Orthognathic Surgery Flashcards
List the 3 treatment objectives for orthognathic surgery.
To improve:
- function
- aesthetics
- stability
List some functional issues.
- Cheek bite
- Malocclusion
- Sleep apnoea
- Breathing problems in young patients
- Difficulty chewing and speaking in syndromal patients (e.g.: CL/CP)
List some common aesthetic issues.
- Weak chin
- Strong lower jaw
- Gummy smile/Mx excess
- Down-tipped nose
In terms of stability, which procedures are the most stable and most unstable?
Most stable:
- Mx impaction
Most unstable:
- Mx down-graft
What do you ask in the patient assessment?
- P/C
- What would they like improved
- How is their bite
- Are you happy with your facial profile?
- Do you have any functional difficulties (e.g.: OSA)?
What do you assess in the clinical evaluation?
- Facial form (frontal and lateral profile, long/short, concave/convex, asymmetry)
- Facial proportions (thirds and fifths)
- Anatomical harmony (midface, nose, lip, smile line)
- Clinical measurements (AP dimension, transverse, intra-arch, vertical)
What other investigations do you conduct in an assessment for orthognathic surgery?
- Radiographs (OPG, Lateral ceph)
- Study models
- Speech, audiometry, psychological, medical (if required)
Describe the sequence of treatment planning for orthognathic surgery.
- General dental and periodontal treatment
- Extractions
- Presurgical orthodontics
- Orthognathic surgery
- Postsurgical orthodontics
- Definitive general dental management and maintenance
What happens in the presurgical orthodontics phase?
- Tooth alignment
- Correct rotated teeth
- Adjust for tooth size discrepancy
- Coordinate upper and lower arch widths
How does surgical treatment attempt to correct excess or deficiency of the jaw?
- Advancing
- Widening
- Set-back
Which planes can one or both jaws have a Dx of excess or deficiency?
- Transverse
- Vertical
- Antero-posterior
Ideal surgery aims to achieve which class occlusion?
Class 1
What should the patient be aware of (and have) preoperatively?
- Full informed consent
- Realistic expectations
- Full understanding of postop regimens for feeding and oral care
- Fit and well
- Normal Hb
- Bilateral patent airways
- Non-smoker
- Emotionally prepared for long surgical journey
What is the ideal tooth and gingiva show to be seen when smiling fully?
Full crown to 2mm gingiva show
What is the ideal length for lips at rest?
0-3 apart at rest
What will a Mx impaction do?
- Reduce gummy smile/Mx excess
- Reduce upper lip length
- Shortens the lower face
- Makes the chin more prominent
- Elevates the nasal tip
What will a Mx advancement do?
- Increase upper lip fullness
- Increase paranasal fullness
- Elevate nasal tip
- Decrease chin prominence
What will a Mx down-graft do?
- Increase upper lip length
- Increase upper teeth exposure
- Increase upper lip prominence
- Makes Md less prominent
- Increase lower third facial height
What will a Md advancement do?
- Increase chin prominence
- Increase lower lip fullness
- Increase lower third facial height
What will a Md setback do?
- Decrease Md prominence
- Increase lower lip fullness
- Decrease lower third facial height
What are Henderson’s 3 classifications of different types of jaw deformities?
- Symmetrical jaw disproportion
- Asymmetrical jaw disproportion
- CL/CP
What are Henderson’s subtypes for symmetrical jaw disproportion?
- Mx enlargement
- Mx deficiency
- Md enlargement
- Md deficiency
- Bimaxillary disproportion
What are common syndromes associated with CL/CP?
- Pierre-Robin’s syndrome
- Treacher-Collins syndrome
- Apert’s syndrome
What are common syndromes associated with facial asymmetry?
- Hemifacial atrophy
- Hemifacial microsomia
- Neurofibromatosis (von Recklinghausen’s disease)
What are common syndromes associated with Md prognathism?
- Gorlin-Goltz syndrome
- Osteogenesis imperfecta
- Marfan’s syndrome
- Klinefelter syndrome
List some surgical techniques.
- SAME
- Bilateral Sagittal Split Osteotomy
- Le Fort 1 Osteotomy
What is Mx impaction indicated for?
- VME with open bite or no open bite
- Dolichofacial
What is Mx down graft indicated for?
- Vertical Mx deficiency
- Brachyfacial
- Mx atrophy due to prolonged edentulism
- Poor incisal display + other aesthetic problems
What is Mx advancement indicated for?
- AP Mx deficiency (Mx hypoplasia)
- Class III malocclusion
When would a bone graft be needed for a Mx advancement?
If the advancement is greater than 5mm.
grafting helps accelerate bone healing b/w segments
What are the indications for a Md advancement?
- Md deficiency (often characterised by C2 skeletal pattern), weak chin
What are the indications for a Md setback?
- Md prognathism (usually C3 skeletal patterns) with bilateral posterior crossbites
Explain a Le Fort 1 OSTEOTOMY
A surgical procedure where the surgeon creates a fracture in the upper jaw to either move it up (impact) or forwards (advance).
The altered jaw will be fixed into plates with titanium mini-plates and mini-screws.
Explain a BSSO
A surgical procedure used to correct lower jaw deformities by either lengthening (advance) or shortening (setback).
The split will be fixed into plates with titanium mini-plates and mini-screws.
List intraoperative complications of orthognathic surgery.
- Nerve damage (IAN_
- Tooth damage
- Vascular compromise (esp. in FL1)
- Haemorrhage
- Visual damage (LF1 - bleeding into optic canal)
- Hemarthrosis of the TMJ)
- Unfavourable osteotomy split
List some postoperative complications of orthognathic surgery.
- Infection
- Oroantral fistulas
- Malocclusion
- Relapse due to fixation problems
- Nerve damage
- Md dysfunction
- Secondary haemorrhage
- Malunion
- Devitalised teeth
- Mx sinusitis
What postoperative advice is given to the patient?
- Soft diet for the first few days + good OH
- IV fluids in first 24 hrs
- Post 24 hrs = nasogastric feeds
- High calorie fluid diet up to 7 days
- Blended diet for minimum 6 weeks
- May require tracheostomy if airway is swelling
May require foley catheter
What timeframe is defined as early relapse of surgical treatment?
3-6 months postop
