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目的:通过对上、下颌第一磨牙不同部位生理性磨耗的观察,探讨磨耗特征及其生理意义.方法:551 个上颌第一磨牙和686 个下颌第一磨牙,根据磨耗程度分为轻、中、重度( 绝对磨耗程度),根据单个牙上不同部位磨耗程度排序( 相对磨耗程度),比较各部差别.结果: 上颌第一磨牙磨耗程度由重到轻排序:近、远舌尖＞ 近、远中边缘嵴＞ 近、远颊尖;下颌第一磨牙排序:远中尖、远中边缘嵴＞ 近、远颊尖＞ 远舌尖＞ 近舌尖、近中边缘嵴.结论:上颌第一磨牙以舌尖磨耗最重,而下颌第一磨牙则为远中部磨耗最重,可能与局部咬合力作用时间及作用强度有关.“,”Aim:To observe the physiological attrition levels and its physiological significance in the upper and lower first molar. Methods:551 upper first molars and 686 lower first molars were collected. The absolute attritional degrees(light, middle and heavy) according to the attrition grade. The relative attritional dogree of the cusps and ridges in individual tooth was recorded and compared among them. Results: The attritional degree in upper first molar was in the order of mesial, distal lingual cusp>mesial, distal marginal ridge >mesial, distal buccal cusp. While in the lower first molar it was distal cusp and marginal ridge> mesial, distal buccal cusp> distal lingual cusp> mesial lingual cusp and mesial marginal ridge. Conclusions: The heavier attrition in upper first molar was lingual cusp and in the lower first molar was distal part. The difference in attrition distribution was probably due to the unbalance of duration and strength of the local occlusion force.