1 month before the lower jaw Baby cuspids 1.5 years of age First molar less than 1.5 years of age Second molar after 2 years of age General time of eruption of the permanent teeth: Middle incisors 6 years of age, lower jaw before the upper jaw Side incisors 7 years of age, lower jaw before the upper jaw Cuspids The first premolar is 10 years old, and the maxilla is earlier than the mandible The second premolar is 10 years old, and the maxilla is earlier than the mandible The first molar is 6 years old The second molar is 11 years old The third molar is 17 years old The timing of tooth replacement: There are two sets of teeth in a person’s life, namely the milk teeth and the permanent teeth. The milk teeth usually fall out on their own before the permanent teeth erupt, which is called tooth replacement. The time when each milk tooth is replaced by a permanent tooth is also the time when the corresponding permanent tooth erupts. The milk incisors are replaced by permanent incisors at age 6 The milk lateral incisors are replaced by permanent lateral incisors at age 7 The milk cuspids are replaced by permanent cuspids at age 9 The first milk molar is replaced by permanent first premolar at age 10 The second milk molar is replaced by permanent second premolar at age 10