Three-dimensional facial changes correlated with sagittal jaw movements in patients with class III skeletal deformities

Abstract

The aim of this prospective study was to correlate the postoperative 3-dimensional facial changes in skeletal class III deformity with sagittal jaw movements in 84 patients who had been treated by one piece Le Fort I maxillary advancement only (n=18), mandibular setback only (n=38), or both procedures (n=28). At the times of evaluation before and six months after operation all patients had fixed orthodontic appliances. Soft tissue changes were evaluated on optical 3-dimensional scans, while lateral cephalograms were superimposed to assess sagittal jaw movements. Three-dimensional surface facial scans were divided into 11 regions. We modelled soft tissue changes in each region by linear regression with maxillary (point A) and mandibular (point B) sagittal movements as predictors, and adjusted for sex, age, body mass index, type of operation, and interincisal angle. We found the highest values of regression coefficients (around 0.5) for the sagittal movements of the variables points A and B within the regions of the upper and lower lips. This meant that for each mm of maxillary advancement and mandibular setback, the soft tissue moved 0.5mm. In the sides of the face the regression coefficients were between 0.1 and 0.3, as were those within regions indirectly affected by the operations.