basics of orthognathic surgery Flashcards
What are the fundamentals of orthognathic surgery?
Team approach
History
Careful clinical examination
Investigations
Prediction planning
Stable surgical techniques
Why is dysmorphophobia important in orthognathic surgery?
If the patient isn’t happy with their face, changing their face won’t then make them happy
Describe body dysmorphophobia
Pt may request tx of non-existing deformity
1. Preoccupation with a defect on appearance, minor defect and excessive concern
2. Preoccupation leads to significant distress
3. Associated mental disorders eg - anorexia nervosa
What are characteristics of body dysmorphophobia?
Obsession with exaggerated defect
Doctor shopping
Who is involved in the MDT of orthognathic surgery?
Psychologist
Orthodontist
Maxillofacial surgeon
Technologist
Restorative dentist
Speech and language therapy
What is viropharyngeal incompetence?
A short soft palate, so air escapes giving a hyper nasal tone
What is an orthodontists role in orthognathic surgery?
Recognition of dentofacial deformities
Orthodontic tx before and after
Follow up
What is the technologists role in orthognathic surgery?
Model surgery planning
Provide occlusal wafer to guide the surgery
Building 3D skull models
Digital prediction of final occlusion
What should be considered in pt history for orthognathic surgery?
May be a congenital cause
May be due to acromegaly (hormone with adenoma in pituitary gland)
May be due to pathology eg - cysts and tumours
Could just be racial characteristics (don’t need to change them all)
Find if there is a psychological motivation
What is paranasal hollowing?
Deficiency of the maxilla that needs treatment
What should be examined intra-orally before orthognathic surgery?
Occlusal relationship
Centreline discrepancies
OJ
OB
Crossbites
Occlusal canting
Incisors inclination
Crowding and spacing
Tongue size, mobility and speech pattern
Speech pattern
VPI
What radiographic views are commonly used before orthognathic surgery?
OPT
Lateral cephalogram
PA cephalogram
Periapicals
Occlusal
CBCT
What 3 points of reference must be recorded on a facebow?
Condylar heads
Orbitale
Maxillary dentition
What is stereophotogrametry?
A 3D image taken of the patient
How is 3D planning carried out for orthognathic surgery?
Soft tissues through 3D image (stereophotogrametry)
Skeletal tissue through CBCT
Dental tissue with intra-oral scan
All compiled together for a pt image for planning
How is a diagnosis that orthognathic surgery is needed made from the maxilla?
Prognathic or retrognathic
Vertical excess or deficiency
Narrow or wide
Asymmetry
How is a diagnosis that orthognathic surgery is needed made from the mandible?
Prognathic or retrognathic
Asymmetry
How is a diagnosis that orthognathic surgery is needed made from the chin?
Progenia or retrogenia
Vertical deficiency or excess
Asymmetry
What are the stages of treatment before and and after orthognathic surgery?
Tooth alignment, eliminating crowding, spaces and cross bites
Alteration and coordination of the arches
Correction of incisors inclination (de-compensation)
Flattening the occlusal plane
Surgical fixation
Post-surgical orthodontic fine tuning
What is the difference between retrognathism and proficiency (hypoplasia)?
In retrognathism the size is okay but it is positioned too far back
If proficient, there is a deficiency in size
What orthognathic surgeries can be carried out for the maxilla?
Le Fort I osteotomy
Anterior maxillary osteotomy (posterior)
Describe a Le Fort I osteotomy
Disarticulating the maxilla from the base of the skull and move it to a pre-planned position
Moves superiorly, inferiorly and forward
Maxilla cannot move backwards due to the pterygoid plates
What surgery is carried out for the mandible and describe this procedure?
Sagittal split mandibular osteotomy
Separated the ramus from the body of the mandible
Body can be moved in any direction
What orthognathic surgery is carried out for the chin and describe this
Genioplasty
Inferior border of the mandible can move in any direction
Advancement, set-back and rotation
Augmentation and reduction
