6000年前成人第三磨牙的研究

The position of the third molar in the adult subjects about 6 000 years ago

目的:观察距今约6 000年前成人第三磨牙的位置情况。方法:研究了200个半坡博物馆内保存的新石器时代人颌骨标本,第三磨牙共383颗(上颌187颗,下颌196颗),观察第三磨牙的萌出情况。第三磨牙未萌出者经X线片证实,按有无第三磨牙牙胚,将其分别归为埋伏阻生组或先天缺失组。结果:上颌第三磨牙先天缺失率为26.74%,下颌第三磨牙先天缺失率为17.35%。上颌第三磨牙阻生率为2.67%,下颌第三磨牙阻生率为14.79%。结论:现代人第三磨牙阻生率与先天缺失率均较新石器时代成人高,人类第三磨牙阻生与先天缺失是伴随整个人类进化而发生的咀嚼器官退化现象的一部分。

Objective：To observe the position of the third molar in the neolithic adults about 6 000 years ago. Methods： On the basis of the maxillary and mandibular specimens preserved in Banpo museum, 200 maxillary and mandibular specimens with 383 third molars, 187 maxillary and 196 mandibular,were observed for the eruption of the third molar. The teeth in the non-eruption group were further divided into impact group and congenital absent group according to the third molar germ presence testified by X ray. Results：The congenital absent rates of maxillary and mandibular third molar were 26.74% and 17.35%, while the impact rates of maxillary and mandibular third molar were 2.67% and 14.79% respectively. Conclusion：Both the congenital absent rate and the impact rate of the third molar in neolithic era adults are lower than those in modern, the impact and congenital absence of the third molar are part of degradation of masticatory organ with whole humanity progressing.