title: Spatial distribution of manganese in enamel and coronal dentine of human primary teeth.
abstract: Emerging evidence indicates that excessive exposure to manganese (Mn) during the prenatal period and early childhood may result in neurodevelopmental deficits. However, accurate exposure biomarkers are not well established, limiting our understanding of exposure-response relationships over these susceptible periods of development. Naturally shed deciduous teeth are potentially a useful biomarker of environmental exposure to Mn. However, the uptake and distribution of Mn in human teeth has not been studied in detail. Mn distribution was measured at high resolution (~20 μm) in eight human primary teeth using laser ablation-inductively coupled plasma-mass spectrometry. A bio-imaging methodology was applied to construct detailed elemental maps of three incisors, and bone meal (NIST SRM 1486) was used to validate the analyses. The distribution of Mn in enamel and coronal dentine showed a distinct and reproducible pattern. In enamel, the ⁵⁵Mn:⁴³Ca ratio was highest at the outer edge of enamel (range=0.57 to 4.74) for approximately 20-40 μm but was substantially lower in deeper layers (range=0.005 to 0.013). The highest levels of Mn were observed in dentine immediately adjacent the pulpal margin (⁵⁵Mn:⁴³Ca range=2.27 to 6.95). Importantly, a clearly demarcated high Mn zone was observed in dentine at the incisal end of the teeth. Using confocal laser scanning microscopy to visualize the neonatal line, this region was identified as being in the prenatally formed dentine. The high-resolution map of the spatial distribution of Mn in human primary teeth highlighted specific reproducible patterns of Mn distribution in enamel and coronal dentine.
authors.affiliation: Institute of Dental Research, Westmead Centre for Oral Health, Westmead Hospital, Westmead, Australia. manish.arora@sydney.edu.au
authors.forename: Manish
authors.initials: M
authors.lastname: Arora
authors.forename: Dominic
authors.initials: D
authors.lastname: Hare
authors.forename: Christine
authors.initials: C
authors.lastname: Austin
authors.forename: Donald R
authors.initials: DR
authors.lastname: Smith
authors.forename: Philip
authors.initials: P
authors.lastname: Doble
mesh_terms: D015415:Biomarkers / Q000737:chemistry / Q000378:metabolism; D003743:Dental Enamel / Q000378:metabolism*; D003804:Dentin / Q000737:chemistry / Q000378:metabolism*; D004784:Environmental Monitoring / Q000379:methods*; D004785:Environmental Pollutants / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008345:Manganese / Q000737:chemistry / Q000378:metabolism*; D013058:Mass Spectrometry; D014094:Tooth, Deciduous / Q000737:chemistry / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D004785:Environmental Pollutants; D008345:Manganese