Maxillofacial Trauma-mandible # Final / orthodontic courses by Indian dental academy / orthodontic courses by Indian dental academy

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MAXILLOFACIAL TRAUMAMANDIBULAR FRACTURES

Mandible is embryologically a membrane bent bone although, resembles physically long bone, it has two

articular cartilages with two nutrient arteries

Mandible fractures sent

Index Introduction Terminologies Classification Incidence & Pathogenesis Clinical Examination Radiographs Treatment Options Closed Reduction & Open Reduction Fixation techniques Surgical Approaches to open reduction Complications

It must be emphasized that any force great enough to cause a fracture of a mandible is capable of injuring any other organ system in the body

Patients rarely die of mandibular fractures , so the clinician has time to carefully and thoroughly evaluate the nature and extent of mandibular injuries.

Surgical anatomyThe positional suseptibility of individual teeth to injury

1) The U/L ant teeth are most liable to injury, with the upper C.I in the most vulnerable position .the increased over jet associated with the anatomical variant known as angles class 2 .

2) Indirectly an upward blow on the mandible with the musculature relaxed,or a fall on the point of the chin , causes the teeth to meet sharply and indirect tooth injury may result.

3) The teeth most susceptible are the upper premolars, being predisposed by their shape and that of the opposing teeth to antero-posterior splitting of the crowns .

The mandible is basically a tubular long bone which is bent into a blunt V- shape.

The cortical bone is thicker anteriorly at the lower border while posteriorly the lower border is relatively thin.

The mandible differs from all other long bones in two aspects

(a) Any movement inevitably causes both condyles to move with respect to the skull base.

(b) Although anatomically the condyles are the articulating surfaces of the mandible, functionally the occlusal surface of the mand teeth subserves this role. In a functional sense , the oral cavity is analogous to joint space.

The teeth

The presence of the teeth is extremely helpful in the reduction and fixation of mand #es.

The teeth may be regarded as row of bone pins offering direct

control of attached fragments of bone with out any of the problems associated with surgically introduced metal pins.

Presence of teeth are the weakness of the mandible ,+nce of teeth are the strength of maxilla .

The alveolar process is invested over half of its depth by tightly attached mucoperiosteum this soft tissue tears in all cases directly over the # both bucally and lingually such #es are thus (open) compound in to the oralcavity and exposed to possible infection.

The mucoperiosteumof the edentulous mandible is , by contrast ,an intact sleeve and is less frequently ruptured in association with underlying #es.in consequence these remain closed and the mucoperiosteum limits their displacement.

Strength of the mandible

Bones fractures at the sites of tensile strain , since their resistance to compressive forces is greater.

Huelke(1961) and Hodgson(1967) The mandible is a strong bone, the energy

required to # in being of 44.6-74.4kg/m, which is about same as zygoma and about half that of frontal bone .

Condylar region The zygomatic arch gives protection to the condyle from

direct trauma.

The subcondylar fracture is invariably produced indirectly as a result of violence to the mental prominence or contra lateral body of the mandible.

An anterior capsular tear associated with rupture of fibers of the lateral pterygoid which is inserted into the disc, would cause inability to close the jaw fully,due to disc being displaced posteriorly.

Posterior tear with out the rupture with the rupture of these muscle fibers' could result in episodes of interference with opening due to the anterior displacement of disc.

Ramus and coronoid process

#es of ramus exhibit very little displacement of the fragments due the splinting effect of the masseter and medial pterygoid.

Occasionally due to the power full contraction of the temporalis muscle ,# of the Coronoid process occurs.

# of ANGLE OF MANDIBLE : It is the second common site of fracture after condyle. It is imp. To distinguish ! ) clinical angle !! ) surgical angle, !!!) anatomical angle. Clinical angle : It is the junction b/n alveolar bone & ramus

at the origin of the internal oblique line.

Surgical angle : Junction b/n body of mandible & ramus at the origin of external oblique ridge.

Anatomical or Gonion angle : where lower border meets the posterior border of ramus.

In most cases the fracture line extends from surgical angle downwards and backwards , terminating at the lower border anterior to the masseter muscle.

when a 3rd molar tooth is present

the# commonly extends through its crypt or socket.

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 fractureGoin 1980

Damage to mandibular division of facial nerve

Types of #1).Simple :Fracture line does not communicate with the exterior Greenstick fracture (rare, exclusively in children) Fracture with no displacement (Linear) Fracture with minimal displacement

2).Compound:Fracture line communicates with interior (oral cavity) or exterior (skin)

3).Comminuted: Multiple fragments at any one fracture site.

(Extensive breakage with possible bone and soft tissue loss)

4).Complicated: Along with injury to bone, direct or indirect injury to adjacent nerves,blood vessels or joints

5).Impacted: Some linear fractures inter digitate to such an extent that there is no appreciable clinical

movement. (Seen more commonly in maxilla)

6. Greenstick: In children due to elasticity of bone, the bone bends producing distortion without break in continuity (discontinuity in cortex on one side & continuity on other)

7. Pathological : Due to underlying pathology the bone is weak enough to be fractured by minimal trauma or muscle contraction.

(osteomyelities, neoplasm and generalized skeletal disease)

8. Direct: Fracture adjacent to the point of contact of trauma

9. Indirect: Fracture arises at a point distant from the site of contact of trauma.

Classification DINGMAN & NATVIG

Based on anatomic location Symphysis ( Midline ) Parasymphysis Body Angle Ramus Coronoid process Condylar process Alveolar Process.

KAZANIAN & CONVERSE 1974

Based on presence or absence of teeth in relation to the line of fracture.

Class I Teeth are present on both sides of fracture line

Class II Teeth only one side of fracture line

Class III Patient edentulous

Based on level of fracture(ROWE & KILLEY 1968)

1.Those not involving basal bone ( Alveolar fractures)

2.Those involving basal bone

Based on relation to the overlying tissues(KRUGER 1974)

Simple Compound Comminuted

KRUGER & SCHILLI 19821. Relation to External environment i. Simple / Closed

ii. Compound / Open

2. Types of fracturesi. Incompleteii. Green Stickiii. Completeiv. Comminuted

3. Dentition of the jaw with reference to the use of splints

i. Sufficiently edentulous jaw

ii. Primary & mixed dentition

4. Localizationi. Fractures of the Symphysis region (b/w the

canines) ii. Fractures of the Parasymphysis (canine

region) iii.Fractures of the Body

(b/w the canine & the angle)iv.Fractures of the Anglev. Fractures of the Ramus (b/w the angle &

the sigmoid notch)vi. Fractures of the Coronoid processvii.Fractures of the Condylar process

Based on muscle pull and direction

Horizontally favorable

Horizontally unfavorable

Vertically favorable

Vertically unfavorable

Horizontally Favorable Horizontally Unfavorable

Vertically Favorable Vertically Unfavorable

Spiessel’s classificationBased on 1) No of # fragments2) Location of fracture3) Status of occlusion4) Soft tissue involvements5) Associated fracture

Classification of # by no of fragments and presence of bone defect(F1 to F4)

1) F0 : incomplete #2) F1 : single #3) F2 : multiple #4) F3 : comminuted #5) F4 : # with bone a defect( # with

bone loss)

Classification of #es by site(l1 to l8)1) l1 : precanine2) L2 : canine3) L3 : postcanine4) L4 : angle5) L5 : supra- angular6) L6 : condylar process7) L7 : coronoid process8) L8 : alveolar process

Classification of #es based on occlusion changes(0o to 02)

1) O0 : no malocclusion2) 01 : malocclusion3) O2 : non-existent occlusion( edentulous mandible)Classification of #es by soft tissue involvement4) s0: closed5) S1 : open intraorally6) S3 : open extraorally7) S3 : open intra- and extraorally8) S4 : soft tissue defect

Associated #es(A0 TO A6)1) A0 : none2) A1 : fractures(or) loss of tooth3) A2 : nasal bone4) A3 : zygoma5) A4 : lefort -16) A5 : lefort -27) A6 : lefort- 3

Point of Impact

Chin To fracture single subcondyle : 425 Lb To fracture both subcondyle : 550 Lb To fracture symphysis : 550 –

900 Lb

Lateral aspect of Md. To fracture Md : 300 –

700 Lb

Epidemiology

Sites of weakness Third molar (esp. impacted) Socket of canine tooth Condylar neck

Pathogenesis of Fracture

When an impact force is delivered on Md : The bone bends inwards producing compressive forces in the impacted (lateral ) surface and tensile forces on the lingual (medial) surface.

Fracture results when the tensile strain

overcomes the resistance of the bone, beginning on the medial side of Md and progressing THROUGH the bone towards the impact point.

Mandibular Forces

ETIOLOGY

A # may be from 1) direct violence 2) indirect violence 3) excessive muscle contraction.

Factors influencing the displacement of #1) The degree of force2) The resistance to the force offered by facial

bones.3) The direction of force4) The point of application of force5) The cross sectional area of the agent or object

struck6) The attached muscles

The effect of force applied from an antero-posterior direction superior direction inferior direction Lateral direction

Clinical Examination

1) General physical examination2) Local examination of mand # a) extra-oral examination b) intra oral examination

Local examination

The first step would be to consider the patients chief complaint :

Patients often complain of the following:

1)Pain or tenderness is often present at the site of impact with the possibility of a direct fracture, or at a distant site in the case of an indirect fracture.

2) Difficulty chewing. Pain could be limiting mandibular function or there may be a malocclusion or mobility at the fracture site.

3) Malocclusion. The patient may be able to tell the clinician of an alteration in the bite from the normal.

4) Numbness in the distribution of the inferior alveolar nerve. This usually indicates a displaced fracture in the region of the body or angle of the mandible on the affected site.

Signs and symptoms

Soft tissue injuries

Inspection may reveal a full thickness wound of the lower lip or a ragged laceration on its inner aspect caused by impaction against the lower anterior teeth.

Lacerations of the gingiva and deformity of the alveolus occurs.

In the anterior region of the mandible a degloving injury may occur as a result of impaction at the point of chin on some resilient surface such as soft earth.the jaw does not # but the soft tissue is rotated violently over the point of the chin and horizontal tear occurs in the buccal sulcus at the junction of attached and free gingiva.

Damage to the teeth

1) fracture of the crown of the individual teeth.

2) Any missing fragments of crown or missing fillings should be noted as these may be

embedded with in the soft tissues or more rarely swallowed or inhaled.

3) Exposure or near exposure of the pulp chamber.

4) Fractures of the roots of teeth.

5) Subluxation of teeth causes derangement of occlusion.

6) Vertical split or a horizontal # just below the gingival margin results from indirect trauma against opposite dentition.

Fractures of the parasymphysis and symphysis

1) Sub lingual ecchymoses- Coleman's sign

2) Crepitation on palpation

3) Restricted mouth opening.

4) Inability to close the jaw causing premature dental contact.

5) A retruded chin can be caused by bilateral parasymphyseal fracture.

6) paraesthesia

# of the body

Swelling and tenderness similar to that as seen in # of the angle of the mandible.

#es between the adjacent teeth tend to cause gingival tears.

When there is a gross displacement, inf dental artery may be torn, and this can give rise to severe intraoral haemorrhage.

Ecchymosis in the floor of the mouth.

Flattened appearance on the lateral aspect of the face.

Crepitation on palpation.

# of the angle

Anterior open bite is seen in bilateral angle fracture.

Ipsilateral open bite is seen in unilateral angle fracture

A deficient mand angle can occur with the unfavorable angle #es in which proximal fragments rotates superiorly.

Appearance of an elongated face may be a result of bilateral angle #es allowing anterior mand to be displaced downward.

Inability to close the jaw causing premature dental contact.

Swelling at the angle externally

Step deformity behind last molar tooth.

Restricted mouth opening

Small haemotoma intraorally adjacent to angle on either lingual or buccalside.

Paraesthesia.

# of ramus

Swelling and ecchymosis is usually noted both extra and intra orally.

Tenderness Restricted mouth opening Flattened appearance on the

lateralaspect of face.

Classification of edentulous atrophic mandible (luhr etal)

1) Class 1: moderate atrophy (16-20mm)

2) Class ll: significant atrophy(11-15mm)

3) Class lll: extreme atrophy (10mm or less)

Radiographs

Panoramic radiograph Single most information radiograph for

diagnosing Md fractures (shows entire mandible, including condyles)

Advantages Simplicity of technique

Ability to visualize entire mandible in one radiograph

Generally good detail

Disadvantages: Requires patient to be upright

(impractical in severely traumatized patient)

Difficult to appreciate buccal – lingual bone displacement or

Medial condylar displacement Lacking fine detail in -TMJ area

- Symphysis region - Dental & Alv. Process region

Equipment not present in all hospital radiology facilities

Lateral Oblique Ramus Angle Post Body

DisadvantagesCondyle region, Bicuspid & Symphysis

region unclear

PA View ( Caldwell)

Medial or lateral displacement of fractures of the ramus, angle, body and Symphysis.

Disadvantages: Condylar region is not well

demonstrated (but midline or Symphyseal fractures are)

Mandibular Occlusal view

Demonstrates discrepancies in the medial and

lateral position of the body fractures and also

shows anteroposterior displacement in the symphysis region.

Reverse Towne’s

Ideal for showing medial displacement of condyle and condylar neck fractures.

Transcranial lateral views of TMJ

TREATMENT:

Reduction

Fixation

Immobilization

Goals Of Management of fracture

1. Restore function (by bony union & reestablishing Pre # strength)

2. Restore contour defect

3. To prevent infection at fracture site

Restore function means: Mastication, Speech,Mouth opening restoring these parameters to normally.

Closed Reduction

Is a ‘blind’ reduction relying on the fragments ‘locking’ together. In closed reduction, occlusion, palpation or post op X-rays are used as a guide to the accuracy of the reduction. This is more likely done in the cases where the periosteum is intact.

Closed reduction Indications Nondisplaced favorable fractures

Grossly Comminuted fractures

Fractures exposed by significant loss of overlying soft tissuse.

Edentulous Mandibular fractures.

Mandibular fractures in children with developing dentition.

Coronoid process fracture.

Condylar fractures.

Open Reduction.

Involves exposure of the fracture either through the skin or the mucosa. Reduction of fracture segments can be done by

- Manual manipulation- Traction

Displaced Unfavorable fractures of Angle,body or parasymphysis

Multiple fractures of the facial bones Midface fractures and displaced bilateral

condylar fractures Fractures of Edentulous mandible with

severe displacement of fragments Edentulous maxilla opposing mandibular

fracture Delay of treatment and interposition of soft

tissue

Open reduction Indications

Fixation

To prevent mobility of fracture segments to aid in healing. Can be -

Direct fixation Indirect fixation

Direct fixation: Fracture site is opened, visualized and reduced stabilized across the fracture site.

eg.Non rigid : Transosseous wiring Semi rigid: Mini bone plateRigid : Compression bone plate.

Indirect fixation: Stabilization of the proximal and distal fragments of the bone at a site distant from the fracture line

Eg. For Md fracture, IMF External pin fixation.

Methods available for Fixation

Fixation

Indirect skeletal Direct Skeletal

(Fixation applied to) (Direct fixation of

TEETH BONE)

Indirect skeletal (Fixation applied to the

TEETH)

1. Dental wiring

Direct interdental wiring. Indirect interdental wiring (Eyelet or

Ivy) Continuous or multiple loop wiring

2. Arch Bars

3. Cap Splints

4. ‘Gunning type ‘ splints

TEETH)

1. Dental wiring a. Direct interdental wiring

TEETH)

1.Dental wiring b. Indirect interdental wiring

(Eyelet or Ivy loop) (Button wiring Leonards)

TEETH)

1. Dental wiring c. Continuous or multiple loop wiring ( Stouts method) ( Obwegeser method)

Indirect skeletal (Fixation applied to

the TEETH) 2. Arch Bars Custom made Commercially

available (Baker precast bar) (Jelenko)

(Erich) (Directly bonded) (Krupps)

(Risdon)

TEETH)

3. Cap Splints ( Cast silver cap splints) ( Acrylic cap splints )

Indirect skeletal (Fixation applied to

the TEETH)

4. Gunning type splints ( Prefabricated Gunning type

splint) ( Old Dentures) ( Disposable trays)

SURGICAL APPROCHES

The surgeon may elect to extend the laceration to provide adequate access to the fractured area, following the relaxed skin tension lines (RSTL).

Vestibular incisionsThe intraoral approach is the usual access for simple fractures of the body, symphysis, and angular regions.The approach can be extended posteriorly (dashed line) for better access to the body, angle and ramus regions.

When the incision is extended posterior to the canine teeth, the mental nerve can be damaged. Keep the incision superior to the mental nerve in the body region.Particularly in the extended intraoral approach, care must be taken to protect the mental nerve in the anterior body region.

Vestibular approach

POSTERIOR VESTIBULAR INCISION

The sensory buccal nerve crosses the upper anterior rim of the mandibular ascending ramus in the region of the coronoid notch. It is usually below the mucosa running above the temporalis muscle fibers. When the posterior vestibular incision is carried sharply along the bony rim, the buccal nerve is at risk of transsection, followed by numbness in the buccal mucosal region. Therefore, to protect the nerve, the posterior dissection is to be extended bluntly as soon as the lower coronoid notch is reached.

The transbuccal trocar may also assist the surgeon in positioning posterior and inferior screws, sometimes avoiding the need for an extraoral approach.

SUB MENTAL INCISION

EXTENDED SUB-MENTAL

This may be necessary in complex fractures such as comminuted, atrophic, and severe bilateral fractures.

VariationsThe incision can either be parallel to the inferior border of the mandible or be placed in an existing skin crease for maximum cosmetic benefit.

In order to protect the marginal mandibular branch of the nerve, the platysma is undermined bluntly with scissors prior to dividing it with a scalpel.

The platysma muscle is divided sharply, preferably 2-3 cm below the mandibular border, not necessarily at the same level of the skin incision.

RETRO MANDIBULAR APPROCHES

Transparotid approach: skin incision A vertical incision through skin and subcutaneous tissue is made, extending from just below the ear lobe towards the mandibular angle. It should be parallel to the posterior border of the mandible.

Retro parotid incision

A frequently used alternative to the retromandibular transparotid approach described above is one in which the parotid gland is lifted rather than dissected through.

This requires the incision to be placed more posteriorly which means that exposure of the mandible is more limited. Rather than approaching the mandible from directly over the ramus, it is approached more posteriorly

Rhytidectomy approach

Methods availablefor Direct Skeletal fixation

Direct Skeletal (Direct fixation of BONE)

1. Trans osseous wiring

a. Upper border b. Lower Borders2. Circumferential straps3. Bone plating 4. Intramedullary pinning 5. Titanium mesh6. Ext. Pin Fixation7. Bone clamps8. Bone staples9. Bone Screws

a. Upper border Oblique Horizontal mattress

Single loop

b. Lower BordersHayton Williams4 hole technique

2. Circumferential straps

3. Bone plating

Miniplates Compression plates Lag screws

Locking versus nonlocking plates

There are several advantages to a locking plate/screw system:

Conventional plate/screw systems require precise adaptation of the plate to the underlying bone.

Without this intimate contact, tightening of the screws will draw the bone segments toward the plate, resulting in alterations in the position of the osseous segments and the occlusal relationship.

Locking plate/screw systems offer certain advantages over other plates in this regard; the most significant being that it becomes unnecessary for the plate to intimately contact the underlying bone in all areas.

As the screws are tightened, they "lock" to the plate, thus stabilizing the segments without the need to compress the bone to the plate. This makes it impossible for the screw insertion to alter the reduction.

Another potential advantage in locking plate/screw systems is that they do not disrupt the underlying cortical bone perfusion as much as conventional plates, which compress the undersurface of the plate to the cortical bone.A third advantage to the use of locking plate/screw systems is that the screws are unlikely to loosen from the plate. This means that even if a screw is inserted into a fracture gap, loosening of the screw will not occur. Similarly, if a bone graft is screwed to the plate, a locking head screw will not loosen during the phase of graft incorporation and healing.

The possible advantage to this property of a locking plate/screw system is a decreased incidence of inflammatory complications due to loosening of the hardware.

Locking plate/screw systems have been shown to provide more stable fixation than conventional nonlocking plate/screw systems

4. Intramedullary pinning (major,1938)Employed by mcdowell,Barrett, and Fryer

(1954).

5. Titanium mesh

6. External Pin Fixation

7. Bone clamps (penn&brown,19448. Bone staples (laws,1977)9. Bone Screws

Immobilization After the fragments are aligned in proper

symmetry they are fixed and immobilized in this position until bony union occurs.

To resist displacing forces acting on fracture site to allow a clinical fracture union

Indicated in cases where Nonrigid Fixation methods are used and the site in question will be subjected to force.

COMPLICATIONS

Intra-op Immediate post-op Post-op

Intra –op complication

Surgical approches- Encountering vital structures like-

mental nerve, marginal mandibular nerve, facial nerve, facial artery.

Infections Hemmorage

Immediate post-op

Infection Hemmorage G.A. related

Post-op

Mal occlusion Mal-union Non-union Infections

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Maxillofacial Trauma-mandible # Final / orthodontic courses by Indian dental academy / orthodontic courses by Indian dental academy

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