Hurnanen Jaana, Visnapuu Vivian, Sillanpää Matti, Löyttyniemi Eliisa, Rautava Jaana
Department of Oral Pathology, Institute of Dentistry, Lemminkäisenkatu 2, FIN-20520 Turku, Finland.
Department of Anatomy, Faculty of Medicine, University of Turku, Kiinamyllynkatu 10, 20520 Turku, Finland.
Forensic Sci Int. 2017 Feb;271:87-91. doi: 10.1016/j.forsciint.2016.12.016. Epub 2016 Dec 21.
The delivery-related neonatal line (NNL) appears into the enamel of primary teeth and first permanent molars at birth and is a marker of live birth process. It varies in width and its location, is different in each deciduous tooth type, and is indicative of gestation time. It is unclear which triggers determine NNL at birth. Our objective was to investigate the effect of the duration and mode of delivery on NNL width. NNL of 129 teeth, a collection derived from a long-term, prospectively followed population cohort, was measured under light microscope. Altogether, 54 sections with most optimal plane of sectioning were analysed for the duration and mode of delivery. NNL was detected in 98% of the deciduous teeth with the median width of 9.63μm (min 3.16μm, max 27.58μm). A prolonged duration of vaginal delivery was highly significantly associated with a narrower NNL (r=-0.41, p=0.0097). No significant association was found between the width of NNL and mode of delivery (p=0.36). NNL is demonstrable in virtually all deciduous teeth. The width seems to be inversely proportional to the duration of delivery. Causes of the inverse proportion are speculated to result from altered amelogenesis induced by prolonged and intensified delivery-associated stress. Further research is needed to clarify the underlying mechanisms.
与分娩相关的新生儿线（NNL）在出生时出现在乳牙和第一恒磨牙的牙釉质中，是活产过程的一个标志。它在宽度和位置上有所变化，在每种乳牙类型中都不同，并且指示妊娠时间。目前尚不清楚哪些触发因素决定了出生时的NNL。我们的目的是研究分娩持续时间和方式对NNL宽度的影响。在光学显微镜下测量了来自一个长期前瞻性随访人群队列的129颗牙齿的NNL。总共分析了54个切片最理想的切片平面的分娩持续时间和方式。在98%的乳牙中检测到NNL，中位宽度为9.63μm（最小值3.16μm，最大值27.58μm）。阴道分娩时间延长与NNL变窄高度显著相关（r=-0.41，p=0.0097）。未发现NNL宽度与分娩方式之间存在显著关联（p=0.36）。几乎所有乳牙中都可显示出NNL。其宽度似乎与分娩持续时间成反比。推测这种反比关系的原因是延长和加剧的分娩相关应激导致釉质形成改变。需要进一步研究以阐明其潜在机制。
