Representative SEM images and energy dispersive spectroscopy (EDS) spectra (insets) obtained from stones overgrown on implants– Regular water group. (a & b) BRP-PA group: In (a), large calcium phosphate crystals are randomly organized amongst a fibrous segment of BRP tissue (thin arrow). In (b), multiple BRP tissue fibers are visible (thin arrows) amidst magnesium phosphate (arrow head) and granular precipitates (thick arrow). (c & d) BRP-OPN group: In (c), a high density of magnesium phosphate (struvite type) crystals. In (d), a crust of poorly defined, granular agglomerates of calcium phosphate and magnesium phosphate crystals or amorphous mineral. Scale bars are as follows: (a) 100 μm, (b) 50 μm, (c) 40 μm, (d) 30 μm