Changes of mandibular third molar angle and position after extraction of mandibular first molar during orthodontic treatment

Objective:To compare the angular and positional changes in mandibular third molars of patients treated orthodotically with mandibular first molar extractions and without extractions.Method:The pretreatment and posttreatment cephalometric radiographs of 34 mandibular first molar extraction cases and 29 nonextraction cases were analyzed.Vertical and horizontal drift and angulation of mandibular third molar were measured.Changes in mandibular third molar angle and position from pretreatment to posttreatment for two groups were compared.Result:There were statistically significant difference between extraction and nonextraction groups in the change in mandibular third molar horizontal position but not in angle and vertical position..At the end of the orthodontic treatment,the mandibular third molars showed more mesial drift in the extraction group.Conclusion:Mandibular first-molar extraction increases the rate of mesial movement of mandibular third molar.