Some teeth may remain unerupted under the effect of local and general factors. In our case, the lower right permanent second premolar which was expected to take the place of second decidious molar which was extracted because of the extreme decay had never erupted owing to the mesialisation of lower right first molar. Applying a hemisection to the apical radiolucent lesioned mesial root of lower right first molar, it was carried out the lower permanent second premolar to erupt.

Keywords: Impacted Teeth, Hemisection