mandibular fractures

Seminar on

MANDIBULAR FRACTURES

Presented by

SYED NABI AHMEDC.R.I.

DEPARTMENT OF ORAL MEDICINE AND RADIOLOGY

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

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

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

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 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.

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 pre-existing disease.

Complicated Fracture : A fracture with significant injury to adjacent soft tissues or structures.

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.

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

According to Anatomic Region Involved Condylar Process Coronoid Ramus Angle Body Symphysis/Parasymphysis Alveolar

According to Radiographic Direction Horizontal Vertical

Favorable Fractures

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

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

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

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

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

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

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 The general physical status should be

thoroughly evaluated. Tetanus Nutrition 40% associated with significant injury,

10% of which are lethal Cerebral contusion is common

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

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

Reduction and fixation

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

Oral care - H2O2 , irrigations, soft toothbrush

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

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.

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

Ivy loops

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 Performed with compression plates and lag

screws MMF generally not required Eccentrically placed holes and screws placed

at angles “compress” the bone

Complications

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 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