Infants and toddlers start to get their first teeth around 6 months of age and all 20 milk teeth in their entire mouths will be in place until they are about 2.5 years old. However, there is a great deal of individual variability, as some children start teething early, at 4 months, while others may not get their first tooth until they are 10 months or even 1 week old. Parents do not need to worry too much about this situation, as the teeth will gradually come in around the age of 2.5 to 3 years old. If you are over 3 years old and still have teeth that have not come in, you can take your baby to the hospital for an examination. A surface tomogram can be taken to see if the baby has congenital missing teeth. At the age of 6, the baby will have alternating permanent teeth; at the age of 12, all permanent teeth will erupt; between the ages of 18 and 25, wisdom teeth will erupt, however, there is a great deal of individual variability and there are many people who do not have wisdom teeth.