Mandibular Fractures

DEPARTMENT OF ORAL MEDICINE AND RADIOLOGY Seminar on

MANDIBULAR FRACTURES Presented by

SYED NABI AHMED C.R.I.

Anatomy: Bony Landmarks      

Condylar Process Coronoid Process Symphysis/parasymphysis Ramus Angle Body

Common Sites of Fracture      

Condyle 36% Body 21% Angle 20% Parasymphysis 14% Coronoid, ramus, alveolus, symphysis 3% Weak areas include 3rd molar and canine fossa

Mandibular Fracture

Innervation 

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The mandibular nerve, through the foramen ovale Inferior alveolar nerve through the mandibular foramen Inferior dental plexus Mental nerve through the mental foramen

Arterial Supply   

Internal maxillary artery Inferior alveolar artery Mental artery

Musculature: Jaw Elevators 

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Masseter: Arises from zygoma and inserts into the angle and ramus Temporalis: Arises from the infratemporal fossa and inserts onto the coronoid and ramus Medial pterygoid: Arises from medial pterygoid plate and pyramidal process and inserts into lower mandible

Musculature: Jaw Depressors  Lateral pterygoid: lateral pterygoid plate to  

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condylar neck and TMJ capsule Mylohyoid: mylohyoid line to body of hyoid Digastric: mastoid notch to the digastric fossa Geniohyoid: inferior genial tubercle to anterior hyoid bone

Classification of Mandibular Fracture 

According to Generic Terms 

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Simple or Closed Fracture : Fracture that does not communicate with external environment. Compound or Open Fracture : Fracture that communicate with external environment through skin, mucosa or periodontal ligament. Commiuted Fracture : Fracture in which a single anatomic region of a bone is broken into pieces.

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Greenstick Fracture : A fracture in which one side of the bone is broken and the other side is bent Pathologic Fracture : A fracture occurring at a site weakened by preexisting disease. Complicated Fracture : A fracture with significant injury to adjacent soft tissues or structures.

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Dislocation Fracture : Fracture of a bone near an articulation with concomitant dislocation from that articulation Direct Fracture : Fracture that occurs at the point of impact Indirect Fracture : Fracture that occurs at a point distant from the site of impact Impacted Fracture : Fracture in which one fragment is driven into the other fragment.

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Incomplete Fracture : Fracture in which the line of fracture does not include the entire bone. Multiple Fracture : Two or more lines of fractures exist on a bone and do not communicate with each other Unstable Fracture : Fracture with intrinsic tendency to slip out of place after reduction

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According to Anatomic Region Involved       

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Condylar Process Coronoid Ramus Angle Body Symphysis/Parasymphysis Alveolar

According to Radiographic Direction  

Horizontal Vertical

Favorable Fractures 

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Those fractures where the muscles tend to draw fragments together Ramus fractures are almost always favorable as the jaw elevators tend to splint the fractured bones in place

Unfavorable Fractures 

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Fractures where the muscles tend to draw fragments apart Most angle fractures are horizontally unfavorable Most symphyseal/parasymphyseal fractures are vertically unfavorable

Physical Examination  

Change in occlusion is highly diagnostic Anterior open bite suggestive bilateral condylar or angle fractures

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Posterior open bite common with alveolar process or parasymphyseal fractures Unilateral open bite with ipsilateral angle or parasymphyseal fracture Retrognathic (Angle III) seen with condylar or angle fractures Prognathic (Angle II) seen with TMJ effusion

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Anesthesia of lower lip is “pathognomonic” of a fracture distal to the mandibular foramen The converse is not true: not all fractures distal to the mandibular foramen have mental n. anesthesia Trismus of less than 35mm also highly suggestive of mandibular fracture

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Inability to open the mandible suggests impingement of the coronoid process on the zygomatic arch Inability to close the mandible suggests a fracture of the alveolar process, angle, ramus or symphysis

Signs and Symptoms  

Anesthesia of the lower lip Abnormal mandibular movement   

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unable to open - coronoid fx unable to close - fx of alveolus, angle or ramus trismus

Lacerations, Hematomas, Ecchymosis Loose teeth Swelling Pain Malocclusion

Radiographic Examination 

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Panorex shows the entire mandible, but requires the patient to be upright. It also has particularly poor detail of the TMJ and medial displacement of the condyles AP - ramus and condyle Submental - symphysis CT - condylar fractures

General Principles of Treatment 

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The general physical status should be thoroughly evaluated. Tetanus Nutrition 40% associated with significant injury, 10% of which are lethal Cerebral contusion is common

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Dental injuries should be treated concurrently Reestablishment of occlusion is the primary goal Fractured teeth may jeopardize occlusion Mandibular cuspids are cornerstone of treatment Prophylactic antibiotics. With multiple facial fractures, mandibular fractures are treated first

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Almost all can be considered open fixation as they communicate with skin or oral cavity

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Reduction and fixation

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Post-op monitoring for N/V, use of wire cutters

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Oral care - H2O2 , irrigations, soft toothbrush

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Biweekly examination - hardware, occlusion, weight

Treatment Options      

Soft diet Maxillomandibular fixation Open reduction - non-rigid fixation Open reduction - rigid fixation External pin fixation Lag screw, DCP

Closed Reduction     

Grossly comminuted fractures Significant tissue loss Edentulous mandibles Fractures in children Condylar fractures

Open Reduction  

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Displaced, unfavorable fractures of angle Displaced unfavorable fractures of the body or parasymphysis, as these tend to open at the inferior border, leading to malocclusion Multiple fractures of facial bones Displaced, bilateral condylar fractures

Open Reduction - Nonrigid Fixation

Open Reduction - Rigid Fixation

Closed Reduction of the Dentulous Patient 

Erich Arch Bars. Can lead to periodontal infalmmation.

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Avoid fixating incisors, as these teeth are moved by the wires Ivy loops

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Ivy Loops

Erich Arch Bars

Closed Reduction of the Partially Edentulous Patient  

Partials and circum wires or screws Acrylic partials with incorporated arch bar wires

Closed Reduction of the Edentulous Patient   

Dentures with circum wires and screws Fabricated acrylic plates (Gunning Splints) In fractures of both the mandible and maxilla, circumzygomatic and circum-mandibular wires should be tied together to prevent telescoping of maxilla

Open Reduction and Osteosynthesis   

Simpler than rigid fixation MMF still required Useful in angle, parasymphyseal fractures

Open Reduction Internal Fixation 

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Performed with compression plates and lag screws MMF generally not required Eccentrically placed holes and screws placed at angles “compress” the bone

Complications   

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Socioeconomic groups Infection (James, et. al.) Delayed healing and malunion. Most commonly caused by infection and noncompliance Nerve paresthesias in less than 2% TMJ problems

Conclusion 

With multiple techniques available, there is still controversy over the best treatment for each type of mandible fracture 

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The decision is a clinical one based on patient factors, the type of mandible fracture, the skill of the surgeon, and the available hardware Further studies are in progress