Comparison of surface treatment protocols for a 3D‐printable resin for definitive crowns: Effects on surface roughness and bonding performance

Purpose This study aimed to compare the effects of surface treatment protocols on the surface roughness and shear bond strength (SBS) of a three‐dimensional (3D)‐printable resin for definitive crowns. Materials and Methods A 3D‐printable resin for definitive crowns (Saremco Print Crowntec) was used to produce 168 specimens (10 × 10 × 2 mm 3 ) using liquid crystal display (LCD)‐based technology. Specimens were allocated to seven surface treatment groups ( n = 24/group): control, Al 2 O 3 air abrasion (110 µm, 50 µm), 9% hydrofluoric acid (HF) etching (1 and 3 min), and CO 2 laser treatment with parallel and grid patterns. Each group included 12 specimens with primer and 12 specimens without primer. Dual‐cure cement was applied via cylindrical molds (Ø2.38 × 3 mm). SBS tests were conducted. Data were analyzed using two‐way ANOVA and the Tukey test ( p < 0.05). Results Surface treatments significantly affected SBS ( p < 0.001). The highest SBS was with 110‐µm Al 2 O 3 air abrasion (14.05 ± 3.78 MPa), followed by CO 2 laser with parallel lines (11.86 ± 5.51 MPa). The 1‐min HF etching (9.47 ± 4.04 MPa) and the control group (7.08 ± 2.98 MPa) showed low SBS. The primer application did not significantly affect SBS. A weak positive correlation was found between SBS and surface roughness ( r = 0.297, p = 0.006). Conclusions Air abrasion with 110‐µm Al 2 O 3 provided the highest bond strength for 3D‐printed restorations. CO 2 laser with parallel line patterns was an alternative. Under the tested conditions, 1‐min HF etching showed low bond strength, whereas a 3‐min application resulted in improved outcomes. Surface roughness appears to aid bonding, but is not sufficient alone.