Staggers J A, Germane N, Fortson W M
Department of Orthodontics, Medical College of Georgia, School of Dentistry, Augusta 30912.
Angle Orthod. 1992 Summer;62(2):135-8. doi: 10.1043/0003-3219(1992)062<0135:ACOTEO>2.0.CO;2.
The effect of third molars on the stability of orthodontic treatment has been studied extensively. Yet the effect of orthodontic treatment, particularly premolar extractions, on third molars has not been substantially studied. The purpose of this investigation was to compare the changes in third molar angulation in patients treated with and without extractions. Records of 45 Class I, nonextraction and 33 Class I, first premolar extraction patients were examined. The pretreatment and posttreatment pantographs were digitized, and the angles between the third molar long axes and the occlusal plane were measured. Changes in third molar angulation from pretreatment to posttreatment for the two groups were compared for statistical differences using a Student's t-test. Statistical analysis revealed there were no significant differences in the change in third molar angulation in either group. On average, the maxillary and mandibular third molars showed an improvement in angulation relative to the occlusal plane. The results suggest that factors other than first premolar extractions may influence third molar angulation.
第三磨牙对正畸治疗稳定性的影响已得到广泛研究。然而，正畸治疗，尤其是前磨牙拔除，对第三磨牙的影响尚未得到充分研究。本研究的目的是比较拔牙和不拔牙患者第三磨牙角度的变化。检查了45例I类不拔牙患者和33例I类拔除第一前磨牙患者的记录。将治疗前和治疗后的全口曲面断层片数字化，并测量第三磨牙长轴与咬合平面之间的角度。使用学生t检验比较两组从治疗前到治疗后第三磨牙角度的变化，以进行统计学差异分析。统计分析显示，两组第三磨牙角度变化均无显著差异。平均而言，上颌和下颌第三磨牙相对于咬合平面的角度有所改善。结果表明，除拔除第一前磨牙外的其他因素可能会影响第三磨牙的角度。
