Morphologic features of the mandibular ramus associated with increased surgical time and blood loss in sagittal split-ramus osteotomy.

PURPOSE: To determine whether specific morphologic features of the mandibular ramus can predict increased surgical time and blood loss in sagittal split-ramus osteotomy (SSRO). MATERIALS AND METHODS: The clinical and morphologic features of the mandibular ramus, obtained from computed tomographic images (n=50), were analyzed to predict the surgical time, the time required for ablation of the medial mandibular ramus, and the time required for sectioning of the mandible in performing a modified Obwegeser SSRO. RESULTS: Significant factors associated with surgical time were an anterior border of the ramus at least 10.5 mm wide, a maximal length of the thickened ramus of at least 8.5 mm, and a distance from the mandibular incisor to the posterior border of the mandible of at least 97.5 mm. There were significant differences in blood loss between the 2 axial aspects of the medial ramus. CONCLUSIONS: The greater protrusion of the medial oblique ridge, thickened ramus, and longer distance from the mandibular incisors to the posterior border of the mandible may increase the surgical time and blood loss in patients undergoing classic SSRO. When planning or performing an SSRO, the morphologic features obtained from computed tomographic images may help surgeons gain a better understanding of the potential difficulties when the surgical site involves the medial aspect of the ascending ramus of the mandible.

Factors predictive of pterygoid process fractures after pterygomaxillary separation without using an osteotome in Le Fort I osteotomy.

OBJECTIVE: This study demonstrated pterygomaxillary disjunction patterns and elucidated factors related to unfavorable pterygomaxillary junction fractures in Le Fort I osteotomy without using an osteotome. STUDY DESIGN: Clinical and anatomical data obtained from computed tomography images (100 sides) were analyzed for their ability to predict patterns of pterygomaxillary disjunction. RESULTS: Separation of the pterygomaxillary junction was most frequently performed at the maxillary tuberosity (48.0%). Twenty-eight pterygoid plates were fractured. Male gender, increased age, thickness of the pterygomaxillary junction, and length of the maxillary tuberosity were significant risk factors for pterygoid process fractures. We also identified that a pterygomaxillary junction thickness less than 2.6 mm and a maxillary tuberosity length of more than 11.5 mm indicated a statistically significant risk of pterygoid process fractures. CONCLUSIONS: Prediction of frangible pterygoid plates by preoperative quantitative evaluation of morphometric values provides useful information for selecting safe procedures.