الفهرس 
Introduction and Review of LiteratureOnly 14 pages are availabe for public view
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Abstract
Skeletal malocclusion is a common birth defect that occurs due to the distortion of the maxillary and/or mandibular development that will have a significant impact on the positioning, alignment, and health of the primary and permanent teeth. Skeletal Class III Malocclusion: One of the most complicated of all dentofacial abnormalities in both childhood and adulthood. It is characterized by mandibular prognathism and maxillary deficiency (although most patients with Class III malocclusion have combinations of both) and has a significant genetic component. Management of Skeletal Class III Growth modification with a chin cup or face mask can be used for the treatment of Class III malocclusion in growing patients. In adult patients, if the severity of the deformity exceeds the dentoalveolar camouflage ranges, combined orthodontic and surgical treatment can help to achieve proper functional and esthetic rehabilitation Orthognathic surgery: is a well-known surgical intervention to change and/or correct facial-related structures.
The surgical intervention for treating Class III malocclusion may involve a single jaw (the mandible) or both jaws (Bi – Maxillary) Aiming at reducing the prominence of the mandible, bringing the maxilla forward, or both. The types of surgery most frequently used are the following: bilateral sagittal split osteotomy (BSSO) or Intraoral vertical ramus osteotomy (IVRO)
Studies showed that the risk of injury to the inferior alveolar nerve and the condylar sag phenomena are higher with BSSO. While the major drawback of the IVRO is the need to put them in maxillomandibular fixation (MMF) to stabilize the occlusion and allow time for osseous healing. The MMF affects the quality of life for the patient with difficulties in breathing, mastication, and speech. The duration of the MMF is still controversial but all are ranging from 2-6 weeks.
Some believe that the most advantageous characteristic of IVRO is its “condylotomy effect,” whereby anterior inferior repositioning of the condyle results in an increase in the articular space and an improvement in the articular disc condyle relationship, with a reduction in the load on the glenoid fossa. These changes may alleviate adverse TMJ symptoms. Therefore, some authors consider IVRO as a therapeutic procedure for the treatment of TMJ symptoms in patients with mandibular prognathism.
The aim of this study is to evaluate the changes in condylar disc morphology and position in patients undergoing mandibular setback orthognathic surgery for the treatment of class III deformities, by means of MRI and related clinical changes.
Twenty patients presented with skeletal Class III were selected. They were divided randomly into two groups the first group was managed by BSSO surgery while the other group was managed by IVRO.
Changes in disk position and the stage of internal derangement were examined by MRI of the TMJ which was performed before, 6 month and 12 month after the operation together with clinical examination of mouth opening, joint noise, muscle pain and joint tenderness
Results: There was reduction in the mouth opening in both groups after surgery, but this reduction was not statistically significant different between the two groups.
Regarding Tenderness, TMJ noise, Muscle pain: For all intervals, majority of cases in both groups didn’t have tenderness, TMJ noise or muscle pain and the difference between both groups was not statistically significant (p>0.05).
For the change in the disk position: For (baseline-6 months) and (basline-12 months), BSSO group had significantly higher change values than IVRO group (p<0.001). While for (6-12 months), the difference was not statistically significant (p=0.202).
Also, the was no Correlation between condylar changes and amount of setback.
Conclusion: BSSO surgery leads to more changes in the disk position in comparison with IVRO surgery which gives advantage of IVRO over BSSO regarding TMJ general function and stability after mandibular setback.