Neonatal line width in deciduous incisors from Neolithic, mediaeval and modern skeletal samples from north-central Poland

Association of Maternal Stress and Social Support During Pregnancy With Growth Marks in Children's Primary Tooth Enamel

Importance

Exposure to maternal psychosocial stressors during the prenatal and perinatal periods can have major long-term mental health consequences for children. However, valid and inexpensive biomarkers are currently unavailable to identify children who have been exposed to psychosocial stress and the buffers of stress exposure.

Objective

To assess whether a growth mark in tooth enamel, the neonatal line, is associated with exposure to prenatal and perinatal maternal psychosocial factors.

Design, Setting, and Participants

This prospective cohort study used exfoliated primary canine teeth and epidemiological survey data from 70 children enrolled in the Avon Longitudinal Study of Parents and Children, a birth cohort based in Bristol, England. Exfoliated teeth were collected from children at 5 to 7 years of age. Data were collected from January 1, 1991, to December 31, 1998, and were analyzed from January 1, 2019, to August 10, 2021.

Exposures

Four types of prenatal and perinatal maternal psychosocial factors were studied: stressful life events, psychopathological history, neighborhood disadvantage, and social support. Data were collected from mailed-in questionnaires completed during and shortly after pregnancy.

Main Outcomes and Measures

Neonatal line width measured within 3 portions of the tooth crown (the cuspal, middle, and innermost third) in exfoliated primary canines.

Results

A total of 70 children (34 of 70 [48.7%] male; 63 of 67 [94.0%] White) were studied. Most children were born full term (57 [83.8%]) and to mothers of typical child-bearing age (60 [88.2%]). Neonatal lines were wider in the canines of children born to mothers who self-reported severe lifetime depression (β = 3.35; 95% CI, 1.48-5.23; P = .001), any lifetime psychiatric problems (β = 2.66; 95% CI, 0.92-4.41; P = .003), or elevated anxiety or depressive symptoms at 32 weeks' gestation (β = 2.29; 95% CI, 0.38-4.20; P = .02). By contrast, neonatal lines were narrower in children born to mothers who self-reported high social support shortly after birth (β = -2.04; 95% CI, -3.70 to -0.38; P = .02). The magnitude of these associations was large, up to 1.2 SD unit differences, and persisted after adjusting for other risk factors.

Conclusions and Relevance

In this cohort study, neonatal line width was associated with exposure to maternal perinatal psychosocial factors. Replication and validation of these findings can further evaluate teeth as possible new biomarkers.

Dental microstructure records life history events: A histological study of mandrills (Mandrillus sphinx) from Gabon

Accentuated lines in dental microstructure are hypothesized to correlate with potentially stressful life history events, but our understanding of when, how and why such accentuated lines form in relation to stressful events is limited. We examined accentuated line formation and life history events in the teeth of three naturally deceased mandrills (Mandrillus sphinx, Cercopithecidae), for whom we had detailed life history information. We determined the ages at formation of accentuated lines in histological tooth sections and used dates of birth and death to calibrate dental histology to calendar time and individual age. We found accentuated lines that matched their mother's resumption of sexual cycles in two individuals, and possibly in the third individual. The subjects also formed lines when their mothers were mate-guarded by males or wounded. Accentuated lines matched the birth of the next sibling in one of two cases. Both females formed accentuated lines when they experienced their own sexual swelling cycles, but lines did not match all sexual swelling cycles. Mate-guarding matched an accentuated line in one case, but not in another. Lines matched all three parturitions in the two females. Changes in alpha male and captures did not consistently coincide with accentuated line formation, but repeated captures were associated with lines. Using simulated data, we show that the observed number of matches between lines and events would be very unlikely under a null hypothesis of random line formation. Our results support the hypothesis that some life history events are physiologically stressful enough to cause accentuated line formation in teeth. They contribute to our understanding of how primate life histories are recorded during dental development and enhance our ability to use teeth to reconstruct life history in the absence of direct observation.

Those who died very young-Inferences from δ15 N and δ13 C in bone collagen and the absence of a neonatal line in enamel related to the possible onset of breastfeeding

OBJECTIVES

Stable isotope analysis has often been used in neonatal remains from archeological contexts to investigate the presence of a signal of breastfeeding and weaning in past populations. Tooth histology on the other hand might be used as an indicator of birth survival. This pilot study aimed to investigate the feasibility of using stable nitrogen (δ¹⁵ N) and carbon (δ¹³ C) isotope values from neonatal bone collagen to elucidate if values deviating from the adult female average could indicate breastfeeding and co-occur with the presence of a neonatal line (NNL). The combination of these independent indicators might be useful in clarifying the fate of individuals who died around birth.

MATERIALS AND METHODS

Bone collagen from 21 archeological human and animal specimens was extracted and analyzed via mass-spectrometry for δ¹⁵ N and δ¹³ C. A verification of the stable isotope results was undertaken using tooth histology on three individuals who were investigated for the presence of a NNL as an indicator of live birth and short survival.

RESULTS

The biological age of the human samples varied between 8.5 lunar months (Lm) and 2 postnatal months (Pm) of age. All except one individual exhibited elevated δ¹⁵ N values compared to the female average. The histological analyses revealed no NNL for this and two further individuals (n = 3).

DISCUSSION

The results indicate that elevated nitrogen values of very young infants relative to a female average in archeological contexts are not necessarily associated with a breastfeeding onset signal, and therefore cannot be used exclusively as a proxy of birth survival. The elevation might be possible due to various reasons; one could be nutritional, in particular maternal stress during pregnancy or a metabolic disorder of mother and/or her child. In those cases, the evaluation of a NNL might reveal a false breastfeeding signal as seen for two individuals in our sample who have elevated nitrogen values despite the fact no NNL could be observed. Overall, our data support the growing awareness that bone collagen δ¹⁵ N values of neonates/infants should not be used as a proxy for breastfeeding or birth survival on its own.

Oral Pathology in Forensic Investigation

Forensic odontology is the subdiscipline of dentistry which analyses dental evidence in the interest of justice. Oral pathology is the subdiscipline of dentistry that deals with the pathology affecting the oral and maxillofacial regions. This subdiscipline is utilized for identification through oral and maxillofacial pathologies with associated syndromes, enamel rod patterns, sex determination using exfoliative cytology, identification from occlusal morphology of teeth, and deoxyribonucleic acid profiling from teeth. This subdiscipline is also utilized for age estimation studies which include Gustafson's method, incremental lines of Retzius, perikymata, natal line formation in teeth, neonatal line, racemization of collagen in dentin, cemental incremental lines, thickness of the cementum, and translucency of dentin. Even though the expertise of an oral pathologist is not taken in forensic investigations, this paper aims to discuss the role of oral pathology in forensic investigation.

Deciduous neonatal line: Width is associated with duration of delivery

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.