Mandibular fractures

Introduction Aetiology Classification Surgical Anatomy Applied Anatomy Clinical examination Radiology Preliminary treatment Fractures of dentulous mandibles Fractures of edentulous mandibles Fractures of condylar regions Fracutres of mandible in children Postoperative crae Complications Fractures with gross comminution of bone and loss of hard and soft tissue

Introduction

The first description of mandible fractures was as early as 1650 BC, when an Egyptian papyrus

described the examination, diagnosis, and treatment of mandible fractures. Many patients either were

not treated properly or received no treatment and subsequently died.

A broken jaw (or mandibular fracture) is a common facial injury. Only the nose is broken more

frequently. A broken jaw is the tenth most common fractured bone in the human body. Fractures

(these are breaks in the bone) are generally the result of a direct force or trauma to the jawbone.

Men are about 3 times more likely than women to sustain a broken jaw. Those aged 20-29 years are

the most common group affected.

Broadly divided into:

Fractures with no gross comminution of bone and without soft tissue/hard tissue loss.

Fractures with gross comminution of bone and significant hard and soft tissue loss.

Aetiology

Road injuries Interpersonal violence Falls

Sporting injuries Industrial trauma Missile injuries Gunshot wounds Pathological fractures

The primary causes of mandible fractures are vehicular accidents and assaults. These vary according

to the area in which the survey was taken and the socioeconomic and ethnic status of the community.

Other significant causes are falls and sports injuries. In a large retrospective study of 2137 patients

with mandibular fractures, Ellis et al reported that 43% were caused by vehicular accidents, 34% by

assaults, 7% were work related, 7% occurred as the result of a fall, 4% occurred in sporting

accidents, and the remainder had miscellaneous causes. Vaillant and Benoist described 14 cases of

gunshot injuries to the mandible. Patients were aged 6-68 years. Two children were victims of

accidents, and the adults were either suicide or assault victims.

Classification

According to

Type of fracture

Simple or closed : Fracture that does not produce a wound open to the external, whether it be through the skin, mucosa, or periodontal membrane .

Compound or open : Fracture in which an external wound, involving skin, mucosa, or periodontal membrane, communicates with the break in the bone

Comminuted : Fracture in which the bone is splintered or crushed Greenstick : Fracture in which one cortex of the bone is broken and the other cortex is bent Pathologic : Fracture occurring from mild injury because of preexisting bone disease Multiple : Variety in which two or more lines of fracture on the same bone are not

communicating with one another

Impacted : Fracture in which one fragment is driven firmly into the other Atrophic : Fracture resulting from severe atrophy of the bone, as in edentulous mandibles Indirect : Fracture at a point distant from the site of injury Complicated or complex : Fracture in which considerable injury to the adjacent soft tissues

or adjacent parts occurs; may be simple or compound

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Site of fracture

Symphysis : Fracture in the region of the central incisors that runs from the alveolar process through the inferior border of the mandible

Parasymphyseal : Fractures occurring within the boundaries of vertical lines distal to the canine teeth

Body : From the distal symphysis to a line coinciding with the alveolar border of the masseter muscle (usually including the third molar)

Angle : Triangular region bounded by the anterior border of the masseter muscle to the posterosuperior attachment of the masseter

Ramus : Bounded by the superior aspect of the angle to two lines forming an apex at the sigmoid notch

Condylar process : Area of the condylar process superior to the ramus region Coronoid process : Includes the coronoid process of the mandible superior to the ramus

region

Alveolar process : Region that normally contains teeth

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Effects of muscle attatchments

The effect of muscle action on the fracture fragments is important in classification of mandibular

angle and body fractures. Angle fractures may be classified as

(1) vertically favorable or unfavorable and

(2) horizontally favorable or unfavorable.

The muscles attached to the ramus (masseter, temporal, medial pterygoid) displace the proximal

segment upward and medially when the fractures are vertically and horizontally unfavorable.

Conversely, these same muscles tend to stabilize the bony fragments in horizontally and vertically

favorable fractures.

In bilateral fractures in the cuspid areas, the symphysis of the mandible is displaced inferiorly and

posteriorly by the pull of the digastric, geniohyoid, and genioglossus muscles.

Condylar fractures

Condylar fractures are classified as extracapsular, subcondylar, or intracapsular. The lateral

pterygoid tends to cause anterior and medial displacement of the condylar head. Five types of

condylar fractures are described in order of increasing severity:

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Type I is a fracture of the neck of the condyle with relatively slight displacement of the head. The angle between head and axis of ramus varies from 10-45.

Type II fractures produce an angle from 45-90, resulting in tearing of the medial portion of the joint capsule.

Type III fractures are those in which the fragments are not in contact, and the head is displaced medially and forward. The fragments are confined within the area of the

glenoid fossa. The capsule is torn, and the head is outside the capsule.

Type IV fractures of the condylar head articulate on or in a forward position with regard to the articular eminence.

Type V fractures consist of vertical or oblique fractures through the head of the condyle.

Cause of fracture

Direct impact Indirect impact Excessive muscular contraction

Surgical anatomy

The mandible is a U-shaped bone. It is the only mobile bone of the facial skeleton, and, since it

houses the lower teeth, its motion is essential for mastication. It is formed by intramembranous

ossification. The mandible is composed of 2 hemimandibles joined at the midline by a vertical

symphysis. The hemimandibles fuse to form a single bone by age 2 years. Each hemimandible is

composed of a horizontal body with a posterior vertical extension termed the ramus.

Body

Lateral surface

On the anterior inferior midline region of the hemimandible body is a triangular thickening of bone

termed the mental protuberance. The thickened inferior rim of the mental protuberance extends

laterally from the midline and forms 2 rounded protrusions termed the mental tubercles. Located

lateral to the midline on the external surface are the mental foramina that transmit the mental nerves

and vessels. They usually are located below the apex of the second bicuspid and have 6-10 mm of

variation in the anteroposterior dimension. The rim of bone lateral to the mental tubercles extends

posteriorly and ascends obliquely as the oblique line to join the anterior edge of the coronoid

process. The inferior rim of the posterior body thickens and flares laterally where it attaches to the

masseter muscle.

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Medial surface

Just lateral to the symphysis on the inner surface of the mandible are 2 paired protuberances termed

the superior and inferior mental spines. The genioglossus muscle attaches to the superior mental

spines, and the geniohyoid muscle attaches to the inferior mental spines. Just lateral to the inferior

mental spines on the inferior border of the mandible are 2 concavities called the digastric fossae,

where the anterior digastric muscles attach. Extending obliquely in a posterosuperior direction from

the midline is a ridge of bone called the mylohyoid line, which serves as the attachment site for the

mylohyoid muscle. Above and below the mylohyoid line on the inner mandibular body are 2 shallow

convexities against which the sublingual and submandibular glands abut, respectively. Medial to the

ascending edge of the anterior ramus is the retromolar trigone, located immediately behind the third

molar.

Rami

Lateral surface

The ramus extends vertically in a posterosuperior direction posterior to the body on each

hemimandible. The mandibular angle is formed by the intersection of the inferior rim of the body

and the posterior rim of the ascending ramus. The superior ramus bifurcates into an anterior coronoid

process and a posterior condylar process. The concavity between the 2 processes is called the

mandibular notch. The coronoid is thin and triangular. With the teeth in occlusion, its superior extent

is medial to the zygomatic arch. The coronoid is the site of attachment of the temporalis muscle.

Inferiorly, the condylar process has a narrow neck that widens to a globular head that articulates with

the glenoid fossa of the temporal bone.

Medial surface

On the medial surface of the ramus, just below the mandibular notch, is an aperture termed the

mandibular foramen; the inferior alveolar nerve and blood vessels run through this aperture. Just

medial to the mandibular foramen is the lingula, a triangular bony protuberance with its apex

pointing posterosuperiorly toward the condylar head. Extending anteriorly and inferiorly from the

mandibular notch toward the inferior rim of the body is the mylohyoid groove, through which the

mylohyoid nerve runs.

Internal anatomy

The mandible has a large medullary core with a cortical rim 2-4 mm thick. The inferior alveolar

canal begins at the mandibular foramen and courses inferiorly, anteriorly, and toward the lingual

surface in the ramus. In adults, the canal comes in close proximity to the roots of the third molar. In

the mandibular body, the canal courses along the inferior border close to the lingual surface.

Anteriorly, the canal runs typically inferior to the level of the mental foramen, to which it ascends at

its terminal end. The mandible houses the lower dentition, which in adults consists of 2 central and 2

lateral incisors, 2 canines, 2 first and 2 second premolars, and 3 sets of molars. Interdental septi run

between the buccal and lingual cortices of the mandible, and interradicular septi run between the

mesial and distal roots of the molars.

Fracture sites

In mandible the forces are directed directly towards the base of the skull through the

temporomandibular joint, thus minor mandibular fractures may cause surprising degree of head

injury. The mandible is more sensitive to lateral impact than the frontal impact. Fracture of condyle

infact acts as a safety mechanism to prevent the transmission of force to the middle cranial fossa.

Lowest tolerance of mandible to frontal impact was found to be 425 lbs (Nahum 1972). For

symphyseal fracture 800-900 lbs (Nahum).

The mandible, the largest and strongest bone of the face, serves for the reception of the lower teeth.

It consists of a curved, horizontal portion, the body, and two perpendicular portions, the rami, which

unite with the ends of the body nearly at right angles.

The Body (corpus mandibul) : The body is curved somewhat like a horseshoe and has two

surfaces and two borders.

Surfaces : The external surface is marked in the median line by a faint ridge, indicating the

symphysis or line of junction of the two pieces of which the bone is composed at an early period of

life. This ridge divides below and encloses a triangular eminence, the mental protuberance, the

base of which is depressed in the center but raised on either side to form the mental tubercle. On

either side of the symphysis, just below the incisor teeth, is a depression, the incisive fossa, which

gives origin to the Mentalis and a small portion of the Orbicularis oris. Below the second premolar

tooth, on either side, midway between the upper and lower borders of the body, is the mental

foramen, for the passage of the mental vessels and nerve. Running backward and upward from each

mental tubercle is a faint ridge, the oblique line, which is continuous with the anterior border of the

ramus; it affords attachment to the Quadratus labii inferioris and Triangularis; the Platysma is

attached below it.

Mandible. Outer surface. Side view.

The internal surface is concave from side to side. Near the lower part of the symphysis is a pair

of laterally placed spines, termed the mental spines, which give origin to the Genioglossi.

Immediately below these is a second pair of spines, or more frequently a median ridge or impression,

for the origin of the Geniohyoidei. In some cases the mental spines are fused to form a single

eminence, in others they are absent and their position is indicated merely by an irregularity of the

surface. Above the mental spines a median foramen and furrow are sometimes seen; they mark the

line of union of the halves of the bone. Below the mental spines, on either side of the middle line, is

an oval depression for the attachment of the anterior belly of the Digastricus. Extending upward and

backward on either side from the lower part of the symphysis is the mylohyoid line, which gives

origin to the Mylohyoideus; the posterior part of this line, near the alveolar margin, gives attachment

to a small part of the Constrictor pharyngis superior, and to the pterygomandibular raph. Above the

anterior part of this line is a smooth triangular area against which the sublingual gland rests, and

below the hinder part, an oval fossa for the submaxillary gland. Borders.The superior or

alveolar border, wider behind than in front, is hollowed into cavities, for the reception of the teeth;

these cavities are sixteen in number, and vary in depth and size according to the teeth which they

contain. To the outer lip of the superior border, on either side, the Buccinator is attached as far

forward as the first molar tooth. The inferior border is rounded, longer than the superior, and

thicker in front than behind; at the point where it joins the lower border of the ramus a shallow

groove; for the external maxillary artery, may be present.

Mandible. Inner surface. Side view.

The Ramus (ramus mandibul; perpendicular portion).The ramus is quadrilateral in shape,

and has two surfaces, four borders, and two processes. Surfaces.The lateral surface is flat and

marked by oblique ridges at its lower part; it gives attachment throughout nearly the whole of its

extent to the Masseter. The medial surface presents about its center the oblique mandibular

foramen, for the entrance of the inferior alveolar vessels and nerve. The margin of this opening is

irregular; it presents in front a prominent ridge, surmounted by a sharp spine, the lingula

mandibul, which gives attachment to the sphenomandibular ligament; at its lower and back part is

a notch from which the mylohyoid groove runs obliquely downward and forward, and lodges the

mylohyoid vessels and nerve. Behind this groove is a rough surface, for the insertion of the

Pterygoideus internus. The mandibular canal runs obliquely downward and forward in the ramus,

and then horizontally forward in the body, where it is placed under the alveoli and communicates

with them by small openings. On arriving at the incisor teeth, it turns back to communicate with the

mental foramen, giving off two small canals which run to the cavities containing the incisor teeth. In

the posterior two-thirds of the bone the canal is situated nearer the internal surface of the mandible;

and in the anterior third, nearer its external surface. It contains the inferior alveolar vessels and

nerve, from which branches are distributed to the teeth. The lower border of the ramus is thick,

straight, and continuous with the inferior border of the body of the bone. At its junction with the

posterior border is the angle of the mandible, which may be either inverted or everted and is

marked by rough, oblique ridges on each side, for the attachment of the Masseter laterally, and the

Pterygoideus internus medially; the stylomandibular ligament is attached to the angle between these

muscles. The anterior border is thin above, thicker below, and continuous with the oblique line.

The posterior border is thick, smooth, rounded, and covered by the parotid gland. The upper

border is thin, and is surmounted by two processes, the coronoid in front and the condyloid behind,

separated by a deep concavity, the mandibular notch. The Coronoid Process (processus

coronoideus) is a thin, triangular eminence, which is flattened from side to side and varies in shape

and size. Its anterior border is convex and is continuous below with the anterior border of the ramus;

its posterior border is concave and forms the anterior boundary of the mandibular notch. Its lateral

surface is smooth, and affords insertion to the Temporalis and Masseter. Its medial surface gives

insertion to the Temporalis, and presents a ridge which begins near the apex of the process and runs

downward and forward to the inner side of the last molar tooth. Between this ridge and the anterior

border is a grooved triangular area, the upper part of which gives attachment to the Temporalis, the

lower part to some fibers of the Buccinator. The Condyloid Process (processus condyloideus) is

thicker than the coronoid, and consists of two portions: the condyle, and the constricted portion

which supports it, the neck. The condyle presents an articular surface for articulation with the

articular disk of the temporomandibular joint; it is convex from before backward and from side to

side, and extends farther on the posterior than on the anterior surface. Its long axis is directed

medialward and slightly backward, and if prolonged to the middle line will meet that of the opposite

condyle near the anterior margin of the foramen magnum. At the lateral extremity of the condyle is a

small tubercle for the attachment of the temporomandibular ligament. The neck is flattened from

before backward, and strengthened by ridges which descend from the forepart and sides of the

condyle. Its posterior surface is convex; its anterior presents a depression for the attachment of the

Pterygoideus externus. The mandibular notch, separating the two processes, is a deep semilunar

depression, and is crossed by the masseteric vessels and nerve. Ossification.The mandible is

ossified in the fibrous membrane covering the outer surfaces of Meckels cartilages. These cartilages

form the cartilaginous bar of the mandibular arch , and are two in number, a right and a left. Their

proximal or cranial ends are connected with the ear capsules, and their distal extremities are joined

to one another at the symphysis by mesodermal tissue. They run forward immediately below the

condyles and then, bending downward, lie in a groove near the lower border of the bone; in front of

the canine tooth they incline upward to the symphysis. From the proximal end of each cartilage the

malleus and incus, two of the bones of the middle ear, are developed; the next succeeding portion, as

far as the lingula, is replaced by fibrous tissue, which persists to form the sphenomandibular

ligament. Between the lingula and the canine tooth the cartilage disappears, while the portion of it

below and behind the incisor teeth becomes ossified and incorporated with this part of the

mandible. Ossification takes place in the membrane covering the outer surface of the ventral end

of Meckels cartilage. and each half of the bone is formed from a single center which appears, near

the mental foramen, about the sixth week of fetal life. By the tenth week the portion of Meckels

cartilage which lies below and behind the incisor teeth is surrounded and invaded by the membrane

bone. Somewhat later, accessory nuclei of cartilage make their appearance, viz., a wedge-shaped

nucleus in the condyloid process and extending downward through the ramus; a small strip along the

anterior border of the coronoid process; and smaller nuclei in the front part of both alveolar walls

and along the front of the lower border of the bone. These accessory nuclei possess no separate

ossific centers, but are invaded by the surrounding membrane bone and undergo absorption. The

inner alveolar border, usually described as arising from a separate ossific center (splenial center), is

formed in the human mandible by an ingrowth from the main mass of the bone. At birth the bone

consists of two parts, united by a fibrous symphysis, in which ossification takes place during the first

year. The foregoing description of the ossification of the mandible is based on the researches of

Low and Fawcett, and differs somewhat from that usually given.

Changes Produced in the Mandible by AgeAt birth the body of the bone is a mere shell,

containing the sockets of the two incisor, the canine, and the two deciduous molar teeth, imperfectly

partitioned off from one another. The mandibular canal is of large size, and runs near the lower

border of the bone; the mental foramen opens beneath the socket of the first deciduous molar tooth.

The angle is obtuse (175), and the condyloid portion is nearly in line with the body. The coronoid

process is of comparatively large size, and projects above the level of the condyle.

At birth.

In childhood.

In the adult.

In old age. Side view of the mandible at different periods of life.

After birth the two segments of the bone become joined at the symphysis, from below upward, in

the first year; but a trace of separation may be visible in the beginning of the second year, near the

alveolar margin. The body becomes elongated in its whole length, but more especially behind the

mental foramen, to provide space for the three additional teeth developed in this part. The depth of

the body increases owing to increased growth of the alveolar part, to afford room for the roots of the

teeth, and by thickening of the subdental portion which enables the jaw to withstand the powerful

action of the masticatory muscles; but the alveolar portion is the deeper of the two, and,

consequently, the chief part of the body lies above the oblique line. The mandibular canal, after the

second dentition, is situated just above the level of the mylohyoid line; and the mental foramen

occupies the position usual to it in the adult. The angle becomes less obtuse, owing to the separation

of the jaws by the teeth; about the fourth year it is 140. In the adult the alveolar and subdental

portions of the body are usually of equal depth. The mental foramen opens midway between the

upper and lower borders of the bone, and the mandibular canal runs nearly parallel with the

mylohyoid line. The ramus is almost vertical in direction, the angle measuring from 110 to

120. In old age the bone becomes greatly reduced in size, for with the loss of the teeth the

alveolar process is absorbed, and, consequently, the chief part of the bone is below the oblique line.

The mandibular canal, with the mental foramen opening from it, is close to the alveolar border. The

ramus is oblique in direction, the angle measures about 140, and the neck of the condyle is more or

less bent backward.

Blood supply of mandible

The mandible is primarily supplied by

Endosteal blood supply Perisoteal blood supply

Endosteal blood supply: Inferior dental artery and vein and is important in young patients.

Occasionally a fracture of mandible will result in complete rupture of inferior dental artery.

Periosteal blood supply: The periosteal blood supply becomes increasingly important with ageing

as the inferior dental artery slowly diminishes in size and gradually disappears (Bradley).

Nerve supply of mandible

Inferior dental nerve is frequently damaged in mandibular body and angle fractures producing

anesthesia and paresthesia within the sites of distribution.

In numerous cases facial nerve has been damaged due to direct trauma to the mandible. Occasionally

the mandibular division of facial nerve may be damaged in association with the fracture of the body

and the angle.

Temporomandibular joint

Traumatic arthritis without condylar fracture from indirect transmitted violence Synovial effusion with widening of joint space causing extreme pain and limited

movements

Intracapsular condylar fractures cause haemarthrosis Meniscus damage Bleeding from external ear due to external auditory meatus damage Damage to middle cranial fossa and base of the skull and glenoid fossa

Clinical examination

Clinical:

History

Obtain a thorough history specific to preexisting systemic bone disease, neoplasia, arthritis, collagen

vascular disorders, and temporomandibular joint (TMJ) dysfunction. Knowledge of the type and

direction of the causative traumatic force helps determine the nature of injury. For example, motor

vehicle accidents (MVAs) have a larger associated magnitude of force than assaults. As a result, a

patient who has experienced an MVA most often sustains multiple, compound, comminuted

mandibular fractures, whereas a patient hit by a fist may sustain a single, simple, nondisplaced

fracture.

Knowing the direction of force and the object associated with the fracture also assists the clinician in

diagnosing additional fractures.

A complete medical and psychiatric history is important for diagnosis and future treatment of mandible fractures.

Thoroughly explore possible bleeding disorders, endocrine disorders, or bony and collagenous disorders prior to surgery.

History of previous mandibular trauma can help prevent misdiagnoses. Any pretraumatic temporomandibular joint dysfunction needs to be documented in detail

prior to treatment.

The source, size, and direction of traumatic force are helpful in diagnosis. Fractures sustained by a fist tend to have single, simple, or nondisplaced fractures

whereas patients involved in motor vehicle accidents sustain compound

comminuted fractures.

Localized trauma (eg, pipe, stick, hammer) tends to cause a single comminuted

fracture since the force is concentrated in a small area.

Trauma distributed to a larger surface area may cause several fractures (eg,

symphysis, condyle) secondary to distribution of the force throughout the

mandible.

Direction of the force can help in making the diagnosis of concomitant fractures.

Trauma directed to the chin often results in a symphyseal fracture with

concomitant unilateral or bilateral condylar fractures.

Clinical examination

Advanced trauma life support protocol Note facial lacerations, swellings, and hematomas. A common site for a laceration

is under the chin, and this should alert the clinician to the possibility of an

associated subcondylar or symphysis fracture.

From behind the supine or seated patient, bimanually palpate the inferior border

of the mandible from the symphysis to the angle on each side. Note areas of

swelling, step deformity, or tenderness.

Note areas of paresthesia, dysesthesia, or anesthesia along the distribution of the

inferior alveolar nerve. Numbness in this region is almost pathognomonic of a

fracture distal to the mandibular foramen.

Standing in front of the patient, palpate the movement of the condyle through the

external auditory meatus. Pain elicited through palpation of the preauricular

region should alert the clinician to a possible condylar fracture.

Observe any deviation on opening of the mouth. Classically, deviation on opening

is toward the side of the mandibular condyle fracture. Note any limited opening

and trismus that may be a result of reflex muscle spasm, temporomandibular

effusion, or mechanical obstruction to the coronoid process resulting from

depression of the zygomatic bone or arch.

Changes in occlusion are highly suggestive of a mandibular fracture. A change in

occlusion may be due to a displaced fracture, fractured teeth and alveolus, or

injury to the temporomandibular joint.

Look for intraoral mucosal or gingival tears. Floor of the mouth ecchymosis may

indicate a mandibular body or symphyseal fracture.

Pertinent physical findings are limited to the injury site.

Change in occlusion may be evident on physical examination. Any change in

occlusion is highly suggestive of mandibular fracture. Ask the patient how his or

her bite feels.

Posttraumatic premature posterior dental contact (anterior open bite) and

retrognathic occlusion may result from an angle fracture. Unilateral open bite is

associated with a unilateral angle fracture.

Anesthesia, paresthesia, or dysesthesia of the lower lip may be evident. Most

nondisplaced mandible fractures are not associated with changes in lower lip

sensation; however, displaced fractures distal to the mandibular foramen (in the

distribution of the inferior alveolar nerve) may exhibit these findings.

Change in facial contour or loss of external mandibular form may indicate

mandibular fracture. A body fracture may cause the lateral aspect of the face to

appear flattened. Loss of the mandibular body on palpation may be due to an

unfavorable fracture. The anterior face may be displaced forward, causing

elongation. In this case, the anterior mandible is displaced downward. Damage to

the condylar growth center can cause retarded growth of the mandible and facial

asymmetry in children.

Lacerations, hematoma, and ecchymosis are associated with mandibular fractures.

Lacerations may provide diagnostic evidence of the type of fracture sustained.

Hematoma and ecchymosis may alert the clinician to a mandibular fracture. Do

not close facial lacerations before treating underlying fractures. Ecchymosis in the

floor of the mouth is a diagnostic sign of a mandibular body or symphysis

fracture.

Pain, swelling, redness, and localized heat are signs of inflammation evident in

primary trauma.

If a fracture site along the mandible is suggested, grasp the mandible on each side

of the suspected site and gently manipulate it to assess mobility.

Bilateral parasymphyseal/body and, at times, subcondylar fractures can result in

the posterior displacement of the tongue, leading to airway compromise. In

accordance with the tenets of trauma care, the airway should always be addressed

first.

Fractures that occur in the region of the teeth are considered to be compound

fractures, which can be predisposed to bacterial contamination from the oral

cavity. An open laceration and bleeding from the site also may be evident with

compound fractures. These types of fractures should, therefore, be

prophylactically treated with antibiotics.

Radiologic diagnosis

Imaging Studies:

The following types of radiographs are helpful in diagnosis of mandibular fractures: Panoramic radiograph

Lateral oblique radiographs

Posteroanterior (PA) mandibular view

Reverse Towne view

Mandibular occlusal view

Periapical radiographs

Temporomandibular joint views including tomography

CT scan

Initial screening of patients is most effective with a panoramic radiograph, since it

shows the entire mandible including the condyles.

Standard mandibular series should consist of at least a panoramic radiograph, a PA view, and a reverse Towne view.

Since an accurate panoramic radiograph requires that the patient is able to stand upright and without any motion, achieving good quality films with severely traumatized patients

may be difficult. Traditional lateral oblique views of the mandible can be used when

obtaining a panoramic radiograph is not possible.

The reverse Towne view is the plain film of choice for excluding condylar and subcondylar fractures. Transcranial temporomandibular radiographs also may be helpful in detecting

condylar fractures and anterior displacement of the condylar head. If visualization of the

condylar head is difficult with plain films, obtain a CT scan. Although high cost and

radiation exposure limit its use, CT scan is ideal for intracapsular and high neck condylar

fractures.

Occlusal views are helpful for accurate assessment of symphyseal fractures. Obtain periapical radiographs of the teeth on either side of a fracture to assess root

fractures.

Diagnostic Procedures:

For cases where the preinjury occlusion is difficult to determine, particularly in partially dentate and edentulous patients, the use of study models is very helpful. Model surgery on

the study models can be performed and acrylic splints fabricated to the new arch form.

These splints may include a lingual, palatal, or labial splint that will be secured in place

during surgery. The splints may be secured with the use of circummandibular wires for the

mandible or with circumzygomatic or piriform wires for the maxilla. A maxillary splint

also may be secured with palatal screws.

For fully edentulous patients, dentures can be secured to the maxilla and mandible and used for splints. If dentures are not available, impressions are taken of the jaws, and acrylic

baseplates are processed and used as dentures. These are known as Gunning splints. An

arch bar also can be processed into the dentures, or holes can be placed into the flange of

the denture for intermaxillary wires. Prosthetic incisor teeth can be removed for existing

dentures, and space can be made in the acrylic to allow food intake.

Preliminary treatment

Airway Haemorrhage Soft tissue lacerations Support of bone fragments Control of pain Control of infection Food and fluid

Management of mandibular fractures

Medical therapy:

Patients with isolated nondisplaced or minimally displaced condylar fractures may be treated

with analgesics, soft diet, and close observation. Patients with coronoid process fractures may

be treated similarly. Additionally, these patients may require mandibular exercises to prevent

trismus. If the fractured coronoid restricts mandible movement, medical therapy is

contraindicated. Use prophylactic antibiotics for compound fractures. Penicillin remains the

antibiotic of choice.

Nondisplaced fractures:

Analgesics

Soft diet

oral surgery referral in 1-2 days

Displaced fractures, open fractures and fractures with associated dental trauma

Urgent oral surgery consultation

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All fractures should be treated with antibiotics and tetanus prophylaxis.

Surgical therapy:

Closed reduction of dentate patients

Erich arch bars

Initially, use a bar of sufficient length to accommodate the maxillary and mandibular arches

from first molar to contralateral first molar.

Next, use 24-gauge stainless steel circumdental wires at the first bicuspid positions, one on

each side of the arch to secure the arch bar.

At this point, tightly place circumdental wires along the greater segment of the fracture.

The greater segment is the fracture segment; that is the most tooth-bearing segment.

Loosely place circumdental wires along the lesser segment of the fracture. The lesser

segment is the fracture segment that bears the least amount of teeth.

Then tightly place circumdental wires along the opposing arch.

Place the patient into his or her preinjury occlusion. With the patient held into occlusion,

tighten the looser segment circumdental wires. This prevents arch bar placement from

interfering with proper occlusion.

Place interarch 25-gauge stainless steel box wires along the molar/premolar region and the

premolar/canine region bilaterally

Placement of arch bars can be difficult when dentition is poor, the fracture is unstable and

comminuted, and dentoalveolar fractures are present.

Bridle wire

Bridle wire is used for temporary stabilization of a fractured segment. This provides some

patient comfort by minimizing mobility of the fracture segments.

Manually reduce the segments with the use of local anesthesia.

Loop two teeth (if available) with 24-gauge wire anterior and posterior to the fracture

segment. The closest stable teeth can be used if the adjacent dentition is poor or missing.

Tighten the wire in a clockwise fashion while manually reducing the segments

Ivy loops

Ivy loops are used for intermaxillary fixation when full dentition is present in good

condition and the fracture is displaced minimally.

Construct a loop in the middle of a 24-gauge wire.

Pass the loose ends of the wire interproximal to two stable teeth.

Loop the wire ends around the mesial and distal sides of the teeth.

Pass the distal wire under or through the loop and then tighten it to the mesial wire in an

apical direction.

Accomplish the same procedure on the opposite arch directly opposing the first wire.

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The loops need to be short enough to allow for an interarch wire to be tightened.

Pass a 25-gauge interarch wire through the two opposing loops and tighten it in a clockwise

fashion.

At least one ivy loop on each side is necessary.

A variety of wiring techniques (eg, Essig wire, continuous-loop [Stout] wiring) besides those

mentioned above has been used for closed reduction and intermaxillary fixation.

Closed reduction of partially edentulous patients

If a patient is partially dentate, the existing partial denture can be used for intermaxillary fixation.

The partial dentures can be secured to either jaw using circummandibular or circumzygomatic

wiring techniques. If the patient has no existing partial denture, acrylic blocks also can be fabricated

with an incorporated arch bar and secured with circummandibular or circumzygomatic wires.

Closed reduction of edentulous patients

If dentures are available, they can be secured with circummandibular wires,

circumzygomatic wires, or palatal screws.

Dentures also can be fabricated with incorporated arch bars as well as a space in the

anterior for feeding (Gunning splint). They are secured in the same fashion with

circummandibular wires, circumzygomatic wires, or palatal screws.

Biphasic pin fixation (external pin fixation or Joe Hall Morris appliance) also is used for

edentulous patients. Its indications for use are as follows:

In edentulous patients with a discontinuity defect because of either severe trauma or

resection

In severely comminuted fractures

When intermaxillary or rigid fixation cannot be used

Biphasic pin fixation using two pins on both the proximal and distal fragments: Use a

transbuccal trocar approach to place two bicortical screws on either side of the fracture.

Secure a series of locking plates and bars to the 4 or more pins and then construct a self-

curing acrylic secondary splint.

Open reduction

Wire osteosynthesis

This is rarely used for definitive fixation since the advent of rigid fixation. However, it may be

useful for help in alignment of fractured segments prior to rigid fixation.

This can be placed either by an intraoral or extraoral route. The wire should be a prestretched

soft stainless steel.

A straight wire can be used across the fracture site. This is placed so the direction of pull of

the wire is perpendicular to the fracture site. This can be placed as a monocortical or

bicortical wire.

A figure-of-8 wire can provide increased strength at the superior and inferior borders

compared to the straight wire.

Intraoral approach

Advantages over the extraoral approach are that it is quicker to perform, results in no

extraoral scar and no damage to the facial nerve, and can be performed under local

anesthesia.

Complication rates and infection rates appear to be similar between the intraoral and

extraoral approaches when large numbers of patients are studied.

Symphysis and parasymphysis fractures can be accessed through a genioplasty-type incision.

Identification of the mental neurovascular bundle is important to preserve its integrity.

Body, angle, and ramus fractures can be accessed through a vestibular incision that may

extend onto the external oblique ridge as high as the mandibular occlusal plane. Extending

the incision higher predisposes the buccal fat pad to prolapsing onto the surgical field. The

entire surface of the ramus and the subcondylar region can be exposed by stripping the

buccinator and temporal tendon with a notched ramus retractor and periosteal elevator. Bauer

retractors placed in the sigmoid and antegonial notch can help in gaining access to the

subcondylar and ramus regions.

Submandibular approach

The submandibular approach often is referred to as the Risdon approach since he first

described it in 1934.

Make the skin incision approximately 2 cm below the angle of the mandible in a natural skin

crease.

Dissect the subcutaneous fat and superficial cervical fasciae to reach the platysma muscle.

Sharply dissect the platysma to reach the superficial layer of the deep cervical fascia. The

marginal mandibular nerve runs just deep to this layer.

Carry dissection to bone through the deep cervical fascia with the aid of a nerve stimulator.

Carry the dissection down to the level of the pterygomasseteric sling.

Sharply divide the sling to expose the bone

Retromandibular approach

Hinds and Girotti first described this approach in 1967.

Make the incision approximately 0.5 cm below the lobe of the ear and continue it inferiorly

3-3.5 cm. Place it just behind the posterior border of the mandible; it may extend below the

level of the mandibular angle.

Carry the dissection through the scant platysma, superficial musculoaponeurotic layer

(SMAS), and parotid capsule.

The marginal mandibular branch and the cervical branch of the facial nerve may be

encountered.

The retromandibular vein runs vertically in this region and commonly is exposed. This vein

rarely requires ligation unless it has been transected inadvertently.

Carry out sharp incision through the pterygomasseteric sling.

Strip the muscle off the lateral surface of the mandible superiorly, which gives access to the

ramus and subcondylar region of the mandible

Preauricular approach

This approach is excellent for exposure to the temporomandibular joint.

Make the incision sharply in the preauricular folds, approximately 2.5-3.5 cm in length as

described by Thoma (1945) and Rowe (1972).

Take care not to extend the incision inferiorly, since it may encounter the facial nerve as it

enters the posterior border of the parotid gland.

Carry the incision and dissection along the perichondrium of the tragal cartilage. Some

surgeons advocate making the incision through the tragus.

The temporal fascia is encountered along the superior portion of the incision. Take care to be

sure one is deep to the superficial temporal fascia or the temporoparietal fascia.

Make an incision through the superficial (outer) layer of the temporalis fascia beginning from

the root of the zygomatic arch just in front of the tragus anterosuperiorly toward the upper

corner of the retracted flap.

Insert the sharp end of a periosteal elevator in the fascial incision, deep to the superficial

layer of temporalis fascia, and sweep it back and forth.

Once the periosteal elevator dissection is approximately 1 cm below the arch, sharply release

the intervening tissue posteriorly along the plane of the initial incision.

Retract the entire flap anteriorly, exposing the joint capsule. Fracture location dictates

whether the capsule is opened.

Intraoperative details: Concomitant dentoalveolar injuries should be evaluated and treated

concurrently with treatment of mandibular fractures. Teeth in the line of fracture should be evaluated

and if necessary, extracted. Whether teeth in the line of mandibular fractures are associated with

increased morbidity is a controversial subject. Neal, Wagner, and Alpert reported that there was no

statistical difference whether teeth in the line of fracture were removed or retained when examining

257 fractures with teeth in the line of fracture (molars, premolars, anteriors). Amaratunga looked at

191 patients with 226 fractures and used the following criteria for removal of teeth in the line of

fracture:

Excessive mobility

Root exposure due to distraction of the fracture

Tooth fracture with pulp exposure

Caries with pulp exposure

Fractures were treated with mobilization mandibular fracture (MMF) for 4 weeks or open reduction.

He found that 13.7% of teeth removed in the line of fracture had complications and that 16.1% of

teeth retained in the line of fracture had complications. He concluded that there was no significant

difference between the number of complications in the teeth removed and teeth retained groups,

which indicates that noninfected teeth in the line of fracture can be preserved when antibiotics are

used. After a review of the literature, Shetty and Freymiller made the following recommendations

concerning teeth in the line of mandibular fracture:

Intact teeth in the fracture line should be left if they show no evidence of severe loosening or

inflammatory change.

Impacted molars, especially full bony impactions, should be left in place to provide a larger

repositioning surface. Exceptions are partially erupted molars with pericoronitis or those

associated with a follicular cyst

Teeth that prevent reduction of fractures should be removed.

Teeth with crown fractures may be retained provided emergency endodontics is performed.

Teeth with fractured roots must be removed Teeth with exposed root apices tend to develop

pulpal or perio complications.

Teeth that appear nonvital at time of injury should be treated conservatively due to potential

for recovery.

Perform primary extraction when there is extensive periodontal damage.

Timing of the fracture is important; less complications occur when reduction and adequate

fixation is instituted as soon as possible.

Complications

Delayed union and nonunion

Delayed union and nonunion occur in approximately 3% of fractures.

Delayed union is a temporary condition in which adequate reduction and immobilization

eventually produce bony union.

Nonunion indicates a lack of bony healing between the segments that persists indefinitely

without evidence of bone healing unless surgical treatment is undertaken to repair the

fracture.

Nonunion is characterized by pain and abnormal mobility following treatment.

Radiographs demonstrate no evidence of healing and in later stages show rounding off of the

bone ends.

The most likely cause for delayed union and nonunion is poor reduction and immobilization.

Infection is often an underlying cause. Carefully assess teeth in the line of fractures for

possible extraction or they may be a nidus for infection.

Decreased blood supply can lead to a delay in healing. Excessive stripping of the periosteum,

especially in comminuted and edentulous fractures, can lead to delayed healing.

Alcoholics have been shown to have an increased incidence of delayed union and nonunion.

These patients usually are at increased likelihood to sustain a mandibular fracture. Whether

metabolic and vitamin deficiencies, poor compliance with intermaxillary fixation, poor bone

quality, impaired local blood supply, or most likely a combination of the above reasons is the

cause for an increased incidence of nonunion and delayed union is unknown.

Infection

In some studies, particularly those without antibiotics, infection may occur in more than 50%

of patients.

Systemic factors include alcoholism, immunocompromised patients, and lack of antibiotic

coverage

Local factors include poor reduction and fixation, fractured teeth in the line of fracture, and

comminuted fractures.

Most infections are mixed in nature, with alpha-hemolytic streptococci and Bacteroides

organisms found most commonly.

When infection is present it must be managed with debridement of sequestra, drainage, and

antibiotic therapy. Apply rigid internal fixation with or without intermaxillary fixation across

the fracture site. If a gap is present between the bone ends, a bone graft may be necessary

Malunion

Malunion is defined as improper alignment of the healed bony segments. Not all malunions

are clinically significant.

When a dentate portion is involved in the malunion, a malocclusion can result.

These malocclusions may be treated with orthodontics or osteotomies after complete bony

union

Ankylosis

Ankylosis is a rare complication of mandibular fractures.

It is most likely to occur in children and is associated with intracapsular fractures and

immobilization of the mandible.

It is believed to occur secondary to intra-articular hemorrhage, leading to abnormal fibrosis

and ultimately ankylosis.

Ankylosis may result in disturbed growth and underdevelopment of the affected side in

children. The use of only short periods of intermaxillary fixation in children can help reduce

the occurrence of this complication.

Nerve injury

The inferior alveolar nerve and its branches are the most commonly injured nerves. The

prominent sign of inferior alveolar nerve deficit is numbness or other sensory changes in the

lower lip and chin.

Damage to the marginal mandibular branch of the facial nerve is rare. More commonly, nerve

damage caused by trauma in the region of the condyle, ramus, and angle of the mandible and

by lacerations along its course is seen.

Most of the sensory and motor functions of these nerves improve and return to normal with

time.

General principles

Reduction Fixation Immobilization

Reduction

Prior to the management of mandibular fractures, the patient should be properly assessed. Reduction

of fractures can be delayed until the patient is stable. Ideally, fracture reduction should be performed

within 7-10 days. After this period, the risks of malunion, malocclusion, and facial asymmetry

increase.

Goals of treatment include anatomic reduction of fracture segments, restoration of premorbid

occlusion, and avoidance of complications. Ideally, treatment should be instituted within 7 days.

Options to consider include closed or open reduction. Closed reduction maintains the segments by

maxillomandibular fixation. Open reduction allows for direct evaluation of the mandibular segments

and further for internal or external fixation. Internal fixation can be accomplished by wire (used

more historically and in children), titanium plate, and screw fixation.

Reduction of fracture means the restoration of functional alignment of the bony fragments. Reduction has to follow exact anatomic alignment in dentulous mandible to restore the

occlusion, whereas it need not be precise in cases of edentulous mandibles where occlusion

doesnt determine the reduction.

Presence of teeth provides an accurate guide for reduction. Note for occlusal facets and wears. Any preexisting occlusal deformity or malocclusion should be recognized prior to

reduction.

Reduction can be carried out as Closed reduction : Alignment without visualization of the fracture line.

o By elastic traction

o By manipulation

Open reduction :

Closed reduction:

Most of mandibular fractures can be treated by closed reduction Relatively simple, low cost, and non invasive nature of the treatment Presence of teeth serves as a guide, but recognise any preexisting occlusal abnormalities

Indications for closed reduction

Nondisplaced favorable fractures: Open reduction carries an increased risk of morbidity, thus

use the simplest method to reduce and fixate the fracture.

Grossly comminuted fractures: Generally, these are best treated by closed reduction to

minimize stripping of the periosteum of small bone fragments.

Severely atrophic edentulous mandibles: These have little cancellous bone remaining and

minimal osteogenic potential for fracture healing. Closed reduction with the use of

circummandibular wires offers a more conservative approach.

Fractures in children involving the developing dentition: Such fractures are difficult to

manage by open reduction because of the possibility of damage to the tooth buds or partially

erupted teeth. A special concern in children is trauma to the mandibular condyle. The condyle

is the growth center of the mandible, and trauma to this area can retard growth and cause

facial asymmetry. Early mobilization (7-10 d of intermaxillary fixation) of the condyle is

important. If open reduction is necessary because of severe displacement of the fracture, the

use of resorbable fixation or wires along the most inferior border of the mandible may be

indicated.

Coronoid fractures: These fractures usually require no treatment unless impingement on the

zygomatic arch is present.

Treatment of condylar fractures: This is one of the most controversial topics in maxillofacial

trauma. Indications for open reduction are discussed below. If condylar fractures do not fall

within this criteria, they can be treated with closed reduction for a period of 2-3 weeks to

allow for initial fibrous union of the fracture segments. If the condylar fracture is in

association with another fracture of the mandible, treat the noncondylar fracture with ORIF,

and treat the condylar fracture with closed reduction.

In closed reduction an arch bar or dental wiring is carried is applied to individual arches and

satisfactory occlusion is gained after reduction and MMF is carried out.

Contraindications:

Contraindications to closed reduction:

Patients with poorly controlled seizure history

Patients with compromised pulmonary function (ie, moderate-to-severe asthma, chronic

obstructive pulmonary disease)

Patients with psychiatric or neurologic problems

Patients with eating or GI disorders

Patients who are noncompliant

Patients with alcoholism, seizure disorder, severe pulmonary dysfunction, mental retardation,

psychosis, or poor nutrition (eg, patients with diabetes)

Patients who are pregnant

Patients with multiple injuries

Patients who are unwilling to make the change in lifestyle that is needed for 4-6 weeks

These patients benefit from ORIF.

Reduction by manipulation :

When fractured segments are adequately mobile without much overriding or impaction and the patient comes for treatment immediately after trauma

Specially designed instruments for grasping Disimpaction forceps

Bone holding forceps

Can be done under GA or LA.

Redution by traction :

Intraoral traction method Prefabricated arch bars are attatched to the arches by means of dental wiring

The fractured segments are subjected to gradual elastic traction by placing elastics in

a specific pattern

Extraoral traction method

Anchorage is taken from skull of the patients and different types of head gears are used

which are connected to archbars

When elastic traction is used slow movements of mandible should be encouraged for

activation of elastics.

Patient should be kept on analgesics for pain control

Following reduction fixation is carried out (MMF)

Open reduction:

With the advent of antibiotic era, open reduction and improved fixation open reduction and rigid

fixation have emerged as the first choice treatment in mandibular fractures.

Indications for open reduction

Displaced unfavorable fractures through the angle of the mandible: Often, the proximal

segment is displaced superiorly and medially and requires an open technique for proper reduction.

Condylar fractures: Although strong evidence supporting open reduction of condylar fractures

is lacking, a specific group of individuals benefit from surgical intervention. The classic article by

Zide and Kent lists absolute and relative indications for open reduction of the fractured mandibular

condyle. Careful evaluation of each case on an individual basis is crucial.

Absolute indications

1. Displacement of the condyle into the middle cranial fossa

2. Inability to obtain adequate occlusion by closed techniques

3. Lateral extracapsular dislocation of the condyle

Relative indications

1. Bilateral condylar fractures in an edentulous patient when splints are unavailable or

impossible because of severe ridge atrophy

2. Unilateral or bilateral condylar fractures when splinting is not recommended because

of concomitant medical conditions or when physiotherapy is not possible

3. Bilateral fractures associated with comminuted midfacial fractures

Medically compromised patients: These patients may require open reduction. This group of

patients includes those with decreased pulmonary function, GI disorders, severe seizure disorders,

and patients with psychiatric or neurologic problems.

Complex facial fractures: Such fractures can be reconstructed best after open reduction and

fixation of the mandibular segments to provide a stable base for restoration.

Other fractures: Consider open reduction with primary bone grafting in fractures of a severely

atrophic edentulous mandible with severe displacement of the fracture segments or a nonunion

after closed reduction of a severely atrophic edentulous mandible fracture.

Mandibular nonunions require open access for debridement and subsequent reduction.

Malunions after improper reduction often require osteotomies through open surgical

approaches to correct mandibular

Fixation

Archbars Winter

Jelenko

Erich

Half round german silver

Dental wiring Direct dental wiring : Gilmers

Ivys interdental eyelet wiring

Essigs wiring

Risdons wiring

Col. Stouts multiloop wiring

Bonded modified orthodontic brackets Cap splints

Archbars:

It is the most versatile form of

Many types of prefabricated arch bars are available but most commonly used is Erichs archbar.

Erich arch bars

Initially, use a bar of sufficient length to accommodate the maxillary and mandibular arches

from first molar to contralateral first molar.

Next, use 24-gauge stainless steel circumdental wires at the first bicuspid positions, one on

each side of the arch to secure the arch bar.

At this point, tightly place circumdental wires along the greater segment of the fracture.

The greater segment is the fracture segment; that is the most tooth-bearing segment.

Loosely place circumdental wires along the lesser segment of the fracture. The lesser

segment is the fracture segment that bears the least amount of teeth.

Then tightly place circumdental wires along the opposing arch.

Place the patient into his or her preinjury occlusion. With the patient held into occlusion,

tighten the looser segment circumdental wires. This prevents arch bar placement from

interfering with proper occlusion.

Place interarch 25-gauge stainless steel box wires along the molar/premolar region and the

premolar/canine region bilaterally

Placement of arch bars can be difficult when dentition is poor, the fracture is unstable and

comminuted, and dentoalveolar fractures are present.

Wiring:

Bridle wire

Bridle wire is used for temporary stabilization of a fractured segment. This provides some

patient comfort by minimizing mobility of the fracture segments.

Manually reduce the segments with the use of local anesthesia.

Loop two teeth (if available) with 24-gauge wire anterior and posterior to the fracture

segment. The closest stable teeth can be used if the adjacent dentition is poor or missing.

Tighten the wire in a clockwise fashion while manually reducing the segments

Ivy loops

Ivy loops are used for intermaxillary fixation when full dentition is present in good

condition and the fracture is displaced minimally.

Construct a loop in the middle of a 24-gauge wire.

Pass the loose ends of the wire interproximal to two stable teeth.

Loop the wire ends around the mesial and distal sides of the teeth.

Pass the distal wire under or through the loop and then tighten it to the mesial wire in an

apical direction.

Accomplish the same procedure on the opposite arch directly opposing the first wire.

The loops need to be short enough to allow for an interarch wire to be tightened.

Pass a 25-gauge interarch wire through the two opposing loops and tighten it in a clockwise

fashion.

At least one ivy loop on each side is necessary.

Essigs wiring

Essigs wiring can be used to stabilize the dentoalveolar fractures as well as an anchoring device for

IMF. Luxated teeth can also be stabilized by this method.

There must be sufficient number of teeth on either side of the fracture line to take anchorage.

40 cm long prestretched wire is used. The wire is passed around the neck of the chosen teeth, one

end going buccal to lingual and other end going lingual to buccal in each interdental space

Body Rami Internal anatomy Closed reduction of dentate patientsClosed reduction of partially edentulous patientsClosed reduction of edentulous patientsOpen reduction