Thanks to 3D images and 3D printed moulds and customized implants, jaw surgery can now be performed with much greater accuracy. This is the conclusion of Joep Kraeima, technical medical specialist at the University Medical Center Groningen. ‘Good preparation using 3D technology means that surgeons no longer have to make on-the-spot decisions, measurements and adjustments during surgery, but can rely on the 3D operation plan and 3D printed moulds that they made in advance.’ On Wednesday 8 May, Kraeima will be awarded a PhD by the University of Groningen for the findings in his thesis.
Kraeima works in the Oral & Maxillofacial Surgery treatment team as a technical medical specialist. It is his job to identify points for improvement in the care that is provided and to develop solutions for these. ‘My research focuses on three areas within the department: oncology, jaw corrections and joint surgery.’ With all three groups of patients, an impression of the condition and how it relates to the jaw needs to be formed, before surgery can be performed and implants fitted. ‘Although 3D technology has certainly proven to be of great help in these areas for several years, I've always thought that we could put it to even better use.’
Imaging is always the first step in the process of jaw surgery. ‘For many years, we’ve been using technology such as CT scans to make an image of the jaw. But I've developed a method for converting the images made by different scans, such as CT, MRI and PET scans, to form a single 3D image. This gives us a much more accurate digital image of what is going on in the jaw. For example, you can’t tell from the outside how far a tumour has infiltrated into the jaw bone. Using this method, the tumour can be precisely localized in advance. The treatment team can then use the images to work out a treatment plan. We run through all the possible treatment options and decide which is best.’
Printing moulds and implants
‘Once the digital plan has been made, we can make a drilling or sawing mould and the implants. We print a made-to-measure mould on a 3D printer. As the mould fits the bone exactly, we can measure where we need to saw into the bone down to the millimetre. The surgeon then saws around the edge of the mould, or drills through the holes in the mould, to implement the plan that was agreed beforehand.’ The third step is to make the implant. ‘Using the same plan, we can decide how we should replace the bone we have removed (because of a tumour, for example) with donor bone in combination with an implant. The technique that has been developed also makes it possible to produce artificial jaw joints that exactly match the patient’s specifications. Implants like these are printed with a 3D printer. If the surgeon follows the mould precisely, the implant will fit precisely. This saves a lot of measuring and adjustment during surgery.’
In his thesis, Kraeima describes not only the development of this 3D virtual plan, but also research into its efficacy. ‘For example, we’ve been able to prove that jaw corrections can be performed more accurately using this 3D plan, but that it’s not particularly beneficial for smaller corrections of less than 3.5 millimetres. This is good to know because making a 3D plan is a time-consuming business. What’s more, we don't have enough experts (technical medical specialists) to make these plans for every patient. More research is needed to identify the situations and patients that will benefit the most from these virtual plans.’
Joep Kraeima (1989, Zwolle) studied Technical Medicine at Twente University. He conducted his research in the Oral & Maxillofacial Surgery department of the UMCG, and his thesis is entitled: ‘Three dimensional virtual surgical planning for patient specific osteosynthesis and devices in oral and maxillofacial surgery. A new era.’ After he has been awarded his PhD, Kraeima will continue to work in the Oral & Maxillofacial Surgery department of the UMCG.