Skeletal Stability after Bilateral Sagittal Split Advancement and Setback Osteotomy of the Mandible with Miniplate Fixation

Abstract

The bilateral sagittal split osteotomy (BSSO) of mandible has been used extensively for the correction of skeletal deformities of the mandible since it was first described by Trauner and Obwegeser.1 Over the past 40 years, it has undergone numerous modifications and improvements. 2-4There are several studies on skeletal stability after BSSO of mandible with wire fixation, fixation either using bicortical screws or miniplates and monocortical screws, although not even one technique has yet been demonstrated to eliminate relapse completely. 5 This study assesses the postoperative stability of bilateral sagittal split advancement and setback osteotomy using miniplates and monocortical screws. Material and MethodsA total of 10 patients underwent BSSO depending upon the deformity present with or without additional osteotomies. Keywords► BSSO ► mandible osteotomy ► orthognathic surgery ► skeletal stability AbstractThe purpose of this study was to evaluate intraorally placed mini plates and monocortical screws in terms of postoperative skeletal stability after bilateral sagittal split advancement and setback osteotomy of the mandible. Ten patients were included in this study with five requiring advancement (group I) and five requiring setback of the mandible (group II). Bell and Epker modified surgical technique was followed for all the patients. All the patients underwent pre-and postsurgical orthodontics. Cephalometric radiographs were taken preoperatively, immediate, 3, 6, and 12 months postoperatively. Cephalometric tracings were performed by one individual examiner using a modified burstone analysis. Statistical analysis was performed using the student paired t-test. In advancement patients, SNB (sella, Nasion, B point) angle showed relapse at 12th month postoperative period which was statistically significant (2.4 degrees). No changes were observed in anterior facial height, posterior facial height, Frankfort-mandibular incisor angle (FmiA), and overjet during the follow-up period. In setback patients, posterior facial height (p < 0.05), angles between the lower incisors and mandibular plane and pogonion had a statistically significant change position of 1.4 mm (paired t-test, p ¼ 0.03). The SNB angle, anterior facial height, interincisal angle, and FmiA remained constant (0.8-1.2 degrees) during the follow-up period. In advancement cases, the relapse was seen from the third month postoperative period but in setback cases, the relapse was noted from the sixth month onward and the skeletal relapse in these cases were noticed cephalometrically.

Skeletal stability following mandibular advancement: is it influenced by the magnitude of advancement or changes of the mandibular plane angle?

“…The B point and pogonion were selected as identifiable anterior references. These two points are the most widely used parameters to assess mandibular movements because of their stability and reliability 7 .…”

“…These problems are mainly due to unbalanced soft tissue tension after surgery 5 . This type of relapse occurs during the first 6-24 weeks after orthognathic surgery 6 , which is considered the period when the majority of relapse occurs 7 . Long-term relapse usually occurs because of progressive condylar coorresorption, which leads to loss of height of the condyle and mandibular ramus 5 8 .…”

Kombi̇ne Ortodonti̇k Cerrahi̇ Tedavi̇de Stabi̇li̇teyi̇ Etki̇leyen Faktörler

“…43 Mandibular Geri Alma: Rao ve ark. 42 , 10 hasta üzerinde yaptıkları bir çalışmada mandibular geri alma cerrahisinden sonra relapsın 6. ayda meydana geldiği rapor etmişlerdir.…”

Kombi̇ne Ortodonti̇k Cerrahi̇ Tedavi̇de Stabi̇li̇teyi̇ Etki̇leyen Faktörler

“…Rao ve ark. 42 , 10 hasta üzerinde yaptıkları bir çalışmada mandibular geri alma cerrahisinden sonra relapsın 6. ayda meydana geldiği rapor etmişlerdir.…”