UCLA

Maxillofacial prostheses are state of art and science to help the patient to overcome acquired head and neck defects and bring them back to their daily routine and social life [1]. Silicone prostheses were introduced at 1960 by Barnhart and exhibited excellent combination of mechanical property, chemical resistance, and stability. However, fabrication of maxillofacial prostheses required multiple labor intense process with human interventions, which hindered accessibility of maxillofacial prostheses to patient. The recent digital processing reduced processing time and required number of patient visits significantly on case studies, but direct 3D printing of silicone prostheses was limited due to non-suitable current 3D printing materials with disadvantages such as poor resolution, single color availability, and instability. Therefore, objective of this research was development of direct silicone 3D printing technology for maxillofacial prostheses with full color 3D printing, proper mechanical properties, complex details availability, and weathering resistance.

In the first study, silica treated silicone powder coated with polymer with hydroxyl functional group and compatible binder system was tested. The polymer coated powder was printed with binder to create porous structure and infiltrated with silicone resin to transform the structure to fully dense parts. This work suggests binder jetting approach on polymer coated silica treated silicone powder, compatible binder system, and silicone infiltration allows direct 3D printing of highly flexible silicone.

Morphology and size of polymer encapsulated silica treated silicone powder was successfully controlled by Ohnesorge number based approach, and the printed parts shows high flexibility with adequate mechanical properties. In clinical testing, the printed ear prosthesis proved complex detail and contour matching requirement. Thus, this study suggests binder jetting of silicone powder strategy is promising for maxillofacial prostheses application.

Cyan, magenta and yellow pigment binders were engineered and, binder showed full color 3D printing availability in skin color printing and full colored ear prosthesis. Weathering resistance in ultraviolet radiation and moisture condition was proved for color and mechanical property, which guarantee enough life span as maxillofacial prostheses. This work suggests a new polymer coated silicone powder 3D printing approach to improve quality of life for patients with head and neck defects.