2.6. Investigation of Bonded Adhesive–Dentin Interface Using SEM Spectroscopy

The remaining five bonded teeth from every group were partitioned using a slow speed saw (Buehler Isomet 2000 Precision saw, Lake Bluff, IL, USA) in order to create beams of 1 mm × 1 mm. The bonded adhesive–resin interface was observed using SEM-EDX spectroscopy. Employing a polisher (Beuhler Polisher, Lake Bluff, IL, USA), beams were wet polished, and placed in an ultrasonic bath containing distilled water (Bandelin Digital-Sigma-Aldrich Darmstadt, Germany) for 5 min. For the samples’ conditioning, 36% phosphoric acid (DeTrey conditioner, Dentsply, PA, USA) was applied. This was followed by washing and immersion in 5.25% sodium hypochlorite solution for 15 min. The samples were cleaned with distilled water, and then their dehydration was carried out with 80–100% concentrations of ethanol solution. The specimens were sputter coated with gold (as mentioned previously). An SEM (JEOL, JSM-6513, SEM, Tokyo, Japan) was used to observe samples’ adhesive–dentin interfaces with 30 kV voltage using different magnifications. EDX spectroscopy was also implemented to analyze the elemental distribution and presence of Si nanoparticles in the adhesives.