Genioplasty overview

1. DR MOHAMMED HANEEF

2.  Introduction and History
 Pre-operative evaluation and facial analysis
 Implant materials and sizing
 Implantation technique
 Complications

3. Introduction
 Multiple factors contribute to the aesthetically
pleasing face
○ Skin
 Texture
 Color
 Thickness
○ Soft tissue
 Composition, location
○ Bony contours
 Size, shape, location, and symmetry
○ Cultural norms

4. CLASSIFICATION OF CHIN DEFORMITIES
 Class I macrogenia
a. Horizontal
b. Vertical
c. Combination of both
 Class II microgenia
a. Horizontal
b. Vertical
c. Combination of both
 Class III combined
a. horizontal macrogenia with vertical microgenia
b. horizontal microgenia with vertical macrogenia

5.  Class IV assymmetric chin
a. Short anterior facial height
b. Normal anterior facial height
c. Long anterior facial height
 Class V Witch’s chin(soft tissue ptosis)
 Class VI pseudomacrogenia
 Class VII pseudomicrogenia

6. PREOPERATIVE EVALUATION
 Lip position, shape
 Depth of labio mental fold
 Soft tissue around chin
 Mentalis muscle activity
 Cephalometric evaluation
downs analysis
steiners analysis
tweeds analysis

7. SOFT TISSUE EVALUATION
 Gonzalez – Uloa & Steven’s analysis
 A line is dropped from the soft tissue
Nasion perpendicular to frankfort
horizontal plane
 This line is called zero meridean
 Ideally Soft tissue pogonian of the chin
should be at or just posterior to the zero
meridean

8. HISTORY OF GENIAL
PROCEDURES
 Hofer in 1942 described horizontal sliding
osteotomy
 Trauner & Obwegesser in 1957 horizontal
sliding osteotomy with intraoral incision
 Reichenbach in 1965 wedge osteotomy &
vertical shortening of chin

9. Advanced sliding genioplasty

10. Chin Augmentation
 Often an adjunct to
rhinoplasty
 Particularly important
in creating an aesthetic
profile

11. Horizontal osteotomy with
advancement
 Incision half way the depth of vestibule and
extended to canine region bilaterally.
 Periosteum left intact on the inferior border
 Line of osteotomy should be 5 mm below canine
root & 10 to 15 mm above the inferior border &
5 mm below the lowest mental foramen

13.  Fragment stabilized by
 unicortical or bicortical wires
 bone plates
 prebent chin plates
 lag screws

15. HORIZONTAL OSTEOTOMY
WITH REDUCTION
 Prefabricated chin fixation plate or H
shaped plate is used
 When the chin is set back postero lingual
area has a palpable step defect.
 To prevent this postero lingual area is
contoured
 Labio mental fold is enhanced by
contouring the anterior superior edge.

18. Vertical increase of the chin

19. Vertical decrease of the chin

20. DOUBLE SLIDING HORIZONTAL
OSTEOTOMY
 In very deficient chin
 Creation of a stepped intermediate wafer of
bone between the inferior fragment and
mandible
 This segment is advanced to produce bony
contact between upper and lower
fragments

21. Correction of assymmetry of chin
 Done in unilateral condylar hyper or
hypoplasia where the chin is deviated.
 Done for the lateral movement of the chin
 Also known as propeller osteotomy
 First osteotomy is performed parallel to the
inter pupillary line
 Second osteotomy is performed parallel to
the lower border of the chin

24. Altering the width of the chin
 Altering the posterior dimension
 Before the chin is mobilised fix a 4 hole
straight plate at the labial cortex of the chin
 Midline osteotomy is performed both
buccal and lingual cortex
 Chin widened using bone plate as a hinge
 To narrow the chin triangular midline
ostectomy is performed.

27. Altering the anterior dimension
 For narrowing the anterior dimension of
chin a midline ostectomy is performed at
the centre and this part is removed
 Lateral segments are moved medially
 For widening the anterior dimension of
chin osteotomy is performed in the centre
of the chin fragment
 After increasing the width bone graft is
placed between the segments

30. Augmentation using implants
 Autologous
 Calvarial bone
 Metals
 Corrosive
 High rate of bone erosion
 Polymers – most commonly used

31.  Polymers – carbon chain based
molecules with crosslinking
 Dimethylsiloxanes
○ Silicone based
○ Silastic
 Polyamide
○ Supramid
 Polyethylene (polyester fiber)
○ Mersilene (Polyethylene terephthalate)
○ Dacron
○ Medpor (porous polyethylene)
 Expanded polytetrafluoroethylene
(PTFE)
○ Gore-Tex
○ Avanta
 PTFE
○ Teflon
○ Proplast I and II
 Polymethylmethacrylate (PMMA)
Silicone chin implants

32.  Composite polymer implants
 Hard Tissue Replacement (HTR)
○ PMMA + polyhydroxyethylmethacrylate and
calcium hydroxide
 Hydrophilic outer layer for osseointegration
 Silastic implant with Dacron backing
○ Increase interface soft tissue ingrowth

33. Complications
 Wound dehiscense
 Prolonged neurosensory disturbances
 Avascular necrosis of mobilised segments
 Hemorrhage causing lingual hematoma
 Chin ptosis
 Bony resorption under alloplasts
 Devitalisation of teeth
 Mandibular fracture
 Mucogingival problems

34. References
 Fonseca vol2 orthognathic surgery
 Johan P Reyneke – Essentials of
orthognathic surgery