曲面断层片和锥形束CT对上颌阻生尖牙的定位分析

目的:通过对曲面断层片中上颌阻生尖牙近远中向和垂直向的影像学分区,判定其与锥形束CT (cone-beam computed tomography, CBCT)中相应尖牙唇腭侧位及相邻恒切牙根吸收之间的关系。方法:对68例患者的94颗上颌阻生尖牙进行曲面断层片的拍摄和CBCT扫描。将曲面断层片中上颌阻生尖牙近远中向牙尖所处的位置分为5区(Ⅰ区-Ⅴ区),将牙冠所处的垂直向高度分为3部分(牙冠段,根中段,根尖段),其唇腭侧位置和相邻恒切牙的根吸收情况则由CBCT判定。结果:曲面断层片中上颌阻生尖牙近远中向的区域定位与CBCT中相应阻生牙的唇腭侧位之间有显著相关(P＜0.001),唇侧阻生的尖牙常出现在曲面断层片中的Ⅰ、Ⅱ、Ⅲ区域,正中牙槽阻生的多在Ⅳ区域,腭侧阻生的常在Ⅴ区域,而垂直向的分段与之无显著相关。CBCT中相邻恒切牙的根吸收常发生在Ⅳ、Ⅴ区域和根中段、根尖段。曲面断层片中阻生尖牙近远中向和垂直向的区域划分均与CBCT中相邻恒切牙的根吸收之间有统计学意义(P＜0.05)结论:利用曲面断层片中上颌阻生尖牙近远中向的区域定位可以预测其唇腭侧位和相邻恒切牙的根吸收,垂直向的分段可用来判断相邻恒切牙的根吸收,而不可推测其唇腭侧阻生情况。

Analysis of Impacted Maxillary Canine Position with Panoramic Radiography and Cone-beam Computed Tomography.

Objective: To judge the correlation between the mesiodistal and vertical position of the maxillary impacted canines on the panoramic radiographs and the labiopalatal position of the impacted canines and root resorption of permanent incisors in cone-beam computed tomography (CBCT). Methods: Sixty-eight patients with ninety-four impacted maxillary canines were scanned by CBCT and the panoramic radiograph. We divided the mesiodistal position of the canine cusp tip on the panoramic radiographs into five sectors (Ⅰsector-Ⅴsector), and in the vertical plane the height of the crown of each impacted canine was classified three zones (apical, middle, or coronal). The labiopalatal position of the impacted canines and root resorption of permanent incisors were evaluated with CBCT. Results: There was a statistically significant association between the labiopalatal position of the canines and the panoramic sectors of the impacted canines (P＜0.001). In CBCT labially impacted canines were more frequent in panoramic sectors Ⅰ, Ⅱ, Ⅲ, mid-alveolus impacted canines were frequent in sector Ⅳ, and palatally impacted canines were most frequent in sector Ⅴ. But the panoramic vertical zones of the impacted canines and the labiopalatal position in CBCT were no statistical significance. Root resorption of permanent incisors was more frequent in panoramic sectors Ⅳ,Ⅴand apical zone, middle zone. Root resorption of permanent incisors showed a significant difference according to sector location and zone location (P＜0.05). Conclusion: The labiopalatal position of impacted canines and resorption of permanent incisors might be predicted using sector location on panoramic radiography. The vertical zone on panoramic radiography can judge the root resorption of permanent incisors, but can not predict labiopalatal position of impacted canines.