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 (n = 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 t-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 (p < 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.