Influence of premolar extraction or non-extraction orthodontic therapy on the angular changes of mandibular third molars.

Aim: To compare the angular changes of the third molars relative to the occlusal plane and to the second molar long axis in extraction group and compare these changes with a non extraction group.

Materials And Methods: The study included pre and post treatment panoramic radiograph records of 90 subjects treated by first premolar extractions and 90 subjects who had been treated with non extraction orthodontic therapy ( = 90). Two angular variables were measured. Firstly, the angle between the long axis of the third molar and the occlusal plane (M3-OP) and secondly, the angle between the long axis of the third molar and the long axis of the second molar (M3-M2). Data were analyzed by paired and student's -test.

Result: The analyzed data to assess the changes in the third molar angulation from pretreatment to post treatment did not vary significantly in both the groups (< 0.05). Both the groups showed decreased angular values. The M3-OP angular difference was (-7.3 ± 2.45) in extraction group as compared to (-5.85 ± 1.77) in non extraction group. The M3-M2 angular difference of (-4.26 ± 3.11) in extraction group and (-2.98 ± 1.74) in non-extraction group was observed.

Conclusion: Extraction of premolars did not demonstrate considerable changes on the angulation of the third molars. The factors other than premolar extractions may influence the angulation of the third molars.