Oral and Maxillofacial Surgery ~ Mandibular Fractures

陳怡睿 醫師
 
Etiology of mandibular fractures
Vehicular accidents ( 43%)
Assaults ( 34%)
Work related ( 7%)
Fall ( 7%)
Sporting accidents ( 4%)
Gunshot injuries... (rare)

Etiology plays a role in fracture location

Automobile accidents ⇔ condylar region; Motorcycle accidents ⇔ symphysis; Assault ⇔ angle

* Fridrich KL et al. 1992
Number of fractures per mandible
Approximately 50%of the patients with mandibular fractures had more than one fracture.
若骨折不只一處,則常見的是:
Double fracture:
angle+對側的body或condyle
Triple fracture:
兩側的condyle+symphysis
Eg. 左側下顎骨體骨折常伴隨右側髁突骨折

Classification
> Simple, or closed
A fracture that does not produce a wound open to the external environment, whether it be through the skin, mucosa, or periodontal membrane.
> Compound, or open
A fracture in which an external wound, involving skin, mucosa, or periodontal membrane, communicates with the break in the bone.                                                                           > Incomplete
> Greenstick
A fracture in which one cortex of the bone is broken, the other cortex being bent.
> Complete
> Comminuted
A fracture in which the bone is splintered or crushed.
> Pathologic
A fracture occurring from mild injury because of pre-existing bone disease.
> Multiple
A variety in which there are two or more lines of fracture on the same bone not communicating with one another.
> Impacted
A fracture in which one fragment is firmly driven into the other.
> Atrophic
A spontaneous fracture resulting from atrophy of the bone, as in edentulous mandibles.
> Indirect
A fracture at a point distant from the side of injury.
> Complicated, or complex
A fracture in which there is considerable injury to the adjacent soft tissues or adjacent parts; may be simple or compound.

Dentition of the jaw with reference to the use of splints
Sufficiently dentulous jaw
Edentulous or insufficiently dentulous jaw
Primary and mixed dentition

Localization
Fractures of the symphysis region between the canines
Fractures of the canine region
Fractures of the body of the mandible between the canine and the angle of the mandible
Fractures of the angle of the mandible in the third molar region
Fractures of the mandibular ramus between the angle of the mandible and the sigmoid notch
Fractures of the coronoid process
Fractures of the condylar process
* Angle fractures classified
Vertically favorable or unfavorable
Horizontally favorable or unfavorable
Relates to:
the direction of the fracture line
the effect of muscle action on the fracture fragments

Diagnosis
* History
... pre-existing systemic bone disease that may cause or be directly related to the fractured jaw
... significant medical and psychiatric problems that will influence the management of the patient
A history of TMJ dysfunction can have significant legal and post-tx ramifications. 
The type and direction of traumatic force can be extremely helpful in diagnosis.
automobile and motorcycle accidents
⇒ multiple, compound, comminuted
hit by a fist
⇒ single, simple, non-displaced
The object that cause the fracture can influence the type and the number of fractures.
broad, blunt object (2×4 piece of wood)
⇒ symphysis, condyle... several fractures
smaller, well-defined object (hammer)
⇒ single comminuted fracture

Force direction:Concomitant fractures
ant. blow directly to the chin:
      bilateral condylar fractures
angled blow to the parasymphysis:
      contra-lateral condylar or angle fracture
teeth clenched together at the moment of impact:
      dental and alveolar process fractures
* Clinical examination
The signs and symptoms of mandibular fractures:
Change in occlusion
Anesthesia, paresthesia, or dysesthesia of the lower lip
Abnormal mandibular movements
Change in facial contour and mandibular arch form
Lacerations, hematoma, and ecchymosis
Loose teeth and crepitation on palpation
Dolor, tumor, rubor, and color
* Radiologic examination
Panoramic radiography: for overall diagnosis
Lateral oblique radiography
Posteroanterior (PA) radiography: good for general appraisal
Occlusal view: for judging the symphyseal region
Periapical view
Reverse Towne’s view: particularly good for condylar fractures
Temporomandibular joint, including tomograms
Computed tomography (CT) scan

** 以X光像診斷下顎骨骨折的概念 **
Skull view以PA view較清楚
懷疑為下顎骨骨折時,照Pano view
檢查X光片中,骨之邊緣是否連續、完整
注意下顎管是否連續
若骨折延伸至牙根部,則懷疑是否已是開放性骨折
若病患無明顯外力撞擊病史,下顎骨骨折須考慮是否為病理性骨折,例如腫瘤

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