Virtual Planning for Orthognathic Surgery with Mimics Enlight CMF

Preparing the anatomy 

1. Importing images 
   • Click on 'From Images' and locate the directory with the DICOM images
   • Select the images to see a preview of the series
   • Click 'Open' to continue with the selected images
   • Click 'Orthognathic Planner' to start planning
   • (Optional) Check DICOM information by right-clicking on the image series and selecting 'Image Information'
2. Segmenting the skull 
   • Click on the skull option
   • Adjust the threshold if necessary (default is set for bone tissue)
   • Click 'Apply' to continue
   • Use the Erase tool to remove any unwanted voxels in 2D or 3D
   • Click 'Finish' to generate the 3D skull model
3. Segmenting the soft tissue 
   • Repeat the steps for soft tissue segmentation
   • Use the Erase tool to remove artifacts like the chin rest

 Positioning the composite models 

1. Importing the cast models 
   • Click on 'Maxilla' and import the STL file of the maxilla cast
   • Repeat for the mandible
2. Aligning the casts to the skull 
   • Place 3 corresponding points on the casts and the skull for initial alignment
   • Let the software complete the precise alignment
   • (Optional) Manually adjust the alignment if necessary
3. Separating the mandible 
   • Allow the software to automatically separate the mandible from the skull
   • (Optional) Manually adjust the split if required
   • Drag the red control points to indicate where the teeth need to be replaced

 (Optional) Identifying the nerves 

1. Place points on the mental foramen and mandibular foramen to re-slice the image
2. Trace the nerve by placing points along the nerve canal
3. Repeat for both sides

 Setting the natural head position 

1. Indicate the Frankfurt horizontal plane:  
   • Place points in each ear canal
   • Place points on the inferior border of each orbit
2. Adjust the position of the skull in the three orthogonal views

 Creating cephalometric analysis 

1. Place anatomical landmarks as prompted by the software
2. Review and adjust points if necessary

 Planning the osteotomy  

1. Le Fort One osteotomy 
   • Place 4 points as instructed by the left panel to generate the osteotomy plane
   • Adjust the shape using the red control points if needed
   • Click 'Split' to perform the cut, then 'Finish'
2. Bilateral sagittal split osteotomy (BSSO) 
   • Start from the right SSO and place points as instructed to generate the osteotomy plane
   • Adjust control points if necessary, then click 'Split'
   • Repeat the same for the left side

 Placing the occlusion 

1. Import the 3D model (STL file) of the occlusion cast
2. Register the mandible and maxilla of the composite models to the mandible and maxilla of the occlusion cast by placing 3 corresponding points
3. Let the software complete the registration

 Repositioning the anatomy 

1. Select components in the workflow panel
2. Use the interactive coordinate system to move parts
3. Monitor measurements in the right panel
4. Visualize soft tissue changes by clicking the eye icon next to 'Soft tissue'

 Designing the splint 

1. Select the type of splint (intermediate or final)
2. Indicate the outline of the splint by placing points
3. Generate the splint shape and edit if necessary by dragging the edges
4. (Optional) Add wiring holes:  
   • Specify diameter 
   • Click to place holes 
5. Click 'Create Splint' to finalize the design

 Exporting the plan 

1. Export 3D models as STL files
2. Export cephalometry analysis as a CSV file
3. Export the natural head position as an XML file
4. Review the comparison between the preoperative situation and the planned outcome

Note: This workflow is for demonstration purposes. Always consult with a trained healthcare professional for actual surgical planning.