Stability of Le Fort I osteotomy in bimaxillary osteotomies: single-piece versus 3-piece maxilla.

PURPOSE: The aim of the present study was to investigate the effect of segmentation on the stability of Le Fort I osteotomies in bimaxillary procedures.

PATIENTS AND METHODS: One hundred twenty patients undergoing bimaxillary osteotomies (60 single-piece maxilla, 60 3-piece maxilla) were included in the study. Cephalometric analysis was performed before surgery (T1), immediately after surgery (T2), and after a follow-up of 12 to 15 months (T3). The positional changes of 6 angles (angle of nasion-sella line to A point-nasion line, angle of nasion-sella line to B point-nasion line, angle of nasal line [plane] to nasion-sella line, angle of mandibular line [plane] to nasion-sella line, angle of upper incisor to nasion-sella line, angle of lower incisor to mandibular line [plane]) and 4 maxillary landmarks (upper incisor edge, mesial cusp upper first molar, anterior nasal spine, posterior nasal spine) were measured by superimposition of radiographs. Paired t test was run to evaluate surgical changes (T2-T1) and postsurgical stability (T3-T2). Differences between the 1-piece maxilla group and the 3-piece maxilla group were analyzed with 2-tailed t test. Pearson correlation coefficient was calculated to determine relations among the magnitude of maxillary advancement, superior and inferior repositioning and postsurgical changes of angle of nasion-sella line to A point-nasion line, and the respective landmarks.

RESULTS: The study variables (T1), surgical changes (T2-T1), and postsurgical changes (T3-T2) showed no significant differences between groups with single-piece and 3-piece maxilla. However, a tendency for more relapse was observed in the 3-piece maxilla group in the vertical direction. A significant inferior movement of the upper molar (mesial cusp upper first molar) was seen in the single-piece maxilla group (0.5 mm) and the 3-piece maxilla group (0.4 mm). In both groups and all directions, the T2-to-T3 changes had no significant correlation with the T1-to-T2 changes. No differences were observed between superior and inferior repositioning.

CONCLUSIONS: Segmentation of the maxilla does not provoke major skeletal or dental instability and should be considered whenever indicated. Adequate bone grafting provides good stability in anterior and inferior repositioning of the maxilla.