A Case of Extreme Skeletal Class III Malocclusion Beyond the Envelope of Discrepancy, Managed Effectively by a Modified Ortho-Surgical Protocol.

Abstract

Correction of a severe anteroposterior skeletal discrepancy, as described in this case of extreme skeletal class III malocclusion, can be quite challenging and fraught with difficulties. Conventional, single-stage bi-jaw orthognathic surgery with pre-and post-surgical orthodontics is associated with drawbacks such as the risk of relapse and an unsatisfactory overall long-term outcome, with persisting occlusal discrepancies and skeletal abnormalities, especially when the magnitude of skeletal correction required is large. Excessive mandibular setback can restrict tongue space, cause narrowing of posterior airway and pharyngeal space, and be prone to relapse from the forward pterygomasseteric muscle pull, while large maxillary advancements are often accompanied by wound dehiscence and bone exposure at the site of pterygomaxillary disjunction, delayed union or malunion at the osteotomy and disjunction sites, and risk of relapse due to backward palatopharyngeal muscle pull. In addition, bi-jaw surgeries invariably involve an appreciable blood loss and a prolonged operating time with its attendant anaesthetic risks such as respiratory insufficiency. To develop an orthosurgical protocol wherein excessive skeletal discrepancy can be successfully managed, achieving the desired magnitude of correction, with little or no relapse. To assess its efficacy and superiority over the hitherto-employed single-stage bi-jaw procedures in the management of severe skeletal discrepancies. A two-staged, shorter 'single-jaw at a time' operative procedure with an intervening period of three months between the two surgical phases was employed. Drawbacks of conventional orthognathic surgery may be obviated by employing a two-staged protocol of bi-jaw surgeries allowing a minimum time period of 3 months to elapse between them. This period of time intervening between the maxillary advancement and mandibular setback allows the oral and maxillofacial musculature to adapt itself to the new jaw position following the first surgery, thus creating a better and more stable environment for the succeeding one, thereby reducing the chances of relapse thereafter, and producing more effective and stable long-term results. Moreover, the intervening time period also allows for observation of the repositioned jaw and arch relations achieved, and scrutiny for any positional changes in this post-surgical phase, which thereby allows modifications in the planned surgery of the next jaw, so as to achieve the most ideal final outcome following the second jaw surgery. A shorter operating time, reduced operator fatigue and less blood loss are other obvious advantages over the conventional bi-jaw procedures. An effective and stable correction of the extreme class III skeletal deformity and malocclusion was achieved, with a dramatic enhancement of facial balance, symmetry and proportion in this patient, following a modified orthosurgical management protocol. The staged protocol of 'maxilla first and mandible after' orthognathic surgery with conventional pre- and post-surgical orthodontics helped in pushing the envelope of skeletal discrepancy correctable by orthognathic surgery, thereby achieving large quantum of jaw movements, with ideal and stable functional as well as aesthetic results. This is suggestive of its efficacy and superiority over the hitherto-employed single stage bi-jaw procedures in the management of severe skeletal discrepancies.