【摘要】 下颌磨牙发育沟有着各种形态，作者采用国际通用的分类方法，将下颌磨牙发有沟的类型分为“Y5”、“Y4、“＋5”、“＋4”、“X5”、“X4”六种形态，经过计算机统计分析，得出结果；（1）下颌第一磨牙“Y5”的发生率最高，“X4”的发生率最低；（2）下颌第二磨牙“＋4”的发生串最高，“Y5”的发生率最低；（3）男、女间发生率经t检验无明显差异。本结果与人类下颌磨牙进化方向一致，对于指导临床治疗、人类学的研究均有非常重要的实际意义。更多还原

【Abstract】 During human evolution, the morphology of mandibular molar occlusalgrooves have changed from the pattern "Y" to pattern "＋" and pattern "X" .Six types of occlusal grooves were classified as: Y5,Y4, +5, +5,X5 and X4. Using computer analysis,we getthe results. (1). The rate of "Y5" in first mandibular molar is the higest,the rate of "x4" isthe lowest. (2). The rate of "+4" in second mandibular molar is the higest,while the rate of"Y5"is the lowest. (3). The rates of each type groove between male and female have no significant difference. Our conclusion coincides in the evolution of human mandibular molar,that ishelpful to direct the clinic and anthropology study.更多还原