Figure 1. TEM micrographs of bonding of Single Bond to acid-etched, deep dentin. The demineralized, epoxy-resin-embedded sections were stained with phosphotungstic acid and uranyl acetate. (a) A low-magnification overall view of the resin-dentin interface. Phase separation of the polyalkenoic acid copolymer (P) component of the adhesive could be seen as globular structures within the adhesive layer (A) and as a continuous layer (arrow) over the surface of the bonding substrate. A 3- to 4-µm-thick hybrid layer (H) could be seen above the laboratory demineralized dentin (D). Bar = 1 µm. (b) A high-magnification view showing the presence of intact, banded collagen fibrils within the hybrid layer. A, adhesive layer. Bar = 300 nm.