正畸拔除下颌第二前磨牙对青少年第三磨牙位置的影响

Impact of extracting the lower second premolar in adolescent on their third molar position

目的研究正畸治疗中拔除下颌第二前磨牙对第三磨牙位置的影响。方法选择39例存在下颌第三磨牙的青少年患者,将其分为拔除下颌第二前磨牙组(17例)和非拔牙组(22例),通过术前术后曲面断层片对患者下颌第三磨牙位置变化进行测量分析。结果拔牙与非拔牙组术前术后第三磨牙位置均有不同程度的改变,与非拔牙组相比,拔牙组下颌第三磨牙萌出间隙增大,第三磨牙长轴与平面的交角变化量大。结论拔除第二前磨牙进行正畸治疗能增大第三磨牙萌出间隙,使第三磨牙更加直立,有利于第三磨牙的正常萌出。

Objective To study the impact subjected by the third molar in adolescent due to exacting the lower second premolar. Methods Thirty-nine adolescents were chosen and divided into extraction and non-extraction groups, having 17 and 22 patients respectively. The pretreatment and posttreatment panoramic radiographs were measured to analyses the change of the third molar position. Results The third molar position were all improved from pretreatment to posttreatment in two groups. Compared with non-extraction group, the changes of the eruption space and third molar angulation in extraction group were all increased significantly in mandible. Conclusion Extraction of the lower second premolar could enlarge the eruption space of the third molar and upright the third molar, which is benefit to eruption of the third molar normally.