The low-shrinking composite composed of combined siloxane-oxirane technology (Filtek Silorane, 3M ESPE) required the development of a specific two-step self-etch adhesive (Silorane System Adhesive), in particular because of the high hydrophobicity of the silorane composite. Objectives: to characterize using transmission TEM the interaction of this adhesive with enamel/dentin to elucidate the underlying mechanisms of adhesion. Methods: Non-demineralized/demineralized 70-90 nm sections were prepared following common TEM-specimen processing procedures. Results: Corresponding to the two-layered application of Silorane System Adhesive, including two separate light-curing steps, TEM revealed a typical two-fold build-up of the adhesive resin, resulting in a total adhesive layer thickness of about 20 µm. At bur-cut enamel, a tight interface was formed, mostly with only tiny micro-tags and without distinct dissolution of hydroxyapatite observable. Immersion of specimens in AgNO3 did reveal traces of Ag along some part of the enamel-adhesive interface and/or between the two adhesive resin layers. At bur-cut dentin, a relatively thin hybrid layer of maximum a few hundreds of nanometer was formed without clear surface demineralization. No clear resin tags were formed. At fractured dentin, the interaction of Silorane System Adhesive appeared very superficial. Distinct resin tags were formed due to the absence of smear plugs. Silver-nitrate infiltration showed a varying pattern of both spot- and cluster-like appearance of nano-leakage. This nano-leakage appearance has been observed to vary widely with the region. Substantially more Ag-infiltration was observed along the dentin-adhesive interface of bur-cut dentin, as compared to that of fractured dentin. Conclusion: The nano-interaction of Silorane System Adhesive should be attributed to its relatively high pH of 2.7. The obtained tight interface at both enamel and dentin indicates that the two-step self-etch adhesive effectively bridged the hydrophilic tooth substrate with the hydrophobic silorane composite.