The use of teeth as the site for the in vivo or ex vivo quantification of skeletal strontium by energy-dispersive X-ray fluorescence spectrometry: A feasibility study

Abstract

<p>The use of an energy-dispersive X-ray fluorescence spectrometry (EDXRF) system equipped with an 125I source was validated for <em>in vivo</em> and <em>ex vivo</em> quantification of strontium in human teeth. The mean concentration of enamel strontium for an area with a high influx of immigration (Toronto, Ontario, Canada) is also reported. It was found that the mass attenuation of the strontium and calcium X-rays allows for a probing depth of 1.8 mm (Sr Kα) allowing the front central incisors to act as the site for the <em>in vivo</em> or <em>ex vivo</em> quantification of strontium as well as for molars to be used <em>ex vivo</em> for the quantification of enamel strontium. The calcium signal for all teeth studied (<em>n</em> = 42) was found to have a relative standard deviation of 5.7% which allowed for successful normalization of the strontium signal to that of calcium. Validation of the EDXRF method was performed on human molars (enamel thickness of (1.9 ± 0.7) mm, <em>p</em> < 0.05), by graphite furnace atomic absorption spectrometry (GFAAS). The EDXRF method was found to produce equivalent strontium determinations to that of GFAAS (<em>p</em> < 0.05). Our results also demonstrate that for a sample from a large metropolitan area, the fresh enamel strontium concentrations range from 42–301 ppm with a mean strontium concentration of (169 ± 80) ppm (<em>p</em> < 0.05).</p>