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Oral Surgery > Mandibular Fractures > Flashcards

Mandibular Fractures Flashcards

1
Q

ANATOMY of mandible

A
  • Lower jaw bone
  • U shaped body
  • 2 vertically directed rami
  • Condylar process
  • Coronoid process
  • Oblique line
  • Mental foramen

INTERNAL ANATOMY
* Mandibular foramen
* Lingula
* Pterygoid fovea
* Mylohyoid line

  • Fossae
    1. Submandibular
    2. Sublingual
    3. Digastric
  • Mental spines
    1. Genioglossus
    2. Geniohyoid
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2
Q

MUSCULATURE:

A

Jaw elevators
* Masseter muscle: from zygoma to angle and ramus
* Temporalis muscle: from infratemporal fossa to coronoid and ramus.
* Medial pterygoid muscle: medial pterygoid plate and pyramidal process into the lower mandible.

Jaw depressors
* Lateral pterygoid muscle: lateral pterygoid plate to condylar neck and TMJ
capsule
* Mylohvoid muscle:
Mylohyoid line to body of hyoid
* Digastric muscle: mastoid notch to digastric fossa
* Geniohyoid muscle: inferior genial tubercle to anterior hyoid bone

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3
Q

INNERVATION

A

• CN3; mandibular nerve through the foramen ovale

• Inferior alveolar nerve through the mandibular foramen

• Inferior dental plexus

• Mental nerve through the mental foramen.

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4
Q

BLOOD SUPPLY

A

• Internal maxillary artery
• Inferior alveolar artery
• Mental artery

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5
Q

CLASSIFICATION OF FRACTURES

A

• Type of fracture
• Site of fracture
• Cause of fracture

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6
Q

TYPE OF FRACTURE

A

1. Simple
Includes a closed linear fractures of the condyle, coronoid, ramus and edentulous body of the mandible.

2. Compound
Fractures of tooth bearing portions of the mandible, into d mouth via the periodontal membrane and at times through the overlying skin.

3. Communited
Usually compound fractures characterized by fragmentation of bone.

4. Pathological
Results from an already weakened mandible by pathological conditions.

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7
Q

SITE OF FRACTURE

A

• Dentoalveolar
• Condyle
• Coronoid
• Ramus
• Angle
• Body (molar and
Ramus
premolar areas)
• Parasymphysis
• Symphysis

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8
Q

Incidence of fractures

A

• Body of mandible (33.6%)
• Sub- condylar area(33.4%)
• Angle (17.4%)
• Dentoalveolar (6.7%)
• Ramus (5.4%)
• Symphyseal 2.9%
• Coronoid 1.3%

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9
Q

GENERAL SIGNS AND SYMPTOMS

A

• Swelling
• Pain
• Drooling
• Tenderness
• Bony discontinuity
• Lacerations
• Limitation in mouth opening
• Ecchymosis
• Fractured, subluxed, luxated teeth.
• Bleeding from the mouth.

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10
Q

CONDYLAR FRACTURE
(unilateral/bilateral and
Intracapsular/extracapsular)

A
  1. Unilateral condylar fractures
    • Swelling over the TMJ
    • Hemorrhage from ear on the affected side
    • Battle’s sign
    • Locked mandible
    • Hollow over the condylar region after edema has subsided
    • Rarely, Paraesthesia of lower lip
    • Deviation to the affected side upon opening
    • Painful limitation of movement
  2. Bilateral condylar fractures
    • Same as above
    • Limitation in mouth opening
    • Restricted mandibular movement
    • Anterior open bite
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11
Q

Essential Extra-oral Radiographs

A
  1. Oblique lateral radiographs (left and right)
    • Fracture of body proximal to canine region
    • Fractures of angle, ramus and condylar region
  2. (a) Posterior-anterior view
    • Shows displacement of fractures in the ramus, angle, body
    (b) Rotated posterior-anterior view
    • Fractures between Symphysis and canine region
  3. Reverse Towne’s view
    • Ideal for showing lateral or medial condylar displacement
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12
Q

Introral radiographs

A
  1. Panoramic tomography
    represents the best single overall view of the mandible especially the condyles
  2. Standard linear tomography
  3. Computed tomography (CT)
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13
Q

MANAGEMENT

A

• Airway
• Tongue falling back
• Blood clots
• Fractured teeth segments
• Broken fillings
• Dentures
• Hemorrhage
• Soft tissue lacerations
• Support of bone fragments
• Pain control
• Infection control e.g. compound fractures
• Food and Fluid

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14
Q

DEFINITIVE TREATMENT

A

A) Reduction
• Restoration of a functional alignment of the bone fragments
• Use of occlusion
1. Open reduction
2. Closed reduction

B) Immobilization
• To allow bone healing
• Through fixation of fracture line
1. Rigid
2. Non-rigid

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15
Q

Bone Healing

A

1. Primary bone healing:
* No fracture callus forms

  • Heals by a process of
    1. Hantact helinee ling directy across the fracture site if no gap exists
    2. Deposition of lamellar bone if small gaps exist (Gap healing)
  • Requires absolute rigid fixation with minimal gaps

2. Secondary bone healing:
* Bony callus forms across fracture site to aid in stability and immobilization

  • Occurs when there is mobility around the fracture site
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16
Q

TEETH IN LINE OF FRACTURE

A

Absolute indications
• Longitudinal fracture involving the root
• Dislocation or subluxation of tooth from socket
• Presence of periapical infection
• Infected fracture line
• Acute pericoronitis

Relative indications
• Functionless tooth which would eventually be removed electively
• Advanced caries
• Advanced periodontal disease
• Teeth involved in untreated fractures presenting more than 3days after injury

Relative indications
• Functionless tooth which would eventually be removed electively
• Advanced caries
• Advanced periodontal disease
• Teeth involved in untreated fractures presenting more than 3days after

Management of teeth retained in fractur line
• Good quality intra-oral periapical radiograph
• Appropriate antibiotic therapy
• Splinting of tooth if mobile
• Endodontic therapy if pulp is exposed
• Immediate extraction if fracture becomes infected

17
Q

METHODS OF IMMOBILIZATION

A

A) Osteosynthesis without intermaxillary fixation
1. Non-compression small plates
2. Compression plates
3. Mini plates
4. Lag screws

B) Intermaxillary fixation
1. Bonded brackets
2. Dental wiring
1. Direct
2. Eyelet
3. Arch bars
4. Cap splints

C) Intermaxillary fixation with Osteosynthesis
1. Trans osseous wiring
2. Circumferential wiring
3. External pin fixation
4. Bone clamps
5. Transfixation with kirschner wires

18
Q

CLOSED REDUCTION

A
  • Fracture reduction that involves techniques of not opening the skin or mucosa covering the fracture site

• Fracture site heals by secondary bone healing
• This is also a form of non-rigid fixation

INDICATIONS
1. Nondisplaced favorable fractures
2. Mandibular fractures in children with developing dentition
3. Condylar fractures

CONTRAINDICATIONS:
1. Alcoholics
2. Seizure disorder
3. Mental retardation
4. Nutritional concerns
5. Respiratory diseases (COPD)
• Unfavorable fractures

ADVANTAGES
1. Low cost
2. Short procedure time
3. Can be done in clinical setting with local anesthesia or sedation
4. Easy procedure

DISADVANTAGES
1. Not absolute stability (secondary bone healing)
2. Oral hygiene difficult
3. Possible TMJ sequelae
a) Muscular atrophy/stiffness
b) Decrease range of motion

TECHNIQUES:
1. Arch bars - Erich arch bars
2. Ivy loops
3. Essig Wire
4. Intermaxillary fixation screws
5. Splints
6. Bridal wires

19
Q

Open Reduction/ Rigid fixation

A

• Implies the opening of skin or mucosa to visualize the fracture and reduction of the fracture
• Can be used for manipulation of fracture only
Can be used for the non-rigid and rigid fixation of the fracture

INDICATIONS
• Unfavorable/unstable mandibular fractures
• Fractures of an edentulous mandible fracture with severe displacement
/ Delayed treatment with interposition of soft tissue that prevents closed reduction techniques to re-approximate the fragments

20
Q

Biomechanics of mandibular fractures

A

The mandible functions like a lever, with the condyles as the fulcrum. When a force is applied (e.g., during trauma), the mandible undergoes both tension and compression forces. Tension occurs on the convex side of the bone (outer surface), and compression occurs on the concave side (inner surface).

What are common weak points in the mandible that are prone to fractures?

A: The condylar neck, the angle of the mandible, and the symphysis.

How does a class 3 lever system impact the force required to move the mandible?

A: In a class 3 lever, the force applied by the muscles is close to the fulcrum, requiring more force to move the load (bite force).

Oral Surgery (15 decks)

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