Mandibular Fractures
Forces acting on mandible
 2 main groups of muscles
1. muscles of mastication
2. hyoid muscles
 The muscles of mastication tend to displace posterior segments superiorly
 The suprahyoid muscles pull the anterior segments inferiorly.
 the lateral pterygoid muscles tend to pull the condylar head medially with high
condyle fractures.
 Masticatory muscle function normally produces tension at the upper border of the
mandible with compressive forces at the lower border.
 Proximal to the canine teeth in the area of the mandibular symphysis, the
prevailing force varies with type of occlusal loading
 Alveolus and inferior border in this area of the mandible may be under
compression or tensile forces at different times during the masticatory cycle, thus
producing an overall torsion effect.
 Based on this, Champy define ideal lines of osteosynthesis.
 Posterior to the mental foramen a single plate is placed below the dental roots
and above the inferior alveolar nerve.
 Anterior to the mental foramina two plates are necessary to neutralize the
torsional forces.
Injury Pattern
Classified according
1. anatomic position
2. whether they are displaced, comminuted, or greensticked.
3. favorable or unfavourable
a. most ramus fractures are favourable
b. Symphyseal and parasymphyseal fractures tend to be vertically
unfavorable and are displaced by the downward pull of the suprahyoid
musculature.
c. High condylar fractures are considered unfavorable and are often
displaced medially by the lateral pterygoid muscle.
Clinical
 Unilateral condylar fractures commonly present with a contralateral open bite
and deviation to the ipsilateral side upon opening.
 Bilateral condylar fractures may present with anterior open bite and premature
posterior contact.
Investigations
 Low Towne’s view - will clearly show the condylar processes of the mandible
 OPG – will diagnose 92 percent of mandible fractures
 CT – 99% sensitivity but will not provide the detailed information on dental
occlusal relation that an OPG examination will.
 Cervical xrays
Management
Goals
1.
2.
3.
4.
to achieve anatomic reduction and stabilization
to reestablish pretraumatic functional dental occlusion
to restore facial contour and symmetry
to balance facial height and projection
Antibiotics
 essentially open fractures that should be considered contaminated, because of the
oral flora, and many surgeons utilize prophylactic antibiotics
 recent randomized prospective study showed no difference in rates of wound
infection in patients with an uncomplicated mandible fracture who received
postoperative antibiotics versus those who received placebo
Management of teeth in line of fracture
 A loose tooth is not necessarily an indication for extraction
 Indications for tooth extraction
o comminuted or displaced fracture contains a tooth
o tooth root is fractured
o there is periodontal disease
o an abscess near the fracture line
o if the tooth is functionless because of lack of opposing teeth.
 The 3rd molar teeth is problematic – removing it will weaken the fixation but
leaving it may lead to higher risk of infection.
 In general, it should be removed.
Conservative Management
1. undisplaced
2. normal occlusion
3. normal ROM
 4 weeks of soft diet, oral hygiene
Closed Reduction
 nondisplaced or grossly comminuted fractures, fractures in the presence of mixed
dentition or in the atrophic mandible, and fractures of the coronoid or condyle.
 Methods
1. Splints and dentures are occasionally used in children with mixed dentition
or in edentulous patients. The splints or dentures are fixed to the mandible and
maxilla by palatal screws or circumferential wires
o Gunning split or dentures in the edentulous mandible (height<2cm)
2. Intermaxillary fixation using arch bars, Ivy loops, or suspension screws.
Occlusion can be maintained with either wires or elastics.
ORIF
 three basic types of internal fixation
1. compression plates
o remain controversial, as the plates are technically difficult to use and
may cause malocclusion and there are no studies showing their
superiority versus other fixation methods.
o If used alone, the DCP would cause compression at the inferior border
with distraction and gapping at the superior border.
o The tension band principle (Champy technique) prevents this from
occurring. A device such as an arch bar or miniplate can be placed on the
alveolar or tension side of the mandible to restore anatomic alignment
before the DCP is applied, allowing even compression along the entire
length of the fracture.
o Compression plating of mandibular fractures may result in higher rates
of complications, especially infections.
o Lag screws may be used for compression if the fracture line is favorable
and if the fracture is noncomminuted.
2. semirigid fixation
o using a small plate with 1.5- to 2.0-mm unicortical screws.
o The advantages are the limited periosteal stripping of the fracture site
needed. This technique relies on the forces of the strong jaw muscles to
hold the fracture in place
o A locking plate may also be used in combination with a dental splint to
add additional fixation if the comminution involves alveolar bone.
Proponents of the locking plate point out that the placement of screws
should not alter the reduction, but this has not been proven.
3. reconstruction plate
o form of internal surgical splint.
o serve to buttress fragments against displacement and to absorb the
functional load while healing occurs.
o particularly useful for the treatment of multiple segmental fractures. The
fracture segments are held together with wires or miniplates. The
reconstruction plate is than contoured and secured with two screws in
each stable lateral segment. The segmental fragments are then secured to
the plate.
Treatment by site
Body
 usually buccal sulcus incision
 occasionally external Risdon incision
 inferior plate  arch bar as tension band
Angle
 Prone to fracture due to 3rd molar, thin bone and lever action
 carry the highest surgical complication rate of all mandibular fracures
 best treated with ORIF due to tendency for displacement of the proximal segment.
 Best result and least complication with single, noncompression, 2.0 miniplate
placed through an intraoral approach
 A transcutaneous approach may be required for screw placement
 More complications are seen with more rigid fixation
Symphysis
 2 plates required for parasymphyseal fractures
 Care to avoid the mental nerve
 Lag screws good for this area
Ramus and Coronoid
 Most are treated conservatively
Mandibular condyle
Classsification (Lindahl)
1. Fracture level
a. Condylar head (intracapsular)
b. Neck – thin region below the head
c. Subcondylar – from sigmoid notch to the posterior border of the ramus just
below the neck of the condyle
2. Displacement at fracture level (relation to condyle to mandible)
a. Angulation with medial override
b. Angulation with lateral override
c. Angulation without override
d. Fissure (no contact)
3. Position of the condylar head to articular fossa
a. No displacement
b. Slight displacement
c. Moderate displacement
d. Dislocation (head usually anteromedial)
 Medial angulation of the condylar fragment with lateral override at the
fracture level was the typical fracture in adults
 Angulation without override the characteristic fracture in growing individuals.
 Medical override occurred both in children and in adults and seemed to be the
result of more severe trauma to the chin.
Bilateral condylar fracture: medial Angulation with Lateral Override
Medial angulation, no override
Closed vs Open Approach
 Controversial, many studies have not shown benefit in terms of mobility, joint
problems or occlusion
 proponents of open reduction are critical of the conservative treatment approach,
and believe that temporomandibular joint dysfunction has been underreported and
that there may be a higher incidence of traumatic arthritis, decreased range of
motion, and malocclusion than previously suspected in closed reduction series.
 With conservative treatment, patients will often deviate with maximal opening
and has some loss of definition of the jawline at rest
 higher incidence of shorter posterior facial height on the side of injury and more
tilting of the occlusal and bigonial planes toward the fractured side.
Benefits of ORIF
1. More consistent occlusal results
2. Greater postoperative condylar mobility
3. More consistent facial symmetry
Strong indications for ORIF (Zide)
1. displacement into the middle cranial fossa
2. impossibility of obtaining dental occlusion by closed reduction
3. lateral extracapsular displacement of the condyle
4. presence of a foreign body
5. open fracture with potential for fibrosis.
6. Displacement of the proximal fragment of 30 degrees or more from the
axis of the ascending ramus.
7. Shortening of the ascending ramus with telescoping of the fragments
with concomitant open bite.
8. Dislocation of the condylar head from the temporomandibular fossa.
Relative indications for ORIF
1. bilateral or unilateral condylar fractures with a midface fractures
2. comminuted symphysis and condyle fracture with tooth loss
3. displaced fracture resulting in open bite or retrusion in mentally retarded or
medically compromised adults who would not tolerate intermaxillary fixation
4. displaced condylar fractures in the edentulous or partially dentate mandible
with posterior bite collapse
Absolute indications for conservative management
1. In nondislocated fractures
2. intracapsular fractures of the condylar head,
3. condylar fractures without functional disturbances
4. condylar fractures in children
Closed treatment
 will normally consist of a delay while swelling and spasm settle, followed by
MMF with elastic guidance, not rigid, for 1-6 weeks.
ORIF
 Open Approaches
1. transparotid, retromandibular
 17% transient facial nerve palsy, 7% hypertrophic scar
 Endoscopic
1. Transcutaneous endoscopic assisted
2. Transoral endoscopic assisted
 Lower risk of facial nerve palsy, imperceptible scar
 High learning curve
 higher rate of hardware loosening, leading to reoperation in at least one
study
 higher rate of nonunion, refracture, and possibly malocclusion
Complications
4 types of complications
1) those arising in the course of proper treatment
2) those caused by inadequate/inappropriate treatment(
3) those due to surgical failure
4) those that result from no treatment.
Nonunion (2.4%)
 normal bony union of the mandible takes place over 4 to 8 weeks, depending on
the age of the patient
 The radiographic appearance is one of sclerotic bony margins and a gap where
bone has not bridged the fracture site.
 Many of these fibrous nonunions will eventually convert to a bony union.
 Mandibular body has the highest incidence of nonunion of all mandibular sites
 Causes
1. incomplete reduction
2. soft tissue interposition
3. teeth in line of fracture
4. infection
5. poor blood supply
6. nutritional/metabolic alterations
 treatment of nonunion generally consists of removing any infected teeth,
debridement of fracture, and reapplication of rigid internal fixation with or
without bone grafting.
Malocclusion
 Postoperative malocclusion secondary to internal fixation requires repeat operation
in the vast majority of cases. Should not rely on elastics.
Nerve injury
 19% permanent infraalveolar nerve injury
Others
 Plate exposure
 Tooth loss
 Trismus
 Ankylosis