Smith B H
Am J Phys Anthropol. 1986 Jan;69(1):21-35. doi: 10.1002/ajpa.1330690105.
The helicoidal plane of dental occlusion is a composite feature involving axial inclination of teeth and effects of dental attrition. Recent studies disagree on its distribution and significance in hominoid primates. The distribution, development, and functional basis of the helicoidal plane are investigated here, based on quantitative analysis of dental morphology and attrition in 667 human and 60 chimpanzee dentitions. Helicoidal planes are nearly universal in the human and chimpanzee dentitions studied. Increasing axial inclination of molars from M1 to M3 is primarily responsible for the helicoidal plane, although attrition acts to increase its expression. In hominoids, increased molar axial tilt appears to be associated with facial shortening and dental reduction. Population and species comparisons suggest a functional relationship with cranial structure. Progressive axial tilt of molars producing a helicoidal plane is found consistently in mammals with cheek teeth positioned partly under the cranium, as in hominids, pongids, some cebids, macropodids, ursids, and sciurids. Facial shortening is an important trend in hominid evolution and axial inclination of molars might be expected to show progressive change from Australopithecus afarensis to recent Homo sapiens.
牙合螺旋平面是一个复合特征，涉及牙齿的轴向倾斜和牙齿磨耗的影响。最近的研究对于其在类人猿灵长类动物中的分布和意义存在分歧。本文基于对667例人类和60例黑猩猩牙列的牙齿形态和磨耗的定量分析，研究了牙合螺旋平面的分布、发育及其功能基础。在所研究的人类和黑猩猩牙列中，牙合螺旋平面几乎普遍存在。从M1到M3磨牙轴向倾斜度的增加是形成牙合螺旋平面的主要原因，尽管磨耗会增强其表现。在类人猿中，磨牙轴向倾斜度增加似乎与面部缩短和牙齿减小有关。群体和物种比较表明其与颅骨结构存在功能关系。在颊齿部分位于颅骨下方的哺乳动物中，如人科动物、猩猩科动物、一些卷尾猴科动物、袋鼠科动物、熊科动物和松鼠科动物，始终能发现磨牙逐渐轴向倾斜产生牙合螺旋平面的情况。面部缩短是人类进化中的一个重要趋势，从阿法南方古猿到现代智人，磨牙的轴向倾斜度可能会呈现出逐渐变化的趋势。
