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Good Morning
Mandibular Orthognathic
Procedures
Presenter-
Dr. Rahul Tiwari
Final Yr MDS
OMFS, SIDS
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1
CONTENTS
• Introduction
• Surgical anatomy
• Revascularisation & healing of
orthognathic surgical procedures
• Classification
• Surgical procedures
• Ramus osteotomies
• Body osteotomies
• Symphysis osteotomies
• Soft tissue changes after mandibular orthognathic procedures
• Complications of mandibular orthognathic surgeries
• References
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• Orthognathic in Greek
Orthos- straight ; Gnathos- jaw
• Orthognathic surgery refers to surgical procedures designed to
correct jaw deformities
• Orthognathic procedures are divided into three categories:
• Maxillary surgery
• Mandibular surgery
• Bimaxillary procedures
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• Indications to orthognathic surgery
• Impaired mastication
• Temporomandibular pain
• Dysfunction
• Sleep apnea
• Susceptibility to caries and periodontal disease
• Unaesthetic appearance
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• Once growth has ceased, the combination of orthognathic
surgery with orthodontics, usually becomes the only means
of correcting severe dentofacial deformities
• In severe malocclusion there are three possibilities for
correction:
• Growth modification
• Orthodontic treatment
• Orthognathic surgery in conjunction with orthodontics to establish
proper jaw relationship
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• Orthognathic surgery was originally developed in the United States
of America (Steinhäuser ).
• The first mandibular osteotomy is considered to be Hullihen´s
procedure in 1849 to correct anterior open bite & mandibular dento
alveolar protrusion with an intraoral osteotomy.
• Osteotomy of the mandibular body for the correction of mandibular
horizontal excess was performed by Vilray Blair.
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HISTORY
• Berger (1897) described a condylar osteotomy for the correction of
prognathism.
• Limberg in 1925 first reported the subcondylar osteotomy as an
extraoral technique, later it was modified to the intraoral vertical
subcondylar osteotomy.
• A variation of the vertical subcondylar osteotomy was suggested
by wassmund in 1927,which is similar to the inverted –L-
osteotomy.
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• Hofer in 1936 demonstrated an anterior mandibular alveolar
osteotomy to advance anterior teeth in correction of a mandibular
dentoalveolar retrusion.
• In 1954, Caldwell and Letterman developed a vertical ramus
osteotomy technique, which had the advantage of minimizing
trauma to the inferior alveolar neurovascular bundle.
The greatest development in osteotomies of the vertical ramus is the
sagittal split osteotomy credited to obwegeser in 1955. The major
modifications in the osteotomies design were first made by Dalpont in
1961.This was further discussed by Hunsuck in 1968 in order to
decrease the trauma to overlying soft tissues.
Kent & Hinds in 1971 initially presented the use of single tooth
osteotomies of the mandible.
Macintosh closely followed with his description of the total
mandibular alveolar osteotomy in 1974.
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Aesthetics
Function
Stability
AIMS OF MANDIBULAR OSTEOTOMIES
• Patient’s perception of the deformity and expectations
• Surgeon’s recognition of the deformity
• Complete physical examination, model surgery, cephalometric analysis
• Optimal treatment plan
• Counseling of the patient
• Informed consent
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PRINCIPLES IN TREATING MANDIBULAR DEFORMITIES
Vascular
structures
NervesMuscles
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ANATOMICAL & PHYSIOLOGICAL CONSIDERATIONS OF
MANDIBULAR OSTEOTOMIES
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Surgical Anatomy
Bell and Levy’s work {1970} demonstrated that blood flow through
the mandibular periosteum could easily maintain a sufficient blood
supply to the teeth of a mobile segment, even when the labial
periosteum was degloved.
subapical osteotomies need to be carefully planned to ensure as large
a vascular pedicle as possible.
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VASCULAR STRUCTURES
The proximal segment of the vertical sub sigmoid osteotomy maintains
its blood supply through the temporomandibular joint capsule and
the attachment of the lateral pterygoid muscle.
But the inferior tip of this fragment has undergone vascular necrosis
in some studies.
This led to the suggestion that fewer problems may occur if the cut
was made above the angle of the mandible.
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We should minimize the periosteal and muscle attachment stripping on
the medial surface of the proximal fragment with either the C or L
osteotomy or any of their variations.
The greater distance from the apices of the teeth not only minimizes
direct pulpal injury but increases the vascular pedicle to the mobile
segment as well.
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NERVES
• In most cases in orthognathic surgery avoiding injury to marginal
mandibular branch of facial nerve is achieved because soft tissue
anatomy in patients undergoing the surgery has not been disturbed
by disease or trauma.
• The course of the inferior alveolar nerve into the vertical ramus
and then through the body of the mandible makes it extremely
susceptible to damage from almost every mandibular surgical
procedure.
• Main goal – “To minimize the trauma because its
avoidance is impossible”
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MUSCLES
Orthognathic surgery affects muscles in primarily two ways:
• It changes the length of a muscle or it changes the direction of
muscle function.
• The muscles commonly discussed in orthognathic surgery of the
mandible have been the muscles of mastication and the suprahyoid
group of muscles .
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• A- S to lingula - 14.8 +/- 2.90 mm
• C- S to mandibular foramen –
21.6 +/- 3.31 mm
• B- Horizontal distance from lingual
to anterior border of ramus –
17.7 +/- 2.89 mm
• D- Mandibular foramen to ramus –
18.6 +/- 2.49 mm
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Int. J. Oral Maxillofac. Surg, 2008
• At a distance between 7.5 to 13.3
mm above the lingula
Buccal and lingual cortex fusion
occurs at a rate of
• 20% in the anterior ramus
• 39% in the posterior ramus
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• The position of the lingula is
posterior-inferior relative to the
position of the antilingula
• Any osteotomies performed at
a measurement of 5 mm
posterior to the antilingula (at
the level of the antilingula)- no
risk of damaging the
neurovascular bundle
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Accuracy of Using the Antilingula as a Sole Determinant of Vertical Ramus
Osteotomy Position . J Oral Maxillofac Surg, 2007
Position of IAN at second
molar
• Bone thickness from mandibular
canal to buccal plate- 7.2 +/-
1.47 mm
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Int. J. Oral Maxillofac. Surg, 2008
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Tsuji et al, Int. J. Oral Maxillofac. Surg, 2005
• PATTERNS OF ANTERIOR LOOP OF MENTAL NERVE
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J Oral Maxillofac Surg, 2007
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• Blood flow is crucial for revascularisation and healing
• Blood flow will be decreased in the areas where the
mucoperiosteum will be elevated
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• Immediate post-operatively
• Intermedullary circulation between the proximal and distal
segments
• Margins of osteotomy- avascular
• One week post-op
• Level of hypervascularity around surgical site
• No soft tissue re-attachment
• Isolated areas of sub- periosteal bone formation
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• 2 weeks post-op
• Avascular zone at the proximal osteotomy site
• Necrotic zone at the distal osteotomy site
• No soft tissue attachment at the distal necrotic zone
• 3 weeks post-op
• Soft tissue re-attachment
• Vascular anastamoses between proximal and distal
segments
• Osteoid formation through out marrow formation
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• 6 weeks post-op
• Circulation reconstituted across the osteotomy site
• Soft tissue re- attachment established
• 12 weeks post- op
• Circulation between the segments is continuous
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CLASSIFICATION
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MANDUBULAR ORTHOGNATHIC PROCEDURES
BODY
OSTEOTOMIES
SUB APICAL
OSTEOTOMIES
RAMUS
OSTEOTOMIES
HORIZONTAL
OSTEOTOMY
OF CHIN
SAGGITAL SPLIT
OSTEOTOMY
VERTICAL RAMUS
OSTEOTOMY
INVERTED “L” &
“C” OSTEOTOMY
ANTERIOR SUB
APICAL OSTEOTOMIES
POSTERIOR SUB
APICAL OSTEOTOMIES
TOTAL SUB APICAL
OSTEOTOMIES
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• First described in 1942 by Schuchardt in German
literature
• Most widely used surgical procedure for correcting mal-
positioned mandible
• It has been modified in many ways, but for longer than 50
years, benefits and advantages of the procedure have
remained unchanged
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• Versatility of the procedure allows wide application
• It increases the range of possible movements
compared with orthodontic treatment alone
• Broad bony overlap of the separated fragments allow
not only advancement or set- backs of the distal
tooth- baring mandible, but also rotations
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• A. Trauner & Obwegezer,
1957
• B. Dal pont, 1961
• C. Hunshuck, 1968
• D. Epcker, 1977
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• Bell and Schendel established the biological basis for
BSSO
• Minimal detachment of the pterygomassetric sling there is
decreased intra- osseous ischemia, and necrosis of the
proximal segment
• 1976, Spiessel advocated rigid internal fixation of
BSSO to promote primary healing, restore early
function, and attenuate relapse
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Indications
• Mandibular deficiency
• Advancements beyond 10- 12 mm, extra oral approach
should be considered
• Mandibular prognathism
• Large setbacks of more than 7 -8 mm, IVRO/ inverted L
osteotomy should be considered
• Mandibular asymmetry
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Surgical Procedure
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ADVANTAGES
• Broad bony overlap of
osteotomised segments
• Minimal alteration of natural
position of muscles of mastication
• Minimal alteration in position of
TMJ
• Short operating time and low
complication rate
DISADVANTSGES
• Requires additional
maxillary surgery for most
dentofacial deformities
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Osteosynthesis
• Post- operative fixation of the osteotomised segments was
once a great challenge
• Initially,
No fixation of the fragments
Healing- intermaxillary splinting of the teeth
• Introduction of wires for fixation
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• Major breakthrough- development of “stable
compression osteosynthesis”-
Spiessl in 1974
• The degree of immediate postoperative stability
achieved with this technique completely obviated the
need for intermaxillary fixation
• Wide variety of methods and materials for fixation
are available
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• Initially the use of three 2.7 mm “lag” screws on
each side was advocated
• Concern
• Compression may cause increased nerve damage
• Displacement of the condyles, with subsequent
temporomandibular joint dysfunction
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• The position screw or bicortical screw
This technique permits maintenance of the gaps
between the proximal and distal fragments, with no
compression of the two segments together
• Osteosynthesis with miniplates
• 4- holed plate with 2screws on each side of the osteotomy
cut
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• Resorbable screws
• Obvious advantage of resorbable fixation is to obviate the
need for future hardware removal
• 4 screws have to be placed on each side of the mandible
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• 1st described by Caldwell and
Letterman in 1954- extra oral
• Introduced by Moose in 1964- intra-
oral technique performed from
lingual aspect
• Wistanley, 1968- performing the
technique from the lateral aspect of
the mandible
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Comparison between SSRO and VRO
SSRO VRO
OSTEOTOMY PA Saggital split Latero medial cut
Open procedure Blind procedure
Along IAN Rear to IAN
Frequent exposure of IAN No exposure of IAN
BONE HEALING Contact on marrow to marrow Contact on cortex to cortex
BONE FIXATION Rigid internal fixation No fixation
CONDYLAR HEAD Original position New equilibrated position
POST OP IMF None or shorter period Required
PROGNOSIS Weakely dependent on PT Strongly dependent on PT
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Indications
• Horizontal mandibular excess
• Mandibular asymmetry
• Minor occlusal discrepancy after
isolated Le Fort I osteotomy
• Asymmetric lateral open bite
• Failure to achieve passive rotation
of the mandible after the release of
MMF
• Patients with significant TMJ
complaints
Contraindications
• Advancement of the distal
segment
• Aesthetic assessment of the soft
tissues of the neck is the
integral factor in planning
mandibular set back by ramus
surgery
• Recent condylar fractures
• Should be differed for 6-12
months
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ADVANTAGES
• Can be performed on OPD basis
• Inherent anatomic architecture of
the mandible poses little
interference to place the cuts
• Less chance of damaging the IAN
bundle
• Found to have curable effects in pts
with pre-op TMD
• Less incidence of condylar sag
DISADVANTSGES
• Need for MMF
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• IMF-7-10 days .elastic traction-4-5 weeks
• Rigid fixation-uncommonly used because of
• Technical difficulty
• Increased operation time
• Good results with wire fixation or IMF
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Bony interference
• Occurring between the overlapped
proximal and distal segments-
causing a backward rotation of the
of the proximal segment
• If interference is not reduced-
forward skeletal relapse upon IMF
release
• Contact between the condyle and
coronoid
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• These are designs in the vertical ramus that include
both the condyle and coronoid in the same segment
• Most commonly done via an extra- oral approach
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• Indications
• Large advancements >12mm
• Mandibular setback -10mm or more-bypasses the need for
coronoidectomy
• Secondary correction of proximal segment malrotation following
BSSO
• Simultaneous advancement and lengthening of ramus in case of severe
ramus under development.
• Less risk of condylar sag compared with VRO
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• Blair -1907-as an extra oral procedure
• Dingman –combination of extraoral and intra oral
access
• Now contemplated only as an intraoral procedure.
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Indications
• Mandibular setback
• Mandibular prognathism with ramus procedure.
• Mandibular prognathism where long body in relation to ramus
• Anterior open bite closure
• Curve of spee reduction
• Progenia correction
• In class III-anterior body osteotomy –wedge of bone
removed and set back
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Pitfalls
• Anatomic discrepancies leading to reduction in bone to bone contact
• Segment control
• Torquing of the proximal segments is the classic problem
• Root anatomy is variable
• Difficult to perform osteotomy in the premolar region when trying
to skrit the mental nerve and root of the 1st premolar
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ANTERIOR MADIBULAR SUB-
APICAL OSTEOTOMY
• Earliest referenced description of symphyseal osteotomies was by
Trauner in 1952
• Aids in correction of dentofacial deformities.
• When combined with AMO non skeletal open bite or bimaxillary
protrusion can be corrected
• Useful to level the plane of occlusion with out decreasing the
vertical facial height
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Complications
• Loss of bone or teeth in osteotomised segment.(lingual
tissues not protected-decrease in blood supply)
• Bone cuts placed close to the teeth-loss of vitality and
periodontal defects
• Mental nerve paresthesia-directly related to the amount of
trauma
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Posterior Subapical Osteotomy
• First described by- Peterson
Indications
• Correction of super eruption of posterior mandibular teeth
• Ankylosis of one or more posterior teeth
• Abnormal buccal or lingual position of these teeth especially if
orthodontics is not feasible
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Total Mandibular Subapical
Osteotomy
• Oldest procedures used to correct Jaw Deformity.
• Described by HULLIHEN in 1849.
• Popularised by Hofer and Koele.
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• Primary indication
Malocclusion caused by
Mandibular Dentoalveolar
deformity with normally
positioned Maxilla and Mandibular
skeletal bases
• Bell concluded that horizantal
osteotomy be completed 0.5cm or
more from the apices of teeth in
order to preserve pulpal
circulation. 9/19/2016 9:29:31
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• Facial features often form a basis for stereotyping of
personality charecteristics
• Chin is most prominent facial feature
• Chin deformities can manifest in 3 dimensions but
majority are in the horizontal direction
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• Horizontal sliding osteotomy-first described by
Hofer in 1942-through extra oral approach.
• Trauner and Obwegeser-1957- horizontal osteotomy
through an intra oral incision.
• Reichenbach-1965-wedge osteotomy and vertical
shortening of the chin.
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Double Sliding Horizontal
Osteotomy
• Indication- severe chin deficiency
• Surgical technique involved-
creation of a stepped
intermediate wafer between the
inferior fragment and mandible.
• Inferior fragment also advanced
to provide bony contact between
upper and lower fragments.
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Propellar Genioplasty
•
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Saggital Splilt Genioplasty
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Sagittal Split Genioplasty: A New Technique . J Oral Maxillofac Surg, 2010
Transverse Reduction Genioplasty
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Transverse Reduction Genioplasty to Reduce Width of the Chin
J Oral Maxillofac Surg, 2010
Chin Sheild Genioplasty
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Chin shield osteotomy – a new genioplasty technique avoiding a deep mento-labial
fold in order to increase the labial competence . Int. J. Oral Maxillofac. Surg, 2009
M- Shaped Genioplasty
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M- shaped genioplasty: new surgical technique for vertical and saggital
chin augmentation: 3 case reports
J Oral Maxillofac Surg, 2012
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• The major goal of orthognathic surgery is the
establishment of a balanced and stable
dentoskeletofacial complex
• Most important aspect- achieving aesthetically
pleasing facial soft tissue envelope
• Ability to predict soft and hard tissue changes before
an orthognathic surgical procedure is critical to
treatment planning
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• Change in soft tissue morphology after orthodontics
+ surgery depends upon
• Method of wound closure
• New spatial arrangement of skeletal and dental elements
• Adaptive qualities of soft tissues
• Vector of tooth movement
• Lip thickness, tonicity, lip area, competence, strength,
postop oedema, etc.
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Anterior Repositioning
• Little change in upper lip &
none above ANS
• Variable advancement in
lower lip, it often lengthens
• Lower labial sulcus & chin
adhere to bone, so advance
more than lower lip-opening
of labiomental fold
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Posterior Repositioning
• No effect on subnasale or the tissues superior to
subnasale
• Slight posterior displacement of upper lip, with
lengthening can occur
• Slight increase in nasolabial angle
• Soft tissues follow the mandible posteriorly, with
chin following most closely, followed by inferior
labial sulcus
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Autorotation
• During autorotation of mandible, the soft tissues
follow the osseous landmarks on approximately 1:1
basis
• But lower lip falls slightly lingual to arc of rotation
• Slight increase in labiomental angle
• Slight thickening of lower lip
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Soft Tissue Changes After
Genioplasty
• The soft tissue changes depend on magnitude & direction of
positional change of the genial segment, design of mucosal &
osseous incisions, amount of soft tissue stripping, & other
concomitant jaw movements
• Advantage of genial surgery is preservation of normal tissue contour
• Vertical reduction allows larger soft tissue advancement
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AM
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Anterior repositioning
• Majority of change is in soft tissue of chin; less effect is in labial sulcus &
lower lip
• Soft tissue follow hard tissue without chin droop
• Small but negligible effect on labiomental sulcus
• Increase in submental length
• Improved lower lip to tooth relationship
• Less soft tissue thinning
• Improved neck chin angle
9/19/2016 9:29:31 AM
RT/8/MANDIBULAR ORTHOGNATHIC
PROCEDURE/115
88
Posterior repositioning
• Little improvement in profile
• Soft tissue changes are little correlated with hard
tissue movements (than with advancement)
• Contraindicated in patient with minimal or no
labiomental fold
• Undesirable changes in neck chin proportion
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AM
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9/19/2016 9:29:31
AM
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• Surgical relapse to varying degree can occur after
mandibular surgery
• Complications in orthognathic surgery
• Pre-operative phase
• Intra-operative phase
• Post-operative phase
9/19/2016 9:29:31
AM
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PRE-OPERATIVE PHASE
• Limitations on surgical movement- failure to eliminate
dental compensations
• Molar root fenestrations, transverse surgical relapse-
Failure to manage transverse discrepancy
• Immpossibilility in achieving class I cusp relation,
overjet and over bite- failure to indentify and manage
tooth size discrepancies
• Root damage during osteotomies- failure to properly
level and achieve root divergence in segmental cases
• Psychological preparation of the patient
9/19/2016 9:29:31
AM
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INTRA-OPERATIVE PHASE
• Attributed to improper surgical technique and/or failure
to appreciate patient’s anatomy
• Unanticipated intra-op complications are not unheard of
• Can be categorised into
• Unfavourable osteotomy splits
• Nerve injury
• Bleeding
• Proximal segment malpositioning
• Miscellenaeous
9/19/2016 9:29:31
AM
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Sagittal Split Ramus Osteotomy
UNFAVORABLE OSTEOTOMY SPLIT
• Incidence- 18%
9/19/2016 9:29:31
AM
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Bad split
Abort the procedure
& perform after healing
Correct the split &
Complete the procedure
Proximal segment fracture
• Also called “Buccal plate fracture”
• Most frequent
• Presence of impacted 3rd molar
• Recent removal of 3rd molar
• Age of the patient
• Incomplete transection of the inferior border
• Surgeon’s experience
• # of distal segment occurred more often in young people with
impacted 3rd molars
9/19/2016 9:29:31
AM
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• Role of impacted 3rd molars in unfavorable # is
debatable
• Advocated removal 6months prior surgery
Fracture of coronoid process
• Occurs when the horizontal cut is placed too high
where the ramus is thin
• Fracture of distal segments
• Inferior border remains attached to distal segment
9/19/2016 9:29:31
AM
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NERVE INJURY
• Damage can occur at many points
• When nerve was transected- usually in 3rd molar region or
anterior to it
• Higher incidence of neurosensory disturbance with
bicortical screws than monocortical screws
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AM
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BLEEDING
• Incidence decreased from 38% in 1972 to 1% in
2005
• Most common sources
• Maxillary artery and its branches (massetric and inferior
alveolar artery)
• Retromandibular vein
• Facial artery and vein
9/19/2016 9:29:31
AM
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PROXIMAL SEGMENT MAL-POSITIONING
• Counterclockwise rotation and condylar distraction
are frequent positional changes in proximal segment
• MINOR DIFFICULTIES
• Herniation of buccal fat pad
• Difficulty in incision closure
• Breaking of bur
9/19/2016 9:29:31
AM
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Vertical Ramus Osteotomy
UNFAVOURABLE OSTEOTOMY
• Inadvertent subcondylar osteotomy
• More likely in
• Prognathic mandible with high mandibular plane angle and
ill- defined gonial angle
9/19/2016 9:29:31
AM
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NERVE INJURY
• Incidence ranges from 0%- 14%
• Less incidence when compared to SSO
• Can occur in 2 phases
• If osteotomy is close to mandibular foramen
• Medial displacement of the proximal segment compressing
and tearing the nerve
9/19/2016 9:29:31
AM
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BLEEDING
• Common source- maxillary artery and its branches
PROXIMAL SEGMENT MALPOSITIONING
• Control of proximal segment- major disadvantage
• May be displaced antero- medially, anteriorly towards
articular eminence or can be displaced medially and
inferiorly
9/19/2016 9:29:31
AM
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Sub- Apical Osteotomies
• Nerve injury
• Damage to teeth roots
• Non- vitality of teeth
• Mal-positioning of mobilised segments
• Inadequate trimming, inadequate bone removal
• Difficulty in stabilisation
9/19/2016 9:29:31
AM
RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 103
Genioplasty
UNFAVOURABLE OSTEOTOMY
• Inadvertent # of body and ramus
• Damage to teeth roots
NERVE INJURY
• Mental nerve is commonly injured
• incision, reflection and retraction, osteotomies, plating or
closure
9/19/2016 9:29:31
AM
RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 104
• BLEEDING
• Damage to lingual soft tissues
• Injury to genioglossus, geniohyoid muscles
• Laceration of sublingual and submental arteries
• Usually not life threatening
• Managed by local measures
9/19/2016 9:29:31
AM
RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 105
COMPLICATIONS
POST-OPERATIVE PHASE
EARLY POSTOP
• Excessive swelling
• Haemorrhage & Haematoma
• PONV
• Neurological dysfunction
• Mandibular dysfunction
• Hypomobility, reduction in bite
force, TMJ dysfunction
• Relapse
9/19/2016 9:29:31
AM
RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 106
Genioplasty
Neurological
dysfunction
Chin asymmetry
Uneven mentalis
muscle contraction
Chin ptosis
LATE POST-OP
• Long term neurological dysfunction
• TMJ dysfunction
• Dental and periodontal problems
9/19/2016 9:29:31
AM
RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 107
• CONDYLAR SAG
• Immediate or late caudal movement of condyle in the glenoid fossa
after surgical establishment of the preplanned occlusion and bone
fragments leading to change in the occlusion
• Types –
• Central
• Peripheral
9/19/2016 9:29:31
AM
RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 108
Central condylar sag
Bilateral
Unilateral
9/19/2016 9:29:31
AM
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9/19/2016 9:29:31
AM
RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 110
Peripheral condylar sag
Type I
Peripheral condylar sag
Type II
Bilateral Unilateral
REFERENCES
• Maxillofacial Surgery-Peter Ward Booth
• Principles Of Oral And Maxillofacial Surgery- Peterson
• Oral And Maxillofacial Surgery-Fonseca
• Essentials Of Orthognathic Surgery-Reyneke
• Chin shield osteotomy – a new genioplasty technique avoiding a deep mento-labial
fold in order to increase the labial competence Int. J. Oral Maxillofac. Surg, 2009
9/19/2016 9:29:31
AM
RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 111
• Transverse Reduction Genioplasty to Reduce Width of the Chin J Oral
Maxillofac Surg, 2010
• Sagittal Split Genioplasty: A New Technique J Oral Maxillofac Surg, 2010
• M- shaped genioplasty: new surgical technique for vertical and saggital chin
augmentation: 3 case reports J Oral Maxillofac Surg, 2012
9/19/2016 9:29:31
AM
RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 112
REFERENCES
THANK YOU
9/19/2016 9:29:31
AM
RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 113

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8. mandibular orthognathic procedures(113) Dr. RAHUL TIWARI

  • 1. Good Morning Mandibular Orthognathic Procedures Presenter- Dr. Rahul Tiwari Final Yr MDS OMFS, SIDS 9/19/2016 9:29:31 AMRT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 1
  • 2. CONTENTS • Introduction • Surgical anatomy • Revascularisation & healing of orthognathic surgical procedures • Classification • Surgical procedures • Ramus osteotomies • Body osteotomies • Symphysis osteotomies • Soft tissue changes after mandibular orthognathic procedures • Complications of mandibular orthognathic surgeries • References 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 2
  • 3. • Orthognathic in Greek Orthos- straight ; Gnathos- jaw • Orthognathic surgery refers to surgical procedures designed to correct jaw deformities • Orthognathic procedures are divided into three categories: • Maxillary surgery • Mandibular surgery • Bimaxillary procedures 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 3
  • 4. • Indications to orthognathic surgery • Impaired mastication • Temporomandibular pain • Dysfunction • Sleep apnea • Susceptibility to caries and periodontal disease • Unaesthetic appearance 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 4
  • 5. • Once growth has ceased, the combination of orthognathic surgery with orthodontics, usually becomes the only means of correcting severe dentofacial deformities • In severe malocclusion there are three possibilities for correction: • Growth modification • Orthodontic treatment • Orthognathic surgery in conjunction with orthodontics to establish proper jaw relationship 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 5
  • 6. • Orthognathic surgery was originally developed in the United States of America (Steinhäuser ). • The first mandibular osteotomy is considered to be Hullihen´s procedure in 1849 to correct anterior open bite & mandibular dento alveolar protrusion with an intraoral osteotomy. • Osteotomy of the mandibular body for the correction of mandibular horizontal excess was performed by Vilray Blair. 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 6 HISTORY
  • 7. • Berger (1897) described a condylar osteotomy for the correction of prognathism. • Limberg in 1925 first reported the subcondylar osteotomy as an extraoral technique, later it was modified to the intraoral vertical subcondylar osteotomy. • A variation of the vertical subcondylar osteotomy was suggested by wassmund in 1927,which is similar to the inverted –L- osteotomy. 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 7
  • 8. 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 8 • Hofer in 1936 demonstrated an anterior mandibular alveolar osteotomy to advance anterior teeth in correction of a mandibular dentoalveolar retrusion. • In 1954, Caldwell and Letterman developed a vertical ramus osteotomy technique, which had the advantage of minimizing trauma to the inferior alveolar neurovascular bundle.
  • 9. The greatest development in osteotomies of the vertical ramus is the sagittal split osteotomy credited to obwegeser in 1955. The major modifications in the osteotomies design were first made by Dalpont in 1961.This was further discussed by Hunsuck in 1968 in order to decrease the trauma to overlying soft tissues. Kent & Hinds in 1971 initially presented the use of single tooth osteotomies of the mandible. Macintosh closely followed with his description of the total mandibular alveolar osteotomy in 1974. 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 9
  • 10. 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 10 Aesthetics Function Stability AIMS OF MANDIBULAR OSTEOTOMIES
  • 11. • Patient’s perception of the deformity and expectations • Surgeon’s recognition of the deformity • Complete physical examination, model surgery, cephalometric analysis • Optimal treatment plan • Counseling of the patient • Informed consent 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 11 PRINCIPLES IN TREATING MANDIBULAR DEFORMITIES
  • 12. Vascular structures NervesMuscles 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 12 ANATOMICAL & PHYSIOLOGICAL CONSIDERATIONS OF MANDIBULAR OSTEOTOMIES
  • 13. 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 13 Surgical Anatomy
  • 14. Bell and Levy’s work {1970} demonstrated that blood flow through the mandibular periosteum could easily maintain a sufficient blood supply to the teeth of a mobile segment, even when the labial periosteum was degloved. subapical osteotomies need to be carefully planned to ensure as large a vascular pedicle as possible. 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 14 VASCULAR STRUCTURES
  • 15. The proximal segment of the vertical sub sigmoid osteotomy maintains its blood supply through the temporomandibular joint capsule and the attachment of the lateral pterygoid muscle. But the inferior tip of this fragment has undergone vascular necrosis in some studies. This led to the suggestion that fewer problems may occur if the cut was made above the angle of the mandible. 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 15
  • 16. We should minimize the periosteal and muscle attachment stripping on the medial surface of the proximal fragment with either the C or L osteotomy or any of their variations. The greater distance from the apices of the teeth not only minimizes direct pulpal injury but increases the vascular pedicle to the mobile segment as well. 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 16
  • 17. NERVES • In most cases in orthognathic surgery avoiding injury to marginal mandibular branch of facial nerve is achieved because soft tissue anatomy in patients undergoing the surgery has not been disturbed by disease or trauma. • The course of the inferior alveolar nerve into the vertical ramus and then through the body of the mandible makes it extremely susceptible to damage from almost every mandibular surgical procedure. • Main goal – “To minimize the trauma because its avoidance is impossible” 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 17
  • 18. MUSCLES Orthognathic surgery affects muscles in primarily two ways: • It changes the length of a muscle or it changes the direction of muscle function. • The muscles commonly discussed in orthognathic surgery of the mandible have been the muscles of mastication and the suprahyoid group of muscles . 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 18
  • 19. • A- S to lingula - 14.8 +/- 2.90 mm • C- S to mandibular foramen – 21.6 +/- 3.31 mm • B- Horizontal distance from lingual to anterior border of ramus – 17.7 +/- 2.89 mm • D- Mandibular foramen to ramus – 18.6 +/- 2.49 mm 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 19 Int. J. Oral Maxillofac. Surg, 2008
  • 20. • At a distance between 7.5 to 13.3 mm above the lingula Buccal and lingual cortex fusion occurs at a rate of • 20% in the anterior ramus • 39% in the posterior ramus 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 20
  • 21. • The position of the lingula is posterior-inferior relative to the position of the antilingula • Any osteotomies performed at a measurement of 5 mm posterior to the antilingula (at the level of the antilingula)- no risk of damaging the neurovascular bundle 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 21 Accuracy of Using the Antilingula as a Sole Determinant of Vertical Ramus Osteotomy Position . J Oral Maxillofac Surg, 2007
  • 22. Position of IAN at second molar • Bone thickness from mandibular canal to buccal plate- 7.2 +/- 1.47 mm 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 22 Int. J. Oral Maxillofac. Surg, 2008
  • 23. 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 23 Tsuji et al, Int. J. Oral Maxillofac. Surg, 2005
  • 24. • PATTERNS OF ANTERIOR LOOP OF MENTAL NERVE 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 24 J Oral Maxillofac Surg, 2007
  • 26. • Blood flow is crucial for revascularisation and healing • Blood flow will be decreased in the areas where the mucoperiosteum will be elevated 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 27
  • 27. • Immediate post-operatively • Intermedullary circulation between the proximal and distal segments • Margins of osteotomy- avascular • One week post-op • Level of hypervascularity around surgical site • No soft tissue re-attachment • Isolated areas of sub- periosteal bone formation 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 28
  • 28. • 2 weeks post-op • Avascular zone at the proximal osteotomy site • Necrotic zone at the distal osteotomy site • No soft tissue attachment at the distal necrotic zone • 3 weeks post-op • Soft tissue re-attachment • Vascular anastamoses between proximal and distal segments • Osteoid formation through out marrow formation 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 29
  • 29. • 6 weeks post-op • Circulation reconstituted across the osteotomy site • Soft tissue re- attachment established • 12 weeks post- op • Circulation between the segments is continuous 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 30
  • 30. CLASSIFICATION 9/19/2016 9:29:31 AMRT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 31 MANDUBULAR ORTHOGNATHIC PROCEDURES BODY OSTEOTOMIES SUB APICAL OSTEOTOMIES RAMUS OSTEOTOMIES HORIZONTAL OSTEOTOMY OF CHIN SAGGITAL SPLIT OSTEOTOMY VERTICAL RAMUS OSTEOTOMY INVERTED “L” & “C” OSTEOTOMY ANTERIOR SUB APICAL OSTEOTOMIES POSTERIOR SUB APICAL OSTEOTOMIES TOTAL SUB APICAL OSTEOTOMIES
  • 32. • First described in 1942 by Schuchardt in German literature • Most widely used surgical procedure for correcting mal- positioned mandible • It has been modified in many ways, but for longer than 50 years, benefits and advantages of the procedure have remained unchanged 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 33
  • 33. • Versatility of the procedure allows wide application • It increases the range of possible movements compared with orthodontic treatment alone • Broad bony overlap of the separated fragments allow not only advancement or set- backs of the distal tooth- baring mandible, but also rotations 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 34
  • 34. • A. Trauner & Obwegezer, 1957 • B. Dal pont, 1961 • C. Hunshuck, 1968 • D. Epcker, 1977 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 35
  • 35. • Bell and Schendel established the biological basis for BSSO • Minimal detachment of the pterygomassetric sling there is decreased intra- osseous ischemia, and necrosis of the proximal segment • 1976, Spiessel advocated rigid internal fixation of BSSO to promote primary healing, restore early function, and attenuate relapse 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 36
  • 36. Indications • Mandibular deficiency • Advancements beyond 10- 12 mm, extra oral approach should be considered • Mandibular prognathism • Large setbacks of more than 7 -8 mm, IVRO/ inverted L osteotomy should be considered • Mandibular asymmetry 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 37
  • 38. ADVANTAGES • Broad bony overlap of osteotomised segments • Minimal alteration of natural position of muscles of mastication • Minimal alteration in position of TMJ • Short operating time and low complication rate DISADVANTSGES • Requires additional maxillary surgery for most dentofacial deformities 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 39
  • 39. Osteosynthesis • Post- operative fixation of the osteotomised segments was once a great challenge • Initially, No fixation of the fragments Healing- intermaxillary splinting of the teeth • Introduction of wires for fixation 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 40
  • 40. • Major breakthrough- development of “stable compression osteosynthesis”- Spiessl in 1974 • The degree of immediate postoperative stability achieved with this technique completely obviated the need for intermaxillary fixation • Wide variety of methods and materials for fixation are available 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 41
  • 41. • Initially the use of three 2.7 mm “lag” screws on each side was advocated • Concern • Compression may cause increased nerve damage • Displacement of the condyles, with subsequent temporomandibular joint dysfunction 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 42
  • 42. • The position screw or bicortical screw This technique permits maintenance of the gaps between the proximal and distal fragments, with no compression of the two segments together • Osteosynthesis with miniplates • 4- holed plate with 2screws on each side of the osteotomy cut 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 43
  • 43. • Resorbable screws • Obvious advantage of resorbable fixation is to obviate the need for future hardware removal • 4 screws have to be placed on each side of the mandible 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 44
  • 45. • 1st described by Caldwell and Letterman in 1954- extra oral • Introduced by Moose in 1964- intra- oral technique performed from lingual aspect • Wistanley, 1968- performing the technique from the lateral aspect of the mandible 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 46
  • 46. Comparison between SSRO and VRO SSRO VRO OSTEOTOMY PA Saggital split Latero medial cut Open procedure Blind procedure Along IAN Rear to IAN Frequent exposure of IAN No exposure of IAN BONE HEALING Contact on marrow to marrow Contact on cortex to cortex BONE FIXATION Rigid internal fixation No fixation CONDYLAR HEAD Original position New equilibrated position POST OP IMF None or shorter period Required PROGNOSIS Weakely dependent on PT Strongly dependent on PT 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 47
  • 47. Indications • Horizontal mandibular excess • Mandibular asymmetry • Minor occlusal discrepancy after isolated Le Fort I osteotomy • Asymmetric lateral open bite • Failure to achieve passive rotation of the mandible after the release of MMF • Patients with significant TMJ complaints Contraindications • Advancement of the distal segment • Aesthetic assessment of the soft tissues of the neck is the integral factor in planning mandibular set back by ramus surgery • Recent condylar fractures • Should be differed for 6-12 months 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 48
  • 48. ADVANTAGES • Can be performed on OPD basis • Inherent anatomic architecture of the mandible poses little interference to place the cuts • Less chance of damaging the IAN bundle • Found to have curable effects in pts with pre-op TMD • Less incidence of condylar sag DISADVANTSGES • Need for MMF 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 49
  • 50. • IMF-7-10 days .elastic traction-4-5 weeks • Rigid fixation-uncommonly used because of • Technical difficulty • Increased operation time • Good results with wire fixation or IMF 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 51
  • 51. Bony interference • Occurring between the overlapped proximal and distal segments- causing a backward rotation of the of the proximal segment • If interference is not reduced- forward skeletal relapse upon IMF release • Contact between the condyle and coronoid 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 52
  • 53. • These are designs in the vertical ramus that include both the condyle and coronoid in the same segment • Most commonly done via an extra- oral approach 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 54
  • 54. • Indications • Large advancements >12mm • Mandibular setback -10mm or more-bypasses the need for coronoidectomy • Secondary correction of proximal segment malrotation following BSSO • Simultaneous advancement and lengthening of ramus in case of severe ramus under development. • Less risk of condylar sag compared with VRO 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 55
  • 57. • Blair -1907-as an extra oral procedure • Dingman –combination of extraoral and intra oral access • Now contemplated only as an intraoral procedure. 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 58
  • 58. Indications • Mandibular setback • Mandibular prognathism with ramus procedure. • Mandibular prognathism where long body in relation to ramus • Anterior open bite closure • Curve of spee reduction • Progenia correction • In class III-anterior body osteotomy –wedge of bone removed and set back 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 59
  • 59. Pitfalls • Anatomic discrepancies leading to reduction in bone to bone contact • Segment control • Torquing of the proximal segments is the classic problem • Root anatomy is variable • Difficult to perform osteotomy in the premolar region when trying to skrit the mental nerve and root of the 1st premolar 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 60
  • 61. ANTERIOR MADIBULAR SUB- APICAL OSTEOTOMY • Earliest referenced description of symphyseal osteotomies was by Trauner in 1952 • Aids in correction of dentofacial deformities. • When combined with AMO non skeletal open bite or bimaxillary protrusion can be corrected • Useful to level the plane of occlusion with out decreasing the vertical facial height 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 62
  • 63. Complications • Loss of bone or teeth in osteotomised segment.(lingual tissues not protected-decrease in blood supply) • Bone cuts placed close to the teeth-loss of vitality and periodontal defects • Mental nerve paresthesia-directly related to the amount of trauma 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 64
  • 64. Posterior Subapical Osteotomy • First described by- Peterson Indications • Correction of super eruption of posterior mandibular teeth • Ankylosis of one or more posterior teeth • Abnormal buccal or lingual position of these teeth especially if orthodontics is not feasible 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 65
  • 65. Total Mandibular Subapical Osteotomy • Oldest procedures used to correct Jaw Deformity. • Described by HULLIHEN in 1849. • Popularised by Hofer and Koele. 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 66
  • 66. • Primary indication Malocclusion caused by Mandibular Dentoalveolar deformity with normally positioned Maxilla and Mandibular skeletal bases • Bell concluded that horizantal osteotomy be completed 0.5cm or more from the apices of teeth in order to preserve pulpal circulation. 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 67
  • 68. • Facial features often form a basis for stereotyping of personality charecteristics • Chin is most prominent facial feature • Chin deformities can manifest in 3 dimensions but majority are in the horizontal direction 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 69
  • 69. • Horizontal sliding osteotomy-first described by Hofer in 1942-through extra oral approach. • Trauner and Obwegeser-1957- horizontal osteotomy through an intra oral incision. • Reichenbach-1965-wedge osteotomy and vertical shortening of the chin. 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 70
  • 73. Double Sliding Horizontal Osteotomy • Indication- severe chin deficiency • Surgical technique involved- creation of a stepped intermediate wafer between the inferior fragment and mandible. • Inferior fragment also advanced to provide bony contact between upper and lower fragments. 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 75
  • 75. Saggital Splilt Genioplasty 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 77 Sagittal Split Genioplasty: A New Technique . J Oral Maxillofac Surg, 2010
  • 76. Transverse Reduction Genioplasty 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 78 Transverse Reduction Genioplasty to Reduce Width of the Chin J Oral Maxillofac Surg, 2010
  • 77. Chin Sheild Genioplasty 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 79 Chin shield osteotomy – a new genioplasty technique avoiding a deep mento-labial fold in order to increase the labial competence . Int. J. Oral Maxillofac. Surg, 2009
  • 78. M- Shaped Genioplasty 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 80 M- shaped genioplasty: new surgical technique for vertical and saggital chin augmentation: 3 case reports J Oral Maxillofac Surg, 2012
  • 80. • The major goal of orthognathic surgery is the establishment of a balanced and stable dentoskeletofacial complex • Most important aspect- achieving aesthetically pleasing facial soft tissue envelope • Ability to predict soft and hard tissue changes before an orthognathic surgical procedure is critical to treatment planning 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 82
  • 81. • Change in soft tissue morphology after orthodontics + surgery depends upon • Method of wound closure • New spatial arrangement of skeletal and dental elements • Adaptive qualities of soft tissues • Vector of tooth movement • Lip thickness, tonicity, lip area, competence, strength, postop oedema, etc. 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 83
  • 82. Anterior Repositioning • Little change in upper lip & none above ANS • Variable advancement in lower lip, it often lengthens • Lower labial sulcus & chin adhere to bone, so advance more than lower lip-opening of labiomental fold 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 84
  • 83. Posterior Repositioning • No effect on subnasale or the tissues superior to subnasale • Slight posterior displacement of upper lip, with lengthening can occur • Slight increase in nasolabial angle • Soft tissues follow the mandible posteriorly, with chin following most closely, followed by inferior labial sulcus 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 85
  • 84. Autorotation • During autorotation of mandible, the soft tissues follow the osseous landmarks on approximately 1:1 basis • But lower lip falls slightly lingual to arc of rotation • Slight increase in labiomental angle • Slight thickening of lower lip 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 86
  • 85. Soft Tissue Changes After Genioplasty • The soft tissue changes depend on magnitude & direction of positional change of the genial segment, design of mucosal & osseous incisions, amount of soft tissue stripping, & other concomitant jaw movements • Advantage of genial surgery is preservation of normal tissue contour • Vertical reduction allows larger soft tissue advancement 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 87
  • 86. Anterior repositioning • Majority of change is in soft tissue of chin; less effect is in labial sulcus & lower lip • Soft tissue follow hard tissue without chin droop • Small but negligible effect on labiomental sulcus • Increase in submental length • Improved lower lip to tooth relationship • Less soft tissue thinning • Improved neck chin angle 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 88
  • 87. Posterior repositioning • Little improvement in profile • Soft tissue changes are little correlated with hard tissue movements (than with advancement) • Contraindicated in patient with minimal or no labiomental fold • Undesirable changes in neck chin proportion 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 89
  • 89. • Surgical relapse to varying degree can occur after mandibular surgery • Complications in orthognathic surgery • Pre-operative phase • Intra-operative phase • Post-operative phase 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 91
  • 90. PRE-OPERATIVE PHASE • Limitations on surgical movement- failure to eliminate dental compensations • Molar root fenestrations, transverse surgical relapse- Failure to manage transverse discrepancy • Immpossibilility in achieving class I cusp relation, overjet and over bite- failure to indentify and manage tooth size discrepancies • Root damage during osteotomies- failure to properly level and achieve root divergence in segmental cases • Psychological preparation of the patient 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 92
  • 91. INTRA-OPERATIVE PHASE • Attributed to improper surgical technique and/or failure to appreciate patient’s anatomy • Unanticipated intra-op complications are not unheard of • Can be categorised into • Unfavourable osteotomy splits • Nerve injury • Bleeding • Proximal segment malpositioning • Miscellenaeous 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 93
  • 92. Sagittal Split Ramus Osteotomy UNFAVORABLE OSTEOTOMY SPLIT • Incidence- 18% 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 94 Bad split Abort the procedure & perform after healing Correct the split & Complete the procedure
  • 93. Proximal segment fracture • Also called “Buccal plate fracture” • Most frequent • Presence of impacted 3rd molar • Recent removal of 3rd molar • Age of the patient • Incomplete transection of the inferior border • Surgeon’s experience • # of distal segment occurred more often in young people with impacted 3rd molars 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 95
  • 94. • Role of impacted 3rd molars in unfavorable # is debatable • Advocated removal 6months prior surgery Fracture of coronoid process • Occurs when the horizontal cut is placed too high where the ramus is thin • Fracture of distal segments • Inferior border remains attached to distal segment 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 96
  • 95. NERVE INJURY • Damage can occur at many points • When nerve was transected- usually in 3rd molar region or anterior to it • Higher incidence of neurosensory disturbance with bicortical screws than monocortical screws 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 97
  • 96. BLEEDING • Incidence decreased from 38% in 1972 to 1% in 2005 • Most common sources • Maxillary artery and its branches (massetric and inferior alveolar artery) • Retromandibular vein • Facial artery and vein 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 98
  • 97. PROXIMAL SEGMENT MAL-POSITIONING • Counterclockwise rotation and condylar distraction are frequent positional changes in proximal segment • MINOR DIFFICULTIES • Herniation of buccal fat pad • Difficulty in incision closure • Breaking of bur 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 99
  • 98. Vertical Ramus Osteotomy UNFAVOURABLE OSTEOTOMY • Inadvertent subcondylar osteotomy • More likely in • Prognathic mandible with high mandibular plane angle and ill- defined gonial angle 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 100
  • 99. NERVE INJURY • Incidence ranges from 0%- 14% • Less incidence when compared to SSO • Can occur in 2 phases • If osteotomy is close to mandibular foramen • Medial displacement of the proximal segment compressing and tearing the nerve 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 101
  • 100. BLEEDING • Common source- maxillary artery and its branches PROXIMAL SEGMENT MALPOSITIONING • Control of proximal segment- major disadvantage • May be displaced antero- medially, anteriorly towards articular eminence or can be displaced medially and inferiorly 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 102
  • 101. Sub- Apical Osteotomies • Nerve injury • Damage to teeth roots • Non- vitality of teeth • Mal-positioning of mobilised segments • Inadequate trimming, inadequate bone removal • Difficulty in stabilisation 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 103
  • 102. Genioplasty UNFAVOURABLE OSTEOTOMY • Inadvertent # of body and ramus • Damage to teeth roots NERVE INJURY • Mental nerve is commonly injured • incision, reflection and retraction, osteotomies, plating or closure 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 104
  • 103. • BLEEDING • Damage to lingual soft tissues • Injury to genioglossus, geniohyoid muscles • Laceration of sublingual and submental arteries • Usually not life threatening • Managed by local measures 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 105 COMPLICATIONS
  • 104. POST-OPERATIVE PHASE EARLY POSTOP • Excessive swelling • Haemorrhage & Haematoma • PONV • Neurological dysfunction • Mandibular dysfunction • Hypomobility, reduction in bite force, TMJ dysfunction • Relapse 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 106 Genioplasty Neurological dysfunction Chin asymmetry Uneven mentalis muscle contraction Chin ptosis
  • 105. LATE POST-OP • Long term neurological dysfunction • TMJ dysfunction • Dental and periodontal problems 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 107
  • 106. • CONDYLAR SAG • Immediate or late caudal movement of condyle in the glenoid fossa after surgical establishment of the preplanned occlusion and bone fragments leading to change in the occlusion • Types – • Central • Peripheral 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 108
  • 107. Central condylar sag Bilateral Unilateral 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 109
  • 108. 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 110 Peripheral condylar sag Type I Peripheral condylar sag Type II Bilateral Unilateral
  • 109. REFERENCES • Maxillofacial Surgery-Peter Ward Booth • Principles Of Oral And Maxillofacial Surgery- Peterson • Oral And Maxillofacial Surgery-Fonseca • Essentials Of Orthognathic Surgery-Reyneke • Chin shield osteotomy – a new genioplasty technique avoiding a deep mento-labial fold in order to increase the labial competence Int. J. Oral Maxillofac. Surg, 2009 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 111
  • 110. • Transverse Reduction Genioplasty to Reduce Width of the Chin J Oral Maxillofac Surg, 2010 • Sagittal Split Genioplasty: A New Technique J Oral Maxillofac Surg, 2010 • M- shaped genioplasty: new surgical technique for vertical and saggital chin augmentation: 3 case reports J Oral Maxillofac Surg, 2012 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 112 REFERENCES
  • 111. THANK YOU 9/19/2016 9:29:31 AM RT/8/MANDIBULAR ORTHOGNATHIC PROCEDURE/115 113

Editor's Notes

  1. The medial horizontal osteotomy. The red line indicates horizontal osteotomy red dash indicates the split The IAN bundle is in yellow to show the entrance of the nerve blue dot marks the position of antilingula Fig. 5. The medial horizontal osteotomy. S. Lowest point of sigmoid notch. Vertical distance from S to antilingula. C. Vertical distance from S to entrance of IAN. B. Horizontal distance from antilingula to anterior border of ramus. D. Horizontal distance from entrance of IAN to anterior border of ramus.
  2. They recommend that the medial horizontal cut be at or just above the tip of the lingula because a higher cut may be associated with an increased difficulty in splitting or incidence of unfavorable fracture.
  3. Classification of the position of the mandibular canal within the bone. (a) Separate type, bone marrow space evident; (b) contact type, outer surface of the canal and inner surface of buccal cortical bone in contact; and (c) fusion type, outer cortical plate of the canal not evident.
  4. Type I: MN divided into A, inferior labial (IL), and M branches, with the IL branch dividing into ILm and ILl branches Type II: MN divided into A, ILm, and M branches, with the ILl branch separating from the A branch. Type III: MN divided into A, ILl, and M branches, with the ILm branch separating from the M branch. Type IV: MN divided into A and M branches, with the ILl and ILm branches separating from the A and M branches, respectively. Type V: MN divided into A and M branches, with the IL branch separating from the A branch and then dividing into the ILm and ILl branches
  5. Schuchardt is generally given credit for the use of an intraoral approach to what some call the “step” osteotomy of the vertical ramus. Specifically he described parallel horizontal cuts through the cortex of the vertical ramus, the medial cut being placed above the lingula and a lateral cut being made about 1 cm below that. Medial cut extended from the anterior border of ramus till the posterior border of ascending ramus Obwegeser- medial horizontal cut above the lingula, extending till the posterior border of the mandible, but the lateral horizontal cut was lower than Schuchardt’s and extended to a point just above the angle, at least 25 mm below the lingual cortical cut Dal pont- 1961 medial horizontal cut is same as in obwegeser. The change commonly attributed to DalPont is the vertical cut through the lateral cortex behind the second molar. Hunshuck- 1968 variation of the lingual cut (original cut ends at the posterior border of the ascending ramus), according to the modification cut ends immediately behind the entrance of the neurovascular bundle, so that the split on the medial aspect occurs in the mylohyoid groove rather than the posterior border of the mandible Epcker – 1977 1. minimal stripping of masseter muscle 2. limited medial dissection these modifications decrease the post-operative swelling, haemorrhage, manipulation of the neurovascular bundle
  6. Advancements beyond 10- 12 mm, extra oral approach should be considered- since the overlap between the segments is less MANDIBULAR DEFICIENCY Increased A/B difference Class II canine and molar relationship Increased overjet Excessive curve of spee in mandible Incisor crowding Deep labiomental fold MANDIBULAR PROGNATHISM- Hapsburg jaw/ Hapsburg lip/ Austrian lip Mandible more protruded compared to maxilla Prominent lower third of face Obtuse gonial angle Anterior cross bite Posterior open bite Concave or straight profile Decreased labiomental fold
  7. Landmarks for intra oral incision-anterior border of ramus and external oblique ridge Incision made through the mucosa starting superiorly ,2/3rds up the anterior border of ramus ,inferiorly lateral to external oblique ridge to the area of second molar Periosteum elevated exposing external oblique ridge. Sub periosteal dissection over the buccal and lingual sides of the anterior ramus. Strip lower fibres of temporalis from anterior border and coronoid Medial sub peiosteal dissection done and lingula identified Medial ramus osteotomy-parallel to occlusal plane, midpoint between the sigmoid notch and the neurovascular bundle the correct location of the of the cut at the anterior border of the ascending ramus is the place where horizontal ramus bends into a vertical line Osteotomy cut terminated posterior to lingula-through lingual cortex into medullary bone. Vertical osteotomy cut-starting superiorly from the medial cut staying in the buccal cortex of ramus and end inferiorly mesial to the second molar. Buccal osteotomy- started at lower border and joined superiorly with the vertical part of ramus osteotomy. The blade should be angled at 60- 45 degrees to protect the inferior neurovascular bundle Cortices should be gently seperated looking for neurovasvular bundle. If the neurovascular bundle is in proximal segment it should be lifted out. Mandible is moved into the desired position, guided into occlusion using occlusal splints, imf is done and the osteotomised segments are fixed in the desired position
  8. Osteosynthesis- is defined as surgical fastening of two separated bone fragments
  9. Position screw or the bicortical screw is same as the lag screw, except that it has screw threads on proximal and distal aspect of the screw, hence on engaging into the bone it does not cause compression of the buccal and lingual cortical plates
  10. Caldwell and letterman- performed the procedure as an extra-oral procedure
  11. Horizontal mandibular excess- good profile, arch and dental relationship can be obtained by retruding intact mandible can also be done with BSSO but this method is faster, safer and less incidence of IAN damage Mandibular asymmetry- VRO is indicated on the side which requires movement in posterior direction, if the distal segment needs to advanced then it should be done with BSSO Aesthetic assessment of the soft tissues of the neck is the integral factor in planning mandibular set back by ramus surgery- Mandibular set back creats, a rounding effect on the cervicomental soft tissues and neck may appear to be broader Alternatively- Isolated maxillary advancement Combination of max. advancement with mand. Setback Recent condylar fractures- inferior half of the ramus contains marrow between the cortices and the upper half from the anti-lingula to the sigmoid notch is mainly cortical, and the cortical bone takes several months to progress to structural integrity
  12. Less incidence of condylar sag- since post-op rigid fixation is not done in most of the cases
  13. The surface shown in this picture is of the buccal side Procedure Straight line incision over bone–level of mandibular occlusal plane medial to external oblique ridge Incision carried forward 2-3 mm inferior and parallel to mucobuccal junction Blunt dissection of soft tissues over ascending ramus –sigmoid notch Periosteum reflected from lateral ramus Inferior border stripped anterior to ante gonial notch. Antilingular eminence marked. Downward vertical guide line –antilingular eminence to antegonial notch.(parallel to posterior boder) Bicortical - Initial osteotomy cut Second osteotomy cut-upper end of lower oseotomy and oblique to sigmoid notch. Same procedure performed on other side. Proximal surface seperated from the distal segment. Setback of 4mm or less-inferior cut carried parallel and about 9-10 mm anterior to posterior border. >5mm-inferior cut-angled progressively anterior-broden base of proximal segment. (maintain sufficient residual width of attachment of masseter and medial pterygoid muscle and tendon to prevent condylar sag
  14. Combined effect of medial pterygoid muscle and masseter provides adequate support and control of proximal segment. Elastic tracton to guide occlusion-4-5 weeks
  15. Pic- pg 127, fonseca Occurring between the overlapped proximal and distal segments- causing a backward rotation of the of the proximal segment This contact occurs in the distal segment between the mid ramus and the sigmoid notch Interference reduced by-
  16. Temp and pterygoid remain attached to condylar segment The basic techniques for C & L are same, with only modification being inferior horizontal cut in the C osteotomy Forms of C osteotomy Pg 1149- petersoon
  17. TRAUNER and OBWEGESER in 1957 Blend of VRO and BSSRO Medial exposure and dissection are done as for SSRO Nerve identified as it enters mandibular foramen medially. Bicortical horizontal osteotomy cut –superior to the foramen Exposure of lateral ramus and completion of inferior vertical osteotomy same as VRO Rigid fixation is performed with patients in MMF Suction drains to be placed MMF -5 to 14 days after surgery Elastic traction -guide the occlusion and resist soft tissue relapse -4-5 weeks
  18. With preservation of inf dental bundle and bone grafting to assist bony union.
  19. gross
  20. Anatomic discrepencies leading to reduction in bone to bone contact- resection in this region leads to reduction in bone contact as distal segment is set into wider proximal segment
  21. rarely used…. blood supply to this area comes through muscle attachments on the lingual. Roots of the teeth should be at least paralleld if not divergentdin the osteotomy/ostectomy sites…….provided that lower vertical height is increased. if in normal limits-mandibular body osteotomy-level plane of occlusion and not dec vertical facial height
  22. Extraction of premolars to obtain space for posterior movements Incision-in lower lip approx 15 mm from vestibule- premolar to premolar. Anterior mandible degloved upto inferior border Vertical bone cuts-passing through premolars Inferior horizontal cut must be made perpendicular to bone connecting vertical cuts at inferior extent. Segment mobilized by gentle prying at osteotomy sites. Preformed surgical splint should be used to guide the segment in its predetermined position. Segment secured by transosseous wires /semirigid fixation
  23. Incision extending from canine to canine. Incision given to the mucosa- mentalis muscle divided on a bevel inferiorly towards bone and periosteal incision given Horizontal osteotomy with anterio- posterior reduction- necessary to reduce the proximal tips of the mobilised fragments to ensure smooth transition along the inferior border and avoid palpable wings
  24. Pg 409- fonseca U shaped mono-cortical osteotomy created centrally on the symphysis, with lateral extensions developed below the mental nerves connecting the tenon corticotomy superiorly Full-hickness osteotomies are completed only on the lateral extensions and only through the lingual cortex on the superior aspect of the tenon The resultant full thickness of the tenon facilitates the mortisising of the tenon and lag screw fixation When the posterior movement is desired the u is inverted and the osteotomy completed
  25. Large cants in chin First osteotomy-superior osteotomy-parallel to occlusal plane Second osteotomy-parallel to lower border of chin Traingular segment rotated 180°while muscle attachment maintained
  26. The osteotomy is begun below and slightly posterior to the mental foramen on either the right or the left side of the mandible. The reciprocating saw blade is used and is oriented almost vertically and in the sagittal plane The cut starts approximately 6 mm below the mental foramen and exits at the inferior border. The saw is carried forward in this plane until the area mesial to the cuspid tooth is reached. At this point the saw blade is rotated into a horizontal position as the remainder of the cut is completed in the usual manner as shown. This results in a sagittal split of the lateral one third to two thirds of the inferior chin segment
  27. Horizontal osteotomy was performed 5 mm below the mental foramina to avoid injury to the inferior alveolar nerve Two vertical osteotomies were performed according to the previously marked lines, and the mobilized central segment was removed Distal segments were positioned medially and fixed together and were then fixed to the upper bone segment by miniplates and screws
  28. (bunching of tissues, which stretch more when advanced)
  29. soft tissue stripping give more predictable hard & soft tissue response because of less bone resorption of advancedsegment
  30. Decision must be made on a case- by- case analysis
  31. Incomplete transection of the inferior border – thin buccal plate is the area of least resistance and can be # by the force used to split the mandible
  32. Fracture of distal segments- occurs when the 3rd molars are present and in edentulous cases where the bone is weakend in these areas
  33. Damage can occur at many points- it can be stretched, avulsed, transected
  34. Facial artery in the antegonial notch- this is the vicinity vor the vertical cut in SSO
  35. Difficulty in incision closure- if it is placed too high and on attached gingiva Breaking of bur- common while giving horizontal osteotomies, due to excessive torquing
  36. Bauer retractors- placed in sigmoid notch lavasseur Merril retractors- along the posterior border of the mandible Inadvertent subcondylar osteotomy-
  37. Maxillary artery close to the sigmoid notch and deep to the ramus If displaced Antero- medially- IAN bundle may be torn when it enters lingula Posteriorly- difficult to set back properly
  38. Nerve injry-
  39. Inadvertent # of body and ramus- incomplete osteotomy of the symphysis and the use of exccessive force and torque in an attempt to down fracture
  40. These result in
  41. Central condylar sag-. The condyle is positioned inferiorly in the glenoid fossa with no contact with bone, while the teeth are in occlusion and rigid fixation is placed (A). After removal of IMF the condyle moves superiorly leading to immediate relapse (B). Central condylar sag Bilateral condylar sag Dental midlines correct Overjet increased Anterior open bite Class II malocclusion Unilateral condylar sag Mandibular dental midline towards offending side Overjet increased Class II dental relationship on the offending side Overjet corrected and the correct occlusion reestablished if mandible is moved until midlines coincide
  42. Peripheral condylar sag- Type I- condyle positioned inferiorly with some fossa contact with MMF in position and rigid fixation Provides physical support to occlusion Post operative resorption or change in condylar shape will lead to late relapse. Difficult to diagnose intra-operatively Type II- condyle positioned correctly in the fossa with MMF in position. with the placement of rigid fixation-torquing force is applied to condyle and ramus of mandible. Tension on ramus released when MMF removed-condyle will move either laterally or medially and slide inferiorly Clinical features Type II-Bilateral peripheral condylar sag Dental midlines correct Ant cross bite or edge to edge incisor relationship Bilateral posterior open bites Unilateral peripheral condylar sag Dental midline of mandible towards contraletaral side Edge to edge incisor relationship with tendency to cross bite on the offending side Posterior open bite on offending site with teeth in occlusion