Eruption of Primary, Mixed, and Permanent Dentitions

The teeth develop and erupt in three different stages: primary (deciduous), mixed, and permanent dentitions. All teeth begin their development in a tooth follicle or dental sac with coronal development occurring first followed by progressive apical formation until the root end is closed. As mentioned previously, the dental pulp is larger in immature teeth and smaller in mature teeth.⁶ As primary or permanent teeth develop, the root apex/apices remain open until the root is fully formed.