ORAL SURG orthognathic surgery

Question 1

definition of orthognathic?

Answer 1

straight jaws

Question 2

what are the types of skeletal discrepancies which orthognathic surgery would treat?

Answer 2

anteroposterior: skeletal class II and III
vertical: open bite, deep bite, and VME
lateral: crossbites and asymmetries

Question 3

what function problems would orthognathic surgery be used to treat?

Answer 3

eating/ chewing
speech
TMD
sleep apnoea

Question 4

what aesthetic problems may orthognathic surgery be used to treat?

Answer 4

social discrimination
physiological distress

Question 5

what factors are important when selecting a case for orthognathic surgery?

Answer 5

psychological status
family support
dental health
cooperation

Question 6

is growth predictable?

Answer 6

height and shoe size - yes
cephalometry and other radiographs - no
radioisotope scans - no

Question 6

at what age, does growth stio?

Answer 6

18-20

Question 7

in unfavourable growth, what skeletal relationships may improve?

Answer 7

class II

Question 8

in unfavourable growth, what skeletal relationships may get worse?

Answer 8

class III

Question 9

list the treatment process for orthognathic surgery?

Answer 9

1. referral
2. assessment and diagnosis
3. joint clinic
4. pre-surgical orthodontics
5. orthognathic surgery
6. post-surgical orthodontic
7. retainers/ review

Question 10

what happens during the assessment and diagnosis stage for orthognathic surgery?

Answer 10

pt complaint - questions about other family members
medical/ dental/ social history
clinical examination - face and occlusion
special tests - radiographs, models

Question 11

what is assessed in the clinical examination?

Answer 11

facial
- anteroposterior
- vertical
- transverse
occlusal
- molar/ canine/ incisor classification
- overjet/ overbite
- midlines
- occlusal canting
- crossbites
- crowding/ spacing
other
- caries/ perio/ teeth of poor prognosis

Question 12

what are DPT/ intra-orals used to assess?

Answer 12

• caries
• perio disease
• root resorption
• condylar hyperplasia/ degenerative changes
• other pathology

Question 13

what are study models used for for orthognathic surgery?

Answer 13

hand articulate or mount on articulator to assess occlusion following surgery
space assessment

Question 14

what are clinical photographs used for in orthognathic surgery?

Answer 14

qualitative assessment of dentofacial relationships

Question 15

what imaging would be used for impacted teeth or condylar destruction

Answer 15

CT/ CBCT

Question 16

what imaging would be used for condylar hyperplasia?

Answer 16

Technetium radioisotope scan

Question 17

give an example of an orthognathic diagnosis?

Answer 17

class II division I malocclusion on a severe class II skeletal base with an increased FMPA

Question 18

what is the psychological assessment for orthognathic surgery?

Answer 18

questionnaire-based
referral to clinical psychologist where required for further assessment
psychological therapies where disorders are identified
may need follow up during tx

Question 19

what percentage of orthognathic pts have psychologic distress/ psychiatric disorders?

Answer 19

20%

Question 20

how is BMI calculated?

Answer 20

weight/ height (squared)

Question 21

what are the WHO categories for BMI?

Answer 21

underweight <18.5
normal weight = 18.5-24.9
overweight = 25-29.9
obesity > 30

Question 22

what is pre-surgical ortho tx for orthognathic tx?

Answer 22

required so teeth occlude properly at time of surgery
upper and lower fixed appliances placed to: align, decompensate, and coordinate

Question 23

what does alignment with a fixed appliance correct?

Answer 23

crowding
spacing
rotations

Question 24

what does decompensation with a fixed appliance correct?

Answer 24

dental compensation limits surgery, so it is 'reverse orthodontics'

Question 25

what teeth are usually extracted for class II cases?

Answer 25

lower premolars

Question 26

what teeth are usually extracted for class III cases?

Answer 26

upper premolars

Question 27

what type of planning for orthognathic surgery would be used for occlusal changes and facial changes?

Answer 27

cephalometric planning - for occlusal and facial changes model surgery planning - occlusal planning 3D CBCT planning - occlusal and facial changes

Question 28

what is the purpose of model surgery for orthognathic surgery?

Answer 28

1. to determine post-surgery occlusion 2. to measure surgical movements 3. for wafer manufacture

Question 29

what wafers are used for what positions?

Answer 29

intermediate wafer - maxillary position final wafer - mandibular position

Question 30

what are wafers?

Answer 30

made after model surgery to allow dental arches to be put in pre-planned positions

Question 31

what isan on-screen 3D CT model used for?

Answer 31

visualisation of skeletal relationships model surgery computer generated wafer manufacture

Question 32

what are 3D printed CT models used for?

Answer 32

model surgery pre-surgical bending of fixation plates

Question 33

how long is the pt in hospital for orthognathic surgery?

Answer 33

1-3 nights

Question 34

what type of anaesthesia is used for orthognathic surgery?

Answer 34

endotracheal

Question 35

how long does orthognathic surgery take?

Answer 35

single jaw = 2-3 hrs bimax = 4-5hrs

Question 36

how much does orthognathic surgery cost?

Answer 36

6360 euros

Question 37

what technique is used for le fort fractures?

Answer 37

fixation: plates and screws

Question 38

list names of orthognathic surgery procedures for the mandible?

Answer 38

bilateral sagittal split osteotomy (BSSO) vertical subsigmoid osteotomy body ostectomy genioplasty

Question 39

what technique is used for surgery of the mandible?

Answer 39

fixation: ideally plates and screws *some require 6 weeks intermax fixation

Question 40

what is BSSO?

Answer 40

a common orthognathic surgery that repositions the lower jaw to correct malocclusion

Question 41

what is a genioplasty?

Answer 41

An operation to change the position of the chin

Question 42

when does post surgical orthodontics start after orthognathic surgery?

Answer 42

starts in the ward before discharge

Question 43

what does post surgical orthodontics inolve?

Answer 43

if occlusion is good: elastics if occlusion is not as planned: return to theatre a post surgery lat ceph is taken on discharge to plan post op ortho

Question 43

how long are retainers monitored post orthognathic surgery ? and how?

Answer 43

2 years questionnaires, photos, lat ceph

Question 44

what are early complications of orthognathic surgery?

Answer 44

bruising swelling pain feeding infectio

Question 45

what are intermediate complications of orthognathic surgery?

Answer 45

numbness - lips, palate, tongue (100%)

Question 46

what are late complications of orthognathic surgery?

Answer 46

prolonged numbness (10%) relapse (partial/ total) infected screw/ plate (12%) speech/ TMD problems