下颌阻生第三磨牙与下颌管重叠时的三维位置关系与拔除方法研究

目的 探讨曲面体层X线片示下颌阻生第三磨牙根尖部与下颌管重叠时的三维位置关系分类,以指导临床采用恰当方法拔出下颌阻生第三磨牙.方法 选取在曲面体层X线片上牙根与下颌管有重叠的57颗下颌阻生第三磨牙,行锥形束CT(cone beam computed tomography,CBCT)检查,了解两者间的三维位置关系,拟定安全的拔除手术方案.结果 55例患者的57颗患牙的CBCT影像中,22颗患牙牙根(38.6％)突破下颌管壁位于下颌管内；30颗患牙(52.6％)的牙根位于下颌管的舌侧,未与下颌管发生接触；4颗患牙(7.0％)的牙根位于下颌管的颊侧,未与下颌管发生接触；1颗患牙(1.8％)的双根跨于下颌管间.57颗患牙均顺利完成拔牙手术,1例患者(1.8％)出现短暂的下唇麻木于术后1个月后恢复.结论 曲面体层X线片上下颌阻生第三磨牙根尖部与下颌管重叠的病例中,下颌第三磨牙的根尖多位于下颌管的舌侧或位于下齿槽神经管内,CBCT检查对拟定正确安全的拔除术式和降低下齿槽神经损伤发生率具有重要的意义.

Three-dimensional position of the overlap relations of impacted mandibular third molar and mandibular canal

Objective To study the method in accurately deciding the three-dimensional positional relationship when impacted mandibular third molar was overlapped with mandibular canal on the panoramic X-ray film,so as to use appropriate clinical methods to extract the mandibular third molar.Methods Fifty-seven impacted mandibular third molars were checkedby CBCT,which were overlapped with mandibular canal on the panoramic X-ray film,and then a detailed classification and appropriate surgical plan were made.Results The position relationship types on CBCT were as follows:22 impacted mandibular third molars’ roots were inside the mandibular canal;30 impacted mandibular third molars