dentistry Archives ⋆ X-Reality: University of Michigan XR

June 28, 2020March 3, 2022

Learning Jaw Surgery with Virtual Reality

Jaw surgery can be complex and there are many factors that contribute to how a procedure is done. From routine corrective surgery to reconstructive surgery, the traditional means of teaching these scenarios has been unchanged for years. In an age populated with computers and the growing popularity of virtual reality, students still find themselves moving paper cut-outs of their patients around on a table top to explore different surgical methods.

Dr. Hera Kim-Berman was inspired to change this. Working with the Duderstadt Center’s 3D artist and programmers, a more immersive and comprehensive learning experience was achieved. Hera was able to provide the Duderstadt Center with patient Dicom data. These data sets were originally comprised of a series of two-dimensional MRI images, which were converted into 3D models and then segmented just as they would be during a surgical procedure. These were then joined to a model of the patient’s skin, allowing the movement of the various bones to influence real-time changes to a person’s facial structure, now visible from any angle.

This was done for several common practice scenarios (such as correcting an extreme over or under bite, or a jaw misalignment) and then imported into the Oculus Rift, where hand tracking controls were developed to allow students to “grab” the bones for adjusting in 3D.

Before re-positioning the jaw segments, the jaw has a shallow profile.

After re-positioning of the jaw segments, the jaw is more pronounced.

As a result, students are now able to gain a more thorough understanding of the spatial movement of bones and more complex scenarios, such as extensive reconstructive surgery, could be practiced well in advance of seeing a patient for a scheduled surgery.

November 2, 2015September 30, 2020

Surgical Planning for Dentistry: Digital Manipulation of the Jaw

CT data was brought into Zbrush & Topogun to be segmented and re-topologized. Influence was then added to the skin mesh allowing it to deform as the bones were manipulated.

Hera Kim-Berman is a Clinical Assistant Professor with the University of Michigan School of Dentistry. She recently approached the Duderstadt Center with an idea that would allow surgeons to prototype jaw surgery specific to patient data extracted from CT scans. Hera’s concept involved the ability to digitally manipulate portions of the skull in virtual reality, just as surgeons would when physically working with a patient, allowing them to preview different scenarios and evaluate how effective a procedure might be prior to engaging in surgery.

After providing the Duderstadt Center with CT scan data, Shawn O’Grady was able to extract 3D meshes of the patient’s skull and skin using Magics. From there, Stephanie O’Malley worked with the models to make them interactive and suitable for real-time platforms. This involved bringing the skull into a software like Zbrush and creating slices in the mesh to correspond to areas identified by Hera as places where the skull would potentially be segmented during surgery. The mesh was then also optimized to perform at a higher frame rate when incorporated into real-time platforms. The skin mesh was also altered, undergoing a process called “re-topologizing” which allowed it to be more smoothly deformed. From there, the segmented pieces of the skull were re-assembled, and then assigned influence over areas of the skin in a process called “rigging”. This allowed for areas of the skin to move with selected bones as they were separated and shifted by a surgeon in 3D space.

Once a working model was achieved, it was passed off to Ted Hall and student programmer Zachary Kiekover, to be implemented into the Duderstadt Center’s Jugular Engine, allowing the demo to run at large scale and in stereoscopic 3D from within the virtual reality MIDEN but also on smaller head mounted displays like the Oculus Rift. Additionally, more intuitive user controls were added which allowed for easier selection of the various bones using a game controller or motion tracked hand gestures via the Leap Motion. This meant surgeons could not only view the procedure from all angles in stereoscopic 3D, but they could also physically grab the bones they wanted to manipulate and transpose them in 3D space.

Zachary demonstrates the ability to manipulate the model using the Leap Motion.

June 19, 2015August 25, 2020

Exploring Human Anatomy with the Anatomage Table

The Anatomage table is a technologically advanced anatomy visualization system that allows users to explore the complex anatomy of the human body in digital form, eliminating the need for a human cadaver. The table presents a human figure at 1:1 scale, and utilizes data from the Visible Human effort with the additional capability of loading real patient data (CT, MRI, etc), making it a great resource for research, collaborative discovery, and the studying of surgical procedures. Funding to obtain the table was a collaborative effort between the schools of Dentistry, Movement Science, and Nursing although utilization is expected to expand to include Biology. Currently on display in the Duderstadt Center for exploration, the Anatomage table will be relocating to its more permanent home inside the Taubman Health Library in early July.