The Le Fort I downsliding osteotomy: a study of long-term hard tissue stability.

Surgical maxillary repositioning in individuals with vertical maxillary deficiency may be accompanied by skeletal instability. Long-term skeletal changes in 13 patients who underwent a Le Fort I downsliding osteotomy were studied retrospectively. Nine patients underwent a single-jaw procedure, and 4 patients underwent a bimaxillary procedure. Rigid fixation was used in 10 patients, and wire osteosynthesis was used in 3. Descriptive statistics, Pearson moment correlation, and significance testing were performed at the 5% level. The maxilla was stable horizontally over the long term, but it underwent a mean 26.7% superior relapse anteriorly. The results were variable, however. Rigid internal fixation appeared to enhance the horizontal stability of the maxilla in patients who underwent single-jaw surgery. The maxilla was more stable vertically in patients who underwent bimaxillary surgery with rigid internal fixation, compared to isolated maxillary surgery and rigid internal fixation. The results indicate that a 2-mm relapse value may be useful in planning the vertical amount of maxillary incisor exposure.