Effect of Surface Treatments on the Repair Bond Strength Between Aged Glass Ceramics and Composite Resin: An In Vitro Study

Background: This study aimed to investigate the effects of glass bead particle abrasion and different primer systems on the repair bond strength of two types of aged glass ceramics and composite resins. Methods: Eighty specimens were prepared from leucite-reinforced (G-Ceram) and lithium disilicate (IPS e.max CAD) glass-ceramic materials. After thermocycling (5–55 °C, 30 s dwell time, 5000 cycles), each ceramic specimen was divided into five test groups (n=8): control (C), air abrasion with 50-µm glass beads (GB), 37% phosphoric acid etching, Clearfil Ceramic Primer Plus application (CP), Monobond Etch&Prime (MEP) application, 4.8% hydrofluoric acid etching, and Monobond N (MN) application. All specimens were coated with a universal adhesive (Nova Compo B Plus) following treatment. Clearfil Majesty Esthetic, a nanohybrid composite resin, was applied. The specimens were kept in distilled water at 37 °C for 24 h and evaluated for the shear bond strength (1 mm/min). Data were statistically analyzed using two-way ANOVA, Tukey HSD and Bonferroni post-hoc tests (α=0.05).Results: Surface treatment and its interaction with the ceramic material exhibited a statistically significant effect on the repair bond strength (P < 0.05), whereas the main effect of the ceramic type was not significant (P > 0.05). The C and GB groups demonstrated significantly lower mean bond strength values than the CP, MEP, and MN groups (P < 0.05). For the lithium disilicate ceramics, both the CP and MN groups produced the highest bond strengths, with no significant difference between them (P > 0.05). In the leucite-reinforced ceramics, the MN group showed significantly higher bond strength than the CP (P < 0.05). Although the overall effect of surface treatment was consistent across ceramic types, in the CP group, lithium disilicate specimens exhibited a higher bond strength than leucite-reinforced ceramics (P < 0.05).Conclusions: Both phosphoric acid and hydrofluoric acid etching followed by different primer applications achieved the highest bond strength for lithium disilicate ceramics, whereas silane-based treatment after hydrofluoric acid etching was the most effective for leucite-reinforced ceramics. Overall, the tested primers significantly enhanced the bonding to aged glass-ceramics, supporting their use in repair procedures.