Adhesion of Composite Resin to Additively Manufactured Zirconia Using a Self-Adhesive Resin Cement: Evaluation of Micro-Shear Bond Strength

Abstract

Effective bonding between zirconia ceramic restorations and resin remains a clinical challenge, particularly in the context of intraoral repair and cementation. This study aimed to investigate the micro-shear bond strength (μSBS) of stereolithography (SLA)- and digital light processing (DLP)-fabricated zirconia–resin cement-composite resin bonding specimens. Rectangular zirconia specimens (10 × 5 × 5 mm3) were fabricated by SLA, DLP, and computer numerical control (CNC) milling technologies. The surface roughness (Ra) of zirconia was measured after air abrasion. A composite resin cylinder (5 mm in height and 1 mm in diameter) was added to each zirconia substrate for the μSBS test. The failure mode images were obtained using a scanning electron microscope. The adhesive, cohesive, and mixed failure patterns were analyzed. The Ra and μSBS values were statistically analyzed with one-way ANOVA followed by S-N-K post hoc comparisons (a = 0.05). The Ra of SLA (1.05 ± 0.03 μm) and DLP (1.02 ± 0.03 μm) zirconia after air-abrasion were significantly higher than that of CNC (0.91 ± 0.02 μm) (p < 0.001). The SLA (23.37 ± 4.66 MPa) and DLP (23.24 ± 3.7 MPa) groups exhibited similar μSBS values for the bonding specimens to those of the CNC group (21.13 ± 3.48 MPa) (p = 0.237), indicating that the bond strength of the zirconia–resin cement-composite resin assembly for SLA and DLP zirconia was comparable to that for CNC zirconia.