OBJECTIVETo evaluate the nanoleakage and ultramorphology of four self-etching adhesives.

METHODSSixteen freshly extracted, caries-free human third molars were selected. A flat dentin surface was exposed by removing occlusal enamel. All teeth were randomly divided into four groups acorrding to four different self-etch adhesive: Adper Prompt (A), iBond (B), Xeno III (C) and SE Bond (D). The dentin were bonded with dentin adhesive system according to manufacturer's directions. Composite layers were built up incrementally. The specimens were sectioned longitudinally across the resin-dentin interface into 4.0 mm×0.9 mm sticks and then traced with ammoniacal silver solution. Epoxy resin-embedded sections were prepared for transmission electron microscope (TEM) to observe nanoleakage. The images were qualitatively compared by NIH software, and data was analyzed by SPSS.

RESULTSDifferent thickness of hybrid layer and adhesives layer were observed for each adhesive. The hybrid layer of A, C was thicker than that of B, D, and adhesive layer of D was thicker than the others. The extent of nanoleakage varied among different adhesives: A (45.02 ± 9.49), B (43.97 ± 8.55), C (27.02 ± 10.86), D (12.94 ± 2.07). D presented significantly less silver deposition than any of the others did (P < 0.05).

CONCLUSIONSThe thickness of hybrid layer and adhesive layer vary among the four adhesives. The shape and extent of nanoleakage of each adhesive are also different. Two-step system shows less nanoleakage than one-step systems do.