The neonatal line is a particular band of incremental growth lines seen in histologic sections of both enamel and dentine of primary and permanent teeth. It is made partly after birth. It belongs to a series of a growth lines in tooth enamel known as the Striae of Retzius. The neonatal line is darker and larger than the rest of the striae of Retzius. It is caused by the different physiologic changes at birth and is used to identify enamel formation before and after birth.
In forensic dentistry, the neonatal line can be used to distinguish matters such as if a child died before or after birth and approximately how long a child lived after birth.
These lines are formed in Enamel and dentine at the point of birth. Therefore, only teeth that are developing at birth can exhibit neonatal lines. All the primary teeth are forming at birth. The first permanent molar is just beginning calcification at or near birth.
References
- Cate, A.R. Ten. Oral Histology: development, structure, and function. 5th ed. 1998. ISBN 0-8151-2952-1.
- Biology of the Human Dentition