2.5. Scanning Electron Microscopy
SMEAR LAYER
Samples were coated with gold and palladium in a vacuum to a thickness of 20 nm and mounted on aluminum stubs. Then the entire area was examined 2 mm from the apex under SEM (SEM 5600, JEOL Ltd., Tokyo, Japan); two SEM images at 2000× magnification were recorded at a fixed distance of 2 mm from the apical foramen at the midpoint for each sample. Images were then saved digitally in TIFF format. The SEM images were assessed to determine the effectiveness of smear layer removal following the digital method described by Ciocca, et al. [