PMC9686285_01
Lateral (A) and dorsoventral (B) radiographs of the dog at presentation. On the lateral view, there are some radiolucent fracture lines (arrow) at the incisive bone, mandible, and multiple metal opacities (arrowhead) around the facial area. In the dorsoventral view, bone and soft tissue loss in the right rostral area was evident.
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F1
More than twenty-five 3 x 3 mm round metal opaque materials suspected to be scattered bullet fragments were also found over the entire facial area (Figure 1).
Emergency surgery was performed to debride devitalized tissues, to extract as many bullet fragments as possible and to stabilize fractured bones temporarily. Extraction of the bullet fragments (A) were made under fluoroscopic guidance (B). A continuous stout loop interdental wire was applied at the right mandibular teeth and the fixation was reinforced with temporary resin over the area (C).
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F2
Bullet fragments were removed as much as possible under fluoroscopic guidance for 30 min (Figures 2A,B). Automix Plus, DMG, New Jersey, USA) from the mandibular second molar teeth to the canine teeth (Figure 2C). A 24-Fr thoracic catheter (PVC thoracic catheter, Sewon medical,
Until healthy granulation tissue filled the defect, the wound was managed wet-dry for 15 days. Two days after open management (A), 5 days after open management (B), 15 days after open management (C). Fresh granulation tissue started to form at some parts of the defect at 5 days, and at 15 days after open management, the wound was fully covered with granulation tissue. Note the endotracheal tube placed through the open nasal cavity (arrow), and loose sutures (arrowhead) around the defect for tie over bandage.
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F3
Until healthy granulation tissue filled the entire wound bed, wet dry bandaging was performed twice daily under mild sedation with medetomidine 10 mug/kg IV for 15 days (Figure 3).
PSI design procedures (A-D), and presurgical application of the titanium PSI on the printed PLA bone. STL file of the maxilla (A) was sectioned to smaller parts (B), mirroring of the left maxilla reconstructed the right maxilla (yellow green area). Implant shape was offset from the bone (C), multiple pores and 2.4 cortical screw holes were added to the design (D). Finger parts of the design (arrow) allows the PSI to snap fit to the bone, the palm part (asterisk) covers the bone defect. After receiving the titanium implant, simulation of the implant was performed on a PLA printed bone model (E,F).
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F4
Tessellation Language (STL). The STL file was then transported to 3D design software (Mesh mixer, Autodesk, California, USA) to build a patient-specific implant (Figure 4A). To construct a snap fit, the implant was designed to look like a c shape on a transverse plane and the finger part was designed to hang over the left nasal bone (Figure 4F). By creating a mirror image of the left maxilla in the median plane, the right maxilla was reconstructed (Figure 4B), and the implant shape was offset from the reconstructed area (Figure 4C). Finally, 2.4/2.7 cortical screw holes were added at the tip of the finger and palm parts (Figure 4D). The bone model was printed in polylactic acid (PLA) filament using a fused deposition modeling (FDM) printer (MakerBot Plus, MakerBot Inc., NY, USA) at our medical center (Figures 4E,F).
Sublingual mucosa graft was applied and undermined soft tissue around the defect was sutured over the graft to secure reconstructed nasal cavity (A). Titanium PSI was seated percutaneously, and screws were placed under fluoroscopic guidance (B). PSI was fully covered with angularis oris flap (C). Post operative radiographs, lateral (D) and dorsoventral (E) view, and 3D reconstruction of post operative CT scan revealed precise fit of the implant (F).
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F5
The soft tissue around the maxillary defect was undermined and sutured over the grafted sublingual mucosa (Figure 5A). The implant was then seated percutaneously and a perfect snap fit was obtained by pushing the PSI through the planned area (Figure 5B). To cover the implant and reconstruct the facial soft tissue, the angularis oris cutaneous flap was sufficient for full coverage of the rostral extent of the defect (Figure 5C). Postoperative radiographs and CT tomography revealed a precise fit of the PSI (Figures 5D-F).
Evaluation of the cosmesis of the reconstruction 6 months after PSI application. Except for the hair color and direction change resulted from angularis oris cutaneous flap seen on lateral view (A), facial symmetry was perfect on front view (B).
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F6
Facial symmetry was achieved 3 months after the flap surgery and was maintained through the last evaluation at the 6 month follow-up (Figure 6).
Six months postoperative evaluation of the implant exposure. Note the pink soft tissue under the implant hole (arrow), and the pigmented tissue suggesting palatal epithelium under one hole (arrowhead) (A). CT taken 6 months after surgery revealed soft tissue formation presumed to be palate mucoperiosteum (red circle) (B,C).
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F7
Because the dog had a habit of biting shoes or a feeding bowl, minor enlargement of the implant exposure was found (Figure 7A).