Figure 4-1.Stages in development of a tooth.
After the crown of the tooth has formed, the root
begins to develop. Now the tooth begins to erupt (fig.
4-l), which is a movement of the tooth into its proper
position in the mouth. For permanent teeth, it takes
about 3 years from crown completion to the time the
tooth emerges into the mouth. Figures 4-2 and 4-3 list
root of the primary tooth resorbs (looses structure) as
the permanent tooth erupts from beneath. The primary
teeth act as guides for the developing permanent teeth.
The premature loss of primary teeth can have a serious
impact on the eruption of permanent teeth and how
they will be in position in the dental arch.
the average emergence periods of primary and
When primary teeth get ready to fall out and make
way for the eruption of permanent teeth, they go
through a process called exfoliation (shedding). The
Histology is the study of anatomy that deals with
the minute structure, composition, and functions of
tissues. Oral histology describes in detail the tissues of
the teeth, periodontium, and the surrounding oral