Figure 2. TEM micrographs from (A-B) Group 9-0-1 (anhydrous), and (C-D) Group 8-1-1 (10 vol% water). C, composite; A, filled adhesive; D, dentin. Open arrowhead: F-PRG fillers. (A) Stained, demineralized section from Group 9-0-1 showing a 200-nm-thick, electron-dense hybrid layer (between open arrows). Some of the smear layer remnants (arrows) were not completely dissolved. (B) The corresponding unstained, undemineralized section, showing that the 200-nm-thick, partially demineralized zone (between open arrows) is heavily filled with silver deposits (nanoleakage). In addition, reticular silver deposits are sporadically present along the interfibrillar spaces (pointer) of the dentin beneath the hybrid layer. Such a feature could not be identified from the stained demineralized sections. (C) Stained, demineralized section from Group 8-1-1, showing a similar 200-nm-thick hybrid layer (between open arrows) with thicker regions containing smear layer remnants (asterisk). (D) The corresponding unstained undemineralized section, showing that the partially demineralized zone (between open arrows) is generally devoid of nanoleakage. Similar to Group 9-0-1, sporadic regions of silver-filled interfibrillar spaces (pointer) can be observed in the underlying intact, mineralized dentin.