Table 1.
Description of the investigated samples.
Fig 1.
A) The tooth sections imaged in this study. B) The x-ray grating interferometer at the imaging beamline ID19 of the European Synchrotron Radiation Facility.
Fig 2.
Schematic representation of an x-ray grating interferometer.
Usually the sample is placed upstream of the two gratings G1 and G2.
Fig 3.
Phase and absorption sagittal slices of sample G and two-dimensional histograms of the entire volumes.
Panels A and B show a sagittal slice from the phase volume of sample G and the two-dimensional histogram of the same volume respectively (see S2 Appendix). This data is compared with the corresponding absorption slice (panel C) and absorption histogram (panel D). The vertical axis in the sagittal slices and 2D histograms indicates the height in the volumes.
Fig 4.
Mass density gradients for sample S and E.
In A and C sagittal slices of sample S and E are shown respectively. Panels B and D are the corresponding two-dimensional histograms (see S2 Appendix). The peaks are related to water (W), dentine (D), enamel (E), and glue (G) used to fix the samples. The density variations observed in panel A are probably caused by blind tract formed as a consequence of damage in the dentine.
Table 2.
Mass density variation in dentine.
Fig 5.
Local density variations detected in dentine.
A comparison of phase (A) and absorption (B) sagittal slices of sample S, and enlarged details of these slices (C and D) emphasize the high sensitivity of phase imaging to local density variations. This is confirmed by the histogram analysis of the regions of interest. The phase histogram E features three peaks associated with (1) lower density region at the top-left of panel C, (2) the medium density covering most of the remainder of the same panel, and (3) the high density features. It should be noted that no variation can be detected in the absorption histogram F which consists of just a single peak.
Fig 6.
Mass density histogram for dentine and enamel.
Mass densities as evaluated in 102 volumes of interest in dentine and 27 volumes of interest in enamel.