Comparison of the effect of premolar extraction and non-extraction on the position and developmental changes of the lower third molars.

The aim of the present study was to comprehensively assess the posttreatment effect of premolar extraction versus non-extraction on the position and development of the lower third molars. The sample consisted of 227 patient's pre- and posttreatment panoramic radiographs (53 with four premolar extractions, 174 without extractions). The position and developmental stage of the lower third molars were evaluated by using Pell-Gregory's, Winter's, modified Miloro-DaBell's and Demirjian's classifications, respectively. Premolar extraction had a considerably positive influence on the position and development of the lower third molars and therefore could provide better prognosis for their eruption.