Multisegmental maxillary osteotomy. Indications, stability and limits

Transverse discrepancies, open bite, intermaxillary tooth size discrepancies, asymmetry of the maxillary dental arch and an unfavorable incisor inclination can be indications for multisegmental LeFort I osteotomy. Compared to single segment LeFort I osteotomy, multisegmental procedures do not show less skeletal or dental stability in the sagittal and vertical dimensions. Surgical expansion provides stable results at the maxillary skeletal base whereas relapse rates of more than 60% occur in the dento-alveolar region. Preoperative orthodontic expansion is probably the main source of transverse relapse. A longer operating time, especially in cases with additional procedures, leads to higher blood loss. However, due to the overall low transfusion rates preoperative blood donation should be reserved for patients with additional transfusion risks. Blood flow to the maxillary dentoosseous segments is significantly reduced by segmentation. Transverse expansion of more than 4 mm results in a further significant decrease of blood supplies. Due to the high relapse rates and the enhanced risk of avascular sequelae, a two-step procedure with transverse maxillary distraction and LeFort I osteotomy should be preferred to manage transverse discrepancies of 7 mm and more.