The aberrant second premolar

Second premolar teeth are one of the final successional teeth to erupt into the occlusion. Although they often erupt without incidence, this is not always the case. There is potential for unerupted second premolars to cause damage to adjacent teeth or migrate from their expected position. This paper presents a summary of second premolar formation and eruption and possible consequences of impaction.

The maxillary and mandibular second premolars begin to calcify between 24 and 30 months post-partum. They are often the last successional teeth to erupt, usually between the ages of 10 and 12 years in both the mandibular and maxillary arches, and are preceded by the second primary molars. Following eruption of the premolars, which are narrower than their predecessors, there is a slight decrease in arch length as the ‘E’ space is closed by physiological mesial drift.

The premolar tooth germs develop apically to the roots of the primary second molars and are in close proximity to either the maxillary sinus or the mental foramen. As the teeth develop, the crowns often become positioned between the roots of the primary tooth (Figure 1). There is subsequent resorption of the primary tooth roots under the eruptive influence of the permanent tooth.