Classification of Dentofacial Deformities
Bite problems are classified by how upper and lower teeth meet: normal (Class I, proper alignment), upper jaw too far forward or lower jaw too far back (Class II malocclusion—misaligned bite), or lower jaw too far forward or upper jaw too far back (Class III malocclusion). This simple system only covers front-to-back problems. Bone deformities are better described in three directions: front-to-back, up-and-down, and side-to-side.
A patient might have a Class II bite from lower jaw being too small (front-to-back problem), open bite in front (up-and-down problem), and crossbite (side-to-side problem). Surgery must fix all three.
Front-to-back problems include lower jaw too small, upper jaw too far forward, lower jaw too far forward, or upper jaw too far back. Severity ranges from cosmetic concerns only to functional problems (chewing, speech, breathing).
Up-and-down problems include open bite in front (teeth don't meet), deep bite in front (too much overlap), and open bite in back (back teeth don't touch). Open bite in front causes chewing and speech problems.
Side-to-side problems include narrow upper jaw with crossbite, uneven growth, or lower jaw shifted to one side. Severe asymmetry causes emotional distress and functional problems.
Pre-Operative Evaluation and Diagnosis
Planning starts with checking your motivation, expectations, and emotional health. Jaw surgery creates major change to appearance. You must be ready for this change and have realistic goals. Some want cosmetic improvement; others want better function.
Medical evaluation checks for conditions that prevent surgery or affect healing. Diabetes, bleeding problems, weak immunity, severe heart disease, or serious mental illness may prevent surgery. Some medicines affect treatment.
Special X-rays (cephalograms) measure jaw relationships precisely. Head X-rays show front-to-back and up-and-down problems. Face X-rays show side-to-side problems. Teeth models show current and target bite.
Mock surgery (moving dental models to planned positions) helps plan the real surgery. Modern 3D imaging and computer planning improve planning. 3D scans show bone anatomy precisely. Virtual surgery shows predicted results and lets doctors explain changes to you before surgery.
Surgical Techniques and Approaches
Bilateral sagittal split osteotomy (BSSO) is the standard lower jaw surgery for front-to-back problems. The surgeon makes cuts inside the mouth, separates the bone, and moves the jaw forward or back. Metal plates hold it in place. Results are predictable.
Le Fort I maxillary advancement cuts the upper jaw horizontally below the nose and separates it from the skull base. The upper jaw is moved forward, down, or rotated and held with plates. This fixes Class II bites from upper jaw being too far back and helps open bite.
Bimaxillary surgery combines both procedures for complex problems. Class II with upper jaw too far forward and lower jaw too small needs both upper setback and lower advancement. Class III with lower jaw too far forward and upper jaw too far back needs both lower setback and upper advancement.
Front open bite surgery moves the front upper jaw down. Uneven vertical problems need palate rotation surgery. Chin surgery improves profile by repositioning the chin. Chin and lower jaw surgeries can be done together.
Pre- and Intra-operative Considerations
Before surgery, braces (12-24 months) align teeth in the right direction. This removes tooth compensation that hides the jaw problem. Good alignment helps after-surgery wiring and improves results.
During surgery, patient position, airway protection, and gentle tissue handling prevent complications. A breathing tube through the nose maintains airway without blocking the mouth. Careful anesthesia reduces bleeding. A plastic splint guides jaw repositioning to the exact planned position for three-dimensional accuracy.
Airway and Breathing Considerations
Moving the lower jaw forward improves airway size in patients with obstructive sleep apnea (OSA). These patients get better breathing and also better appearance and bite. They are ideal candidates.
Moving the upper jaw forward can improve airway. But moving the jaw backward may narrow airway. Careful planning and X-rays predict airway changes, though results vary. Sleep studies before and after measure OSA improvement.
Post-Operative Management
Right after surgery, pain control, swelling reduction, and airway monitoring are priorities. Most patients stay overnight. Many have wires for 4-6 weeks while bone heals. Wires guide bite with elastics. Some surgeons use rigid plates instead of wires for better comfort and diet.
Soft food for 6-8 weeks protects healing. As healing improves, normal food returns. Physical therapy with gentle jaw opening and soft tissue work helps healing and prevents stiffness.
Normal activity usually resumes in 4-6 weeks, but full healing takes months. Braces after surgery (6-12 months) fine-tune bite. Permanent retainers prevent relapse.
Stability and Relapse
Surgical corrections stay stable long-term if healing is good and you wear retainers. Most relapse (jaw shifting back) happens in the first 6 months, then stabilizes. Relapse of 5-10% of the change is typical, though severe asymmetry may relapse more.
Factors affecting relapse: how much the jaw was moved (more movement equals more relapse), surgery type, post-operative braces, and continued growth in younger patients. Waiting until growth stops (age 16-17 for girls, 18+ for boys) minimizes relapse from continued growth.
Every patient's situation is unique—always consult your dentist before making treatment decisions.Related reading: Oral Surgical Complications and Managing Post-Operative Swelling: Clinical Timeline.
Conclusion
Jaw repositioning surgery (orthognathic surgery) corrects severe bite problems where the jaw bones are misaligned. Using techniques like bilateral sagittal split osteotomy (BSSO) for lower jaw advancement and Le Fort I for upper jaw repositioning, surgeons move jaw bones to create proper alignment. Results are permanent and dramatic for both appearance and function.
Pre-operative orthodontics (braces) for 12-24 months align teeth properly before surgery. Post-operative braces fine-tune bite during healing. Most relapse (shifting back) happens in the first 6 months then stabilizes—properly planned and executed surgery with good technique minimizes relapse. Long-term outcomes show stable corrections, improved airway in sleep apnea cases, better chewing function, and significant quality-of-life improvements.
> Key Takeaway: Jaw repositioning surgery produces permanent correction of severe bite problems and dramatically improves function and appearance when carefully planned, properly executed, and combined with orthodontic treatment before and after surgery.