Tooth coronal and tooth root boundary show one arc curve, call tooth neck, renown neck predestined relationship or neck line.
牙冠与牙根交界处呈一弧形曲线，称为牙颈，又名颈缘或颈线。
2
Radiographic examination included Cobb Angle, rotation Angle of apical vertebrae, and translation of the C7 vertebra from the center sacral line on the coronal plane.
线检查包括Cobb角，椎体顶点的旋转角和C7椎体在冠状面从骶正中线的平移。
3
Generally, the anterior line of the coronal sulcus was indistinct, whereas the posterior line was clear and easy to be identified.