THE VALIDITY OF THE PREDICTION OF SOFT-TISSUE PROFILE CHANGES AFTER LEFORT-I OSTEOTOMY USING THE DENTOFACIAL PLANNER (COMPUTER SOFTWARE)

The purpose of this study was to examine the validity of the predictio n of soft tissue changes after LeFort I osteotomy with the DentoFacial Planner (DFP) (computer software). The preoperative and postoperative lateral cephalograms of 21 white adult orthodontic patients (10 males and 11 females) who underwent only LeFort I osteotomy as part of thei r overall treatment were digitized. A coordinate system of X and Y axe s were used to assess the amount and direction of movement of the maxi lla. The SN + 7-degrees was the X axis, and a perpendicular to this pl ane from nasion was the Y axis. The sample was divided into two groups depending on the amount of forward movement of the maxilla. More than 2 mm of anterior placement of the maxilla comprised the advancement g roup (13 patients) and less than 2 mm comprised the impaction group (8 patients). The selection criteria for the sample were (1) before and after cephalograms taken with lips in repose and in centric occlusion; (2) all preoperative records taken almost immediately before surgery; (3) postoperative records taken at least 6 months after surgery and c hecked by regional superimposition of the preoperative and postoperati ve lateral cephalograms onto the maxilla and the mandible. No tooth mo vement occurred between the time the records were taken. The following soft tissue landmarks were examined: pronasale, subnasale, stomion su perior, middle upper lip, stomion inferior, middle lower lip, labrale inferior, labiomental fold, and pogonion. The results indicate that fo r some of these landmarks the amount and direction of soft tissue chan ges differed between the DFP prediction and the actual surgical change s by LeFort I osteotomy. Differences between actual and predicted chan ges may be partially attributed to the variability of surgical procedu res of previous studies that provided the data for the DFP computer so ftware.