School of Anthropology and Conservation, University of Kent, Canterbury, CT2 7NR, UK.
Am J Phys Anthropol. 2011 Feb;144(2):204-14. doi: 10.1002/ajpa.21386. Epub 2010 Aug 25.
Quantitative studies of incremental markings retained within human enamel have reconstructed the duration and rate (crown and cusp formation times, initiation and completion, daily enamel secretion rates) of permanent tooth development. This approach has provided one way of estimating human age-at-death, and facilitated comparative dental studies of primate evolution. Similar applications from deciduous enamel are inhibited because developmental reconstructions from incremental markings for these teeth are less frequently reported in the literature. This study quantified the duration and rate of enamel development for mesial (protoconid, metaconid) and distal cusps (hypoconid, entoconid) for first (dm1) and second (dm2) deciduous mandibular molars from an archaeological sample of modern human juveniles. Crown formation time can be calculated from the dm1 protoconid because growth initiates and completes in this cusp, and from the dm2 protoconid combined with the final period of hypoconid growth. The dm1 postnatal crown formation time included the time taken for the tubercle of Zuckerkandl to develop, and differed slightly compared to radiographic methods. The majority of dm1 protoconid cuspal (occlusal region) enamel formed before birth. The dm2 entoconid enamel formed mainly after birth. Birth reduced daily enamel secretion rates, changed the visibility of incremental markings, and disrupted enamel growth for 3 to 8 days. Findings presented here can contribute to age-at-death estimates for human infants aged 13-postnatal months or less, and should facilitate comparisons of primate deciduous incremental enamel development in an evolutionary context. Regression equations are included so that cuspal formation time can be estimated from enamel thickness.
定量研究人类牙釉质内保留的增量标记物，重建了恒牙发育的持续时间和速率（牙冠和牙尖形成时间、起始和完成时间、每日牙釉质分泌率）。这种方法提供了一种估计人类死亡年龄的方法，并促进了灵长类动物进化的比较牙科研究。由于这些牙齿的增量标记物的发育重建在文献中较少报道，因此乳牙的类似应用受到抑制。本研究量化了来自现代人类青少年考古样本的第一（dm1）和第二（dm2）下颌乳磨牙近中（原尖，后尖）和远中（下尖，内尖）牙尖的牙釉质发育的持续时间和速率。由于生长在这个牙尖中开始和完成，因此可以从 dm1 原尖计算出牙冠形成时间，并且可以从 dm2 原尖结合下尖的最后生长阶段计算出牙冠形成时间。dm1 出生后牙冠形成时间包括 Zuckerkandl 结节发育所花费的时间，并且与放射学方法略有不同。大部分 dm1 原尖牙尖（咬合区）牙釉质在出生前形成。dm2 内尖牙釉质主要在出生后形成。出生降低了每日牙釉质分泌率，改变了增量标记物的可见性，并中断了牙釉质生长 3 到 8 天。本文提出的研究结果可以为 13 个月或以下的人类婴儿的死亡年龄估计做出贡献，并应有助于在进化背景下比较灵长类动物乳牙的增量牙釉质发育。本研究还包括回归方程，以便可以根据牙釉质厚度估计牙尖形成时间。
