The purpose of this study was to evaluate the impact of replacing P90 primer with simplified adhesive systems (with a conventional, two-step adhesive or a self-etching, one-step adhesive) on bond strength to dentin in Class I restorations. The interfaces were also analyzed using confocal microscopy by adding a fluorophore to the adhesive components and SEM using silver nitrate for nanoleakage investigation. X-ray diffraction (XRD) characterized the chemical interaction of the adhesives. Failure mode and nanoleakage varied among groups. Characteristic micromorphology and higher nanoleakage were noted for silorane combinations. On the other hand, no signs of phase crystallization in the silorane adhesive combinations were noted. Replacing the silorane primer with simplified adhesives proved successful as the modified systems provided bonding to dentin comparable to that of the unmodified silorane systems. However, the dedicated adhesive exhibited signs of degradation immediately after application, which may impact the longevity of restorations in short periods.