Comparing Stability and Cost-Effectiveness of 3 Bicortical Screws Vs Adjustable Plate and 2 Bicortical Screws in Fixation of BSSRO

Overview

In this current study a comparison between 3 positional screws versus the adjustable plating system in conjunction with 2 positional screws. The patients will be selected to have retrognathic mandible requiring advancement. Hypothetically the advantage of the adjustable plating system will be compared with the three positional screws. In theory, the investigators will be using the inherent advantage of the intraoperative flexibility of the adjustable plating system in verifying the position of the proximal segment (condylar segment), hence eliminating the immediate postoperative relapse that is reported with using three positional screws. This will be evaluated both clinically and cephalometrically.

Trauner and Obwegeser in 1957, reported the first correction of jaw deformity by the sagittal split technique. Dal Pont in 1961, a student of Obwegeser, made a modification to the latter technique, to further enhance the precision and the accuracy of movement of both proximal distal segments his technique has become widely publicized. He changed the lower horizontal cut to a vertical cut on the buccal cortex between the first and second molars, there by obtaining broader bony contact. Hunsuck in 1968, modified the technique, to decrease the soft tissue dissection; he advocated a shorter horizontal medial cut. Epker in 1977, modified the technique in several ways to decrease swelling, manipulation to the neurovascular bundle and hemorrhage, his modification included minimal stripping of the masseter muscle and medial dissection. BSSRO is now the most common procedure used to advance the mandible is a bilateral sagittal split osteotomy. There are many different methods of mandibular fixation such as using intra osseous wiring combined with inter maxillary fixation (IMF) which showed significant amount of relapse and patient dissatisfaction, this is called nonrigid fixation. Another type of mandibular fixation is the three point fixation using positioning screws called rigid fixation. Rigid internal fixation was introduced in 1976 by Spiessel to promote healing, restore early function, and decrease relapse. The introduction of an internal rigid fixation method, instead of 5-6 week intermaxillary fixation, had the added benefit of shorter periods of hospital stay and patient convenience.' Minimal or no immobilization of the jaws allows patients to function sooner, resume their daily activities, and return to work earlier. In a relatively short period of time, the use of rigid fixation of bony segments in orthognathic surgery had become a standard of care. A major concern in the surgical correction of a anteroposterior mandibular deficient patients is potential postsurgical relapse. Clinical studies have shown a wide array of successful techniques used to fix segments. Three bicortical screws placed in an inverted-L fashion has become the gold standard for stabilizing a bilateral sagittal split advancement. Various problems emerged, however, showing that the stability necessary for the stabilization of an osteotomy site cannot be directly compared with that of a fracture. Other problems encountered were difficulties in positioning the fragments in new sites, which resulted in malposition of the condyle. This led to the term 'immediate postoperative relapse'. In addition, pain and dysfunction of the temporomandibular joint (TMJ) complicated the treatment and made the target of long-term stability difficult to achieve. In this current study a comparison between 3 positional screws in comparison with the adjustable plate in conjunction with 2 positional screws will be used in a group of patients suffering from retrognathia and will be treated by BSSRO, thus the investigators are using the advantage of the inherent adjustability of the plate intraoperatively with the good fixation and the stability inherent in the bicortical screws short term stability. This will be evaluated both clinically and cephalometrically.