Genioplasty of the mandible

1. GENIOPLASTY
Pesented by
KANIMOZHIY SENGUTTUVAN
2nd year post graduate
Thaimoogambigai Dental College and Hospital

2. INTRODUCTION
Genioplasty is the surgical procedure used to alter the size and morphology of
the bony chin with concomitant changes in the surrounding soft tissues. It can
be used as a single procedure or it can be used as an adjunctive procedure
along with other major osteotomies of the jaw.

3. • Successful treatment of the orthognathic surgical patient is dependent
on careful diagnosis.
• Cephalometrics can be an aid in the diagnosis of skeletal and dental
problems and a tool for simulating surgery and orthodontics treatment.

4. • While patients seeking about facial cosmetic surgery often focus on
structures such as the nose, the eyes, and the laxity of their skin, but the
lower third of the face is an area that could be surgically modified to improve
overall facial appearance and harmony.
• The profile of a patient can be significantly altered with either a chin
augmentation or reduction procedure. This, in turn, has a significant effect
on overall facial symmetry.
• Chin deformity can be corrected by genioplasty approaches.

5. History of Genial Procedures
• Hofer(1942) first described horizontal sliding osteotomy- extraoral incision
• Converse(1950), discussed the feasibility of bone grafts introduced through intraoral
approaches
• Trauner and Obwegeser, (1957), used the horizontal osteotomy through an intraoral
incision with de--gloving of the anterior mandible.
• Converse and Wood-Smith described various applications and versatility of, the
horizontal osteotomy

6. • Reichenbach and colleagues (1965)proposed wedge osteotomy and vertical
shortening of the chin.
• Hinds and Kent(1969) realize the importance off maintaining the soft tissue
attachment along the inferior segment and the role of these attachments in
achieving maximal soft tissue change.

7. CHIN
• The chin should, however, be evaluated in all three dimensions. The width of the chin
should be assessed in relation to the overall facial shape.
• A narrow chin often has a knobby appearance, and if surgical advancement of the chin
is planned, widening of the chin should be contemplated.
• The labiomental fold, chin shape, relation to the dental midline, symmetry, and cant of
the lower border should be considered.

8. SURGICAL ANATOMY
• The primary sensory innervation to the chin area is from the paired mental
nerves that exit the body of the mandible near the apices of the premolar
teeth.

9. • The primary motor component to the muscles associated with the anterior aspect of
the chin are from the buccal and marginal mandibular branches of the facial nerve.
• These muscles include the depressor labii inferioris, depressor anguli oris, mentalis
and orbicularis oris muscles.

10. • The primary muscle involved with the genioplasty procedure itself is the mentalis muscle,
which provides the primary vertical support to the lower lip.
• The depth of labiomental fold may dictate which technique is suitable. The mentolabial sulcus
becomes less pronounced in a vertical lengthening of the chin.
• Position of mental foramen is utmost importance during surgery. The mentalis muscle
elevates the chin at a place just below the tooth roots.
• The arterial supply to the muscles of the chin area is from the inferior labial arteries, which
are terminal extensions from the facial arteries.

11. 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

12. 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

13. INDICATIONS
• Surgical goals include creating an aesthetically pleasing
facial contour and establishing proportionate facial height.

14. CONTRAINDICATIONS
• Carefully evaluate the teeth and the height of the
mandible prior to surgery.
• Long teeth with a short mandibular height is a relative
contraindication for an osseous genioplasty or an
aggressive bony reduction.

15. PREOPERATIVE EVALUATION
• Cephalometric evaluation
• Soft TissueAnalysis
 Lip competence
 Facial height
 Facial symmetry
 Lip–chin relationship
 Cervicomental angle
 Nose–chin evaluation
• The skin of the lower face

16. CEPHALOMETRIC EVALUATION

17. A combination of Down’s, Steiner’s and Tweed’s analysis is used to assess the
relationships of skeletal and dental structures so that an accurate diagnosis of
dental and facial anomalies can be made. The information obtained from this
analysis is considered when performing sagittal or vertical changes in chin position.

18. 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 meridian
• Ideally Soft tissue pogonion of the chin should be
at or just posterior to the zero meridean

19. • Merrifield’s ‘Z’ angle is a line from
the soft tissue chin tangent to the
most procumbent lip, which forms an
angle with the Frankfort horizontal
plane.
• Normal range- 70 to 80 degrees

20. RICKETTS LIP ANALYSIS
• Reference line connects NOSE TIP TO
SOFT TISSUE POGONION- E LINE
• Lip are analyzed depending on the
distance of the lips from the line
• NORMAL VALUES
 UPPER : 2-3 mm
 LOWER: 1-2 mm

21. • A line connecting the midpoint of the
columella of the nose to the soft tissue
pogonion.
• According to C.C. Steiner, the lips should
fall on this line and any deviation shows
prominence or flatness of the lip.
S-LINE (ESTHETIC PLANE OF STEINER)

22. • Lastly, the skin of the lower face should be examined in both frontal
and profile views, noting the quality, thickness, and laxity as well as
any irregularities.
• Because these factors can impact outcome, a patient’s expectations
should be managed by discussing these factors in the preoperative
setting.

23. SURGICAL PROCEDURE

24. STEP 1: INFILTRATION OF SOFT TISSUE WITH A
VASOCONSTRICTOR
• Infiltrate the area of dissection with 2 mL of local anesthetic
containing a vasoconstrictor (epinephrine in a concentration of
1:100,000) 10 minutes before surgery.

25. STEP 2: MUCOSAL INCISION
• Make the first soft tissue incision through the labial mucosa of the mandible
from just distal to the canine to a similar point on the contralateral side.
• Branches of the mental nerve can often be identified in the submucosal
tissue laterally.
• Leave at least 5 mm of non-keratinized mucosa superiorly to make later
suturing easier.

26. STEP 3: SUBMUCOSAL INCISION
• Make the second incision through the submucosal tissue and periosteum onto the bone,
avoiding damage to the mental nerve at the lateral aspects of the incision.
• This incision is angled at 45 degrees to the bone so that more submucosal tissue and
periosteum remain at the superior aspect, which will make later suturing easier
The soft tissue incision is angled to maintain more
submucosal tissue for later ease of suturing.

27. STEP 4: MUCOPERIOSTEAL DISSECTION
• Start the mucoperiosteal dissection from the center, and dissect laterally and inferiorly.
• Identify the mental nerves bilaterally.
• Also elevate the mucoperiosteum at the superior aspect to make later suturing easier.
Subperiosteal dissection is carried downward and laterally to
identify the mental nerve. The mucoperiosteum at the
superior aspect is also elevated to make reapproximation of
the mentalis muscle and mucosa easier.

28. STEP 5: ESTABLISHING REFERENCE POINTS
• Use a 701 bur to mark the dental midline on the bone superiorly and inferiorly to the
intended osteotomy.
• Make small, shallow holes, keeping the roots of the incisors in mind, and score a line into
the cortex to connect the holes.
The dental midline is marked on the
bone. Two vertical reference lines are
placed lateral to this line.

29. • Deepen the inferior hole by angling the bur
superiorly and extending the hole well through the
cortex.
• This hole is intended for the placement of a
positioning wire later in the procedure.
• Place the hole in thick bone to ensure that the
wire will not pull through.
• For accurate repositioning of the chin, place
reference marks approximately 15 mm lateral to
the midline to assist with symmetric repositioning.
A superiorly angled hole is drilled in the midline
below the intended osteotomy line. A positioning
wire will be placed through this hole once the
chin has been mobilized.

30. STEP 6: OSTEOTOMY DESIGN
• The osteotomy should be performed at least 5 mm below the roots of the incisors and 5 mm
below the mental foramen.
• View and mark the angle of the osteotomy as planned on the surgical visual treatment
objective.
The angle and position of the osteotomy is seen. The position of the mental nerve
and the roots of the incisors and canines should be kept in mind

31. • Most genioplasty procedures are performed to
improve the anteroposterior position of the chin.
• However, consideration must be given to the
angulation of the osteotomy because variations in the
angle will lead to changes in the vertical dimension of
the chin, with obvious esthetic consequences.
• The angle of the osteotomy creates a plane along
which the bony segment will slide.
The change of the angulation of the osteotomy
and its effects on the vertical dimension after
repositioning are demonstrated.

32. • The steepness of the angle of the osteotomy will be influenced by
the esthetic requirements, the roots of the incisors and canines, and
the position of the mental foramen.
• Keep in mind that the course of the mental nerve prior to its exit
through the mental foramen is approximately 5 mm inferior and
anterior to the foramen.

33. STEP 7: OSTEOTOMY OF THE CHIN
• Perform the osteotomy with an oscillating saw by starting in the centre and
cutting laterally.
• Ensure that both cortices are osteotomized.
• Failure to include the lower border in the osteotomy will lead to an
unfavourable fracture at the inferior border of the bone segment and thus
inaccurate repositioning of the chin (unless contoured).

34. STEP 8: MOBILIZATION OF THE CHIN
• After completion of the osteotomy, the chin segment should be mobile.
• However, it may be necessary to finally mobilize it with a light tap and then rotate a
small osteotome in the osteotomy line.
• The need for excessive force to mobilize the chin indicates that the osteotomy is not
completely through both cortices or the inferior border of the mandible, which may
lead to an unpredicted fracture of the lower border.
• When the genioplasty is combined with a bilateral sagittal split osteotomy of the
mandible, it is preferable to perform the genioplasty after completing the sagittal split
osteotomy.

35. • At this stage, the mandible is still held in position by maxillomandibular fixation.
• Performing the genioplasty at this point allows the surgeon to evaluate the
esthetics and, if necessary, make small positional changes to the chin to improve
the appearance.
• Keeping the teeth in occlusion while performing the genioplasty provides the
added advantage of supporting the mandible and reducing the forces on the rigid
fixation screws that were recently placed.

36. STEP 9: ENGAGING THE POSITIONING WIRE
• Place a 26 gauge wire through the hole drilled in the osteotomized
segment during marking, and attach a wire twister to it.
• This wire will be helpful both during the mobilization and in accurate
repositioning of the chin.

37. STEP 10: FINAL MOBILIZATION OF THE CHIN SEGMENT
• Place a Howarth elevator behind the lingual cortex, and pull the chin forward by stretching
the soft tissue (the suprahyoid muscles and periosteum).
• Adequate mobilization of the segment will facilitate easy and accurate repositioning of the
chin.
Mobilizing the chin. A Howarth elevator is placed behind
the chin segment while the chin is pulled forward by the
positioning wire.

38. STEP 11: REFINEMENT OF THE OSTEOTOMY
• Check the posterior aspect of the osteotomized segment for any sharp or irregular edges,
and remove the interferences using a large round vulcanite bur.
• Failure to smooth any irregularities will prevent accurate repositioning of the chin.
• Interferences are often found at the postero-lingual area of the mobilized segment and
the soft tissue; the sublingual salivary gland, facial artery, mentalis nerve, and geniohyoid
muscles should also be protected during removal of these bony interferences.
All bony interferences should be removed and
irregularities smoothed prior to repositioning. Special
attention should be given to the posterior area of the
chin segment.

39. • Use the positioning wire and extraoral digital
pressure to accurately reposition the chin
according to the treatment plan.
• Although a golden rule in orthognathic surgery is
“Never change your treatment plan on the
operating table,” genioplasty may be the
exception.
• The surgeon may use clinical judgment at the time
of surgery to slightly alter the repositioning of the
chin for a better esthetic result. The chin segment is placed in its planned
position via the positioning wire.

40. • When tri-cortical bone screw fixation is contemplated,
countersink two holes in the buccal cortex approximately
8 mm on either side of the marked midline of the
osteotomized segment.
• Position the countersunk holes at least 5 mm from the
superior edge of the segment to accommodate the head
of the screw.
A countersink hole is placed to
accommodate the head of the
screw.
Step 13: Counter sinking holes for tri-cortical
screw fixation

41. • Drill the holes, and place the bone screws while the assistant holds the chin in its planned
position using the holding wire and digital pressure.
• Drill the holes into the center of the countersunk holes using a trocar to protect the soft
tissue, and simultaneously guide the drill at an appropriate angle to engage all three
cortices. Ensure that the screw is long enough to engage all three cortices.
A trocar is used to place a tricortical screw to fixate the chin
segment. At least two screws should be placed to secure
the bone segment.
STEP 14: PLACEMENT OF TRICORTICAL SCREWS
A hole is drilled through all three cortices using a trocar
to protect the soft tissue.

42. • Use a prefabricated chin fixation plate, an X- or H-
shaped bone plate, or two straight bone plates
with two screws on either side of the osteotomy.
• The positioning wire and digital pressure help
stabilize the chin segment in its planned position
while the bone plates are bent to fit accurately
and passively.
• Avoid damaging the roots of the incisors with the
screws. It is recommended that fixation be placed
on each side of the midline.
STEP 15: BONE PLATE FIXATION AS AN ALTERNATIVE TO
SCREW FIXATION
As an alternative to tricortical screw fixation,
bone plates may be used as rigid fixation.

43. • Position the chin using extraoral digital
pressure, check the position of the bone using a
caliper, and use a prefabricated chin fixation
plate or bend the appropriate plate to fit
accurately and passively.
Step 16: Anteroposterior reduction of the chin
For setback procedures of the chin, bone plate
fixation is the method of choice. In setback
procedures, the use of a positioning wire is
impractical.

44. • When the chin is set back, the postero-lingual
area often has a palpable step defect at the
inferior border of the mandible, which may
concern the patient.
• To contour this area, the osteotomized
segment is pulled downward and forward, and
the postero-lingual aspect of the chin segment
is contoured.
• Protect the soft tissue at all times during this
step.
The medial aspect of the posterior area of
the chin segment is removed to prevent a
palpable step defect on the lower border
of the mandible (arrow).

45. • Anteroposterior reduction of the chin may
result in flattening of the labiomental fold.
• The sharp anterior edge on the superior
aspect may be contoured to counter this effect
and enhance the depth of the labiomental fold
and chin shape.
The labiomental fold is enhanced by contouring
the anterior edge on the superior aspect of the
mandible.

46. • Using a 701 fissure bur, drill reference holes recording the vertical dimensions of the
chin.
• To maintain the symmetry of the chin, the reference marks should be made in the
midline as well as approximately 15 mm lateral to the midline and the distances
between them recorded.
• Place a bone plate while the assistant uses the positioning wire and an instrument
wedged between the segments to maintain the required space between the bony
segments.
STEP 17: VERTICAL INCREASE OF THE CHIN

47. • At least two screws should be placed superiorly and inferiorly to the osteotomy using an H- or
X-shaped plate or two straight plates to secure the segment and maintain the vertical height.
• It is recommended that a bone graft be placed in the defect however, do not force the bone
graft into the defect because doing so might displace or mobilize the chin segment.
Vertical increase of the chin. The chin segment is held at the planned
height with a positioning wire. Two bone plates are then placed to fixate
the segment. Finally, the defect is grafted.

48. • Drill reference marks recording the vertical
dimensions of the chin.
• To maintain symmetry of the chin, place the
marks in the midline and approximately 15 mm
lateral to the midline, and record the distances
between them.
• Perform the first osteotomy low enough to
facilitate performing the second osteotomy from
the superior aspect.
• Complete the lower osteotomy, and mobilize
the chin.
STEP 18: VERTICAL REDUCTION OF THE CHIN
Vertical reduction of the chin. The lower
osteotomy is performed first, and the planned
amount of bone is then removed superiorly.

49. • Mark the amount and shape of bone to be removed, and then complete the superior
osteotomy.
• The shape of the ostectomized bone will influence the final anteroposterior position
of the tip of the chin; that is, if the ostectomy is wider anteriorly, the chin will rotate
anteriorly, whereas an ostectomy that is wider posteriorly will rotate the chin
posteriorly.
• Maintain as much soft tissue attachment to the chin as possible to ensure good blood
supply to the repositioned bone and to reduce dead space.
• This will also yield a more predictable esthetic result.

50. • Drill reference holes recording the dimensions of
the chin.
• For lateral movement of the chin, the dental
midline is marked on the superior aspect of the
osteotomy line whereas the midline of the chin is
marked on the inferior aspect.
• When correction of asymmetry requires vertical
change as well, marks are placed lateral to the
midline to record vertical dimensions on both the
left and right sides.
Step 19: Correction of asymmetry of the chin
Lateral movement of the chin. The midline of
the chin is marked below the osteotomy line
and the facial midline above the osteotomy
line. After mobilization of the chin, the chin
segment is moved laterally until the lines
coincide.

51. • Large cants in the chin contour (eg, in unilateral
condylar hyperplasia or hypoplasia) may have to
be corrected by a propeller osteotomy.
• The first osteotomy is performed superior and
parallel to the occlusal plane or interpupillary
plane.
• A second osteotomy is performed parallel to the
lower border of the chin.
Propeller osteotomy. A first osteotomy (1) is
performed parallel to the interpupillary Line.
A second osteotomy (2) is then performed
parallel to the lower border of the chin.

52. • The small, triangular segment is rotated 180 degrees while its muscle
attachment is maintained.
• The inferior segment can now be secured by rigid fixation.
The triangular segment, pedicled to the hyoid
muscles, is rotated 180 degrees.
The two segments are secured by rigid fixation.

53. STEP 20: ALTERING THE WIDTH OF THE CHIN
Using a 701 fissure bur, drill reference marks recording the pre-surgical chin dimensions.
WIDENING OR NARROWING THE POSTERIOR
DIMENSION OF THE CHIN
• To widen the chin, perform a midline osteotomy through
the buccal and lingual cortex, and complete the
osteotomy with a small osteotome.
• Before the chin is mobilized, a four-hole straight plate
fixation is done horizontally across the midline to the
labial cortex of the chin.
• The chin can now be widened by using the bone plate as a
hinge.
Widening the posterior dimension of the
chin. A midline osteotomy is performed
through the chin segment after placement
of a bone plate on the anterior surface.
The plate is now used as a hinge, widening
the posterior chin, and a small bone graft
is placed in the midline defect.

54. • To narrow the chin, perform a triangular midline
ostectomy on the lingual aspect of the chin segment,
again using the bone plate as a hinge.
• Once the desired shape of the chin has been
achieved, additional fixation can be placed. Fixation
should be placed on both sides of the midline
osteotomy.
Narrowing the posterior dimension of the chin. A
bone plate is placed on the anterior surface of the
chin and a triangular midline ostectomy performed.
The segment is now bent medially to narrow the
chin.

55. • In widening the chin, a predetermined width can
be achieved by performing a midline osteotomy
and increasing the anterior width by moving the
segments laterally.
• Secure the graft between the segments with a
bone plate before fixation of the segments to the
mandible.
WIDENING OR NARROWING THE ANTERIOR DIMENSION
OF THE CHIN
After increasing the anterior width of the chin,
a bone graft is placed between the segments.
Widening the anterior dimension of the chin. An
osteotomy is performed in the center of the chin
segment.

56. • To narrow the chin, a predetermined amount of bone is ostectomized from the
mobilized segment.
• To simplify the removal of the ostectomized bone from the center of the chin,
complete all the osteotomies before mobilizing the segments.
Narrowing the anterior dimension of the chin. A midline
ostectomy is performed in the center part of the chin.
After removal of the ostectomized bone, the
lateral segments are moved medially

57. STEP 21: SUTURING THE SUBMUCOSAL TISSUE
• Place an interrupted midline suture to
accurately re-establish midline soft tissue
alignment.
• Then use a continuous 3-0 chromic suture
to re-approximate the periosteum and
muscle.
• Accurate re-approximation of the mentalis
muscle is of the utmost importance in
maintaining the soft tissue contour.
To achieve the best esthetic results, it is mandatory
that the mentalis muscles be accurately re-
approximated. Mucosal suturing should follow.

58. STEP 22: SUTURING THE MUCOSA
• Place a single midline 4-0 chromic suture to maintain lip symmetry.
• Use a continuous suture to secure the rest of the mucosa.

59. STEP 23: APPLYING A PRESSURE DRESSING
• Vertical and horizontal pressure is applied to the chin via a pressure
bandage.
• Postoperative hematoma formation and swelling is limited by keeping
the bandage in place for approximately 3 days.

60. KOLE’S PROCEDURE
• The procedure is done for the correction of an
anterior open bite.
• Hofer (1936) demonstrated an anterior
mandibular alveolar osteotomy to advance
anterior teeth in correction of a mandibular
dento-alveolar retrusion.

61. • In 1959, Kole modified this procedure employing Hofer’s
osteotomy generally use some form of bone graft in the alveolar
defect if significant movement of the fragment is planned.

62. TENON TECHNIQUE
• Michelet and associated described this techenique in 1974.
• A ‘U’ shaped monocortical osteotomy is created on the center of the symphysis.
• Lateral extensions are developed below the mental nerves, which connect to the
superior aspects of the tenon corticotomy.

63. • Full thickness osteotomies are completed on the lateral extensions and
only through the lingual cortex on the superior aspect of the tenon.
• The resultant full thickness of bone behind the tenon facilitates the
mortising of the tenon and lag-screw fixation

64. RECENT ADVANCES

65. HORIZONTAL FLIP PEDICLED GENIOPLASTY

66. BOX GENIOPLASTY

67. ADVANTAGES OF CHIN OSTEOTOMY
i. Very versatile procedure
ii. Corrects vertical problems
iii. Stable over time
iv. Improves submental length and cervicomental angle
v. Advances genial-tongue-hyoid position, of benefit in sleep apnea

68. DISADVANTAGES OF CHIN OSTEOTOMY
i. Requires osteotomy, adding risk from surgery and anesthesia
ii. Vascular injury risk
iii. Airway problem risk
iv. Not easily reversible
v. Increased expense for anesthesia, time and fixation materials when compared
to implants

69. Augmentation using implants
• Autologous
Calvarial bone
• Metals
Corrosive
High rate of bone erosion
• Polymers – most commonly used

70. ADVANTAGES
• Quick procedure
• Requires minimal instrumentation
• Less dissection than osteotomy
• No risk to floor of mouth vasculature
• “Easily” reversible procedure
• Wide selection of implant options
• Customizable
DISADVANTAGES
• Capsular contracture
• Infection
• Bone resorption
• Dislodgement/malposition
• Soft tissue chin pad issues
• Vertical changes are difficult
• Lower lip retraction
CHIN IMPLANTS

71. COMPLICATIONS
• SOFT TISSUE
i. Hematoma
ii. Scar
iii. Wound dehiscence
iv. Cellulitis
v. Draining fistula
vi. Capsular contracture
vii. Skin bunching/dimpling
viii. Skin necrosis
• NERVE
• Hypoesthesia/dysesthesia

72. • MUSCLE
a. Chin ptosis
b. Mentalis muscle dysfunction
c. Lower lip retraction
• BONE/TOOTH ABSCESS
a. Tooth root damage
b. Mandibular bone resorption
• TECHNICAL
a. Implant malposition
b. Under-augmentation/over-augmentation

73. CONCLUSION
• Genial procedure or genioplasty afford the surgeon the ability to make
small but necessary changes or dramatic alteration in the overall form of
the lower third of the face.
• This can be accomplished with detailed pre-operative planning and
application of good surgical technique.

74. REFERENCES
• Fonseca vol –III
• Johan P Reyneke – Essentials of orthognathic surgery
• Guyuron B, Michelow BJ and Willis L: Practical classification of chin deformities. Aesthetic Plast Surg
19: 257, 1995
• Horizontal flip pedicled genioplasty for correction of asymmetric chin in adult unilateral
temperomandibular joint ankylosis. Kiran Shrikrishna Garde, et al, Published 2011,The Journal of
craniofacial surgery
• An alternative option to conventional genioplasty: box genioplasty,S. Colbert, T.E.Seah, V. Ilankovan,
H. Bellis, DOI:https://doi.org/10.1016/j.bjoms.2011.04.009
• Oblique sagittal split sliding genioplasty: a new techniqueDavid P. Tauroa,∗, Uday Kiran UppadabaThe
Taulin’s Clinic, Centre for Craniomaxillofacial, Plastic & Reconstructive Surgery, Banglore, India
Department of Oral & Maxillofacial Surgery, Sri Sai College of Dental Surgery, Vikarabad, BJOMS