Maxillofacial Surgery and 3D printing: Past and Present

The maxillofacial surgery is a broad specialty that includes a lot of different procedures with the aim to correct acquired conditions like trauma, or congenital pathologies – such as facial deformities i.e. lip and palatal clefts, or tumors.

Historically, the planning phase for those situations was fully analogical, based on the surgeon capability to interpret two-dimensional exams (X-rays) of a three-dimensional structure, leading to inaccuracies, especially in complex cases, where the surgeon’s ability was highly demanded. With the advent of three-dimensional computer tomographies, the spatial visualization of patient’s structures was facilitated, but it was still a virtual image in a computer screen and surgeons were looking for more.

With the advancements of 3D printing (additive manufacturing), surgeons now are able to materialize those virtual images into a tactile instrument to help locate themselves spatially during the surgical procedure or even perform the surgeries prior to the real case itself, but not limited to that. Anatomical models work as an educational tool for patients, showing their condition, and explain to them what is going to be the procedure, narrowing the bonds of trust between the professional and the patient.

In terms of the educational purpose of anatomical models, not only surgeons and patients can benefit from them, teaching institutions are able to replicate special cases multiple times, so residents could use them to simulate and train complex procedures. With the ability to manipulate three-dimensional images, it is even possible to create from scratch challenging scenarios to help future professionals to get better qualified from their training programs.

With the models in hand, the natural next step is the ability to replicate three-dimensionally surgical procedures and physically manipulating them. Initially, traditional CAD software was used to perform such process, but during the last years, many companies developed solutions dedicated to simulating surgical procedures digitally, with a lot of publications corroborating their accuracy and replicability.

3D Printed Pre-surgical planning model for Cranio-Maxillofacial Surgery Graphic credit: Dr. Devid Zille

Now, that we solve the problem of virtual surgical planning (VSP), how can we translate the virtual procedure made in the digital patient into the operative room and the real one? Basically, we can use two systems to transfer that information into the physical scenario: Navigation surgery –  a complex system of cameras and fiducial markers that locates in real-time the position of the surgical instruments and/or bone segments, trying to match the images in the computer screen with the real situation – or using surgical templates (guides) to replicate the desired cutting paths or bone positions. Multiples authors compared both methods in the Oral and Maxillofacial Surgery field and it was observed a tendency for better results using surgical guides. Zinzer MJ. et. al (2013), for example, found that 3D-printed surgical guides can provide results about three times more accurate that navigational procedures in orthognathic surgery.

Traditionally, cutting and positioning guides were used in conjunction with off-the-shelf fixation systems that still require the surgeon’s ability to contour them into the patient’s anatomy, requiring high skills to exactly match the contoured plate into the bone surface. Sometimes this process can take precious time, with the patient under general anesthesia. Evolving on that idea, we get into what I believe is the gold standard protocol for treatment in Oral and Maxillofacial Surgery: The combination of 3D-printed surgical guides and Patient-Specific Implants.

3D printed CMF tool Graphic credit: Dr. Devid Zille

As showed by Heufelder M. et al. (2017) and Suojanen J. et al. (2017), patient-specific implants for orthognathic surgery, in conjunction to drilling guides, provide excellent stability and predictability, not limited to that. The utilization of VSP in conjunction with 3D printed devices can bring multiple benefits: lower surgical time due the unnecessity of bending and fitting off-the-shelf implants into the perfect position; Decreased surgical global costs due reduced surgical and hospitalization time; Higher safeties to the surgeon and the patient due to higher predictability and the possibility to anticipate possible surgical difficulties and complications.

Modern software used to plan and design this type of systems can provide additional valuable information like optimal bone thickness areas, where screws theoretically stabilize better, avoiding thin areas and providing the possibility to control plate curvatures precisely.

Graphic credit: Dr. Devid Zille

The era of 3D printing in Oral and Maxillofacial surgery is evolving every day, providing better results to surgeons and patients. There are some aspects still under development, with promising results. I can see space for improvement on multiples fronts such as the following:

-Software: Incorporate artificial intelligence/machine learning to help surgeons take the best decisions for each individual case. Additionally, incorporate even more topological optimization concepts to diminishing the implants volume and lattice structures for lower weight.

-Hardware: Provide cheaper and faster manufacture alternatives.

-Material Science: Develop new 3D-printable materials with enhanced mechanical and biocompatible properties.

References:

  1. Suojanen, Juho, Junnu Leikola, and Patricia Stoor. “The use of patient-specific implants in orthognathic surgery: a series of 32 maxillary osteotomy patients.” Journal of Cranio-Maxillofacial Surgery 44.12 (2016): 1913-1916. https://www.ncbi.nlm.nih.gov/pubmed/27769722 
  2. Heufelder, Marcus, et al. “Clinical accuracy of waferless maxillary positioning using customized surgical guides and patient-specific osteosynthesis in bimaxillary orthognathic surgery.” Journal of Cranio-Maxillofacial Surgery 45.9 (2017): 1578-1585.  https://www.ncbi.nlm.nih.gov/pubmed/28793965 
  3. Zinser, Max J., et al. “A paradigm shift in orthognathic surgery? A comparison of navigation, computer-aided designed/computer-aided manufactured splints and “classic” intermaxillary splints to the surgical transfer of virtual orthognathic planning.” Journal of oral and maxillofacial surgery 71.12 (2013): 2151-e1. https://www.ncbi.nlm.nih.gov/pubmed/24237776     

About the author:

Dr. Devid Zille leads the Patient-Specific Implant initiative for Osteomed, one of the world’s largest small-bone implant manufacturer, dealing with Maxillofacial, Neuro and Extremities surgery. He is post-graduate in Oral and Maxillofacial Surgery mainly focused on the correction of facial deformities. His expertise includes 3D modeling and design using advanced concepts like lightweight structures and topological optimization based on FEA analysis and 3D printing.

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