Microscopic X-ray fluorescence analysis of human dental calculus using synchrotron radiation

In this work, new results of one- and two-dimensional spatial distributions of major, minor and trace elements of human dental calculus are presented. X-ray fluorescence induced by a synchrotron radiation source was used. The measurements were carried out in the X-ray microprobe station mounted at the X-ray fluorescence beamline of the Brazilian National Synchrotron Light Laboratory (LNLS). Two-dimensional distributions show that calcium, the major element in this type of sample, has a uniform pattern over the mapped area, while trace elements are non-homogeneously distributed. By means of different linear scans along the growing axis of the dental calculus, a markedly spatial correlation between Cu and Zn was found. A semi-quantitative analysis for Cu and Zn was performed by means of calibration curves using appropriate fabricated standards. The concentration values found for these metals were higher than those obtained in conventional bulk analysis. It was observed that these metals accumulated preferentially in the subgingival part of the calculus, near the tooth surface. These results indicate that the mineralization processes, which take place for both type of calculus, are essentially different.