Chemical interaction of specific functional monomers with hydroxyapatite (HAp) has been shown to contribute to bond durability. In previous research (Yoshida et al., JDR 2012; 91:376-81), some 10-MDP-based adhesives were found to produce ‘nano-layering’ at the interface with dentin. Objectives: Here, we investigated the nano-layering potential of two phosphoric-acid monomer containing 1-step self-etch adhesives, ‘G-aenial Bond/G-Bond Plus’ (GC) and the experimental derivative ‘G-Bond Plus AM-3’ (GC), at dentin using thin-film X-ray diffraction (TF-XRD) and transmission electron microscopy (TEM). Methods: Both adhesives were applied on dentin for 20s, and G-aenial Bond also for 12hrs; they were subsequently air-dried and analyzed using XRD (CuKα XRD; RINT2500, Rigaku) under 40 kV acceleration and 200 mA current. For TEM, each adhesive was applied on dentin for 20s, light-cured for 10s, covered by a thin layer of low-viscosity composite (Protect Liner F, Kuraray) and again light-cured for 40s. TEM sections were prepared following common TEM-specimen processing, and eventually examined by TEM (JEM-1200EX II, Jeol). Results: XRD disclosed nano-layering for both adhesives, but for G-aenial Bond only after 12hrs. Remarkably and different from our previous findings (Yoshida et al., JDR 2012; 91:376-81), the XRD peaks representing nano-layering produced by G-Bond Plus AM-3 consisted of two subpeaks (of yet unknown origin). In addition, high-magnification TEM disclosed nano-layering near the interface between G-Bond Plus AM-3 and composite, again different from our previous findings when nano-layering was typically found at the adhesive-dentin interface. Conclusion: As G-Bond Plus AM-3 contains more phosphoric-acid monomer than G-aenial Bond, the former produced nano-layering already after 20s (in contrast to G-aenial Bond: nano-layering only after 12hrs). Further analysis of the nano-layering characteristics (such as the two-fold XRD peaks, the actual interfacial location, its physico-mechanical properties, etc.) is highly needed to get a better insight in the relevance of interfacial nano-layering.