Specimens are collected using a slow cutting machine (M618, Jiangsu Nantong machine tool factory, China), applied perpendicular to the bonding interface between the resin and cement. Then, 400# and 800# sand paper was used for polishing, and after polishing, the specimens were cleaned in distilled water by ultrasonic cleaning for 5 minutes, followed by drying and sputtering with gold. Finally, the specimens were evaluated with a SEM (JSM-6360LV, JEOL ltd., Kyoto, Japan).
The specimens were then fixed to a specially fabricated jig and mounted to a universal testing machine (MTS-585, MTS, USA), and a load was applied at a crosshead speed of 0.5 mm/min until failure. The maximum force at debonding was recorded, and the shear bond strength (SBS) was calculated.
After SBS testing, the fractured interface was examined using stereomicroscopy (magnification ×30; KH7700, Hirox, Japan). The specimens were classified according to fracture patterns: type I: adhesive failure, type II: mixed failure (combination of cohesive and adhesive failure), and type III: cohesive failure.