segmental Le Fort I (SLF-1) osteotomy technique for repair of facial deformities of cleft lip and palate patients, as regards to the stability and predictability and cleft-alveolar gap dimension changes

CBCT DICOM images of the patient's scan were imported into 3D Slicer software (BWH, USA). Volume rendering was calculated based on selection of region between the base of the nose superiorly, and edges of the alveolar cleft inferiorly, posteriorly, anteriorly, and on both sides. Segmentation of air present in this region was done, and exported in Standard Tessellation Language (stl) file format. The volume of this file was calculated to give an estimate of volume of the alveolar defect, using Meshmixer™ Version 3.5.474 (Autodesk®, California, USA). 6 months' postoperative CBCT and preoperative CBCT. were compared to determine the amount of change.

Planned amount of advancement was extracted from the digital planning procedure for each subject, and this was compared with the actual amount of advancement achieved from the surgery. This actual amount of advancement was calculated by superimposing the 3D-generated skulls of the preoperative CBCT on the 3D-generated skull of the postoperative CBCT, and a point placed on the upper first molar of each of the preoperative and postoperative CBCT. The distance between the two points is the amount of advancemenet achieved.