Faraedon M Zardawi, Kaida Xiao, Richard van Noort and Julian M Yates
Objectives: 3D colour printing, a method of additive manufacturing, has been developed and utilised to produce facial soft tissue prostheses. This was achieved by layered fabrication of a biocompatible powder held together by an aqueous binder containing a resin and coloured inks, followed by infiltration with a medical grade silicone polymer. The aim of this study was to investigate the elastomer infiltration depths within the 3D printed models. Methods: Three sets of 30 cubes ? 20x20x20 mm ? were used to investigate the infiltration depth of Sil-25 maxillofacial silicone polymer (an MSP) under atmospheric pressure, 2 bar and 3 bar pressure for 5, 10, 15, 20 and 25 min. The investigation was also repeated with two other MSPs ? Promax-10 and M-3428 ? under 3 bar pressure. Following infiltration, the cubes were bisected, the internal aspects stained with dye, and the infiltration depth measured using a travelling microscope. Infiltration quality was also assessed using scanning electron microscopy (SEM). Results: At standard atmospheric pressure, the maximum infiltration depth of Sil-25 was 1.45 mm after 25 min. However, after 25 min at 2 and 3 bars pressure, the infiltration depth increased to 3.9 mm and 8.7 mm, respectively. At 3 bars the infiltration depth of Promax-10 and M-3428 was 2.4 mm and 7.5 mm, respectively. In all samples SEM revealed a disorganised distribution of starch particles within the MSP infiltrate. Significance: Pressure significantly increased the infiltration rate and depth of the MSPs within 3D printed constructs. The infiltration depth obtained is sufficient for prostheses that are less than 16 mm thick.
