A three dimensional analysis of soft and hard tissue changes following bimaxillary orthognathic surgery in skeletal III patients.

The three dimensional changes in the bone and the ratio of soft tissue to bone movement were investigated in a group of 16 Skeletal III patients following orthognathic surgery. Computerised tomogram scans were taken for each patient pre-operatively and 1 year postoperatively. The scans were superimposed, radial measurements calculated, and the changes illustrated by two separate colour scales. There was no constant pattern of movement in the maxilla or mandible in these patients. However, following a Le Fort 1 osteotomy there was commonly a 1:1 ratio in the midline which increased to 1.25:1 at the alar bases and over the canine regions bilaterally. There was also a 1.25:1 ratio or greater over the chin and mentalis regions following mandibular set back.