Impact of post printing cleaning methods on geometry, transmission, roughness parameters, and flexural strength of 3D-printed zirconia.

Abstract

To analyze the impact of different post printing cleaning methods on geometry, transmission, roughness parameters, and flexural strength of additively manufactured zirconia. Disc-shaped specimens (N = 100) were 3D-printed from 3mol%-yttria-stabilized zirconia (material: LithaCon3Y210; printer: CeraFab7500, Lithoz) and were cleaned with five different methods (n = 20): (A) 25s of airbrushing with the dedicated cleaning solution (LithaSol30®, Lithoz) and 1-week storage in a drying oven (40°C); (B) 25s airbrushing (LithaSol30®) without drying oven; (C) 30s ultrasonic bath (US) filled with Lithasol30®; (D) 300s US filled with LithaSol30®; (E) 30s US filled with LithaSol30® followed by 40s of airbrushing (LithaSol30®). After cleaning, the samples were sintered. Geometry, transmission, roughness (Ra, Rz), characteristic strengths (σ0), and Weibull moduli (m) were analyzed. Statistical analyses were performed using Kolmogorov-Smirnov-, t-, Kruskal-Wallis-, and Mann-Whitney-U-tests (α<0.05). Short US (C) resulted in the thickest and widest samples. Highest transmission was found for US combined with airbrushing (E, p≤0.004), followed by D and B (same range, p = 0.070). Roughness was lowest for US combined with airbrushing (E, p≤0.039), followed by A and B (same range, p = 0.172). A (σ0 = 1030MPa, m = 8.2), B (σ0 = 1165MPa, m = 9.8), and E (σ0 = 1146MPa, m = 8.3) were significantly stronger (p<0.001) and substantially more reliable than C (σ0 = 480MPa, m = 1.9) and D (σ0 = 486MPa, m = 2.1). For 3D-printed zirconia, cleaning strategy selection is important. Airbrushing (B) and short US combined with airbrushing (E) were most favorable regarding transmission, roughness, and strength. Ultrasonic cleaning alone was ineffective (short duration) or detrimental (long duration). Strategy E could be particularly promising for hollow or porous structures.