Aas I H, Risnes S
Acta Odontol Scand. 1982;40(6):421-8. doi: 10.3109/00016358209025116.
A morphologic trait, not previously registered, on the incisor lingual surface: "The lingual angle of incisors", was studied in Norwegians. The lingual angle is the angle between the floor of the lingual fossa and the dental tubercle. Measurements of the lingual angle could be performed with sufficient accuracy. Deviations from normal distribution in skewness and kurtosis values did not affect statistical testing. The general similarity of the frequency polygons for all incisors in the way they were peaked and stepped is possibly due to participation of the same factors on the genetic level in the determination of the trait. The mean lingual angles were (in degrees): I1sup = 142, I2sup equal 156, I1inf = 153 and I2inf = 154. No significant bilateral asymmetry or sex differences were found. Correlations were high for both central to central and lateral to lateral incisors in both jaws, highest for centrals in the maxilla and laterals in the mandibula. Central to lateral correlations were relatively low, especially in the upper jaw. Interjaw correlations were low, but I1sup showed a tendency to be better correlated than I2sup to lower incisors. I2sup and I1inf were the most variable incisors in each jaw. The dental tubercle probably plays an important role in determining the lingual angle. Measurements of the lingual angle give information on the profile of the lingual surface in inciso-cervical direction. Statistical analysis of a phenotypic trait may give information on factors which determine the trait.
“切牙舌角”。舌角是舌窝底部与牙结节之间的夹角。舌角的测量可以达到足够的精度。偏度和峰度值偏离正态分布并不影响统计检验。所有切牙的频率多边形在峰值和阶梯状方面的总体相似性可能是由于在该特征的决定过程中，相同因素在基因层面的参与。舌角的平均值（单位：度）为：上中切牙（I1sup）= 142，上侧切牙（I2sup）= 156，下中切牙（I1inf）= 153，下侧切牙（I2inf）= 154。未发现明显的双侧不对称或性别差异。上下颌中，中切牙与中切牙、侧切牙与侧切牙之间的相关性都很高，在上颌中中切牙之间的相关性最高，在下颌中侧切牙之间的相关性最高。中切牙与侧切牙之间的相关性相对较低，尤其是在上颌。上下颌之间的相关性较低，但上中切牙（I1sup）与下切牙的相关性比上侧切牙（I2sup）与下切牙的相关性有更好的趋势。在每个颌骨中，上侧切牙（I2sup）和下中切牙（I1inf）是变异性最大的切牙。牙结节可能在决定舌角方面起重要作用。舌角的测量提供了切牙舌面在切缘 - 颈部方向的轮廓信息。对一种表型特征的统计分析可能提供关于决定该特征的因素的信息。
