摘要目的:探讨口腔颌面部锥形束CT(CBCT)在下颌阻生第三磨牙(IMTM)拔除术中舌侧骨板损伤的风险预判价值。方法:选取2018年1月至2019年12月四川省攀枝花市中心医院诊断为IMTM的150颗牙(垂直、近中及水平各50颗)的CBCT图像为研究对象。通过CBCT系统自带的软件测量每颗IMTM釉质牙骨质界、根中份及根尖三处舌侧骨板厚度，采用方差分析对相关数据进行统计分析。结果:垂直、水平及近中三组IMTM釉质牙骨质界舌侧骨板的厚度分别是(1.36±0.43)mm、(1.21±0.44)mm及(1.28±0.40)mm，差异无统计学意义( P＝0.35)；根中份厚度分别是(1.48±0.33)mm、(1.06±0.57)mm及(1.11±0.45)mm，差异有统计学意义( F＝8.78， P<0.01)；根尖区厚度分别是(1.44±0.49)mm、(0.84±0.58)mm及(0.86±0.64)mm，差异有统计学意义( F＝12.35， P<0.01)。相对于下颌第二磨牙远中面，居中、偏颊及偏舌三组IMTM釉质牙骨质界舌侧骨板厚度( F＝5.03， P<0.01)、根中份( F＝15.13， P<0.01)及根尖( F＝33.12， P<0.01)差异均有统计学意义。水平和近中IMTM较垂直IMTM容易发生根尖区舌侧骨板菲薄现象，而牙冠偏颊侧者更易发生根尖区舌侧骨板缺如。 结论:当CBCT显示IMTM根尖区舌侧骨板菲薄或缺如时，拔牙术前应充分医患沟通及风险预判。同时在拔牙过程中应重点保护舌侧骨板，避免暴力操作，谨防发生下颌骨舌侧骨板穿孔、断裂或牙根移位等严重并发症。

abstractsObjective:The present study was aimed to determine the value of cone beam CT (CBCT) in predicting the risk of lingual bone plate injury during extraction of impacted mandible third molar (IMTM).Methods:The original CBCT data of 150 teeth (50 in vertical, 50 in angular and 50 in horizontal ) in January 2018 to December 2019 in Panzhihua Central Hospital of Sichuan Province were collected and analyzed. The thickness of lingual bone plate in enamel cementum boundary (ECB), root middle (RM) and root tip (RT) of each IMTM was measured by the software of CBCT system, and datas were analyzed by one-way ANOVA.Results:The average thickness of lingual bone plate in ECB of IMTM was (1.36±0.43)mm, (1.21±0.44)mm and (1.28±0.40)mm in vertical, horizontal and angular groups, respectively, with no significant difference ( F=1.07, P=0.35). The average thickness of lingual bone plate in RM of IMTM was (1.48±0.33)mm, (1.06±0.57)mm and (1.11±0.45)mm, respectively, with statistically significant difference ( F=8.78, P<0.01). The average thickness of lingual bone plate in RT of IMTM was (1.44±0.49)mm, (0.84±0.58)mm and (0.86±0.64)mm, respectively, with statistically significant difference ( F=12.35, P<0.01). Compared with the mandibular second molar, there were statistically significant differences in the average thickness of the lingual bone plate in ECB ( F=5.03, P<0.01), the RM ( F=15.13, P<0.01) and the RT ( F=33.12, P<0.01) of the IMTM among the three groups. In addition, the horizontal and angular IMTM, the thinness of lingual bone plate in RT region was more likely to occur than in vertical, and the absence of lingual bone plate was most likely to occur in patients with partial buccal crown. Conclusions:The doctor-patient communication and risk prediction should be sufficient before IMTM extraction when CBCT shows that the lingual bone plate of RT region is thin or absent. At the same time, we should avoid violent operation and thoroughly protect the lingual bone plate in the process of tooth extraction, and guard against serious complications such as perforation or fracture of lingual bone plate of mandible, and root displacement.