1. Human beings have two sets of teeth: milk teeth and permanent teeth. Generally, milk teeth begin to erupt 4~10 months after birth, and most of them come out before the age of 3. Those who do not erupt milk teeth after 13 months are called delayed eruption of milk teeth.
2. The general pattern of eruption of milk teeth is 2 teeth erupted at 6 months, 6 teeth erupted at 9 months, 8 teeth erupted at 12 months, 12 teeth erupted at 18 months, 16 teeth erupted at the age of 2 years, and 20 teeth erupted at the age of 2.5 years. The order of eruption is generally lower jaw first than upper jaw, from front to back. 8 teeth erupted at 14 months is normal.
The timing and sequence of eruption of milk teeth are related to genetics, endocrinology, and food characteristics, and therefore vary greatly from one individual to another.