The purpose of this study was to identify possible interactions between impression material and dentin bonding agent and their effect on cement/dentin shear bond strength. Material and methods: twenty extracted molars (n=5) with flat midcoronal preparations underwent 1 of 4 procedures: Control group, unsealed tooth surface/impression; group2, immediate dentin sealing /impression; group3, immediate dentin sealing/air blocking /impression; group4, immediate dentin sealing/air blocking /sandblasting/ impression. Scanning electron microscopy was used to detect unpolymerized impression material on the bonded tooth surface and detect mode of failure of shear bond strength test. Results: layer of unpolymerized resin was found in the IDS group2. Air blocking the resin coating did not completely eliminate the oxygen-inhibited layer. Sandblasting of sealed dentin surface had no effect on the dentin/cement shear bond strength. Key word: impression, dentin bonding agent, adhesion, oxygen inhibited layer.