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BDS4 Orthodontics > Orthognathic Surgery > Flashcards

Orthognathic Surgery Flashcards

1
Q

What is the role of the GDP in orthognathic surgery?

A

Diagnose need for treatment, refer and be able to explain orthognathic surgery to patients, recognise it when patients are receiving treatment

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2
Q

What are patients typically complaining of when they are being assessed for orthognathic surgery?

A

 Don’t like appearance due to prominence of one jaw and deficiency of the other
 Functional deficit- difficulty chewing and biting

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3
Q

Who are the members of the MDT for orthognathic surgery?

A

consultant in orthodontics

technician

surgeon

psychologist

restorative dentist

SLT (CLP)

hygienist

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4
Q

What is the role of the psychologist in orthognathic surgery?

A

Early recognition of psychological problems
-> Dysmorphophobia & Neurosis

Understand real motivation for surgery

Help with postsurgical depression and psychological adaptation to the new face

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5
Q

What are the aspects to consider when assessing a patient psychologically for orhtognathic surgery?

A

Previous psychiatric problems
-> existing disorders (anxiety & depression
sleeping patterns, eating habits)

Systemic symptoms linked to psychiatric issues
-> shortness of breath, abdominal pain, nausea

Is the patient doctor shopping?

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6
Q

What is body dysmorphic disorder?

A

Obsession over minor defect or non-existent deformity
-> exaggerated response

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7
Q

What is the role of the technologist in orthognathic surgery?

A

Model surgery planning

Provide occlusal wafer to guide the surgery

Building 3D skull models

Digital Prediction of final occlusion

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8
Q

What is the role of the orthodontist in orthognathic surgery?

A

 Early recognition of dento-facial abnormalities

 Comments on quality of occlusion and how this can be improved

 Pre/post orthodontic treatment may be required (this must be coordinated and decided on with input with surgeon)

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9
Q

What must be considered when planning orthognathic surgery?

A

What the soft tissue change is to be
-> how much hard tissue movement would be required to achieve this (teeth are attached and still need to be class 1)

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10
Q

What is assessed when carrying out an EO exam for orthognathic surgery?

A

Aesthetic proportions

Vertical asymmetry

Lip and Nose morphology

Horizontal asymmetry (Mediolateral)

Antero-posterior relationship

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11
Q

What factors are involved in aetiology of facial deformities?

A

 Family- TCS

 Racial- normal in Africa to have prominence of lips (in white populations this is unusual- may be treated)

 Congenital- hemifacial microsomia

 Untreated trauma

 Developmental- happens through life due to over/undergrowth

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12
Q

What is likely to be the cause of increased size of mandible and altered occlusion in middle aged patients?

A

 Acromegaly- excess GH from pituitary adenoma (requires neurosurgery)

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13
Q

What is the difference between a horizontal and vertical asymmetry?

A

Vertical asymmetry- one side is taller than the other

Horizontal- one side is broader than the other

 May split each half into 3 parts to help identify
 Deviation of mandible (can be other parts of the face too)
 Document this on assessment

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14
Q

What is the difference between a horizontal and vertical asymmetry?

A

Vertical asymmetry- one side is taller than the other

Horizontal- one side is broader than the other

 May split each half into 3 parts to help identify
 Deviation of mandible (can be other parts of the face too)
 Document this on assessment

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15
Q

How should the lips be arranged in terms of proportion ideally?

A

Lips- upper 1/3 and lower lip 2/3 of total length

-> At rest we hope to show 2mm of upper teeth (some patients show whole crown length and have gummy smile when smiling)

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16
Q

How do we evaluate the chin position in an orthognathic surgery assessment

A

Look at degree of deviation and mentalis competence

17
Q

What is checked in an IO exam prior to orthognathic surgery?

A

General dental assessment

Occlusal relationship

Central line discrepancy relative to the face

OJ/OB

Crossbite

Occlusal canting

Incisors’ inclination

Crowding and spacing

Tongue size, mobility, speech pattern

Cleft cases and velopharyngeal incompetence

18
Q

Which special investigations may be utilised for orthognathic surgery?

A

Radiographs

Study models

Photographs- 2D/3D

19
Q

What radiographic modalities may be used in orthognathic surgery?

A

OPT

Lateral Cephs- show relationship of jaw bones

PA cephs- vertical and lateral asymmetry

Periapicals

Occlusal

CBCT- ICAT machine

20
Q

Why are OPTs useful for orthognathic surgery?

A

It shows us- impacted teeth, unerupted teeth, infection, root morphology, tooth morphology, shape of bone (trabeculation pattern)

21
Q

What is CBCT useful for looking at prior to orthognathic surgery?

A

 Can be used for prediction planning
 Shows ID nerve, position of impacted teeth
-> Can look at coronal, axial and sagittal slices

22
Q

What is used to mount study models used in orthoignathuic surgery on articulators?

A

Facebow registration

23
Q

What are the uses of study models in orthognathic surgery?

A

Study occlusion

Orthodontic analysis

Orthognathic surgery planning

Model surgery

Occlusal wafer production for surgery

Assess surgical changes

Assess long-term stability/relapse

24
Q

Which 2D photographs are taken prior to orthognathic surgery?

A

2D full face at rest and smiling

Right and left profiles

Teeth in occlusion (anterior and posterior)

1:1 profile photograph

25
Q

What does stereophotogrametry allow?

A

Allows 3d model to be seen on computer screen
 Measurements can be made
 Prediction planning carried out using this
 Can show to patient to see if they’d be happy with outcome

26
Q

What are the different orthognathic surgery diagnoses in the maxilla/mandible?

A

Prognathic- too prominent
Retrognathic- deficiency
Vertical excess- a lot of gingiva on show at rest
Vertical deficiency- not enough teeth on show at rest
Asymmetry- shifted/canted

27
Q

What are the different orthognathic surgery diagnoses in the chin?

A

Progenia

Retrogenia

Vertical excess/deficiency

28
Q

What are the treatment options for patients considering orthognathic surgery?

A

Orthodontics only
Combined ortho and surgery
Surgery only

29
Q

What are the stages in combined orthodontic/ orthognathic treatment

A

Initial ortho
-> Tooth alignment, eliminating crowding, spaces, and cross bite
-> Alteration and co-ordination of the arches
-> Correction of incisors’ inclination (de-compensation)
-> Flattening the occlusal plane

Surgical fixation

Postsurgical orthodontic fine tuning

30
Q

Which surgical procedures are used in orthognathic treatment of maxilla?

A

Le Fort I osteotomy (superior, inferior, forward movements)

Anterior maxillary osteotomy (posterior)

31
Q

Why does a Le Fort 1 not allow backwards movement of the maxilla?

A

Due to position of pterygoid plate

32
Q

What are the steps in a Le Fort 1?

A

 Cut from 1st molar to 1st molar high in gum (mucoperiosteal flap)- expose area as far back as pterygoid plate
 Expose anterior part of maxilla
 Dissect nasal floor and septum from inside of mouth
 Cut bone to separate maxilla from base of skull- using chisel and surgical saw
 Mobilise maxilla- move to desired position (figure of 8 movement to ensure no bony connections
 If you are dropping maxilla down, you may be able to see nasal floor and maxillary sinus on top
 As you go posteriorly- you can see greater palatine neurovascular bundle
 Use wafer to guide maxilla-fix in position using plate and screw (titanium or resorbable polylactic acid)
 Fix lips if required
 Fix with 4 plates

33
Q

Which surgical procedures can be done in the mandible?

A

Advancement
-> Sagittal split osteotomy- 2 plates required
-> inverted L ramus osteotomy

Set-back
-> sagittal split osteotomy
-> VSSO

34
Q

What is done in a saggital split?

A

Ramus is split from body of mandible allowing it to be moved forward or backward

35
Q

What is a vertical sub-sigmoid osteotomy?

A

When you separate ramus from body it risks IDN (if cut there will be lack of sensation to teeth, lips, gums)
-> VSSO can be used to move mandible back

Go vertically above sigmoid notch and cut mandible- protecting nerve

Require teeth to be wired together for 6 weeks after

36
Q

Which surgical procedures can be done on the chin?

A

Genioplasty- Advancement, set-back, rotation, augmentation, reduction
-> requires 1 plate for fixation

37
Q

What are the advantages of using surgery as a first approach for facial deformity cases?

A
  1. Reduction of the duration of the treatment
  2. Faster orthodontic tooth movement
  3. Immediate improvement in facial appearances
  4. Cost effectiveness

BDS4 Orthodontics (14 decks)

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