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

根据牙冠和牙根-宫颈测量，日本居民牙齿尺寸的时间和区域变化。

• 批准号: 10640692
• 负责人: ROKUTANDA Atsushi
• 金额: $ 0.77万
• 依托单位: Nagasaki University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10640692/
• 关键词: tooth size; root cervix; temporal variation; Japanese; Yayoi period; tooth reduction; microevolution; 歯の人類学; 時代的変異; 地域的変異; 日本列島; 歯根歯頚部; 渡来

Temporal variations(2,300-O.B.P.) of the various tooth sizes of the Aeneolithic Yayoi(2,300-1,799 B.P.), Protohistoric Kofun(1,700-1,300 B.P.), Medieval Kamakura (800-700 B.P.), and Late Modern period(130-O.B.P.) in the Japanese archipelago were investigated, using not only the maximum diameter of crown but also a new measurement of root-cervix uninfluenced by tooth attrition.Total tooth size in the Kofun period is the biggest, and the size in the Yayoi period is the next biggest. On the other hand, the total size in the Kamakura peroid is the smallest, and the next smallest period is the modern. The total tooth size reduced finally, but the size did not reduce constantly. There were some increase and some reducton in the temporal reduction.In general, mesiodistal diameters have stronger reduction than buccolingual diameters. The tooth root-cervix reduced stronger than tooth crown. Upper teeth has stronger reduction than lower teeth. Some teeth has more reduction than other teeth. Thus is was made clear that different parts of the dentition have different reduction rates.Temporal change of crown index and root index(buccolingual diameter/mesiodistal diameter)indicated that changing rate of buccolingual diameter and mesiodistal diameter are different. Temporal variation of crown-root index(root-cervix measurement /crown measurement) made it clear that robustness of the tooth cervix reduced gradually.Though old studies of the temporal change of the tooth size paid attention to the total change of the tooth size, this study suggested that different parts of the dentition have different direction and rate of temporal change. Further research will be required in order to clarify the factor of the temporal change of the tooth size in the Japanese archipelago.

时间变化(2,300-O.B.P.)在古石器时代雅代(2,300-1,799 B.P.)、史前科芬(1,700-1,300 B.P.)、中世纪镰仓(800-700 B.P.)和现代晚期(130-O.B.P.)的各种牙齿大小中，在日本群岛，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根颈测量方法，总牙齿尺寸在高峰期最大，弥生时期次之。而镰仓时期的总规模最小，其次是现代时期。总的牙齿大小最终减小，但大小并没有持续减小。颞部直径有增加也有减少，总体上近远中径比颊舌径的减少程度更大。牙根颈部缩小程度大于牙冠。上牙比下牙有更强的还原能力。有些牙齿比其他牙齿有更多的缩小量。牙冠指数和牙根指数(颊舌径/近远中径)的动态变化表明，颊舌径和近远中径的变化率不同。冠根指数(根颈测量/牙冠测量)的时间变化表明牙颈的稳健性逐渐降低，虽然以往关于牙齿大小随时间变化的研究关注牙齿大小的总体变化，但本研究表明牙列不同部位的时间变化方向和速度不同。为了弄清日本群岛牙齿大小随时间变化的因素，还需要进一步的研究。