Additional XRF analyses of elemental gradients in cementum, dentin and alveolar bone.

<p>A) Correlation (density) plots for cementum, dentin, and alveolar bone show the degree of equivalency between Ca to P and Ca to Zn patterns. Ca/P line plots (insets on the correlation plots) reveal Ca/P ratio range within each tissue. Correlation plots indicate a spread of Ca and P x-ray fluorescence signals in cementum and bone, while distinct zones in hypomineralized dentin (1* and 2*) were found. The reverse was identified for Ca to Zn correlation plots, which show distinct zones in cementum (area maps indicating AC and C) and alveolar bone (area maps indicating AB and NB) due to a range in Zn concentration for a narrow variation in Ca. For Ca/Zn plots, insets indicate summated regions that contributed to the overall spread in Zn vs. Ca signals. XRF bicolor maps (Ca and Zn for cementum and bone, Ca and P for dentin; bottom panel in A) indicate segmented zones from which the correlation plots are derived (C = cellular, AC = acellular, HD = healthy dentin, AB = alveolar bone, NB = new bone). Regions 1* and 2* are both hypomineralized zones, 1* being at the lesion site with severe demineralization (Ca/P = 0.32 ± 0.05) and 2* being directly adjacent to the lesion site with slightly higher mineralization (Ca/P = 0.46 ± 0.04); B) Correlation between micro-CT (N = 5) and XRF data (N = 1) for bone, dentin, and cementum with a corresponding line plot of mean MD vs. Ca/P ratio are shown. No correlation was found between mineral density and the Ca/Zn ratio. Zn dominant regions identified using XRF were not identified using micro-CT For example, an adapted or new bone (NB), Zn rich (AC) and Zn poor (C) layers within cementum were not discerned using micro-CT. The bottom right plot illustrates spread between mineral density and Ca/P ratio and an apparent linearity within diseased and healthy dentin.