an impacted tooth is one that is embedded
in the alveolus so that its eruption is prevented
or the tooth is locked in position
by bone or the adjacent teeth.1 Mandibular
second premolars rank third — after third permanent
molars and maxillary permanent
canines — in frequency of impaction.2 The
prevalence of impacted premolars has been
found to vary according to age.3 The overall
prevalence in adults has been reported to be
0.5% (the range is 0.1% to 0.3% for maxillary
premolars and 0.2% to 0.3% for mandibular
premolars).3,4 Premolar impactions may be
due to local factors such as mesial drift of teeth
arising from premature loss of primary molars;
ectopic positioning of the developing premolar
tooth buds; or pathology such as inflammatory
or dentigerous cysts. They may also be associated
with over-retained or infraocclusal ankylosed
primary molars or with syndromes such
as cleidocranial dysostosis.5