Ryan A S
Am J Phys Anthropol. 1979 Feb;50(2):155-68. doi: 10.1002/ajpa.1330500204.
Two experimental methods were used to produce wear striations in one direction on unworn teeth. These include: (1) sliding 22 American Indian (Juntunen site, Michigan; Late Woodland) newly erupted incisors, by hand, across a flat grass surface covered with fine loose sand; and (2) using a unidirectional motor driven mechanical wear machine to draw 56 modern human dental extractions across a flat glass surface covered with silicon carbide powder of different grit sizes. A scanning electron microscope examination of individual wear striation morphology indicates that these wear striations begin with broad pits and have extending grooves that become narrower; characteristics that indicate the motion of wear. Patterns of wear striations on the worn dentitions of American Indians (Juntunen site) and the paleocene primate Phenacolemur pagei show similar characteristics and correspond to the buccal phase of mastication when the mandible is drawn upward, forward and slightly medially into centric occlusion. The data provided by this study can be used to test competing hypotheses concerning the direction of mandibular movement during mastication and food preparation.
采用两种实验方法在未磨损的牙齿上产生单向磨损条纹。这些方法包括：（1）用手将22颗美国印第安人（密歇根州Juntunen遗址；晚期林地文化）新萌出的门牙，在覆盖着细松散沙子的平坦草地表面上滑动；（2）使用单向电动机械磨损机，将56颗现代人类拔牙样本在覆盖有不同粒度碳化硅粉末的平坦玻璃表面上拖动。对单个磨损条纹形态的扫描电子显微镜检查表明，这些磨损条纹始于宽凹坑，并具有延伸且变窄的沟槽；这些特征表明了磨损的运动情况。美国印第安人（Juntunen遗址）磨损牙列上的磨损条纹模式与古新世灵长类动物菲纳科尔穆尔·帕吉的磨损条纹模式显示出相似特征，并且与下颌向上、向前并略微向内移动至正中咬合时的咀嚼颊侧阶段相对应。本研究提供的数据可用于检验有关咀嚼和食物准备过程中下颌运动方向的相互竞争的假设。
