Beyond the X-Ray

In addition to skulls, jaws, and teeth, the Planmeca ProModel service depicts tumors and existing dental hardware, such as implant screws and reconstruction plates.
An X-ray tells doctors a lot about a patient's anatomy. However, surgery takes place in three dimensions, and an X-ray is ultimately nothing more than a picture. Surgeons would benefit significantly from tangible physical models of patients' bones, precisely rendered in real size.

Three-dimensional printing technology is now providing such models on demand from 3D X-ray data, enabling maxillofacial surgeons to better plan their operations, shorten procedure time, lower costs, and, most importantly, improve results.

Better Surgical Outcomes
The models come from Planmeca Oy, Helsinki, Finland, the largest privately owned high-tech dental equipment maker. The company manufactures most everything one might encounter in a dental office, including specialized dental units, their attachments, X-ray machines, and software for running an entire practice. The company recently saw an opportunity to maximize the value of the 3D data its X-ray machines produce. The data, they knew, could form the basis of 3D physical models created in a few short hours with 3D printing. Three-dimensional printing is the automatic, layer-by-layer construction of a physical model from 3D data. It works much as document printing produces a business letter line by line from word-processing data.

"X-rays provide a lot of critical information, but for complex procedures, a 3D physical model can make a world of difference," says Jukka Kanerva, product manager for Planmeca Oy. "As the surgeon can familiarize themselves with the anatomy beforehand, the patients spend less time under anesthesia, less time with open tissue, less time in the hospital afterward, and less time undergoing remedial procedures."

Multi-Color 3D Printing
3D printing is the automatic, layer-by-layer construction of a physical model from 3D data.The Planmeca ProModel service employs a ZPrinter 450 multicolor 3D printer from Z Corporation, Burlington, MA, to produce the models. The process starts in the dental office or hospital. Doctors X-ray the patient, typically with a Planmeca ProMax 3D machine, and then use an electronic form in Planmeca Romexis imaging software to send the data, electronically, to Planmeca headquarters. Planmeca ProModel professionals then use Z Corporation's ZEdit Pro software to apply colors and labels to print the anatomy.

In addition to skulls, jaws, and teeth, the Planmeca ProModel service depicts tumors and existing dental hardware, such as implant screws and reconstruction plates. Multicolor 3D printing enables Planmeca to spotlight critical areas and to annotate models with text labels. Many models, for example, call out the sensitive mandibular nerve in color. Planmeca ProModel requires no additional effort or special imaging protocols – just a routine 3D X-ray exposure from any Planmeca ProMax 3D imaging system. In less than 24 hours, the model is finished and shipped to the doctor.

In addition to examining the anatomy and planning procedures, surgeons can use ZPrinted Planmeca ProModels to precisely bend reconstruction plates, fit screws, design drill guides, and practice removing tumors, all prior to entering the operating room. Because the models are autoclavable, drill guides are usable on the patient, and models can be brought into sterile areas during the surgery.

Shorter Stays, Better Results
In addition to examining the anatomy and planning procedures, surgeons can use ZPrinted Planmeca ProModels to precisely bend reconstruction plates, fit screws, design drill guides, and practice removing tumors, all prior to entering the operating room.
Medical professionals have found Planmeca's ZPrinted models enormously helpful in a wide range of cases, including implants, overgrowth, tumor removal, bone grafts, and skull reconstruction. ZPrinted Planmeca ProModels are also useful in educating the patient, students, and other medical professionals in clinical, education, and written forums. When there is a tangible replica of the patient's anatomy to work with, the case and treatment options become clear.

Used as a pre-operative planning tool, doctors say a ZPrinted Planmeca ProModel reduces operation times by one to two hours, on average, lowers intensive care days by one to two per patient, and decreases operation costs by an additional 10%. By enabling practice, fitting, and deep understanding, it generates better aesthetic results and fewer complications.

Planmeca chose a ZPrinter from Z Corporation, because they are the only ones capable of simultaneously printing in multiple colors. The ZPrinter 450, in particular, is easy to use, highly automated, self-contained, and suitable for a professional environment, according to Kanerva.

"Planmeca ProModel is an important service for Planmeca," Kanerva says. "It is improving the lives of patients and helping us continually develop products and services that improve results for patients and providers alike. ZPrinting is an indispensable part of the cycle."

Multicolor Models
Medical professionals have found Planmeca’s ZPrinted models enormously helpful in a wide range of cases, including implants, tumor removal, bone grafts, and skull reconstruction.The same multicolor 3D printing that Planmeca uses has helped doctors at The Walter Reed Army Medical Center, Washington, D.C., improve the success of delicate surgeries. This venerable institution closed in August, and operations moved to new and upgraded facilities at the National Naval Medical Center in Bethesda, MD, and at Fort Belvoir, VA. The ZPrinters moved to the Bethesda facilities, Walter Reed National Military Medical Center.

Walter Reed's 3D Medical Applications Center uses CT scans or camera images, transformes them into 3D computer files, digitally applies any desired color to the resulting digital models, and uses Z Corporation 3D printing technology to produce multicolor physical models in as little as a few hours. Surgeons can hold these 3D models in their hands, turn them upside down, and closely examine them from any angle to understand what they will be dealing with when the patient is on the table. The center typically prints out several models per week. 

Neurosurgery uses models of aneurysms and arterio-venous malformations to help them with delicate surgeries. The 3D model essentially created a 3D roadmap for treatment. Surgeons spent less time investigating the anatomical structures of the patient after making the incision, possibly reducing blood loss and chances of infection. Some surgeons say they, "feel like they have been there before."

On one occasion, in orthopedics, creation of a model was for the removal of bony growths on a patient's knee. Using Z Corporation's ZPrinter 450, specialists 3D printed a white model of the joint with blood vessels highlighted in red and a nerve in yellow, enabling the surgeon to determine safe routes of attack on the tumors. The surgeon brought the model into the operating room in a sterile bag and aligned his cutting instrument on the model, then aligned his instrument on the patient in the same fashion.

Specialists in Anaplastology also use 3D printing to create models of patients' faces in the construction of facial prosthetics. No longer do already traumatized patients have to endure plaster on their faces to produce the moulage casting. The 3D printed mask becomes the perfect platform for the creation of a facial prosthetic.

How it Works
Surgeons can benefit, significantly, from tangible physical models of patients’ bones, precisely rendered in real size.The fundamental purpose of a 3D printer is to quickly transform an idea into a physical object. That idea starts as a 3D computer model, be it an X-ray, CT scan, or most commonly a product design created in 3D computer aided design (CAD) software. First, the file must be watertight so that the computer model is a solid, not just images of surfaces that may not have any thickness.

With the file now in a printable format, the 3D printer user launches software, such as ZPrint. Using ZPrint, the user can scale up or scale down the file to print, orient the part in the build chamber of the 3D printer, add or modify colors, and direct the 3D printer to print multiple versions of the part in the same build (with or without variations). Then ZPrint slices the 3D model file into hundreds of digital cross-sections, or layers. Each slice corresponds to a layer of the model to be fabricated in the ZPrinter. When ready to start the print job, the user clicks 3D Print. This sends the digital layer files to the ZPrinter, and immediately, the model begins printing.

The machine deposits powder from the hopper in the back of the machine, spreading a thin 0.004" (0.1mm) layer across the build platform. The print carriage then moves across this layer, depositing binder (and various inks for a color model) in the pattern of the first slice that sent from ZPrint. The binder solidifies the powder in that cross-section of the model. At this point, the piston below the build chamber lowers the powder bed 0.004" (0.1mm), preparing for the next layer. The cycle repeats itself until the model is complete.

Z Corporation
Burlington, MA
zcorp.com

Planmeca Oy
Helsinki, Finland
planmeca.com/en