Figure 2. FE-ESEM micrographs demonstrating the appearance of osmotic water blisters after enamel bonded with different one-step self-etch adhesives was immersed in water. (A) A single water blister (arrow) in Adper Prompt that was found next to a large, irregular blister (pointer). The latter were more commonly observed in this adhesive and were probably formed by the coalescence of multiple smaller blisters. The surface texture of the adhesive (A) adjacent to the blisters was also altered (open arrowheads), and appears swollen and exhibits cracking, even when the specimen was examined under wet conditions. (B) Another view of a coalesced osmotic water blister (OB) in Adper Prompt, showing that the film coating that formed the blister wall was derived from, and is still connected with (arrows), the underlying adhesive resin (A). (C) A partially collapsed blister in Xeno-III-bonded enamel after the specimen was re-immersed in the concentrated CaCl₂ solution. The top of the blister (asterisk) is partially collapsed. Connection of blister with the underlying adhesive can be clearly identified (arrows). A, adhesive. (D) Partial (arrow) and complete collapse of the pre-existing water blisters in iBond after re-immersion in the concentrated CaCl₂ solution. Subsurface adhesive cratering (pointer) can be observed beneath the completely collapsed blisters.