Mandible is embryologically a membrane bent bone although, resembles
physically long bone it has two articular cartilages with two nutrient arteries.
Mandible in trauma
Mandibular
fracture is more common than middle third fracture (anatomical factor)
It could be
observed either alone or in combination with other facial fractures
Minor mandibular fracture may
be associated with head injury owing to the cranio-mandibular articulation
Mandibular
fracture may compromise the patency of the airway in particular with loss of
consciousness
Fracture of
mandible occurred with frontal impact force as low as 425 lb (190 Kg) {Condylar
fracture}
Fracture of
condyle regarded as a safety mechanism to the patient
Frontal
force of 800-900 lb (350-400 Kg) is required to cause symphesial fracture
Mandible
was more sensitive to lateral impact than frontal one
Frontal
impact is substantially cushioned by opening and retrusion of the jaw
(Nahum
1975)
Long canine
tooth and partially erupted wisdoms represent line of relatively weakness
Anatomical considerations
Attached
muscles:
- Masseter
- Temporalis
- Medial and
lateral pterygoid
- Mylohyoid
- Geniohyoid
and genioglosus
- anterior
belly of digastrics
Blood supply
Endosteal
supply via the ID artery and vein
Periosteal
supply, important in aging due to diminishes and disappearance of alveolar
artery
Bradley
1972
Nerve
Damage of
inferior dental nerve
Facial
palsy by direct trauma to ramus
Damage of
facial nerve in temporal bone fracture
Goin
1980
Damage
to mandibular division of facial nerve
Factors influenced site of fracture and displacement
Anatomy of
the mandible and attached muscle (canine & wisdoms)
Weakening
areas of mandible (resorption and pathologyl)
Direction
of force of the blow
Age of the
patient
Types of fracture
Simple
Greenstick
fracture (rare, exclusively in children)
Fracture with
no displacement (Linear)
Fracture
with minimal displacement
Displaced
fracture
Comminuted
fracture
Extensive
breakage with possible bone and soft tissue loss
Compound
fracture
Severe and
tooth bearing area fractures
Pathological
fracture
(osteomyelities,
neoplasm and generalized skeletal disease)
Sites of fractures
Condyle
fracture
Intracapsular
fracture
Extracapsular
fracture
High condyle neck fracture
Low condylar fracture
Angle/
ramus fracture (body fracture)
Canine
region (parasymphesial fracture)
Midline
fracture (symphesis fracture)
Coronoid
fracture (rare)
Incidence of mandibular fractures
Body
fractures 33.6%
Subcondylar
fracture 33.4%
Fractures
at the angle 17.4%
Alveolar
fractures 6.7%
Ramus
fractures 5.4%
Midline
fractures 2.9%
Fracture of
coronoid process 1.3%
Oikarinen
& Malmstrom 1969
Favourable or unfavourable
They can be
vertically or horizontally in direction
They are
influenced by the medial pterygoid-masseter “sling”
If the vertical
direction of the fracture favours the unopposed action of medial pterygoid
muscle, the posterior fragment will be pulled lingually
If the
horizontal direction of the fracture favours the unopposed action of messeter
and pterygoid muscles in upward direction, the posterior fragment will be
pulled lingually
Favourable
fracture line makes the reduced fragment easier to stabilize
Effects of muscles on displacement
Transverse
midline fracture (symphesial) stabilizes by the action of mylohyoid and
geniohyoid
Oblique
fracture (parasymphesial) tends to overlap under the influence of muscles
action
Bilateral
parasymphesial fracture results in backward displacement associated with loss
of tongue control when the level of consciousness is depressed
Condylar fractures
The most
common mandibular fracture
Unilateral
or bilateral
Intracapsular
or extracapsular
Antero-medial
displacement is common but it may remain angulated with the ramus
Dislocation
of the glenoid fossa and fracture of petrous temporal bone which is very rare
Sign and symptoms
Swelling,
pain, tenderness and restriction of movement
Deviation
of mandible towards the side of fracture
Gagging of
occlussion (premature contact on the posterior teeth) with bilateral condylar
displaced or over-riding fractures
Displacement
of mandible toward the affected side
Anterior
open bite on opposite side of fracture
Laceration
of EAM****
Retroauricular
ecchymosis****
Cerebrospinal
leak and otorrhea in association with skull base fracture
Sequlae of TMJ injury
Artheritic
changes
Haemartherosis,
fibrosis and aknylosis
Meniscal
damage and detachment
TMD
Staph
infection with
condylar backward displacement and external auditory meatus injury
Meningitis with petrous temporal bone fracture
and intracranial involvement
Coronoid process fracture:
Rare
fracture caused by direct trauma to ramus and results from reflux contraction
of temporalis
Can be seen
following operation of large ramus cyst
Elicit
tenderness over the anterior part of ramus
Development
of tell-tale haematoma
Fracture of the ramus:
Type I
Single fracture
Mimics
low condylar fracture that runs below the sigmoid notch
Type II
comminuted fracture
Common
in missile injuries and appears to be with little displacement due to effects
of messeter and medial pterygoid muscles
Fracture of the angle and body
Pain,
tenderness and trismus
Extra-oral
swelling at the angle with obvious deformity
Step
deformity behind the molar teeth
Movement
and crepitus at the fracture site
Derangement
of occlussion
Intra-oral
buccal and lingula heamatoma
Involvement
of IDN
Gingival
tear if fracture in dentated area
Tooth
involvement and possible longitudinal split fracture
Midline fracture
The most
common missed fracture (always fine crack)
Can be
symphesial or parasymphesial fracture
Commonly
associated with one or both condyles fracture
Unilateral
fracture leads to over-riding of the fragments and bilateral may contribute in loss of voluntery tongue
control
Long canine
tooth represent a weak area and contributes to parasymphesial fracture
Rarely runs
across mental foramen
Signs and symptoms
Pain and
tenderness
Swelling
and odemea
Development
of step deformity
Mental
anesthesia
Heamatoma
in the floor of mouth and buccal mucosa
Soft tissue
injury of the chin and lower lip
If
associated with condylar fractures
Absence of
condyle movement on the contrlateral side
Deviation
of mandible
Anterior
open bite
Gagging of
oclussion
Limitation
of mouth opening
Clinical assessment and diagnosis
History
of trauma (traumatized patients with possible head injury) and facial injuries
Clinical
Examination
▶ Extroral
Inspection
(assessment of asymmetery, swelling, ecchymosis, laceration and cut wounds)
Palpation
for eliction of tenderness, pain, step deformity and malfunction
▶ Intra- and paraoral
Bleeding,
heamatoma, gingival tear, gagging of occlussion and step deformity and sensory
and motor deficiency
Radiographs
Radiographs
Plain
radiograph
OPG
Lateral
oblique
PA mandible
AP mandible
(reverse Townes)
Lower
occlusal
CT scan
3-D CT
imaging
MRI
Principles of treatment
similar to
elsewhere fractures in the body
Reduction
of fragments in good position
Immobilization
until bony union occurs
These
are achieved by:
Close
reduction and immobilization
Open
reduction and rigid fixation
Other
objective of mandible fracture treatment:
Control of
bleeding
Control of
infection
Definitive treatment
Soft
tissue repair
Debridment
Irrigation
with saline and antibiotics
Closure in
layers
Dressing
Reduction
and fixation of the jaw
▶ Close
reduction and IMF (traditional method by means of manipulation)
▶ Open
reduction and semi-rigid fixation (using inter-ossous wirings)
▶ Open
reduction and rigid fixation (using bone palates osteosynthesis)
Objective:
Restoration
of functional alignment of the bone fragments in anatomically precise position
utilizing the present teeth for guidance
Close
reduction
Arch
bars
Jelenko
Erich
pattern
German
silver notched
Cap
splints
▶ IMF prior to rigid fixation
▶ For the purpose of close
reduction
Close reduction
Bonded
brackets
IMF screws
Dental
wiring:
Direct
wiring
Eyelet
wiring
Local
anesthesia or sedation
Minimal
displacement
IMF for 6
weeks
Treatment
can be performed under GA or LA and when surgery is contraindicated
Fracture mandible in children
Close
reduction
Open
reduction and fixation
Plating at
the inferior border
Resorpable
plates
Gunning’s splint
Old
modality
Edentulous
patient
Rigid
fixation is not possible
To
establish the occlusion
Open reduction and fixation
Intraoral
approach
Extraoral
approach
▶
Submandibular approach
Rigid fixation
Intraossous
wiring
Plates and
screws
Kirchener
wire
Lag screws
Reconstruction palate
Severe
trauma
Loss of
part of the bone
Condylar fractures
Intraoral
approach
Ramus incision
Extraoral
approach
Preauricular
approach
Retromandibular
approach
IMF
Transosseous
wiring
Circumferential
wiring
External
pin fixation
Bone clamps
Trans-fixation
with Kirschner wires
Osteosynthesis
Non-compression
small plates
Compression
plates
Miniplates
Lag screws
Resorbable
plates and screws
Teeth in the fracture line
The
fracture is compound into the mouth
The tooth
may be damaged or lose its blood supply
The tooth
may be affected by some preexisting pathology
Management of teeth retained in fracture line
Good
quality intra-oral periapical radiograph
Insinuation
of appropriate systemic antibiotic therapy
Splinting
of tooth if mobile
Endodontic
therapy if pulp is exposed
Immediate
extraction if fracture becomes infected
Follow up
for 1 year and endodontic therapy if there is a loss of vitality
Absolute indications
Longitudinal
fracture
Dislocation
or subluxation from socket
Presence
of periapical infection
Infected
fracture line
Acute
pericoronitis
Relative indications
Functional
tooth that would be removed
Advanced
caries or periodontal diseases
Doubtful
tooth which would be added to existing denture
Tooth in
untreated fracture presenting more than 3 days after injury
