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

Abstract

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.

Keywords: interglobular dentine; maternal health; neonatal line; prenatal vitamin D deficiency.

Figure 1

Diagram showing five stages of incremental deposition of enamel and dentine (modified from Avery, 2002, p. 91; Shellis, 1981, p. 167) in a generic first permanent molar. (a) Initial dentine deposition that occurs prenatally. Note that dentine horns form prior to enamel during tooth development. (b) Incremental growth of enamel, arrows = direction of growth for enamel. (c) Incremental growth of dentine, arrows = direction of growth for dentine. (d) Pattern of growth of both dentine and enamel. (e) Continued growth of dentine and enamel and initiation of pulp chamber. Enamel = light color; dentine = dark color; pulp chamber = darkest color; dotted lines = neonatal line in enamel and dentine; crosshatching = prenatal zone in dentine

Figure 2

15A‐S36 showing the neonatal line in the enamel (white dashed line) and location of the measurement taken to extrapolate the prenatal zone in dentine using ImageJ. The prenatal zone in dentine (black dotted triangular region) was measured as equidistant from the neonatal line visible in the enamel (×50 magnification using a polarizing filter). The white arrow approximates the enamel and dentine formed prenatally, where IGD can be observed in the dentine. DEJ, dentino–enamel junction

Figure 3

Approximate ages of mineralization using the incremental pattern of growth for human teeth. (a) Ages of mineralization in deciduous teeth. (b) Ages of mineralization for permanent teeth. Enamel = white, dentine = grey; dotted line = neonatal line; AC = apical closure. Data for the compilation for the figure were drawn from the following sources: AlQahtani, 2008; Dean, Beynon, Reid, & Whittaker, 1993; Gustafson & Koch, 1974; Haavikko, 1974; Hillson, 2002, 2014; Liversidge & Molleson, 2004; Lunt & Law, 1974; Massler, Schour, & Poncher, 1941; Moorrees, Fanning, & Hunt, 1963; Smith, 1991; van Beek, 1983. Note: Ages were averaged from above sources. New information on age of incremental dentine deposition was added for the permanent third molar from our analysis of this tooth type

Figure 4

Image of sectioned tooth obtained using a polarizing filter, 2E4, Saint‐Marie (RM¹). The tooth is at Crc (crown complete), Ri (root initiated) stage (Moorrees et al., 1963). The two episodes of deficiency identified (Table 2) are indicated *1 = prenatal episode and *2 = 2.5 years. (a, b) Close‐ups of episode 1 in which prenatal IGD formed beneath both the dentine horns. (c, d) Close‐ups showing the relationship between episode 1 and episode 2 which formed in dentine under the crown at a later age. DEJ, dentino–enamel junction; IGD, interglobular dentine