Bond Strength Of Repaired 3Dprinted Dimethacrylate Restorations With Surface Treatments

To study the effect of different surface treatment methods on the shear bond strength of flowable composite resin used to repair 3D-printed dimethacrylate interim restorative materials. Disk-shaped 3D-printed dimethacrylate (Optiprint Temp) specimens were subjected to different surface treatments: 1) no surface treatment, 2) sandblasting (50 µm Al₂O₃), 3) adhesive (Single Bond Universal Adhesive), and 4) sandblasting/adhesive (n = 8). Each specimen underwent thermocycling (2,500 cycles at 5°-55°C) before and after being repaired with flowable composite resin (Filtek Supreme Flowable Restorative). Shear bond strength was evaluated using a universal testing machine (crosshead speed: 0.5 mm/min). Data were analyzed using one-way ANOVA with the Tukey HSD test (p = 0.05). The shear bond strength values (mean ± SD) were 3.02 ± 1.27 MPa, 12.98 ± 3.19 MPa, 15.00 ± 3.11 MPa, and 15.57 ± 1.82 MPa for the no surface treatment, sandblasting, adhesive, and sandblasting/adhesive groups, respectively. The no surface treatment group had the lowest shear bond strength, which was significantly different from the other groups. The sandblasting/adhesive group had the highest shear bond strength, with no statistically significant difference compared to the sandblasting and adhesive groups. Surface treatments significantly influenced shear bond strength in repairing 3D-printed dimethacrylate interim restorations with flowable resin composite. Clinically, sandblasting, adhesive, or sandblasting/adhesive treatments can be used prior to repair with flowable resin composite.