“…methylene blue or silver nitrate solutions) leakage through the dentin-restorative materials interface using light, scanning electron (SEM) or transmission electron (TEM) microscopy [25][26][27][28][29][30][31][32]. Silver staining provides sharp SEM pictures of penetration at tooth-restoration margins [33] and leakage patterns have been detected [31,32] even in apparent gap-free margins of the dentin-restoration interface, obtained using the 'total-etch' technique [34].…”