Mandibular Fractures

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