曲面断层片和锥形束CT对下颌阻生第三磨牙与下颌神经管位置关系的研究

Study on the relative position relationship between impacted mandibular third molar and the mandibular canal in CBCT

目的应用曲面断层片和锥形束CT(cone beam computed tomography,CBCT)对下颌阻生第三磨牙(impacted mandibular third molar,IMTM)进行术前评估。方法统计牙根与下颌神经管在曲面断层片上有重叠影像的于2015年5—10月在安徽省口腔医院就诊的51例患者共87颗牙,通过应用CBCT进一步从三维空间上分析其牙根与下颌神经管的位置关系。结果 51例患者的87颗IMTM的CBCT示,40颗患牙(46.0%)牙根位于下颌神经管舌侧;22颗患牙(25.3%)牙根进入下颌神经管中,未突破下颌神经管下缘;13颗患牙(14.9%)牙根位于下颌神经管上方,未接触下颌神经管;9颗患牙(10.4%)牙根位于下颌神经管颊侧;3颗患牙(3.4%)的下颌神经管位于其两根之间。51例患者在微创下顺利完成IMTM拔除术,均未出现下唇麻木。结论在IMTM的术前影像学评估中,CBCT在评估牙根与下颌神经管的位置上较曲面断层片准确性更高。

Objective Preoperative evaluation of impacted mandibular third molar by using panoramic radiographs and CBCT.Meth-ods 87 impacted mandibular third molars from 51 patients treated during the period from May 2015 to October 2015 in Stomatologic Hospital , were investigated, of which the roots and the mandibular canal in panoramic radiographs have overlapping images.Through the application of CBCT and panoramic radiographs, the position relationship between the roots and the mandibular canal was analyzed. Results The position relationship types in CBCT were as follows： 40 impacted mandibular third molars’ roots were located in lingual side of the mandibular canal, 22 impacted mandibular third molars’ roots were located in the mandibular canal,13 impacted mandibu-lar third molars’ roots were above the mandibular canal, and not in contact with the mandibular canal, 9 impacted mandibular third molars’ roots were located in the buccal side of the mandibular canal, and 3 impacted mandibular third molars’ roots were in both sides of the mandibular canal, with the canal lied between the two roots of the impacted molars.None of them underwent minimal inva-sive surgery had lower lip numbness.Conclusions In the preoperative imaging evaluation of IMIM, the accuracy of CBCT in evalua-ting the position of the root and the mandibular canal was higher than panoramic radiographs.