Neonatal line on fetus and infant teeth: An indicator of live birth and mode of delivery

摘要

Background: The neonatal line (NL) is an important issue in forensic odontology. It is the sign of a developmental birth defect, which is caused by the effect of metabolic stress on tooth structures when the fetus passes to extrauterine life. Aims: The aim of this research is to determine the existence and thickness of NL in teeth, as it is a legal necessity to indicate the signs of viability at birth in a forensic examination of a fetus or infant case. Study design and subjects: This research was conducted on 48 lower left and right lateral teeth, which were taken from 24 autopsy cases (46% female and 54% male). Left lateral teeth were sectioned in a vertical plane and right lateral teeth were sectioned in a horizontal plane. The NL thickness was measured with a scanning electron microscope (SEM). These cases comprised three conditions as: 70.3% normal birth, 16.7% caesarean sections, and 12.5% still birth cases under the legal and ethical permission. Outcome measures: The mean NL thickness of normal birth cases was higher than caesarean cases as 7.7. μm and 2.5. μm, respectively. Results and conclusions: The results showed a statistical significance between all birth conditions. NL does not exist in still birth cases (p < 0.001). Not only is the presence of NL a sign of live birth, but also its thickness is an indicator of the delivery mode where NL thickness of normal birth was found thicker than the caesarean cases.