Effect of different surface treatments on bond strength between additively manufactured definitive restorative materials

Background Definitive restorative materials using additive manufacturing techniques have gained popularity recently. This study investigates the effects of surface treatment and thermocycling on the bond strength between additively manufactured definitive restoration materials and self-adhesive resin cement (SARC). Materials and Methods Disc-shaped specimens were fabricated using four 3D printable definitive resin materials: two composites (Crowntec (Crowntec), CRS Composite (CRS) and two ceramic-filled composites (Alias Dental Crown (Alias), Permanent Crown (PC). Each material group (n = 24) was subdivided according to surface treatment: control (C; no treatment), 9% hydrofluoric acid–etched (HF), 50 µm Al₂O₃–sandblasted (S50), and 110 µm Al₂O₃–sandblasted (S110). SARC was applied to the center of each specimen using teflon molds (Ø3 × 3 mm). Shear bond strength (SBS) tests were performed after 24 h of storage in water at 37°C or after 10,000 thermocycles (n = 12). Data were analyzed with the Kruskal–Wallis and Mann–Whitney U tests (α = 0.05). Failure modes were examined microscopically and classified as adhesive, mixed, or cohesive. Results SBS values of Crowntec significantly decreased following HF treatment compared to other groups ( p  < 0.05). No significant differences were observed among surface treatments for CRS and PC ( p  > 0.05). However, Alias demonstrated statistically significant increases in SBS compared to control after S110 treatment ( p  < 0.05). Following thermocycling, SBS values were affected by both material type and the surface treatments used. All surface-treated CRS and Alias groups had significantly higher SBS values than their respective controls ( p  < 0.05). Crowntec showed significant increases after HF and S50, whereas for PC only after S50. No significant differences were observed among control groups ( p  > 0.05). Failure mode analysis revealed mainly adhesive failures in the control groups, whereas the surface-treated groups had a mix of cohesive and adhesive failure patterns after thermocycling. Conclusion The application of surface treatments provided higher bond strength between the SARC and additively manufactured definitive restorative materials after 10,000 thermocycling.