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

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