The Mandible is Further Retruded Under General Anesthesia: The Latent Concept for a Favorable Outcome in Sagittal Split Ramus Osteotomy.

Abstract

In orthognathic surgery, we often experience that model mounting by the occlusal bite record taken at centric relation under the conscious condition in the sitting position does not always correctly replicate the actual maxilla-mandibular relationship under general anesthesia. Mandible often moves backward further in the latter condition. The present study was carried out to investigate the degree of extra retrusion of the mandible under general anesthesia and to determine the characteristics in each of the three original skeletal class patterns in a Japanese population. Fifty patients with jaw deformities (14 males and 36 females) were enrolled in this prospective study, their ages ranging from 16 to 49 years. The occlusal bite record at the incisor region obtained from a mounted articulator was compared with the records from the oral cavity of the patient under general anesthesia before surgery. Retrusion in the supine position under general anesthesia was observed in all skeletal classes, and it was significantly greater in skeletal Class II, compared to skeletal Class I and Class III. This study clearly revealed the difference among three different skeletal classes, and the mandible in the skeletal Class II moved backward significantly compared to other classes.