Permeability of dental adhesives centers of the specimens, forming thin, elongat- AP presented an intense silver deposition over ed structures. In high magnifications, elongated the entire specimen, and it occurred predomi- structures look like thin fissures incompletely nantly in thin, elongated structures similar to the filled with silver (Figure 4). ones observed in the SB specimens. Cracks and EX presented just the granular pattern of sil- irregular margins were also observed (Figure 7). ver deposition. An intense silver concentration can In OU micrographs, the granular pattern of be observed along the margin of the specimen. A deposition was predominant and was spread over more sparse distribution extended a few microm- the entire specimen. Permeation was more con- eters into the center. No deposition could be seen centrated along the interface with the epoxy resin. in the center of the specimen (Figure 5). The reticular pattern of silver deposition was also OS exhibited an intense silver permeation present but smaller in length and more rarely ob- distributed over the margin of the specimen and served compared with OS (Figure 8). also protruding to its center as isolated granules. The reticular pattern of the deposition could be dIscuIon observed in all superficies evaluated, protruding Since the wet bonding technique21 became an through almost all of the specimen’s thickness imperative procedure when bonding resin com- as images known as “water trees.” A deformed, posites to intrinsically wet acid-etched dentin, shrunken interface with embedded epoxy resin the development of new adhesive systems has was observed for this material (Figure 6). been oriented toward making them technically 432 Figure 1. SEM micrographs of a specimen of the bonding resin of Clearfil SE Bond (SE) embedded in epoxy resin (R). (A) At low magnification (90 X), an eletronluscent line at the interface of the adhesive-epoxy resin can be seen, indicating that the silver deposition was concentrated in the outer surface of the specimen (narrow arrows). Between the upper and the lower eletronluscent lines, no silver infiltration was observed. (B) At higher magnification (330 X), it is confirmed that the silver im- pregnation was practically restricted to the outer portion of the specimen (between large arrows). European Journal of Dentistry Figure 2. SEM micrographs of a specimen of the bonding resin of Scotchbond Multi-Purpose System (MP). (A) At the lowest magnification (90 X), deposits of silver showed as being restricted to the interface adhesive-epoxy resin (narrow arrows). (B) Even at higher magnification (500 X), it can be observed that silver infiltration was practically restricted to the outer portion of the specimen (narrow arrows).