Evaluation of the effect of printing orientations onwater sorption, solubility, and color stability of a 3D-printedpermanent crown material

Background and aim: The aim of this study was to evaluate the water sorption, solubility, and color stability properties of a 3B-printed permanent crown material manufactured at different printing orientations (0°, 45°, and 90°). Materials and Methods: In this study, a total of 150 disc-shaped specimens (n=50 per group) were produced using Permanent CB Resin (Formlabs, Sommerville, MA, USA) with a FormLabs SLA 3D printer. The specimens were printed at three different angles (0°, 45°, and 90°) and prepared with dimensions of 10×10×1 mm. Water sorption and solubility tests were performed according to ISO 4049 standards. Each specimen was stored in a desiccator until reaching constant mass, recorded as m₁. All measurements were performed with an analytical balance (AUW-220D, Shimadzu, Japan) with 0.1 mg precision. Specimens with less than 0.1 mg variation in two consecutive weighings were considered fully dried. The dried specimens were immersed in distilled water and incubated at 37 °C for 7 days. After this period, the specimens were gently blotted and weighed again to obtain m₂. Subsequently, they were re-dried in a desiccator and their final mass (m₃) was recorded. Water sorption (Wsp) and solubility (Wsl) values were calculated and expressed in µg/mm³. To evaluate color stability, the specimens were immersed in five different solutions (distilled water, cola, red wine, orange juice, and coffee), and color measurements were performed on days 1, 3, 6, and 12 using a spectrophotometer (Vita EasyShade V). Color differences were calculated using the CIEDE2000 (ΔE00) formula. Statistical analyses were conducted using IBM SPSS V23 and Jamovi 2.3.28 software. Results: The findings showed that the printing orientation had a statistically significant effect on both water sorption and solubility (p<0.05). The highest water sorption and solubility values were observed at 0°, while the lowest were found at 90°. Regarding color change, the highest ΔE values were recorded in red wine and orange juice solutions, especially in the 90° group. In contrast, the distilled water group exhibited the lowest ΔE values across all angles. Conclusion: It was concluded that printing orientation has a direct influence on water sorption, solubility, and color stability in permanent crown materials produced with 3D printing. In clinical applications, appropriate selection of printing angle plays a critical role in achieving restorations with enhanced aesthetic and structural durability. Keywords: 3D printing, permanent crown, printing orientation, water sorption, solubility, color stability