Using teeth as tools: Investigating the mother-infant dyad and developmental origins of health and disease hypothesis using vitamin D deficiency.

OBJECTIVES: With a growing interest in the mother-infant dyad and the Developmental Origins of Health and Disease hypothesis among biological and medical anthropologists, this study set out to provide all the information required to evaluate if mineralization defects in dentine might be caused by vitamin D deficiency in the critical first 1000 days of life. MATERIALS AND METHODS: Information was compiled on dentine formation in utero to approximately 18 years, and a method for determining the location of the neonatal line in dentine was devised, allowing the assessment of the prenatal and early life period. Re-evaluation of previously analyzed teeth (n = 61) was undertaken with detailed examination of n = 5/22 first permanent molars forming in the prenatal and critical early life periods. RESULTS: First permanent molars and all deciduous teeth give information on intrauterine development and on the first 1000 days postnatally providing a direct window on maternal and fetal health. Three archaeological individuals had interglobular dentine that formed prenatally suggesting that their mothers experienced vitamin D deficiency at the time dentine was forming and all other individuals had a deficiency during the first 1000 days of life. Conditions that could cause systemic mineralization defects were determined, and in each, case they were found to be consistent with vitamin D deficiency. DISCUSSION: The neonatal line serves as a clear baseline for determining prenatal and postnatal events, particularly those related to vitamin D, calcium, and phosphate metabolism, and can be used to investigate the maternal-infant dyad for both past and present communities.

Micro-CT assessment of dental mineralization defects indicative of vitamin D deficiency in two 17th-19th century Dutch communities.

OBJECTIVES: This study investigates vitamin D deficiency patterns in individuals from birth to the beginning of adolescence. Microscopic computed tomography (micro-CT) evaluation of interglobular dentine (IGD) in teeth provides information on the age of disease onset and the number of deficient periods per individual, which will increase our understanding of factors influencing vitamin D deficiency prevalence, including sociocultural practices and latitude. MATERIALS AND METHODS: Beemster and Hattem, two Dutch 17th-19th century communities, yielded relatively high prevalences of rickets (15-24%) and residual rickets (15-24%). From the affected individuals, a subsample of 20 teeth were selected for micro-CT scanning. Thin sections were made of 17 teeth, consisting of 6 teeth with and 11 teeth without observable IGD on micro-CT that were included for method comparison. RESULTS: About 19 out of 29 (65.5%) individuals (one tooth was deemed unobservable) presented with IGD on micro-CT. Eight of the 11 (72.7%) individuals without IGD on micro-CT demonstrated histologically visible IGD. In 40.7% (11/27) of the affected individuals (combined micro-CT and histology results), vitamin D deficiency was recurrent, and in four individuals, some episodes occurred at approximately annual intervals suggesting vitamin D deficiency was seasonal. In three individuals, IGD occurred in the dentine formed around birth, suggesting maternal vitamin D deficiency. DISCUSSION: Micro-CT analysis of IGD is found to be a valuable non-destructive method that can improve our understanding of the influence of sociocultural practices and latitude on disease development within age and sex groups in past communities.

The rachitic tooth: The use of radiographs as a screening technique.

This study investigates morphological changes in pulp chambers of living and archaeological individuals with past vitamin D deficiency. Living individuals (n=29), four with detailed medical and dental records and three groups of archaeological individuals (n=25) were radiographed; selected individuals were further evaluated histologically for the presence of incremental interglobular dentin (IIGD), indicative of deficiency (28 living; 17 archaeological). Measurements of pulp horns/chambers from radiographs were conducted to quantify morphological observations. One group had clear skeletal evidence of rickets from St. Matthew, Quebec (n=1) and St. Jacques, France (n=4); a second group had slight skeletal indicators from Bastion des Ursulines, Quebec (n=6); and a third group lacked both skeletal and radiological evidence of deficiency from St. Antoine (n=6) and Pointe-aux-Trembles (n=4). Results showed archaeological individuals with clear and slight skeletal evidence of past deficiency displayed constricted or chair shaped pulp horns. Living individuals with deficiency exhibited similar pulp chamber morphology. Radiographic pulp horn/chamber measurements corroborated morphological findings and significant differences were found in pulp horn/chamber measurements between those with and without deficiency. Results suggest that radiograph assessment of teeth can be used as a screening technique to elucidate patterns of deficiency and select individuals for microCT or histological assessment.

The rachitic tooth: Refining the use of interglobular dentine in diagnosing vitamin D deficiency.

PURPOSE: This study provides guidelines on how IGD can be differentiated from other microstructures that naturally occur in dentine. Interglobular dentine (IGD) has recently been linked to disruption in vitamin D, calcium, and phosphorous pathways offering a valuable method to investigate vitamin D deficiency in archaeological individuals, but not all dentine defects are IGD. METHODS: A detailed review of dental literature and dental histology cases gathered from known living and archaeological individuals were incorporated into interpretations. RESULTS: Investigation of tooth dentine revealed that there can be instances where IGD is not linked to vitamin D deficiency. Information on how to differentiate different forms of defects in dentine were identified. CONCLUSIONS: We conclude that caution is required when evaluating low-grade IGD, as it may be misidentified. CONTRIBUTION TO KNOWLEDGE: Information reviewed and assimilated contributes to refining the role of IGD to act as a biological marker, particularly in less severe cases of vitamin D deficiency through provision of clear guidance. LIMITATIONS OF THIS STUDY: Information from earlier experimental work is limited and until recently understanding of vitamin D and deficiency of this pro-hormone was restricted. SUGGESTIONS FOR FURTHER RESEARCH: Further data could be gathered from living individuals with known biological/medical information.

Age estimation in older adults: Use of pulp/tooth ratios calculated from tooth sections.

OBJECTIVES: Accurate age estimates are foundational for bioarchaeological research, yet the ability to accurately age older adult skeletons remains elusive. This study uses a new version of pulp/tooth area calculations to investigate chronological age of older archaeological individuals. MATERIALS AND METHODS: Pulp/tooth area ratios were calculated on modern control teeth (n = 10) that were first radiographed and then sectioned for comparative analysis. Pulp/tooth area ratios were determined on sectioned teeth using ImageJ software for: (a) modern individuals of known age (n = 26); (b) individuals from Belleville, Ontario, Canada (1821-1874) with documented age (n = 50); and (c) Belleville individuals with skeletally estimated age (n = 122). RESULTS: Calculations from tooth sections on modern teeth (n = 10) resulted in a mean absolute error (MAE) of ±3.9 years, whereas the radiographic method for the same teeth had an MAE of ±14.45 years. Results indicate that sectioned pulp/tooth area ratios are a significant predictor of chronological age (p < .005), with MAEs of ±4.53 years for Belleville and ±3.77 years for modern individuals. There were no statistically significant differences in age estimations between modern and archaeological individuals, or with respect to tooth type, sex, or intra/inter-observer estimations. DISCUSSION: This study provides a new more accurate method for estimating age-at-death, particularly for individuals in the 50+ age category. Sectioning the teeth and directly measuring exposed pulp chambers results in age estimations that were within ±4.15 years for both modern and archaeological individuals, thus presenting a method that will enhance the ability to age older individuals.

You are not what you eat during physiological stress: Isotopic evaluation of human hair.

Variation in δ(13) C and δ(15) N values can be assessed to understand not only diet, but also the influence of physiological factors on an individual. The metabolic balance of an individual can impact isotopic signals in tissues that are forming during the periods of metabolic stress. Fluctuating δ(15) N values are associated with physiological stressors that alter an individual's metabolism such as infection, injury, or pregnancy. This study examines variation in δ(13) C and δ(15) N values along sequentially segmented hair in both modern and archaeological individuals. Subjects with an observable skeletal pathology, known chronic illness, or evidence of pregnancy were compared with controls exhibiting no evidence of physiological stress. The results on hair samples from individuals from 19(th) century Belleville, Ontario, four modern cadavers (two with cancer and two sudden deaths), and two living pregnant women indicate that δ(15) N values are approximately 1‰ higher in individuals with a pathological condition (e.g., infection, fracture, or cancer) and are 1‰ lower during pregnancy, whereas δ(13) C values show less variability. Higher nitrogen values may represent the recycling of nitrogen derived from the breakdown of existing proteins in the body (catabolism), whereas lower δ(15) N values are related to increased utilization of dietary and urea nitrogen for tissue synthesis during pregnancy. These findings suggest that short-term fluctuations of δ(15) N values may be the result of changes in an individual's metabolic balance, and that metabolic imbalance poses a confounding factor to ancient dietary studies when using rapidly growing tissues such as hair.