Jaw Reconstruction and 3D Planning for Orthognathic Surgery

Formulating a Treatment Plan

A British man had suffered a severe trauma to the lower jaw, leaving him with a damaged left side of the mandible and missing teeth. The function of the temporomandibular joint remained intact, although the condyle left was displaced. The patient received treatment from a medical team at King’s College Hospital, led by Dr Christoph Huppa, Dr Muhanad Hatamleh and Dr Gavin Mack. As the trauma had resulted in malocclusion, the patient first underwent orthodontic treatment for 18 months udner the guidance of Dr Mack to align his teeth. Then the surgical team began planning the bi-maxillary surgery to move both jaws into the optimal position, for a class I occlusion. The patient’s left mandible was deficient, which meant that a titanium plate would need to be implanted to join the left condyle and mandible and at the same time reconstruct the left side of the mandible.

Visualizing the Defect in 3D

In order to accurately visualize the defect, Dr Hatamleh processed a CT scan of the patient’s skull and mandible using PROPLAN CMF. The software allowed him to segment the skull and mandible separately, visualize the defect in 3D, and decide upon the best course of action.

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The virtual 3D reconstructions revealed the in-situ orthodontic metal brackets, a hypoplastic left hemi-mandible, small and displaced mandibular condyle, fragmentation of the ramus, malocclusion, an edentulous posterior left hemi-mandible
and marked reduction in the bulk of the left masseter muscle.

Pre-Operative Planning with PROPLAN CMF®

The surgical team began the pre-operative planning by taking cephalometric planned measurements, using the Orthognathic Wizard of PROPLAN CMF. The software also helped to improve the quality of the CT scan by superimposing the upper and lower dentition from the scanned models of the patient’s intra-oral tissues (Figure 1).

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As part of the bi-maxillary surgical plan, the team planned a LeFort I osteotomy to move the maxilla to the desired position by performing three movements along the x-y-z planes: 3mm forward, 3mm rotation to the left and 1.5mm set down anteriorly. A Bilateral Sagittal Split Osteotomy (BSSO) was performed on the mandible, bringing the mandible into the desired occlusion with the maxilla (Figure 2).

The next step was a 3D planning of the reconstruction of the deficient left mandible with simulation tools in PROPLAN CMF. A mirrored image of the right, healthy side of the mandible was superimposed over the left and optimally positioned to restore facial symmetry (Figure 3).

Designing the Patient-Specific Mandible Plate

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Figure 1: CT scan of the patient (1a) showing noise and reduced quality, which was enhanced by amalgamating with the patient’s scanned casts (1b left) as shown (1b right) using PROPLAN CMF
Figure 2: Bi-max 3D surgery performed using PROPLAN CMF
Figure 3: Mirrored plate design in 3-matic
Figure 4: Titanium patient specific plate
Figure 5: Intra-oral restorative treatment

To design the mandible plate for the specific requirements of the patient’s case, the team at King’s College Hospital worked with OBL, a Materialise daughter company offering surgical planning as well as a range of standard and patient-specific medical devices for maxillofacial surgery, neurosurgery and plastic surgery.

OBL modeled the devices, which included a titanium megaplate and polyamide SynpliciTI plate positioning guide, according to the virtual surgical plan using 3-matic software. Once the designs were validated by the surgeon, the plate and guide were manufactured in titanium using Selected Laser Melting and Selected Laser Sintering technology. During surgery (Figure 4), the plate was placed and the iliac crest bone was grafted on the left to be used later on during the subsequent intra-oral restorative treatment (Figure 5).

The reconstructive surgery went well and thanks to the accurate plate fit, facial symmetry was restored along with class I occlusion.

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“It was a challenging case where we had to combine multiple procedures. PROPLAN CMF enabled us to validate the initial bi-maxillary orthognathic treatment plan in 3D, restore facial symmetry and check soft tissue changes. It helped us optimize treatment and create an aesthetically pleasing result.“ 
Dr. Muhanad Hatamleh, King’s College Hospital, UK