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Orthognathic Surgery: General Considerations

Abstract

Orthognathic surgery to reposition the maxilla, mandible, or chin is the mainstay treatment for patients who are too old for growth modification and for dentofacial conditions that are too severe for either surgical or orthodontic camouflage. Today’s orthognathic surgical treatment for dentofacial deformity consists of standard orthognathic procedures to correct jaw deformity, as well as adjunctive procedures to improve hard and soft tissue contours. These adjunctive procedures include an osseous versus alloplastic genioplasty, septorhinoplasty, and suction lipectomy of the neck. A collaborative approach between the orthodontist and maxillofacial surgeon is imperative to successfully devise and execute a comprehensive treatment plan with predictable outcomes. Orthognathic surgery to treat jaw discrepancy and malocclusion may be viewed variably by insurance carriers. Often, “medical necessity” is difficult to establish and substantiate. For some patients, the out-of-pocket cost of combined orthodontic and orthognathic treatment is prohibitive. The treating professionals should be aware of this relevant issue when devising and recommending a specific treatment plan. Typically, most patients will solicit surgical evaluation based primarily on the recommendation of the treating orthodontist. The patient may present to the surgeon, having already implicitly selected a preferred treatment option based on the treatment focus of the orthodontist. In general, orthodontic camouflage approaches to achieve a specific occlusal relationship with disregard to skeletal discrepancy, facial aesthetics, and degree of dental compensation should be discouraged. This is especially true in a patient who places high value on overall facial aesthetic improvement. Key principles of surgical care and overall patient care include psychologic preparation of the patient; good preoperative and postoperative nutrition; preservation of blood supply to the mobilized teeth and jaw segments; protection of bone, neurovascular structures, and teeth; appropriate postoperative wound management; fixation of bony segments; proper control of occlusion; and rehabilitation to full jaw function.

Sequence of Treatment

Once a patient (child or adult) is diagnosed with a dentofacial deformity that may merit a surgical correction, a comprehensive evaluation by a surgeon and orthodontist is paramount. The maxillofacial surgeon examines the patient, reviews all available records, and discusses with patient and family the available treatment options. The surgeon focuses this discussion on achieving both functional (occlusal) and facial aesthetic goals. An orthodontist acquires complete records, including lateral and Panorex radiographs, facial and occlusal radiographs, dental models, and centric bite impressions. The surgeon and orthodontist then jointly review and organize the available information into a recommended treatment plan that is then presented to the patient.1 Preoperative orthodontics holds as its basic objective the leveling and alignment of teeth over basal bone. Some specific goals may include correcting (reversing) dental compensation, establishing proper incisor inclination and transverse arch width, and maintenance of the dental midline. Dr. John Wirthlin, craniofacial orthodontist, expertly reviews these considerations in this publication. The orthognathic surgical procedures may include maxillary or mandibular surgery, or both. Concomitant intranasal surgery with septoplasty and reduction of the inferior turbinate may be required to improve nasal airflow dynamics. Genioplasty and neck liposuction may also be considered in select patients to improve the overall aesthetic outcome. Postoperative orthodontic treatment usually starts 4 to 6 weeks after the operation. Once final detailing of occlusion is completed by the orthodontist, a postorthodontic retention phase begins.

Psychologic Preparation

Psychological factors should be strongly weighed by both treating surgeon and orthodontist. It is imperative for the treating team to understand the patient’s underlying motivation to seek treatment for correction of skeletal jaw deformity, the psychosocial impact of the condition, and the psychosocial response to treatment. It is key to anticipate and match patient’s expectations to the proposed treatment plan.

It is equally important to counsel the patient about surgical sequelae, common complications, period of recovery, and the expected course of rehabilitation. The patient should be informed about the abrupt shifts in lifestyle that occur for the first 4 to 6 weeks following the operation.

Most patients will suffer through a period of acute mood shifts (depression) in the early postoperative period. This acute mood disturbance is typically short lived in most patients, lasting only a few days. Patients should be forewarned about the possibility of a postoperative mood change. Some patients, in whom postoperative depression or difficulty with adjustment with new facial appearance persist, may require a referral for specialized professional counseling. Psychological preparation of the patient is critical and consists of good rapport; continued, open dialogue between patient, orthodontist, and surgeon; and thorough patient education. This helps the patient stay informed and to be better equipped to anticipate the major changes in jaw function and facial aesthetics that are brought about by orthognathic surgery.2

Most patients can expect to return to school or work within 10 to 14 days following an operation. Although postoperative facial edema is highly disturbing to most patients, acute facial edema typically resolves in the first 3 weeks after surgery. With rigid internal fixation (RIF), early jaw function promotes diminution of residual edema by 6 to 8 weeks postoperatively.

Patient Management at Surgery

Preservation of Blood Supply
Bell’s pioneering work in experimental animal model established the biologic basis for preservation of blood supply to mobilized bony segments, soft tissue, and teeth (dental pulp and periodontal ligament) through maintenance of attached soft tissue pedicle.3 As a general rule, it is not recommended to create more than four dentoalveolar segments within a single arch; it is also unwise to have only a single tooth in a mobilized skeletal segment. Penetrating vessels from mandibular elevator muscles preserve the blood supply to the segments that result from ramus osteotomies. Minimizing subperiosteal stripping in the posterior mandible is recommended.
Protection of Teeth, Bone, and Neurovascular Structures
With mandible procedures, protection of lingual, inferior alveolar, and facial nerves is important during surgical approach and osteotomy.
Teeth in osteotomized and mobilized skeletal segments are at risk for devascularization. Teeth that are adjacent to osteotomy sites are at greatest risk. Preservation of periodontal ligament space during an interdental osteotomy prevents postoperative dental ankylosis. Presurgical orthodontic preparation should leave 3 to 4 mm of bone between tooth roots where an interdental osteotomy is planned. Transverse osteotomy cuts should be kept at least 3 to 5 mm away from root apices to preserve vascular supply to the dental pulp. Alveolar segments should be positioned to preserve equal and consistent vertical height among segments to minimize the risk of postoperative periodontal pocketing and attendant bone loss.
Nutrition
Adequate protein and caloric intake is vital in the postoperative period to counteract catabolic metabolism that ensues as a reaction to the stress of an operation. The patient’s nutritional requirements increase at the same time as the function of the jaws is temporarily impaired. Prolonged postoperative maxillomandibular fixation exacerbates the problem. Reasonable goals for caloric and protein intake are 2500 to 3000 calories per day and 1 to 1.5 g protein/kg body weight/d. Supplementation with protein shakes or nutritionally complete liquids may be required. Body weight is typically used as a guide for adequate fluid and nutrition intake. Inpatient consultation by a dietitian may be indicated. Having a designated caregiver who supervises and monitors the patient’s caloric and fluid intake is helpful.

Conclusion

Orthognathic surgery relies on a close collaboration between the surgeon and the orthodontist across all stages of treatment, from preoperative planning to finalization of occlusion. Virtual computer planning promotes a more accurate analysis of dentofacial deformity and preoperative planning. It is also an invaluable aid in providing comprehensive patient education.