Figure 3. TEM micrographs from the experimental group with the highest bond strength (Group 7-2-1; 20 vol% water). C, composite; A, filled adhesive; D, dentin; open arrowhead, fully pre-reacted glass-ionomer-type fillers (F-PRG) from the Fluoro-Bond bonding resin. (A) Stained, demineralized section showing a 500-nm- to 1-µm-thick hybrid layer (between open arrows). The smear layer was completely dissolved, and collagen fibrils (pointer) from the intact dentin exhibit a ‘shag carpet’ appearance. (B) The corresponding unstained, undemineralized section after tracer penetration, showing the overall absence of nanoleakage from the resin-dentin interface. The partially demineralized zone (between open arrows) corresponded to the hybrid layer depicted in the stained section. (C) A high-magnification view of Fig. 3B, showing the presence of minimal nanoleakage that existed in the form of isolated silver grains (arrow) within the partially demineralized zone (between open arrows).