One of the greatest applications of 3D printing technology is the fabrication of custom goods. The impact of this ability is felt that much more strongly when applied to the medical field, where patient-specific models, devices and implants are leveraged for very personal and life-enhancing purposes.
In the case of a man named Shirley Anderson, 3D printing was used as an important auxiliary technology for producing a perfect facial prosthesis. After discovering a cancerous lump on his tongue, Anderson underwent countless radiation therapies and surgeries, including one to implant radium in his jaw and another to recreate a portion of his face using muscles from his chest, neither of which proved successful.
Left without a jaw or Adam’s apple, Anderson cannot eat solid food, speaks with a handheld whiteboard and hides his lower face in public with a surgical mask. For this reason, Anderson eventually turned to Dr. Travis Bellicchi, a maxillofacial prosthetics expert at the Indiana University (IU) School of Dentistry.
Bellicchi determined that Anderson would require a prosthesis four times larger than any he’d previously made. Initially, Bellicchi attempted time-honored and time-intensive techniques to make the device, obtaining an impression of Anderson’s face with plaster, sculpting a mold of the prosthesis and casting the final mask in silicone. The result, however, was unrealistic looking and too heavy and uncomfortable for the patient to wear.
In turn, Bellicchi sought a digital solution through IU’s School of Media Arts and Sciences, where IU student Cade Jacobs combined 3D scanning and 3D modeling to create a more realistic model. Using a CT scan of Anderson’s face as the basis for bone detail, Jacobs then created a likeness of Anderson’s jaw in ZBrush, with a focus on feathering the edges of the model so that the final prosthesis would blend with the patient’s skin.
The resulting model was then 3D printed on a Form 2 stereolithography (SLA) 3D printer, with resolution capable of representing skin details Jacobs had sculpted into the model. This was then used to cast the final silicone prosthesis.
The process was such a successful one that Bellicchi has implemented the same methodology with other patients, calling it “The Shirley Technique.” Bellicchi said, “We started with Shirley Anderson, and we’ve expanded that workflow to several other patients.” He went on to say, “We’ve used 3D printing to replace about 75 to 80 percent of the process in traditional prosthetic fabrication.”
The Shirley Technique is not just unique because it deals with the story of a unique individual, but it also demonstrates the way that 3D printing can be used to support a larger workflow in a way that streamlines and speeds up that workflow by replacing outmoded traditional methods. Though a high-resolution SLA machine was used in this case to create a mold, the future may see such devices as a facial prosthetic produced with 3D printing directly, if not using a silicone 3D printer like the one announced by Wacker Chemie, then with a bioprinter 3D printing actual human tissue.