Silicone 3D Printing: Process Optimization, Product Biocompatibility, and Reliability of Silicone Meniscus Implants

A novel custom-made 3D silicone printer and two-part Ecoflex silicone resins were used to 3D-print standard-shaped silicone coupon and irregular-shaped meniscus structures via a heat-cured extrusion-based method. This article is segmented into three parts: (1) study on the effect of 3D printing parameters on dimensional accuracy and mechanical properties of 3D-printed silicone, (2) reliability and failure analysis of 3D-printed silicone according to ASTM D575 standards under monotonic and cyclic compressive loading, and (3) cytotoxicity of 3D-printed silicone by extraction method according to ISO 10993-12 for different extraction time and extract volume/surface area ratios. Based on analysis using regression method and analysis of variance, we found that the dimensional accuracy of lengths and widths is sensitive to both nozzle diameters and bed temperatures (BTs), while the height is only sensitive to BTs. Failure results were analyzed using the two-parameter Weibull probability distribution model and Weibull regression analysis and revealed that the Weibull modulus had a value greater than 1 in all groups, indicating an increasing failure rate with time for Ecoflex 30 and 50 meniscus implants. Results from quantitative cell proliferative assay exhibit statistically insignificant differences for all samples, pointing to the low cytotoxicity and excellent biocompatibility of printed silicone.