Fig. 4.

Representative CP-OCT images for SG (a) and NSG (b) groups. a) The CP-OCT image for the SG was showing a strong reflection at the composite-tooth interface. a*) A binary image for the selected axial walls (dashed rectangles) and cavity floor (dotted square). Image processing showed continuous dark cluster along the axial walls (dashed rectangles) and cavity floor (dotted square). b) B-scan image for NSG group. b*) A binary image for the selected areas; axial walls and the cavity floor. Image processing showed variable length of bright pixels at the composite-tooth interface, which transformed to black pixels after binarization. CR; composite resin, D; dentin.