Temporal and regional variation of the tooth size in the Japanese inhabitants based on crown and root-cervix measurements.

研究了日本居民从柔门期(约10,000-6,000 BP)到现代不同牙齿大小的时间和地区变化，不仅使用了牙冠的最大直径，而且还使用了一种新的不受牙齿磨损影响的牙根颈部测量方法。从雅瑶河石器时代(约2300-1700BP)到现代的移民群体的牙齿比本地群体，如琼蒙人和阿伊努人更大。移民Yayoi人口或史前科芬人口在移民群体中拥有最大的牙齿。Yayoi或Kofun牙齿大小在向现代逐渐减小，但时间上的减小伴随着一定的波动。新石器时代的乔蒙人和原住民的牙齿大小比原住民中的现代阿伊努人略有减少。最有趣的结果是绳纹时期长期的时间变化。在柔门期的开始-早期-中期-晚期(约10,000-2,300BP)，总牙齿大小随时间的增加而增加。柔门期的时间变化与同期全球范围内的牙齿减少趋势相反。近远中径与颊舌径、冠径与根颈径在变化方面存在一定差异。另一方面，第三磨牙与另一磨牙的比值随时间的增加而减少，而这种减少可能与总牙齿大小的时间增加相反。还需要进一步的研究，以澄清绳文时期发生特殊变化的因素。

Temporal and regional variations of the various tooth sizes from the Initial Jomon period (about 10,000-6,000 BP) to the modern period in the Japanese inhabitants were investigated, using not only the maximum diameter of tooth crown but also a new measurement of tooth root-cervix uninfluenced by tooth attrition.1. The migrant group from the Aeneolithic Yayoi period (about 2,300-1,700 BP) to the modern period has larger teeth than the native group such as the Jomonese and the Ainu.2. The migrant Yayoi population or the protohistoric Kofun population has the largest teeth in the migrant group. The Yayoi or Kofun tooth size finally decreases toward the modern period, but the temporal decrease is accompanied with some fluctuations.3. The tooth sizes of the Neolithic Jomonese and the native Yayoi population show some reduction toward the recent Ainu in the native group.4. The most interesting result is a temporal change in a long term of the Jomon period. A temporal increase of the general tooth size was observed in the Initial-Early-Middle-Late-Final Jomon period (about 10,000-2,300 BP). The temporal change in the Jomon period shows an opposite change to the tooth reduction of a global tendency in the same period. There are some differences of the changing aspects between mesiodistal diameters and buccolingual diameters, and between crown diameters and root-cervix diameters. On the other hand, a temporal reduction of the ratio of the third molar to the other molar was shown, while the reduction might be contrary to the temporal increase of the general tooth size. Further research will be required in order to clarify the factor of the peculiar change in the Jomon period.