Analysis of Craniomaxillofacial Malformations in Mice Using Three-dimensional Microcomputed Tomography

To begin import Micro-CT image of the mouse skull into the software. Right Click on the Masks page and select New Mask. A new layer named green will appear.

On the Thresholding page that pops up select the required threshold range. Click on the newly created layer green in the Masks page, and select Calculate 3D from the dropdown menu. In the 3D objects interface right click Green and click Properties.

Then click Color to change the coding of all the 3D models reconstructed with different bones. Next, using the eraser tool from the edit menu, manually erase the bones attached to the mandible in each layer on the 2D sagittal plane. After clicking on the region growing option, select the region of the mandible on the 2D sagittal plane.

In the Masks page, select Calculate 3D from the dropdown menu and click on the newly created layer to label it as mandible. Turn off visible right click on the screen and select Zoom to Full Screen. Then click on Measure and select distance from the dropdown menu.

To calculate the length, mark the correct points on the 3D image. In the 3D objects interface, right click on mandible, followed by a Properties and properties info Volume module. To read the reconstructed volume values for each cranio maxillofacial bone block, measure the mandible frontal bone, parietal bone, nasal bone, premaxilla, maxilla, inter parietal bone and occipital bone in the same way.

The Micro-CT analysis showed a dose dependent correlation between dominant negative RAR alpha expression and skeletal defects, including reduced lengths of the mandible, frontal, and parietal bones. The inhibition of our RAR in osteoblasts led to craniofacial deformities characterized by changes in the shape, size, and ossification levels of cranial facial bones.