Oral Histology & Development
Tooth Eruption

Tooth eruption occurs when the teeth enter the mouth and become visible. Although researchers agree that tooth eruption is a complex process, the most widely held current theory is that while several forces might be involved in eruption, the periodontal ligaments provide the main impetus for the process. Theorists hypothesize that the periodontal ligaments promote eruption through the shrinking and cross-linking of their collagen fibers and the contraction of their fibroblasts.

Tooth eruption occurs at different times for different people. Typically, humans have 20
primary (milk) teeth and 32 permanent teeth.

Tooth eruption has three stages: The first, known as deciduous
dentition stage, occurs when only primary teeth are visible. Once the first permanent tooth erupts into the mouth, the teeth are in the mixed (or transitional) dentition. After the last primary tooth falls out of the mouth the teeth are in the permanent dentition.

The following table presents the eruption times for primary and permanent teeth:

Tooth Disturbances