X-ray Fluorescence, x-ray scattering, and x-ray attenuation measurements of a primary incisor tooth slice using a table-top microbeam system*

Primary teeth are easily accessible human tissues. Measurements of their bulk and trace elemental composition can be used to study developmental health issues such as malnutrition or exposure to toxic elements. X-ray fluorescence (XRF) elemental detection is nondestructive, fast, and inexpensive. An experimental and modelling approach to find the concentrations of five chemical elements in a primary incisor tooth slice is presented. An incisor primary tooth was cleaned by distilled water sonication, embedded in resin, and cut into a slice of 0.63 mm thickness, 5 mm length, and 1 to 3 mm width. A 3D positioning stage assembly placed the sample perpendicular to the microbeam from an integrated x-ray lens and tube unit. X-ray attenuation and XRF spectra were acquired by placing the detector in transmission and backscatter geometries, respectively. 2D XRF measurements (10-s per point, 3 mm by 5 mm grid in the y-z plane, 0.5 mm steps) mapped the tooth area of the sample. Two 1D transmission measurements along the y-axis (100 and 50 µm steps) at z = 8.5 mm and z = 10 mm were used to compute the linear attenuation coefficient (µ) at four photon energies of the tungsten L-shell XRF spectrum. Increasingly higher µ values identified the resin, dentin, dentin-enamel junction, and enamel regions. At z = 10 mm, XRF spectra (3 trials of 300-s each) were acquired at two locations in the dentin and enamel layers. Peak fitting analysis identified the K-shell XRF peaks of five elements P, Ca, Cu, Zn, and Sr. X-ray scatter and fundamental parameter XRF models were applied to the 300-s XRF spectra to measure the mass density and elemental concentrations in the dentin and enamel layers. The results were comparable to literature values.