orthognathic basics for post graduate students ,part 1 and 2

1. Orthognathic surgery
Basics(part 1):
BY DR SAQBA ALAM

2. Pt workup and planning sequence
 Facial profiles
 Imaging
 Pre surgical orthodontics
 Models
 VSp
 CASS

3. HISTORY ,EXAMINATION -INSPECT !!
 Think beyond asymmetry (why the problem happened? Can it be
syndromic?TMJ??condyle?? Breathing?? Growth spurt?

4. Downs’ witts’ steiner mc namara (analysis)
KNOW YOUR CEPH!
Frankfort plane
A
B
SNA
SNB
PO
GO
MENTON
Post Airway space
calculation
MMA

5. Facial proportions and growth assessment

6. C2
C3
c4
CVM CLASSIFICATION

7. 1=130+-7m 130+-7 women
2=for rhinoplasty
3=90-95m,95-100f
160-175

8. Other concerns /Envelope of discrepancy
Max:
5 up
5 down
2 back 5 front
Mand:
8 front
>7mm consider
bimax/genio 8 back
sso ,ivro 12
Autorotation few mm

9. MODEL SURGERY
 CT maxilla ,mandible and TMJ
 Fabrication of models
 Surgeon will reposition models in the final position and fixate it
 Condyle will be removed if needed and model sent to TMJ CONCEPTS for
reconstruction of TMJR
 Approval of prosthesis by the surgeon
 Manufacturing of custom prosthesis

10. Protocol for model surgery (w.b vol 3)
Surgical steps:
1 Ct of entire mandible, maxilla and TMJ
2processing of the DICOM data to create CASS
3correction of dentofacial deformity including final positioning of maxilla and mandible with
computer simulated surgery.
4stereolithic models created with jaws in final position and sent to surgeon for
condylectomy and rami and fossa contouring if indicated.
5surgeon evaluation and design approval and TMJR reconstruction
6Two weeks before surgery acquisition of final models
7 maxillary segmentation may be done on the maxillary model to maximize occlusal fit
8models incorporated into CASS to fabricate the intermediate and final splints
Models,splints and print outs sent to surgeon before surgery!

11. 3d analysis using CASS

12. OSTEOTOMIES – preplanning for reducing
complications
 HISTORY,EXAMINATION,COMPLIANCE,EXPECTATIONS
 Piezo,read scans well,measure osteotome 5mm or 7mm osteotome ,cbct,cortical
vs cancellous junction (ref reny k) limit incisions to 1st molar in the maxilla,pedicle
length,any gap >5mm consider bone grafts
 Condylar positioning
 Orientation and direction of instrument
 Inferior border continuity
 Cutting throughout the cortex over the planned osteotomy line(pyriform
platy/septoplasty)
 Re evaluate hindrances and interferences

13. Maxilla
 Anterior osteotomies(Wassmund,Wunderer,Cupars) removal of 1st premolar.
 WUNDERER: posterior positioning of the premaxilla(labial and transpalatal incisions
behind 4)downfracture in superior direction.
 CUPARS’: superior repositioning of the premaxilla with no palatal incision.sub
periosteal tunneling after buccal and medial cut perform the palatal osteotomy and
downfracture premaxilla.remove the reqd bone ,ligate canine and 5.fix lateral pyriform
rims.
 WASSMUND: blood supply maintained.palatal and medial cut osteotomies through
tunneling.
 SEGMENTAL OSTEOTOTOMIES GOOD FOR CORRECTING TRANSVERSE
DISCREPANCIES UPTO 7MM/3d asymmetries –(think of fistulas/infection and tooth
trauma-partial or total segment loss!)

14. MAXILLARY OSTEOTOMY
Blood supply of
downfractured segment
lefort 1

15. LEFORT 1 OSTEOTOMY:
(von langen bak)
 Versatile both for cosmesis and non cosmetic purposes
 Surgical steps (standard)
 GA,La infilteration
 Soft tissue incision and subperiosteal dissection
 Design osteotomy II to occlusal plane after reference marks
 Lateral wall osteotomy
 Step cut
 Posterior wall osteotomy till pterygomaxillary junction
 Lateral nasal wall osteotomy (posteriolaterally)25-30mm protect DPA
 Dysjunction using finger palpation(inferiomedially)
 Complete and repeat on opp side
 Nasal septal osteotomy posterioinferiorly by nasal septal osteotome
 Mobilization after removal of all sharp bony projections.Downfracture the maxilla with gentle pressure
 Prepare nasal groove to prevent septal deviation.Bone grafts at this point if needed.
 Condylar positioning,IMF and fixate!(L lateral pyrifom then zygomatic buttress region)1.5-2mm

16. Closure
 Alar base cinch (prevents alar flaring)
 Alar cinch suture restores the normal alar width by
 preventing the lateral drift of the naso-labial muscle and
thereby reducing the postoperative nasal flare significantly.
 V-y or inverted T mucosal suturing to prevent
 shortening of vestibule and upper lip
Nasalis muscle tie to ANS

17. COMPLICATIONS
preop
per-op
Tooth
Sinus post- op
Nose
Base of skull
Eye
Ear
Senses
Blood
Splits
Hardware

18. MANDIBLE SSO (obwegeser)
 Versatile.indicated in excess,deficiency,open bite CCW,OSA
 BONE CUTS
 1-medial ramus osteotomy (original vs Hunsuck mod)
 2-Sagittal coticotomy btw 1 and 2 inferiorly (caution)nerve and splits!
 3-Bucacl vertical osteotomy original vs dalpont mod-
 Oblique (directed back towards antigonial vs
vertical downward cut btw 1 and 2 to increase
bony contact.
Wolfords mod-include both plates buccal and lingual
Epkers’ mod-minimum stripping

19. Completing bone cuts and fixation
 Smith spreader to split the fragments
 Proximal vs distal fragment.Id nerve Distal tooth bearing segment!
 Clean the latter,separate sling/masseter fibres ( relapse!)
 Condylar repositioning! (condylar sag)CPD,angle pressure
superioanteriorly.occlusion.IMF
 Fixation –bone plates 2mm/bicortical screws 2 on each side of osteotomy(transbuccal
trocar-stab skin at lower border)
 Release IMF recheck occlusion
 2 layered closure muscle/mucosa
 Three-dimensional model of different fixation methods after BSSo: a – bicortical
screws, b – monocortical 4-hole straight plate, c – monocortical 6-holes sagittal plate-
------------

20. COMPLICATIONS OF BSSO (REF ,LAURA A-BSSO Semin Plast Surg.
2013
doi: 10.1055/s-0033-1357111
 Complications related to BSSO include bleeding from injury to the inferior alveolar artery or
masseteric artery, unanticipated fractures and unfavorable splits, avascular necrosis, condylar
resorption, malposition of the proximal segment, and worsening of temporomandibular joint (TMJ)
symptoms.
 The risk of injury to the inferior alveolar nerve is a significant consideration when performing a
BSSO. The incidence of transection is reported between 2 to 3.5% and the incidence of some form
of long-term neurologic deficit is reported in 10 to 30% of patients, whether symptomatic or
not.13 When the sagittal split osteotomy is performed with an osseous genioplasty, nearly 70% of
patients have some degree of neurosensory deficit at 1 year.14 Fixation of the segments without
proper seating of the condyles can result in condylar malposition, which can lead to rotation of the
proximal segment and ultimate relapse, malocclusion, worsening of TMJ symptoms, and
remodeling of the condylar head. Malocclusion in the form of an open bite is often the result of
inadequate original fixation or hardware failure. When noted intraoperatively, the fixation should
be revised; when noted in the postoperative course films should be obtained to assess for
hardware function. Small postoperative posterior open bites can often be managed
orthodontically.

21. SSO vs VRO and Inverted L Osteotomy
 Versatile Bsso.
 Prolonged periods of MMF not necessary
 Less gonial angle change as compared to VRO after set back.pts requiring greater reduction in the
gonial angle should go for VRO.
 Sso permits slight rotation without step formation.
 Large asymmetries ,Class 2(short ramus) and high angle---inverted L large set backs/large
advancements.no MMF
 VRO----thin ramus/TMD/class 3/decreased MO,MMF,transoral rigid fixation possible.,not used for
sk classs 2 and AOB.upto 10mm set back can be performed.modifications allow less stripping of
masseter and medial pterygoid.
 Sso->medial inf alveolar artery,inf=facial artery.Bony contact is enhanced in sagittal section,no need
for grafting in mild cases.more stable with bicortical screws.
 Vro-- No bony contact,bone grafts needed for advancement.less vascular neural damage to
Inferior alveolar.sigmoid notch(think masseteric artery),inf to ramus=inf
alveolar artery,retromandibular vein.Condyle remains passive,less chance of sagging.
 ID nerve injuries BSSO-INVERTED L-VRO(look for less height of the body of mandible
and inferior positioning of nerve.

22. Condylar sag

23. VRO
Use of a ramus measuring instrument to locate the
vertical osteotomy 7 to 8 mm anterior to the posterior
border of the ramus. B,
Medial view of the osteotomy preserving the medial
pterygoid insertion.
An unfavorable osteotomy compromises the medial
pterygoid insertion.
An alternate, anteriorly directed osteotomy optimizes
the proximal segment muscle attachment in larger
setbacks.
Medial edge of the proximal segment trimmed with a
rotary instrument to ensure passive overlap of segments
and close bone contact

24. Inverted L osteotomy
 The inverted L osteotomy may be the operation of choice for large advancements
(greater than 12 mm) with counterclockwise rotation or for large setbacks (greater
than 10 mm). It is also a good choice for reoperations resulting from altered ramal
morphology and in patients with masseter hypertrophy with dense underlying
cortical bone
1.Risdon incision/submandibular
2.Nerve stimulater MM
3.Masseter dissection
4.Exposure uptil sigmoid notch,identify
posterior border of ramus
5.

25. Complications of mandibular
Osteotomies:
The risk of injury to the inferior alveolar nerve is a significant
consideration when performing a BSSO. The incidence of
transection is reported between 2 to 3.5% and the incidence of
some form of long-term neurologic deficit is reported in 10 to
30% of patients, whether symptomatic or not.13 When the
sagittal split osteotomy is performed with an osseous
genioplasty, nearly 70% of patients have some degree of
neurosensory deficit at 1 year
lingual nerve injuries are uncommon ,some paresthesia
spontaneously resolves, but Pepersack and Chausse
reported a 3% neurosensory deficit at 5 years

26. COMPLICATIONS SSO (cont)
 Proximal segment fractures occur most often as a result of failure to completely cut the
inferior border; this results in a fracture line that propagates along the buccal side of the
inferior border. As the two fragments are split and this is noted, the inferior border should
be recut.
 Impacted third molars are another cause of unfavorable fractures and should ideally be
removed 6 months to 1 year prior to mandibular surgery. When an impacted third molar
must be removed at the time of surgery, care should be taken to not use excessive force.
Cutting the tooth into smaller fragments will facilitate this.
 Temporomandibular dysfunction (TMD) is a common finding in the general population,
with a reported incidence between 20% and 25%.16 The incidence of preoperative TMD in
the orthognathic population is reported to be between 16 and 50%.1 The most frequent
symptoms identified were pain and clicking of the TMJ.

27. INVERTED L-VSP CASS
Figure:
Clinical photograph of computer-aided design and
computer-aided manufacturing fabricated cutting jig for
the inverted L osteotomy and the respective virtual
surgically planned cutting jig.
1.Standard intraoral incison 2cm lateral to
mucosa of mandible
2.Incise periosteum,notched ramus
retractor,expose superior limit sigmoid
notch,inferior limit gonial angle
3.Identify posterior border of ramus.Use cutting
jigs for further aid
CUTTING JIG
ADAPTED TO
MANDIBLE --

28. Which jaw 1st? Surgical Sequencing
 Clockwise rotation=maxilla first (do mandible cuts,do not completely
osteotomize,do maxilla,fix it then come to mandible
 If maxilla has to go up,do it first.when VRO planned
 For counter clockwise rotation do mandible first.when large movements are
required.when increase chances of bad splits.
Regardless of which jaw to do first,safer
approach is to make the cuts first in one
jaw and do not OSTEOTOMIZE
COMPLETELY-follow with the other
jaw,completely osteotomize and fix,then
return to previous uncut jaw

29. FIXATION
K wire
fixation
in IVRO
Transbuc
cal trocar
BSSO fixation
options/orient
ation
Pt
specific
RECON

30. END OF PART 1