Mandibular reconstruction / oral surgery courses

MANDIBULAR
RECONSTRUCTION

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INDIAN DENTAL ACADEMY
Leader in continuing dental education



Importance of the mandible
Plays a central role for the complex functions of the oral cavity
Muscles of the floor of the mouth and the tongue
are inserted to the mandible

Provides an essential skeletal counterpart for
Chewing
Deglutition
Speech

Prevents collapse of the upper airway
by anterior fixation of the hyoid bone and the hypopharynx.

Supports the tongue

Forms the contour of the lower third of the face

Mandibular continuity is thus indispensable for
oral functions and requires reconstruction

HCL Classification
According reconstructive difficulty

H

Lateral defects which include the condyle but do not cross the midline

L

Are basically H defects with the condyle excluded

C


C

Consist of the central component of the mandible
including the four incisors and two canine teeth.

For example, Angle to Angle defect would be described as

LCL

Inadequate repair leads to
Jaw deviation

Soft tissue attachments to the mandible are affected

Oral incompetence & difficulty with
speech , mastication and swallowing fluids

Malocclusion and problem with propioception


Reconstruction

Refers to the rebuilding of original form and function that have
been lost owing to maxillofacial trauma, disease or treatment of that
disease.


The Goals of Reconstruction
Restablishment of mandibular continuity
Restablishment of an osseous-alveolar base
Osseous bulk for full prosthetic rehabilitation
Capable of withstanding the functional demands
Graft must be able to maintain a correct arch form and continuity
Reconstruction should be dimensionally and structurally stable
Acceptable facial form

Mandibular defects can be restored by four basic methods

Alloplastic material
Alloplastic with bone
Non vascularised bone graft
Vascularised bone graft

Distraction osteogenesis

Why is bone used for the replacement of native tissues

?

It has a natural matrix similar to the material it is replacing.

Is strong by nature so that it can support masticatory forces.

When bone is a transplant, no immunosuppression is required.


Autograft
Bone taken from the same individual.

Allograft
Bone taken from another individual of the same species.

Xenograft
Bone from another species.


K – Wire Fixation

With the help of hand drilling instrument hole is made in the segment
Wire is threaded at the ends
If inferior dental canal is present wire is threaded into the canal


Disadvantages
Not a rigid fixation

Can be used as only temporary fixation

Gross facial discrepancy


Mandibular Reconstruction Plate

Mandibular reconstruction plates constructed with
Stainless Steel (AO plates)
Vitallium
Titanium.


Reconstruction plates are usually shaped before
the mandibular resection.
Screws are drilled into the proximal and distal mandible segments.


Advantages
Can be used as a temporary spacer to span the missing segment.

Can be an alternative until a reconstructive procedure is performed.
Used as permanent fixation in patients who are in poor health or
medically compromised.
Reliable reconstruction with no donor site morbidity
and excellent facial contour.
Ability to reconstruct the condyle.

Complications
Plate exposure
Loosening of screws
Plate fracture


Alveolar defect with Alloplastic material
Organic Materials
calcium aluminate
calcium apatite
calcium sulfate
Hydroxyapatite

Synthetic Materials
methylmethacrylate
teflon

Graft act as a supportive matrix or link between native bones.

At the interface of the native bone and the transplanted graft, native
osteoblast cells begin to infiltrate and revascularize the porous matrix.

Osteoblasts deposit new bone & graft is converted into osteum

Osteoconduction

Alloplastic Material with
Non vascularized Autogenous Bone Graft
Used for reconstruction of small to medium size mandibular defects
Rib
iIium
Tibia
Fibula
Scapula


iliac bone graft
Cortical bone
Cancellous bone
Corticocancellous bone


Cancellous bone grafts consisting of medullary bone
contain the highest percentage of viable osteoblasts.

Cortical grafts consisting of lamellar bone struts
contain large numbers of osteoclasts.
The combination of particulate cortical bone and cancellous marrow
.
provides the best potential for osteogenesis.

The particulate nature of the graft allows rapid revascularization.

Cortical bone provide structural support

Procedure
With no 15 blade skin incision is made
Extended to subcutaneous tissues

Electrocautery is used to gain haemostatic control

Incision is then oriented towards the crest of the iliac bone
Subperiosteal dissection in the medial direction is preferred
Elevation of the iliac muscle in the medial aspect allows to
take adequate bone chuck

Lateral Cutaneous branch of illiohypogastric nerve
Lateral Cutaneous branch of subcostal nerve

Rib Graft
Ribs on each side of the thorax protects intrathoraxic contents
including lungs and heart.
We use 4th and 5th and rib for reconstruction
because of good costochondral junction

Ribs have a pronounced curve from posterior to anterior

Ribs allow curve in two dimensions


180 degrees

A 5cm long incision is made in the submammary crease starting 4cm
from the mid line

Incision is carried out in layers
Skin

Subcutaneous fat

Muscles of the anterior chest wall


Once subperiosteal plane is attained

Small raspatory such as Howarth or a larger rougine such as Farabeuf is
used to elevate the periosteum

Elevator may perforate the pleural cavity

Tuduor Edward`s rib shears are introduced and slide along the rib


Alternative to it we can use gauze piece and slide

Neurovascular intercostal bundles run in a groove along the lower
surface of the rib , so it is protected

Rib can provide
Cartilage alone

used as secondary growth center

Combination of cartilage and bone
Bone alone


Storage Media
Most ideal storage medium is tissue culture media
isotonic
balanced
pH 7.42
contain essential organic and inorganic cell nutrients

Next best is the saline

Loss of growth factor due to soaking

Bone graft can be preserved in blood or blood soaked sponge
Temp should be 4 degree C

Alloplastic tray
Polyester coated polyurethane is radiolucent and flexible

Tray made up of stainless steel is also used
Titanium mesh
Dacron
Vitallium


CAD CAM


Alloplastic crib adapted to the defect & contoured to overlap the host
bone ends on each ends

Surgeon must ensure that all pores remain open

Capillary ingrowth

Crib fixation is best if one use at least three screws on each
host bone segments


The mesh is packed with autologous particulate cancellous marrowbone

Platelet rich plasma
Contain platelet derived growth factor
Transforming growth factors
Insulin growth factors


BMP
Protein complex responsible for osteoinduction
BMP is more present in the cortical bone

Recombinant technology have now made purified BMP readily
available as a commercial product


Healing of the Bone Graft
Three ways in which a bone graft can help to repair a defect.

Osteogenesis
Formation of new bone by cells contained with in the graft

Osteoinduction
Molecules contained within the graft convert patients cells which
are capable of forming bone

Osteoconduction
Matrix upon which new bone can be formed

Healing After Grafting

Graft

Bed in which it lies
Host


Type of joints
Butt Joint

Graft is placed end to end without any overlap

Mortoise Joint
Cortex of the inner aspect of the graft and cortex of the outer
aspect of the mandible exposed and joint together


Distraction Osteogenesis
Distraction osteogenesis is a method utilizing body’s own healing
mechanism to generate new bone
Introduced by ILIZAROV in 1951

“Distraction Osteogenesis is a biologic process of new bone
formation between the surfaces of bone segments that are gradually
separated by incremental traction.”

Distraction forces applied to bone also create tension in
the surrounding soft tissue, initiating a sequence of adaptive changes termed
as DISTRACTION HISTOGENESIS.

Transport Distraction Osteogenesis
Technique of regenerating bone & soft tissue in a discontinuity
defect
An osteotomy is made 1.5cm from the end of the distal stump
of bone
adjacent to the discontinuity defect creating a
transport disc.


Using a distraction device,the transport disc is advanced thro’ the soft tissue
discontinuity defect creating new bone within the distraction gap


Latency period
From bone division to the on set of traction . This is the time to
form reparative callus. Usually 3 -5 Days

Distraction Period
Time period from application of traction forces to the
cessation of traction forces
Consolidation Period
Time period between the cessation of traction forces and removal
of distraction device. This is the time required for complete
mineralisation. Usually 8 -12 weeks

Rate

Usually 1mm/ day is optimal
<0.5mm/day
>2mm/day

Premature Ossification
Fibrous ossification


Advantages of distraction osteogenesis
No need of autogenous bone grafting
Formation of not only the hard tissues but also of the soft tissues
Multi-directional expansion of the skeleton
Minimal evidence of relapse
The neurovascular elements contained within the distracted bony
segment .
are also stimulated and
regenerated.

Limitation
Osseous continuity should be there

Vascularised Autogenous Bone Grafts
Development of microvascular surgery and free tissue transfer has
revolutionized the reconstruction of head and neck

Uses microscope with high quality and good optics and a strong light source

200-mm lens is optimal for working

Microsurgical instruments are used


Key factor in microvascular surgery is establish high rate of blood flow
.
into and out of
the graft
To accomplish the goal large blood vessels selected
External Carotid artery
Internal Jugular Vein
No 8.0 or 9.0 sutures are used


•
•
•
•

Radial forearm flap
Fibula
Scapula
Rib


Fibula
Fibula is the longest transplantable bone segment found in humans
26cm/40cm
Cranial 8cm left to preserve peroneal nerve
Distal 8cm left to preserve angle joint

Not a weight bearing bone


The peroneal artery and its vein course the inner aspect of the fibula
bone in the deep posterior compartment
The artery provides vessels nourishing the bone and supporting
its blood flow.

In reconstruction of the mandible, multiple osteotomies of the fibula
are often necessary to reconstruct the ramus& body.


Thank you
Leader in continuing dental education


Mandibular reconstruction / oral surgery courses

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