Optimizing adhesion protocols between 3D-printed ceramic-containing composite and resin cement

Abstract

This study evaluated the microshear bond strength (μSBS) of resin cement to a 3D-printed ceramic-containing resin composite (PriZma 3D Bio Crown, Makertech) subjected to different adhesive protocols (surface pretreatments and adhesive systems), in both baseline and aging conditions. For this, 3D-printed resin composite slices were fabricated and divided into groups based on adhesive protocols, considering three surface pretreatments: alumina grit-blasting (AlOx), 37 % phosphoric acid (PA), and a combination of both (AlOx + PA); and two adhesive systems: conventional (Adper Single Bond 2, 3M) and universal (Single Bond Universal, 3M). The resin cement (RelyX Ultimate, 3M) cylinder specimens (n = 18) underwent μSBS testing before and after thermocycling (12,000 cycles, 5-55 °C). Surface roughness (R_a and R_z), SEM topography, and failure modes were analyzed. Statistical analysis included One- and Two-Way ANOVA with Tukey tests for roughness and μSBS, respectively, and paired t-test to compare baseline and aging conditions considering the same adhesive protocol (α = 0.05). AlOx + PA with the universal adhesive demonstrated the highest bond strength in both baseline and aged conditions, with a minimal reduction after aging (11.68 %, p = 0.294). The PA-conventional adhesive group had the greatest reduction post-aging (50.32 %, p < 0.001). After aging, AlOx and PA with universal adhesive showed intermediate bond strengths, similar to AlOx + PA-universal, while the use of conventional adhesive resulted in lower bonding performance. In Baseline, AlOx + PA-universal exhibited the highest Weibull modulus, while AlOx + PA-conventional had the lowest. After aging, AlOx + PA-universal remained the highest, differing from the other groups but similar to AlOx + PA-conventional, whereas PA-universal had the lowest modulus. The other groups showed intermediate values without significant differences. The combination of alumina grit-blasting and phosphoric acid with a universal adhesive provides superior and more reliable bond strength under aging conditions.