The UC Davis Biomedical Engineering Department’s TEAM Design, Prototyping, and Fabrication Laboratory has been making 3D printed replicas of dogs’ skulls to help veterinarians at the Dentistry and Oral Surgery Service at the UC Davis Veterinary Medical Teaching Hospital plan surgeries. The models are based on CT scans and allow the surgeons to better assess the patient’s damage, and to measure the best surgical routes for avoiding the brain, eyes, and other critical areas. This makes surgeries safer by reducing the amount of time the patient is anaesthetized.
“It’s one thing to study a CT image on screen – we learn a tremendous amount about a patient that way,” says Dr. Frank Verstraete, Chief of Dentistry and Oral Surgery. “But to be able to hold a replica of that same image in your hand and see exactly what your patient’s skull looks like takes the experience to a completely different level. The advantages of that are tenfold compared to a screen image.”
Using the replicas, Dr. Verstraete and Dr. Boaz Arzi have been able to measure and size the plates used in the cutting-edge jawbone regrowth trials they have been doing in collaboration with Biomedical Engineering.
To make the replicas, the surgeons convert CT scan data from the patient into a digital model called a 3-Dimensional Point Cloud file (commonly referred to an STL file) and send it to the TEAM Prototyping Facility. The data is often imperfect, and requires modification before printing. Files will often have a lot of noise, or improperly created features.
“To give you an example, when we print dog skulls, the jaw is often rendered as one piece with the skull. Due to the current limitations of scanning equipment, the tiny gap between the mandible and skull is not recognized. Thus, before printing I need to go into the model, and extract each individual component (in this example, the mandible and skull). If the doctor needed a cross-section of the item to be printed, I would also add a partition line between the parts,” explains Steven Lucero, TEAM Manager.
The repaired model is then loaded into the printer’s proprietary software, where it is sliced up into layers 16 microns thick. These layers are then deposited from bottom up, until a completed model is left on the build tray. After a bit of cleaning, the skull is complete and ready for pickup. A skull print can take anywhere from 2 to 16 hours.
“One of the things I appreciate the most about the replicas is that it helps us to better explain the situation to our clients,” says VMTH oral surgeon Dr. Boaz Arzi. “If I bring this skull to the waiting room and let the clients see the exact damage to their pet, they understand the procedure better. I have gotten many positive responses from clients who are excited that this technology exists, and that they are better able to understand the treatment plan for their pet.”