A STUDY OF THE ACCURACY OF PREDICTED SOFT-TISSUE CHANGES PRODUCED BY A COMPUTER SOFTWARE PACKAGE (COG-3.4) IN A SERIES OF PATIENTS TREATED BY THE LEFORT-I OSTEOTOMY

This study was performed to compare soft tissue movements resulting fr om a series of Le Fort I osteotomies with those predicted for the same cases by means of a computerised software package (COG 3.4), The sour ce material consisted of serial lateral cephalometric radiographs for 25 consecutive patients that had received similar Le Fort I osteotomie s primarily to correct an antero-posterior skeletal discrepancy. Gener ally it was found that many of the digitised points on the facial prof ile were surprisingly well predicted, In addition, the chin and profil e changes resulting from mandibular auto-rotation also were reasonably well predicted, However, in a number of cases prediction was less con sistent and this was particularly true in the region of the nose and l ips, In such instances, initial size, thickness and the existing morph ology of the soft tissues appeared to be important factors, The tenden cy of the software occasionally to 'cross-over' the plots for the uppe r and lower lip profile made the judgement in this area of predicted p rofile change difficult in some cases,