Wu Y, Xu J
Department of Prosthodontics, Wuxi Dental Hospital, Wuxi 214001, China.
Zhonghua Kou Qiang Yi Xue Za Zhi. 2000 Jul;35(4):274-6.
To investigate the relationship of axial crown contour and surrounding healthy gingiva contour.
Mandibular second premolars were selected as the object of study. Three cross-sections were made through crown and gingiva of the model tooth. Curve functions of axial buccal crown and gingiva contour of each section were acquired by means of curve fitting, and the angle of emergence profile was calculated, which represents the degree of undercut.
There is unique relationship between axial crown and gingiva contour individually. This character of tooth is similar to its contralateral tooth. The emergence profile angles are in the range of 40 degrees-110 degrees, 84.1% of the angles are in range of 70 degrees-110 degrees, 15.9% in 40 degrees-70 degrees, that is to say natural teeth are inclined to be of less undercut.
The geometric relationship between crown contour and gingiva contour is so characteristic that contralateral tooth should be the only guidance to replace lost tooth.
研究牙冠轴向轮廓与周围健康牙龈轮廓之间的关系。
选择下颌第二前磨牙作为研究对象。通过模型牙的牙冠和牙龈制作三个横截面。通过曲线拟合获得每个截面的牙冠颊侧轴向和牙龈轮廓的曲线函数，并计算出代表倒凹程度的牙冠龈缘角。
牙冠轴向轮廓与牙龈轮廓之间分别存在独特的关系。牙齿的这一特征与其对侧牙齿相似。牙冠龈缘角在40度至110度范围内，其中84.1%的角度在70度至110度范围内，15.9%在40度至70度范围内，也就是说天然牙倾向于倒凹较小。
牙冠轮廓与牙龈轮廓之间的几何关系具有如此特征，以至于对侧牙齿应是缺失牙修复的唯一指导。
