Elemental bio-imaging of trace elements in teeth using laser ablation-inductively coupled plasma-mass spectrometry

Objectives: In this study we present the application of a novel laboratory method that employs laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to construct two-dimensional maps of trace elements in teeth. Methods: Teeth were sectioned longitudinally, embedded in resin and polished to a smooth surface. Data were generated by laser ablating the entire sectioned tooth surface. Elemental images were constructed using custom-built software. Results: Quantified images of ⁶⁶Zn, ⁸⁸Sr, ¹¹¹Cd and ²⁰⁸Pb, with a spatial resolution of 30 μm², were generated from three teeth. Concentrations were determined by single-point calibration against NIST SRM 1486 (bone meal). Zn and Sr concentrations were determined in the μg g^-1 range and Cd and Pb in the ng g ^-1 range. Concentrations of Pb, Zn and Cd were higher in dentine particularly in regions adjacent the pulp. Conclusions: Elemental bio-imaging employing LA-ICP-MS is a novel method for constructing μm-scale maps of trace elements in teeth. This simple imaging method displays the heterogeneity of trace elements throughout the tooth structure that correspond to specific structural and developmental features of teeth. As a preliminary study, this work demonstrates the capabilities of LA-ICP-MS imaging in dental research.