Sewerin I, Andersen V, Stoltze K
Scand J Dent Res. 1987 Feb;95(1):74-81. doi: 10.1111/j.1600-0722.1987.tb01396.x.
The CEJ on radiographs is often used as a reference point in the assessment of alveolar bone loss. The aim of the present study was to test the stability of the radiographic CEJ ("RCEJ") in relation to the alveolar crest under varying angulations of the central X-ray beam. In an experimental model four types of extracted teeth were radiographed at 0 degree and 20 degrees vertical angulation and at 15 horizontal angulations varying from a 17.5 degrees mesial view to a 17.5 degrees distal view. The buccal alveolar bone margin was simulated by a steel needle. RCEJ-"crest" distances were read at a X 10 magnification. Changing the vertical angulation from 0 degree to 20 degrees reduced the RCEJ-"crest" distances for all tooth types (range of average reduction 2.2-4.1 mm). Horizontal angulations without concomitant vertical angulation had a significant effect but were without clinical significance. Horizontal angulations in combination with a 20 degrees vertical angulation had a considerable influence; in a mesial view, mesial RCEJ-"crest" distances decreased and distal ones increased, and vice versa in a distal view. The deviations from the true CEJ-crest distance demonstrated may be of clinical significance, and a critical attitude to alveolar bone loss measures on radiographs using the RCEJ as reference point is recommended.
根尖片上的釉牙骨质界（CEJ）常被用作评估牙槽骨吸收的参考点。本研究的目的是检测在X线中心线不同角度下，根尖片上釉牙骨质界（“RCEJ”）相对于牙槽嵴的稳定性。在一个实验模型中，对四种类型的离体牙分别在垂直角度为0度和20度、水平角度从近中17.5度到远中17.5度共15个角度下进行拍摄。用一根钢针模拟颊侧牙槽骨边缘。在10倍放大倍数下读取RCEJ与牙槽嵴之间的距离。将垂直角度从0度改为20度会使所有类型牙齿的RCEJ与牙槽嵴之间的距离减小（平均减小范围为2.2 - 4.1毫米）。单纯水平角度改变有显著影响，但无临床意义。水平角度与20度垂直角度相结合有相当大的影响；在近中视角下，近中侧RCEJ与牙槽嵴之间的距离减小，远中侧增大，在远中视角下则相反。所显示的与真实CEJ与牙槽嵴距离的偏差可能具有临床意义，因此建议在以RCEJ为参考点的根尖片上评估牙槽骨吸收情况时持谨慎态度。
