The Clinical Retrospective Study Of Sagittal Split Ramus Osteotomy

Orthognathic surgery had been developed for many years in our country, and the bilateral sagittal split ramus osteotomy had been used extensively to correct mandibular prognathism, but seldom scholar had systemic study its effect after surgery. So the purpose of this study is to review and analyze the regularity of soft to hard tissue movement and the hard tissue stability and the change of pharyngeal cavity after surgery. So to guide the predictability before surgery.Part 1 Propertion Relation of Soft to Hard Tissue Movement After Bilateral Sagittal Split Ramus OsteotomyObjective: To observe the soft to hard tissue movement ratios after bilateral sagittal split ramus osteotomy (BSSRO) and retropositioning of mandible and give the reference to clinic. Mathods: BSSRO was performed in 33cases to setback the mandible. The patients were examined with lateral cephalometric radiographs one week before and six months or more after surgery. Results: The ratios in soft tissue points L1 and Mes are different to other articles. There is correlation between soft and hard tissueonly in points B and Pg. Conclusions: The ratios of soft to hard tissue are difference in ethnic. When to predict the soft tissue profile, the hard tissue points B and Pg have more significance.Part2 The stability of hard tissue after bilateral sagittal split ramus osteotomy and setbackObjective: to discuss the stability of hard tissue after bilateral sagittal split ramus osteotomy and setback and comprehend the factors of relapse. Mathods: BSSRO was performed in 46 cases to setback the mandible. The patients were examined with lateral cephalometric radiographs one week before and one week after and six months or more after surgery. Results: After setback the mandible, point Li had setback 6.5mm, point B had setback 7.3mm, point Pg had setback 8.5mm, point Me had setback 9.1mm. The average relapse is: Li 23.1%, B 24.7%, Pg 25.9%, Me 26.4%. Conclusions: By the influence of condyle, the relapse of mandible is anti-clockwise rotation and forward, not horizontally forward. Relapse and the distance of setback have correlated relation, but had to over some definited distance.Part3 the change of pharyngeal cavity after bilateral sagittal split ramus osteotomy and setback.Objective: to study it is whether or not can cause obstructive sleep apnea syndrome(OSAS) after bilateral sagittal split ramus osteotomy and setback. Mathods: BSSRO was performed in 28 cases to setback the mandible. The patients were examined with lateral cephalometric radiographs one week before and one week after and six months or more after surgery. To measure the area of pharyngeal cavity by the method of Nagai's. Results: the area of pharyngeal cavity descented significantly in short time after surgery, and it can be restoration later, but can not get back the level of Preoperative. The change of pharyngeal cavity and thedistance of mandible setback have correlated relation. Conclusions: the change of pharyngeal cavity after bilateral sagittal split ramus osteotomy and setback is permanence, but it can not cause OSAS in therapy range. The change of pharyngeal cavity and the distance of mandible setback have correlated relation. If distance of mandible setback over some limitation, it will maybe cause OSAS.