Influence of Surface Treatments and Thermal Aging Duration on the Shear Bond Strength of Resin Cement to CAD/CAM Monolithic Zirconia

This study aimed to evaluate the individual and combined effects of mechanical, plasma-based, and laser-based surface treatments, along with short- and long-term thermal aging, on the surface morphology, surface energy, and resin cement bond strength of CAD/CAM monolithic zirconia. Significant numerical differences were observed among the treatment groups. Surface roughness increased from 0.22 µm (control) to 0.98 µm after sandblasting, 1.12 µm after sandblasting + plasma, and 1.07 µm after laser treatment, while plasma alone produced a moderate increase (0.31 µm). Wettability improved most notably in the plasma group, where the contact angle decreased to 43.27° compared with 67.00° in the control. The highest shear bond strength after 5000 thermal cycles was recorded in the sandblasting + plasma group (14.80 ± 1.53 MPa), whereas laser treatment demonstrated the best long-term stability, showing no significant decrease after 10,000 cycles (12.48 → 12.02 MPa). From a practical perspective, these findings indicate that sandblasting followed by plasma treatment provides high initial bond strength, making it suitable for clinical situations requiring strong immediate adhesion of zirconia restorations. Conversely, femtosecond laser treatment offers superior resistance to aging-related degradation, suggesting its potential value in cases where long-term durability is critical, such as high-stress posterior restorations or patients with parafunctional habits.