title: Deciduous neonatal line: Width is associated with duration of delivery.
abstract: 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.
authors.affiliation: Department of Oral Pathology, Institute of Dentistry, Lemminkäisenkatu 2, FIN-20520 Turku, Finland. Electronic address: jaanahurnanen@hotmail.com.
authors.forename: Jaana
authors.initials: J
authors.lastname: Hurnanen
authors.affiliation: Department of Anatomy, Faculty of Medicine, University of Turku, Kiinamyllynkatu 10, 20520 Turku, Finland.
authors.forename: Vivian
authors.initials: V
authors.lastname: Visnapuu
authors.affiliation: Department of Child Neurology, Faculty of Medicine, University of Turku, Kiinamyllynkatu 10, 20520 Turku, Finland; Department of Public Health, Faculty of Medicine, University of Turku, Kiinamyllynkatu 10, 20520 Turku, Finland.
authors.forename: Matti
authors.initials: M
authors.lastname: Sillanpää
authors.affiliation: Department of Biostatistics, Faculty of Medicine, University of Turku, Kiinamyllynkatu 10, 20520 Turku, Finland.
authors.forename: Eliisa
authors.initials: E
authors.lastname: Löyttyniemi
authors.affiliation: Department of Oral Pathology, Institute of Dentistry, Lemminkäisenkatu 2, FIN-20520 Turku, Finland; Department of Pathology, Faculty of Medicine, University of Turku, Kiinamyllynkatu 10, 20520 Turku, Finland.
authors.forename: Jaana
authors.initials: J
authors.lastname: Rautava
mesh_terms: D000328:Adult; D015415:Biomarkers; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D036861:Delivery, Obstetric; D003743:Dental Enamel / Q000033:anatomy & histology*; D003804:Dentin / Q000033:anatomy & histology*; D019229:Dentition, Permanent; D005260:Female; D005500:Follow-Up Studies; D005553:Forensic Dentistry; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D050498:Live Birth; D008297:Male; D008853:Microscopy; D011247:Pregnancy; D012494:Sampling Studies; D013997:Time Factors; D014094:Tooth, Deciduous / Q000033:anatomy & histology*
chemical_list: D015415:Biomarkers
keywords: Duration of delivery; Forensic odontology; Long-term study; Mode of delivery; Neonatal line; Population sample