Orthodontic Preparation for Orthognathic Surgery: Basics

Orthognathic surgery — corrective jaw surgery — repositions the upper jaw, lower jaw or chin when their mismatch is too large for braces alone. Orthodontic preparation aligns the teeth within each jaw first, so the jaws fit together correctly once the surgeon moves them.

It matters because surgery moves bone, not teeth. Left unprepared, tilted or compensating teeth would prevent the jaws from meeting in a stable bite. Proper preparation is what makes a surgical result last instead of relapsing.

Key Concepts

• Decompensation — the core of presurgical orthodontics. Teeth tilt over years to camouflage the jaw mismatch; the orthodontist deliberately untilts them to their correct positions over the bone. The bite often looks worse before surgery — a planned, temporary step.
• Le Fort I osteotomy — the standard upper-jaw surgery: the maxilla is separated above the roots, repositioned and fixed with titanium plates.
• BSSO (bilateral sagittal split osteotomy) — the standard lower-jaw surgery: each side of the mandible is split lengthwise so the tooth-bearing segment slides forward or back.
• Genioplasty — reshaping the chin, often combined with jaw surgery for profile balance.
• Surgical splint (wafer) — an acrylic bite guide made from the final tooth positions; it tells the surgeon exactly where to fix the jaws during the operation.

How It Works

1. Joint planning. Orthodontist and surgeon agree on final jaw positions from photos, X-rays and 3D scans, then work backward to the tooth movements needed.
2. Presurgical orthodontics (12–18 months). Full braces align, level and decompensate both arches; surgical hooks go on the wire near the end.
3. Surgery. Under general anaesthesia the jaws are repositioned (commonly Le Fort I plus BSSO) and fixed with small titanium plates; most patients stay 1–3 nights in hospital.
4. Postsurgical orthodontics (6–9 months). Light elastics settle the bite into the planned position while healing completes, then braces come off and retainers go on.

Worked Example

A 19-year-old has a 9 mm underbite. Fourteen months of presurgical braces upright lower incisors that had leaned back 15 degrees to camouflage the jaw, so the underbite temporarily measures 12 mm — the planned “worse before better”. Surgery moves the upper jaw forward 5 mm and the lower jaw back 7 mm: 12 mm of total correction. Six months of postsurgical elastics settle the bite to a normal 2 mm overjet. Total: about 24 months, of which surgery is a single day.

Common Misconceptions

• “Surgery alone straightens everything.” The surgeon moves whole jaws; wrongly angled teeth would stop the jaws meeting correctly. Braces before and after are non-negotiable.
• “The bite getting worse means failure.” Decompensation reverses years of dental camouflage on purpose — the worsening proves the teeth are being placed correctly for the new jaw position.
• “The jaw is wired shut for months.” Modern titanium-plate fixation means no wiring shut; patients eat soft food for weeks and use guiding elastics.

Real-World Applications

Surgical orthodontics treats severe underbites and overbites, marked facial asymmetry, open bites unclosable with braces, sleep apnoea from a retruded lower jaw, and cleft-related jaw discrepancies after growth completes.

Recap: Braces prepare the teeth, surgery moves the jaws, braces finish the bite. Decompensation first, precise repositioning second, settling elastics third — that sequence keeps jaw surgery stable for life.