应用CBCT分析阻生下颌第三磨牙牙根与下颌管的相对位置关系

摘要

Objective: To determine the positional relationship between impacted mandibular third molar(IMTM) and mandibular canal(MC) by CBCT. Methods: 664 IMTMs with root apexes contacted to MCs on panoramic radiograph were further examined by CBCT,the exact positional relationship between IMTMs and MCs was observed and analyzed by I-Dixel software. Results: The 664 cases were divided into lowly(6. 3％),intermediately(60. 7％) and highly(33. 0％) impacted groups by the depth of IMTMs in mandibulae showed on CBCT images. The distance(mm) from the root apexes of IMTMs to the intact superior wall of MCs(n = 329) in lowly, intermediately and highly impacted cases were 1. 39 ± 1. 38,1. 28 ± 1. 03 and 1. 79 ± 1. 54 respectively(P ＜ 0. 05). MCs on the buccal side,lingual side,under the IMTMs and between the root apexes were found in 49. 8％,12. 0％,36. 6％ and 1. 5％ of the cases; the MC wall deffect was found in 65. 8％,27. 5％ and 95. 0％ of the cases with the MCs under,on buccal and lingual side of the IMTMs, respectively(P ＜ 0. 001). Conclusion: CBCT examination is necessary for the determination of the positional relationship between MC canal and IMTM with the root apex cotacted or overlapped to MC.%目的: 应用CBCT进一步明确第三磨牙牙根与下颌管之间的相对位置关系.方法: 对曲面体层X线片提示下颌阻生第三磨牙牙根与下颌管接触或重叠的患者,使用CBCT回顾性分析下颌阻生第三磨牙牙根与下颌管的相对位置关系.结果: 664侧CBCT影像中,低位阻生、中位阻生、高位阻生例数分别占6. 3％、60. 7％和33. 0％,下颌管完整的病例(329例) 中牙根到下颌管在3组中的距离(mm) 分别为1. 39 ± 1. 38、1. 28 ± 1. 03和1. 79 ± 1. 54(P ＜ 0. 05).下颌管分别位于阻生牙颊侧(49. 8％) 、舌侧(12. 0％) 、下方(36. 6％) 和牙根之间(1. 5％);下颌管完整者329例(49. 5％),有缺损者335例(50. 5％);下颌管位于下颌第三磨牙下方、颊侧和舌侧下颌管缺损率分别为65. 8％、27. 5％和95. 0％(P ＜ 0. 001).结论: 对于曲面体层X线片提示与下颌管接触或重叠的下颌第三磨牙,有必要进一步行CBCT检查.