Once the crown of the tooth has formed and the root has begun to develop, the tooth moves vertically toward the oral cavity so it can erupt into the correct position. Some of the jawbone above the tooth will resorb and other connective tissues will break down to help the tooth move. Depending on the type and position of the tooth, each will erupt at different ages. Primary teeth will erupt first, starting around 6 months of age, according to the American Dental Association.
The permanent teeth will develop in the same manner as the primary teeth, beginning at 20 weeks in utero and continuing 10 months after birth. The third molars, or wisdom teeth, are not completely formed until an individual is approximately 5 years old, explains the Reference Module in Biomedical Sciences article.