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

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

Official Title
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Stability of Bilateral Sagittal Split Ramus Osteotomy (BSSRO) Using Adjustable Mandibular Plates in Adjunction With Bicortical Screws Versus Traditional Positional Screws for Antero-posterior Mandibular Deficient Patients

Conditions
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Mandibular Hypoplasia

Intervention / Treatment
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* Device: 3 bicortical screws
* Device: adjustable plate and 2 bicortical screws


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients suffering from mandibular retrognathia (anteroposterior deficient mandible) Patients should be free from any systemic disease that may affect normal healing, and predictable outcome Exclusion Criteria: Patients with any systemic disease that may affect normal healing Intra-bony lesions or infections that may retard the osteotomy healing Uncooperative Patient with bad oral hygiene
Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 3 bicortical screw<br>1st group:3 bicortical screws will be used to fix the sagittal split ramus osteotomy. | Device: 3 bicortical screws<br>* after mandibular bilateral sagittal split ramus osteotomy surgery is performed in the first group the osteotomy will be fixed using 3 bicortical screws<br>|
| Active Comparator: adjustable plate and 2 bicortical screws<br>adjustable plate and 2 bicortical screws will be used to fix the sagittal split ramus osteotomy. | Device: adjustable plate and 2 bicortical screws<br>* after mandibular bilateral sagittal split ramus osteotomy surgery is performed in the second group the osteotomy will be fixed using adjustable plate and 2 bicortical screws<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| cephalometric analysis to measure angles(degrees) |  | (an xray preoperative, immediate postoperative, 6 weeks and 6 months) | 
| cephalometric analysis to measure lines(mm) |  | (an xray preoperative, immediate postoperative, 6 weeks and 6 months) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| operation time in minutes |  | intraoperative timing during surgery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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orthognathic surgery, bicortical screws, monocortical plates