OSB Flashcards
Indications for orthognathic treatment
-IOFTN 4 or 5
-Facial aesthetics
-Very severe bite problems, beyond scope of orthodontics only
-Sleep apnoea – due to bottom jaw too far back
-Syndromes
-Stability -pts where orthodontics won’t be stable long term
-Only for adult patients- as young pts still growing
-severe class II or III, AOB, vertical maxillary excess (gummy smile), traumatic overbite, skeletal asymmetry, craniofacial anomalies
Contraindications for orthographic surgery
-unrealistic expectations
-not mentally prepared
-poor oral hygiene and diet
-active caries or perio
-unhealthy BMI >30
-under 19-20 years old (absolute minimum is At least 17 in girls and 18 in boys)
-IOTN and IOFTN <4
-smoker
-poor compliance
Post-op care for orthographic surgery
-Patients will stay in hospital for 1-2 nights and receive IV steroids, analgesics, fluids, and anti-nausea. Antibiotic prophylaxis is also usually required
- liquid diet for first few days
-soft diet which is high in calories for the first 6 weeks to allow bony union
-warm saltwater rinses, chlorhexidine mouthwash, soft bristle toothbrush, physiotherapy of the jaw, ice packs for swelling management.
-Patients usually start feeling normal again after 6 weeks.
-Regular follow-up is crucial over the first 5 years to monitor relapse.
Most common malocclusion to relapse after orthognathic surgery
-anterior open bite most common
-class II cases as condyle can resorb
Types of orthognathic surgeries
-Bilateral sagittal split osteotomy - repositioning the mandible forward or back. incisions are above the lingula to avoid the IAN.
-A vertical subsigmoid osteotomy - correcting class III skeletal bases
-The Le Fort 1 maxillary advancement
Risks and complications of orthognathic surgery
-pain, swelling, bruising, bleeding, infection (rare),
-nerve injury (lingual nerve rare as large flaps created, IAN more common, superior alveolar nerve.
- relapse (AOB common, and class II cases as condyle can resorb)
- bad split (shatters into lots of pieces during the cut),
-80% temporary numbness
-patients being fed up after
-poor nutrition afterward
-Permanent sensation impairment is most common in lower lip (1 in 10)
What orthodontic treatment is required before orthognathic surgery
-2 years
-Aligning the teeth relative to skeletal bases
-relief of crowding (XLA, expansion)
- levelling & alignment, decompensation (teeth relative to jaws)
- arch coordination (top teeth slightly wider than lower arch)
-Lower UE8s XLA 6-month prior to surgery
-Braces present for surgery and stay on for 6-12 months after surgery for minor adjustments
Causes of anterior open bite (causing increased LFH). Most common surgery required
- due to condylar resorption, mouth breathing, digit sucking, over eruption of posteriors, TMJ ankylosis after fracture etc.
-posterior impaction of maxilla using le fort I cut
Surgery for vertical maxillary excess causing gummy smile and increased LFH
Le Fort I osteotomy
Surgery required for severe class II malocclusions and the specific orthodontics required before hand
-class III elastics to upright proclined lower incisors
-3 point landing- done in patients with reduced LFH to increase it post-op
-Bilateral sagittal split osteotomy -mandibular advancement. +/- genioplasty of chin
Orthodontics and surgery required for severe class III
-decompensation using class II elastics to procline the retroclined lower incisors. This can significantly worsen patient’s appearance prior to op.
-Le Fort I maxillary advancement – if maxilla too small
-Bilateral sagittal split osteotomy if mandible too big
-Or Combination of both +/- genioplasty of chin
Difference between graft and flap
-Graft= tissue being transferred will gain new blood supply from new vessels
-Flap= has its own blood supply so take a vessel with it
