Maxillofacial defects are difficult to treat due to their important functional, esthetic, and psychological aspects. The anatomical complexity of this region has also contributed to the challenge it presents all surgeons, including veterans. Traditional pre-made implants often require many adjustments and usually offer suboptimal results . The advances made in AM technology as well as 3D imaging have contributed greatly to the management of maxillofacial defects. This has facilitated the manufacturing of custom-made PSI that mirrors the healthy side to achieve a satisfactory result.
Computer-designed PSI offers higher accuracy and defect adaption, enhanced stability, more predictable outcomes, and better facial contour refinement . Pre-made alloplastic implants usually require major intraoperative adjustments for large complex defects. In the literature, the usual complications associated with other materials, such as infection, foreign body reaction, and displacement, are seldom reported in relation to custom-made PSI . This is in line with our experience in which none of the aforementioned complications occurred.
Using AM technology, we were able to operate on 6 patients with various maxillofacial defects using a total of 8 PEEKs and 2 titanium PSIs. We initially faced challenges meeting the requirements for completing proper preoperative CT for 3D planning. This was solved by always requesting 1–mm-thick CT for all PSI cases.
When designing custom-made PSI, engineers tend to design fixation screw holes in the area where the thickest bone is found irrespective of any vital tissues in the area. However, it is easy to drill wherever it is more preferable in the final implant regardless of the pre-designed screw hole. This is one of the advantages of using PEEK versus pre-made alloplastic implants such as silicone. It is not possible to drill a screw hole anywhere other than the pre-designed screw hole; doing so otherwise would lead to implant tearing and loss.
One of the challenges we faced was fixing mandibular angle PSI. In preformed alloplastic implants, the superior border is usually extended near the dentition to facilitate the fixation process. However, since PSI is based on mirroring of the healthy side, the superior portion is usually located near the inferior border of the mandible or middle part of the lateral cortex. We believe that this issue could be solved by planning all mandibular angle PSIs to have an extended superior border with a minimum thickness to facilitate the fixation process.
PEEK was used to fabricate 8 of the 10 PSIs used here. The use of PEEK in reconstructive surgery is well documented in the literature owing to its excellent biocompatibility, adjustability, stability, chemical inertness, radiolucency, and mechanical properties [12, 13].
In reconstructing the secondary deformity involving the zygoma and orbit, custom-made titanium implant was used in the orbit instead of PEEK because it is more affordable, and no further adjustments would be needed. The zygoma was reconstructed using a separate PEEK PSI.
In our experience, the PSI we used required minimal adjustments that were easily made intraoperatively. However, it should be noted that we faced issues inserting larger implants, requiring the extension of our surgical approach. We believe this could be easily alleviated by separating larger implants into separate smaller pieces with connectors in between as opposed to using 1 large piece.
A custom cutting guide was used in the post-traumatic secondary deformity case to design the zygomatic osteotomy. This was done to facilitate zygoma repositioning followed by PSI placement.
A major issue we faced was designing custom implants for the nasal area. This problem stemmed from the fact that it was impossible to mirror the healthy side since the entire bone was affected. To overcome this limitation, an average of healthy nasal bones was taken and implemented into the final design. However, the resulting implant was too bulky and required further intraoperative adjustments.
In all of our cases, we only reconstructed bony hard tissues. However, soft tissue evaluations were still necessary to ensure that optimum results were met. In the future, we believe that PSI designs should incorporate soft-tissue defects into it to plan PSI thickness accordingly.
None of our patients developed any complications related to the PSI reconstruction. The infection rate in our cases was 0%; wound healing was uneventful. In other reported cases, the infection rate following maxillofacial reconstruction PSI was low (7.7–14.3%) to nonexistent [14,15,16].
Our follow-up period was too short (mean, 9.4 months) to draw any long-term conclusions. However, the main concern following PSI reconstruction is postoperative infection . No patient developed any signs of infection. Based on our long-term experience with non-custom-made implants such as silicone and porous polyethylene, postoperative infections are usually seen in the first few weeks and seldom seen soon after 1 month.
In our experience, the major drawback to the use of PSI is its high cost, which will surely drive many patients toward more affordable options. However, we believe the many advantages of using PSI outweigh this disadvantage.