Seminar 12 mandibular fractures/ dental implant courses by Indian dental academy

GITAM DENTAL COLLEGE & HOSPITAL

DEPARTMENT OF

Oral & Maxillofacial Surgery

SEMINAR on Mandibular fractures Presented By: Dr. Satyajit Sahu III MDS

CONTENTS

⇒

HISTORY

⇒

ANATOMY

⇒

BIOMECHANICS

⇒

CLASSIFICATION

⇒

DIAGNOSIS:

HISTORY

,

CLINICAL

EXAMINATION

,

RADIOLOGIC EXAMINATION ⇒

CLINICAL FEATURES

⇒

GENERAL PRINCIPLES OF TREATMENT OF MANDIBULAR FRACTURES

⇒

OPEN VERSUS CLOSED REDUCTION

⇒

METHODS OF IMMOBILIZATION

⇒

COMPLICATIONS

⇒

CONCLUSION

⇒

REFERENCES

INTRODUCTION Management of trauma has always been one of the surgical subsets in which oral and maxillofacial surgeons have excelled over the years. More particularly, our experience with dental anatomy, head and neck physiology and occlusion provides us with unparalleled skills for the management of mandibular fractures.

The mandible is the second most commonly fractured part of the maxillofacial skeleton because of its prominence and its position. The location and pattern of fractures are determined by the mechanism of injury and the direction of the vector of force. In addition to this, the patient’s age, the presence of teeth and the physical properties of the causing agent also have a direct effect on the characteristics of the resulting injury.

The goals of treatment, are to restore proper function by ensuring union of the fractured segments and reestablishing pre-injury strength; to restore any contour defect that might arise as a result of the injury and to prevent infection at the fractured site. restoration of the mandibular function, in particular, as past of the stomatognathic system must include the ability to masticate properly, to speak normally and to allow for articular movements as ample as before treatment. In order to achieve these goals, restoration of the normal occlusion of the patient becomes paramount for the treating surgeon.

ANATOMY : Mandible is the largest, heaviest and strongest bone of the face. The normal mandible provides a normal airway and proper facial contour. A solid movable mandible allows normal chewing, swallowing and speech. Even though, it is a very strong structure, it is prone to injury because of its

prominent position in the facial skeleton. It is a common site of electron for receiving intentional or unintentional violence.

The body of the mandible has got horeshoe or parabola shape. Two rami project upward from the posterior aspect of the body. The condylar processes of these rami articulate with the temporal bone to form the TMJ joints. The mandible has been compared to an archery bow, which is strongest at its center and weakest at its ends, where it often breaks.

The lower jaw is a movable body, which carries the alveolar process and the teeth. The adult mandible is composed of a compact outer and inner plate of cortical bone and a central portion of medullary bone (spongiosa), whose trabeculae are distributed along the lines of maximum stress.

The lower portion of the body is heavy and thick and consist of dense cortical bone with little spongiosa and changes very little during adult life.

The alveolar process has got lingual and buccal plate of compact but thin bone. The body of mandible is naturally strengthened by a strong system of buttresses which extend into the region of rami.

On the lateral surface strong external oblique ridge extends from the body obliquely upward to the anterior border of the ramus. Medial surface is thinner than the lateral thick compact bone. Here the myelohyoid line extends from the area of the socket of the 3rd molar diagonally downwards and forwards towards the genial tubercle at the midline. Bony clin is the most vulnerable endangered targeted area, but it is naturally strengthened by the mental protuberances. In childhood, body of the mandible is buds of permanent teeth, but naturally protected due to resiliency of the bone.

The ramus consists essentially of two thin plates of compact bone, separated by a narrow portion of cancellous bone. The posterior border of the ramus is strong and rounded.

Blood supply :

•

Central blood supply through the inferior alveolar artery.

•

Peripheral blood supply through the periosteum.

In case of severely atrophic mandible, there is greater dependence on

periosteal blood supply than the central supply. Therefore if open reduction is planned, stripping of the periosteum is such that, it should be kept to a minimum.

Nerve supply : Damage to inferior alveolar nerve often fracture, results in the parasthesia or anaesthesia of the lower lip on the affected side. If the nerve is completely severed, then recovery by regeneration takes 3 to 12 months, usually proceeded by tingling sensation, parasthesia and hyperanaesthesia of the area. The rate of recovery depends on following: 1) Accurate approximation of the nerve ends. (proper reduction of fragments).

2) Elimination of infection 3) Proper fixation 4) Absence of any intervening hard or soft tissue in the inferior dental canal (muscle entrapment in the fracture line or foreign body or bone fragments.

BIOMECHANICS : The mandibular body is a parabola shaped curved bone composed of external and internal cortical layers surrounding a central core of cancellous bone. The outer cortical layer is particularly strong and gives good anchorage for osteosynthesis devices. In the chin region the cortical bone is thickest at the lower border, where as more posteriorly it is relatively thin. At the angle stronger parts are found along the upper part, along the oblique line which runs from the coronoid process to the molar region, forming a ridge cross

sections in a sub-apical region reveal on average a thickness of 2.2 – 2.4 mm at the symphysis and in the canine regions. From the host bicuspid to 1 st molar the density increases from 2.5 to 3.4 mm. In the tooth bearing alveolar process, the bone is of variable thickness.

Another important anatomic factor with references to fracture treatment using internal fixation is the mandibular canal, including nemovascualr bundle. The mandibular canal runs from the lingual of the mandible to the mental foramen in a concave course directed upwards and forwards. The distance between the canal and the outer cortical layer averages 4.0 mm in the bicuspid regions increasing to 5.9 mm at the second molar. The distance between the root apices varies from 3.4 mm (central incisor) to 6.3 mm (third molar).

The maxillary and mandibular teeth, in occlusion form a very sensitivity balanced system; Any displacement caused by fragments leads to diminution of masticatory function and comfort. The main aim in fracture treatment is therefore the restoration of normal occlusion.

Displacement of the fragments of the mandibular body is predominantly the result of activity of muscles of mastication. From a biomechanical point of view, the ideal method of osteosyhthesis would be to nentralze these unfavourable forces. The mechanical characteristic of the material used for this purpose should on one hand contain there forces and on the other hand not be so rigid that stress shielding occurs and delays healing.

Champy et al ultimately developed the technique into a practicable clinical method. Based on a methametical model of the mandible and taking into account the active biting forces applied to the mandible and performing different experimental evaluation, they were able to define the strains created within the bone by muscular activity. Moments of flexion were found at the upper border of the mandible, increasing progressively from the front of the

teeth to a maximum of approximately 600 N in the angles. Then are also tortion movements between the canines, which increases in sleight towards the middle to 1000 N. They recommended that, behind the mental foramen only one plate should be applied, immediately below the dental roots and above the inferior alveolar canal. In front of the mental foramen, in order to neutralive higher torsion forces between the canines another plate near the lower border of the mandible is necessary in addition to the subapical plate.

Muscle attachments and displacement of fractures : The periosteum is a most important structure in determining the stability or otherwise of a mandibular fracture. The periosteum of the mandible is stout and unyielding and gross displacement of fragments cannot occur if it remains attached to the bone. Perisoteum may be stripped from the bone ends by the extremity of the force applied, but frequently it yields to the accumulation of blood seeping from the ruptured cancellous bone. Once the periosteal splint has been removed displacement of the bone ends is free to occur under the influence of the attached muscles.

Fractures at the angle of the mandible : Fractures at the angle of the mandible are influenced by the medial pterygoid-masseter ‘sling’ of which the medial pterygoid is the stronger component. Fractures in this region have been classified as vertically and horizontally favourable or unfavourable. If the vertical direction of the fracture line favours the unopposed action of the medial pterygoid muscle, the posterior fragment will be pulled lingually. If the horizontal direction of the fracture line favours the unopposed action of the masseter and medial pterygoid muscle in an upward direction, the posterior fragment will be

displaced upwards. It must be remembered that vertically and horizontally unfavourable fractures may be undisplaced if the periosteum is undisturbed.

The concept is only important when the periosteum has been ruptured or stripped from the bone. A favourable facture line will, however, make the reduced fragments easier to stabilize. The presence of an erupted tooth on the posterior fragment will sometimes prevent gross displacement of this fragment in an upward direction if its crown impacts on the opposing upper tooth.

Fractures at the symphysis and parasymphysis : In the symphysis region muscle attachments are also important. The mylohyoid muscle constitutes a diaphragm between the hyoid bone and the

mylohyoid ridge on the inner aspect of the mandible. In transverse midline

fractures of the symphysis the mylohyoid and geniohyoid muscles act as a stabilizing force. An oblique fracture in this region will tend to overlap under the influence of the geniohyoid/mylohyoid diaphragm.

When a bilateral parasymphyseal fracture occurs it usually results from considerable force which disrupts the periosteum over a wide area. Such a fracture is readily displaced posteriorly under the influence of the genioglossus muscle and to a lesser extent the geniohyoid. It is often statd that such a fracture removes the attachment of the tongue to the mandible and allows the tongue to fall back and obstruct the oropharynx. This is in fact not the case, as the tongue is still firmly attached to the hyoid bone which in turn remains connected to the mandible by the posterior parts of the mylohyoid muscle. In addition, the intrinsic muscles of the tongue continue to exert control and the tongue remains forward in the oral cavity. Voluntary tongue control is lost only when the patient’s level of consciousness is depressed and consequently it is only in these circumstances that the detached symphysis constitutes a threat to the airway.

Fractures of the condylar process : When a fracture of the condylar neck occurs the condylar head is frequently displaced and sometimes dislocates from the articular fossa. The most frequent direction of displacement is medially and forward under the

influence of the lateral pterygoid muscle. The importance of this muscle as a displacing force is more dramatically illustrated in those cases where anteromedial dislocation occurs some days after injury in a previously undisplaced fracture.

Fracture of the coronoid process : This is a rare fracture which is said to be brought about b reflex muscular contraction of the strong temporalis muscle which then displaces the fragment upwards towards the infratemporal fossa.

Comminuted fractures : Extensively comminuted fractures, such as occur following missile injuries, may involve a considerable area of mandibular bone. Where there are strong muscle attachments as at the ramus and angle the amount of displacement of the comminuted segment is often remarkably little. This is explained by the fragmentation at the site of the muscle attachments. The small fragments are pulled away by the contracting muscle leaving the bulk of the comminuted bone relatively undisplaced.

HISTORY OF MANDIBULAR FRACTURES : Writings on mandibular fractures appeared as early as 1650 BC, when Egyptian papyras described the examination, diagnosis and treatment of mandible fractures and other surgical ailments.

Hippocrates described direct reappoximation of the fracture segments with the use of circumdental wires, similar to today’s bridal wires. He advocated wiring of the adjacent teeth with external bandaging to immobilize the fracture fragments. The importance of establishing proper occlusion was described in 1180, Salerno, Italy. In 1492, the use of maxillomandibular fixation in the treatment of mandibular fracture was advocated 1795 Chopart

and Desault described the effects of elevator and depressor muscle on mandibular fragments.

Through 1800s and early 1900s, several methods were used to reduce and immobilize mandibular fractures.

HISTORY OF

TREATMENT

BANDAGES

AND

EXTERNAL

APPLIANCES:

Bandages, first mentioned by Hippocrates, gained notoriety and acceptance as a standard of care when John Rhe Barton described his Barton bandage. This bandage provided posterior directional forces on the fractured mandible, resulting in deformities such as the “bird face” and maluniouns.

Extraoral and Intraoral Appliance: The appliance worked by placing a rigid splint on the occlusal surface of the teeth and one on the undersurface of the mandible. A viselike device

was then used to apply pressure to the two splints, theoretically immobilizing and fixating the fractured segments.

Gunning was the first to use a custom-fitted intraoral dental splint for immobilization. He used the splint in conjunction with an external head appliance. His splints could also be applied to both the maxilla and the mandible, resulting in intermaxillary fixation. An anterior space was provided for nourishment. This basic principle of using splints for intermaxillary fixation, although modified, is still used routinely in the treatment of edentulous and partially edentulous mandible fractures.

Monomaxillary wiring, Bars, Arches, and Splints:

Originally advocated by Hippocrates, then later supported in the writings of numerous authors, monomaxillary wiring was popular in the treatment of mandible fractures. Being similar in concept to today’s bridle wire and to the Risdon wire of the early 1920s, monomaxillary wiring afforded ed some element of reduction, but without supplemental fixation, fractures were inadequately immobilized.

Splints became popular in the middle of the nineteenth century and were usually cast of metal and custom-fitted for the patient. Splints were fabricated with the use of models made after reduction of the fragments.

Some were cemented to lingual segments together.

The use of monomaxillary wiring, bars, arches, and splints is limited to fractures containing stable teeth on both sides of the fracture.

Intermaxillary Wiring: Guglielmo Salicetti (William of Saliceto) has been credited with being the first to use intermaxillary fixation. Gilmer, also credited with being the first to use this technique, passed wires around individual teeth of both arches and then ligated these opposing wires.

Orthodontic bands and arches were used in patients with loose, fractured, or missing teeth. The famous American orthodontist Angle described many methods of intermaxillary fixation that used bands and other orthodontic techniques.

Open Reduction and Internal Fixation: Sutures: In the middle of the nineteenth century, Buck and Kinlock described the use of wire ligature for the immobilization of mandible fractures. Using this method, one would drill a hole on both sides of the fracture site and then pass a wire. The wire, which was iron or silver, was then tightened periodically by creating pigtails on each end of it. This method was hampered by a high incidence of infection.

Bone Plates: In 1881, Gilmer described a method of mandibular fracture fixation the used two heavy rods placed on either side of the fracture and wired together.

The rods were pushed through skin, mucous membrane, and bone and were wired on both the mouth and the skin sides. Dorrance and Bransfield state that the earliest reference to the use of true bone plates was that of Schede, who, around 1888, used a solid steel plate held by four screws. During World War I, Kazanjian used, wire sutures through bone fragments and tied the wire to an arch bar for fixation.

Biodegradable Plates and Plating Systems:

Internal rigid fixation of the facial skeleton is a reliable method of obtaining osteosynthesis. Historically, metallic plates and screws have been used to allow for early passive and active function. Depending on the type and location of the implants, it may be necessary to remove the materials at a later time. Scher and colleagues (1988) and Merrit and Brown (1985) have reported multiple potential problems with maintaining metallic implants in the facial skeleton. It may become necessary to remove plates because of stress -protection-induced osteopenia in the cortex beneath the plate, causing a reduction in cortical thickness and shaft caliper.

The use of resorbable plates and screws has been studied for nearly 20 years. Most of the studies included polymers (e.g., poly L-lactide polyglycolide, and polydioxanone).Bos (1989) and Rozema and associates (1990) reported on studies in which Champy’s principles were followed and healing was uneventful, without callus formation. They also reported that no backscatter was seen with irradiation. Gerlach, (1988) also reported uneventful healing, although reported healing included callus formation.

The dimensions of plates for these studies were usually large, when compared to miniplates. This would limit their use in the maxillofacial region.

These materials have less strength, which would limit their use in loaded and functional bone.

In the mid-1960s, Luhr pursued research in rigid fixation for the facial skeleton and developed the Vitallium mandibular compression plate, using glide screw principles. Throughout the 1960s. Luhr continued research on rigid fixation and also contributed the self-threading screw. In the 1970s, investigators, including Spiessl, studied AO/ASIF principles. They found that adaptation of a compression plate on the lateral cortex, at the inferior border, the superior border (tension zone) splayed. Many investigators thought a second tension-zone plate would be necessary, others, believed that arch bars in tooth-bearing areas were sufficient to limit the tension-zones splaying. In 1973, Schmocker and Speissl developed the eccentric dynamic compression plate, which provided compression at the tension and compression zones of the mandible. When the screws closest to the fracture were tightened, the fracture line would be placed under compression. When the eccentric terminals were tightened, the alveolar segment would be reduced.

In the early 1970s investigations were started to evaluate the use of smaller plating systems. In 1973, Michelet and colleagues placed bendable, monocortical miniplates to treat mandible fractures. The advantages of miniplates were their thinness and the fact that they could be placed through intraoral incisions.

Edentulous Mandibular Fractures :

The history of treating fractures of edentulous jaws began with a report

by Baudens (1844), who used circumferential wiring to reduce and fix the bone. Gunning used splints, as described previously. Robert (1851) used silver wire passed circumferentially around the mandible with a needles, and tied the wire around a piece of lead that had been molded to the edentulous mandible.

STATISTICS ASSOCCIATED WITH MANDIBULAR FRACTURES: Demographic data related to mandibular fractures are difficult to evaluate because of the many variables associated with the studies. Statisticsrelated to mandibular fractures are available from countries throughout the world. However, most are retrospective. The studies discuss maxillofacial injures, situations that require extensive treatment. Statistics from smaller developing countries tend to show that mandibular fractures are usually isolated, single, nondisplaced fractures caused by assaults and treated only by intermaxillary fixation. Study of Ellis and coworkers, vehicular accidents accounted for only 15% of the fractures. The difference may be explained by the environmental and social characteristics of the locality under study.

A decade later, however, the etiologic trend had changed, as shown by Fridrich and associates in retrospective study involving the same demographic area. They demonstrated that altercations accounted for 47% of fractures, and automobile accidents 27%. Vetter and coworkers also commented on the change in etiology when they mentioned that within a decade’s time the ratio of motor vehicle accidents to interpersonal assault as the cause of mandible fractures in creased from around 3:2 to almost 1:1.

Etiology of Mandibular Fractures: Despite the many variables associated with the etiology of mandibular fractures, vehicular accidents and assaults are undoubtedly the primary causes of mandibular fractures throughout the world.

Location of Mandibular Fractures : In the cases evaluated for fracture location, the mean percentages were in following: body (29%), condyle (26%), angle (25%), symphysis (17%), ramus (4%), and coronoid proces (1%). As discussed, the variables are enormous, but certainly, as a generalization, fractures that occur in the body, condyle, and angle do not differ much in incidence, and fractures of the ramus and coronoid process are rare.

Individual studies demonstrate how etiology plays a role in fracture location. Fridrich and associates showed that when fractures due to automobile accidents were considered, the condylar region was the most common site. When motorcycle accidents were considered, the symphysis was the are most often affected. When assault was considered, the angle demonstrated the highest incidence of fracture.

Facial Fractures Associated With Mandibular Fractures : Mandibular fractures were the only facial bone fractures in fractures in an average of 70% of the

patients. The literature is generally divided

between patients with mandibular and midface fractures and those with mandibular and “other facial bone� fractures. Of the patients reported, 15% had another facial bone fracture, along with the fractured mandible.

Non maxillofacial Trauma Associated With Mandibular Fractures The literature dealing with concomitant non maxillofacial injuries associated with mandibular fractures is difficult to interpret with the wide variation in reported injuries. In the study of Ellis and colleagues, 90% of the patients had no other injuries, probably because the etiology was primarily assault. olson and colleagues reported associated injuries in 46.6% of all patients treated, most of whom were involved in vehicular accidents.

CLASSIFICATION OF MANDIBULAR FRACTURES: 1. Simple, or closed: A fracture that does not produce a wound open to the external environment, whether it be through the skin, mucosa, or periodontal membrane.

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

3. Comminuted: A fracture in which the bone is splintered or crushed.

4. Greenstick: A fracture in which one cortex of the bone is broken, the other cortex being bent.

5. Pathologic: A fracture occurring from mild injury because of pre-existing bone disease.

6. Multiple: A variety in which there are two or more lines of fracture on the same bone not comunicating with one another.

7. Impacted: A fracture in which one fragment is firmly driven into the other.

8. Atrophic: A spontaneous fracture resulting from atrophy of the bone, as in edentulous mandibles.

9. Indirect: A fracture at a point distant from the site of injury.

10.Complicated, or complex: A fracture in which there is considerable injury to the adjacent soft tissues or adjacent parts; may be simple or compound.

Classification by Anatomic Region : Mandibular fractures are also classified by the anatomic areas involved. These areas are as follows: symphysis, body, angle, ramus, condylar proces, coronoid process, and alveolar process. Dingman and Nativig defined these regions as follows: 1. Midline : Fractures between central incisors 2. Parasymphyseal: Fractures occurring within the area of the symphsis 3. symphysis: Bounded by vertical lines distal to the canine teeth 4. Body : From the distal symphysis to a line coinciding with the alveolar boreder of the masseter muscle (usually including the third molar)

5. Angle : Traingular region bounded by the anterior border of the masseter muscle to-the posterosuperior attachment of the masseter muscle (usually distal to the third molar) 6. Ramus : Bounded by the superior aspect of the angle to two lines forming an apex at the sigmoid notch 7. Condylar Process: Area of the condylar process superior to the ramus regions 8. Coronoid Process: Includes the coronoid process of the mandible superior to the ramus region.

9. Alveolar Process : The region the would normally contain teeth.

Kazanjian and Converse classified mandibular fractures by the presence or absence of serviceable teeth in relation to the line of fracture. They thought that their classification was helpful in determining treatment. Three classes were defined: Class I:

Teeth are present on both sides of the

fracture

line.

Class II: Teeth are present on only side of the fracture

line.

Class III: The patient is edentulous.

They believed that class I fractures could be treated by a variety of techniques, using the teeth for monomaxillary or intermaxillary fixation. Class II fractures, usually involving for monomaxillary angle or partially edentulous body of the mandible, require intermaxillary fixation. Class III fractures require prosthetic techniques or open reduction methods, or both, for stabilization.

Rowe and Killey divided mandibular fractures into two classes: (1) those not involving basal bone and (2) those invovling basal bone. The first class primarily comprised alveolar process fractures. The second class was divided into single unilateral, double unilateral, bilateral, and multiple.

Kruger and Schilli took into account many of the aforementioned classifications and developed four categories of mandibular fractures:

I.

II.

III.

IV.

Relation the External Environment A.

Simple or closed

B.

Compound or open

Type of Fractures A.

Incomplete

B.

Greenstick

C.

Complete

D.

Comminuted.

Dentition of the Jaw With Reference to the Use of Splints A.

Sufficiently dentulous jaw

B.

Edentulous or insufficiently dentulous jaw

C.

primary and mixed dentition

Localization A.

Fractures of the symphysis region between the

canines B.

Fractures of the canine region

C.

Fractures of the body of the mandible between the

canine

and the angle of the mandible D. molar region

Fractures of the angle of the mandible in the

third

E.

Fractures of the mandibular ramus between the

angle of the mandible and the sigmoid notch F.

Fractures of the coronoid process

G.

Fractures of the condylar process.

An important classification of mandibular angle and body fractures relates to the direction of the fracture line and the effect of muscle action on the fractures fragments. Angle fractures may be classified as (1) vertically favorable or unfavorable and (2) horizontally favorable or unfavorable.

In fractures of the angle of the mandible, the muscles attached to the ramus (masseter, temporal, and medial pterygoid) displace the proximal segment upward and medially when the fractures are vertically and horizontally unfavorable. Conversely, these same muscles tend to impact the bone, minimizing displacement in horizontally and vertically favorable fractures. The farther forward the fracture occurs in the body of the mandible, the more the upwards displacement of those muscles is counteracted by the downward pull of the mylohyoid muscles. In bilateral fractures in the cuspid areas, the symphysis of the mandible displaced inferiorly and posteriorly by the pull of the digastric, geniohyoid, and genioglossus muslces.

DIAGNOSIS OF MANDIBULAR FRACTURES: History:

A thorough history is imperative for the proper diagnosis of mandibular fractures. The patient’s health history may reveal pre-existing systemic bone disease, neoplasia with potential metastasis, arthritis and related collagen disorders, nutritional and metabolic disorder, and endocrine disease that may cause or be directly related to the fractured jaw. The history also reveals significant medical and psychiatric problems that will influence tha management of the patient and perhaps even dictate treatment modalities.

A history of temporomandibular joint dysfunction can have significant legal and post-treatment ramifications.

The type and direction of traumatic force can be extremely helpful in diagnosis. Fractures sustained in vehicular accidents are usually far different from those sustained in personal altercations. Since the magnitude of the force can be much great, victims of automobile and motorcycle accidents tend to have multiple, compound, comminuted mandibular fractures, whereas the patient hit by a fist may sustain single, simple, non displaced fractures.

The object that caused the fractures can also influence the type and number of fractures. A blow from a broad, blunt object (2 X 4 piece of wood) may cause several fractures (e.g., symphysis and condyle) because the impact of the force is sustained throughout the bone, whereas a smaller, welldefined object (hammer or pipe) may cause a single comminuted fracture, since the impact of the force is concentrated in a smaller area.

Knowing the direction of force can help the clinician diagnose concomitant fractures. An anterior blow directly to the chin can result in bilateral condylar fractures, and an angled blow to the parasymphsis may cause a contralateral condylar or angle fracture. A patient with teeth clenched together at the moment of impact is more likely to have dental and alveolar process fractures than moment of impact is more likely to have dental and alveolar process fractures than basal bone fractures. Even knowing where the patient was sitting in an automobile may aid in the diagnosis of mandibular or other injuries. Chest injuries caused by nonecollapsible steering wheels, facial fractures caused by striking unpadded of predictable injuries that have been eliminated by the use of seat belts and by effective automotive safety engineering.

Clinical Examination : The signs and symptoms of mandibular fractures are as follows.

Change in Occlusion :

Any change in occlusion is highly suggestive of mandibular fracture.

The clinician should ask the patient whether his or her bite feels different. A change in occlusion can result from fractured teeth, a fractured alveolar process, a fractured mandible at any location, and trauma to the temporomandibular joint and muscles of mastication. Post-traumatic premature posterior dental contact or anterior open bite may result from bilateral fractures of the mandibular condyle or angle as well as from maxillary fractures with inferior displacement of the posterior maxilla.

Posterior open bite may occur with fractures of the anterior alveolar process or parasymphyeal fractures. Unilateral open bite may occur owing to ipsilateral angle and parasymphyseal fractures. Posterior crossbite can result from midline symphyseal and condylar fractures with splaying of the posterior mandibular segments.

Retrognathic occlusion is assocated with condylar or angle fractures (as well as forward displaced maxillary fractures), and prognathic occlusion can occur with effusion of the temporomandibular joints, and with protective forward posturing of the mandible (also retro positioning of the maxilla).

These examples are only a few of the multiple occlusal disharmonies that can exist, but any change in occlusion has to be considered the primary diagnostic sign of mandibular fracture.

Anesthesia, Paresthesia, or Dysesthesia the Lower Lip:

Although changes in sensation in the lower lip and chin may be related to chin and lip lacerations as well a s blunt trauma, numbness in the distribution of the inferior alveolar nerve after trauma is almost path gnomonic of a fracture distal to the mandibular foramen. Conversely, most nodisplaced fractures of the mandibular angle, body, and symphsis are not characterized by anesthesia, so the clinicians must not use lip anesthesia as the sole feature in diagnosis.

Abnormal Mandibular Movements:

Most patient presenting with a fractured mandible have limited opening and trismus owing to guarding of the muscle of mastication. However, certain mandibular fractures or associated facial fractures result in predictable abnormal mandibular movements. A classic example is deviation on opening toward the side of a mandibular condylar fracture. Because lateral pterygoid muscle function on the unaffected side is not counteracted on the opposite side by the nonfunctioning lateral pterygoid muscle, deviation results.

Inllability to open the mandible may be caused by the impingement of the coronoid process on the zygomatic arch either from fractures of the ramus and coronoid process or from depression of a zygomatic arch fracture.

Inability to close the jaw can be the result of fractures of the alveolar process, angle, ramus, or symphysis, causing premature dental contact. Lateral mandibular rmovements may be inhibited by bilateral condylar fractures and fractures of the ramus with bone displacement.

Change in Facial Contour and Mandibular Arch Form

Although facial contour may be masked by swelling, the clinicinan should examine the face and mandible for abnormal contours. A flattened appearance of the lateral aspect of the face may be the result of a fractured body, angle, or ramus. A deficient mandibular angle can occur with unfavorable angle fractures in

which the proximal fragment rotates

superiorly. A retruded chin can be caused by bilateral parasymphyseal fractures. The appearance of an elongated face may be the result of bilateral subcondylar, angle, or body fractures, allowing the anterior mandible to be displaced downward. Facial asymmetry should alert the clinician to the possibility of mandibular fracture. The same holds true for mandibular arch form. If there is a deviation from the normal U-shaped curve of the mandible, fracture should be suspected.

Laceration, Hematoma, and Ecchymosis :

Trauma significant enough to cause loss of skin or mucosal continuity or subcutaneous-sub mucosal bleeding certainly can result in trauma to the underlying mandible. Lacerations should be carefully inspected prior to closure. The direction and type of fracture may be visualized directly through the laceration, with the clinician thus gaining diagnostic information that may be impossible to ascertain clinically or radio graphically. The common practice of closing facial lacerations before treatment standpoint. The diagnostic sing of ecchymosis in the floor of the mouth indicates mandibular body or symphyseal fracture.

Loose Teeth and Crepitation on Palpation : A thorough examination of the teeth and supporting bone can help diagnose alveolar process, body, and symphyseal fractures. A force strong enough to loosen teeth certainly can fracture than underlying bone. Multiple fractured teeth that are firm indicate that the jaws were clenched during traumatic insult, thus lessening the effect on the supporting bone.

The

clinician should palpate the mandible using both hands, with the thumb on the teeth and the fingers on the lower border of the mandible. By slowly and carefully placing pressure between the two hands, the clinician can detect crepitation in a fracture.

Too often, this simple diagnostic technique is

overlooked in favour of extensive (and expensive) radiologic diagnostic methods.

Dolor, Tumor, Rubor and Color : Pain, swelling, redness, and localized heat have been noted as signs of inflammation since the time of the ancient Greeks. All these findings are excellent primary sings of trauma and can greatly increase the index of suspicion for mandibular fracture.

Radiologic Examination: The following are types of radiologic studies that are helpful in the diagnosis of mandibular fractures : • Panoramic radiograph • Lateral oblique radiograph • Posteroanterior radiograph • Occlusal view • Periapical view • Reverse Towne’s view • Temporaomandibular joint, including tomograms • Computed tomography (CT) scan.

The single most informative radio logic study used in diagnosing mandibular fractures is the panoramic radiograph, showing the entire mandible, including condyles. The advantages are simplicity of technique, the ability to visualize the entire mandible in one radiograph, and the generally good detail.

The disadvantages are as follows; The technique

usually requires the patient to be upright (machines that allow the patient to be prone are available), which may make it impractical in the severely traumatized patient; it is difficult to appreciate buccal-lingual bone displacement or medical condylar displacement; and fine detail is lacking in the temporomandibular joint area, the symphysis region (depending on type of equipment), and the dental and alveolar process region. A secondary but important disadvantage is that panoramic radiographic equipment is not present in all hospital radiology facilities.

The lateral oblique view of the mandible can be help in the diagnosis of ramus, angle, and posterior body fracture. The technique is simple and can be done in any radiology department. The condyle region is often unclear, as is the bicuspid and symphysis region. The Caldwell posteroanterior view demonstrates any medial or lateral displacement of fractures of the ramus, angle, body and symphysis. The condylar region is not well demonstrated on this view, but midline or symphyseal fractures can be well visualized. The anteroposterior view is occasionally used for patients who cannot be positioned in the supine position; however, considerable magnification and distortion occur with this view. The mandibular occlusal view demonstrated on this view, but midline or symphyseal fractures can be well visualized. The anteroposterior view is occasionally used for patients who cannot be positioned in the supine position; however, considerable magnification and distortion occur with this view. The mandibular occlusal view demonstrates discrepancies in the medial and lateral position of body fractures and also shows anteroposterior displacement in the symphysis region.

The reverse

Towne’s view is ideal for showing medial displacement of condyle and condylar neck fractures. Transcranial lateral views of the temporomandibular joint are helpful in detecting condylar fractures and anterior displacement of the condylar head. Periapical dental films show the most detail and can be used for nondisplaced linear fractures of the dody as well as alveolar process

and dental trauma. Plain tomograms can be used in an anteroposterior and lateral direction when greater detail is necessary. The CT scan is ideal for condylar fractures that are difficult to visualize; however, greater expense and radiation exposure limit its use to cases that cannot be diagnosed with plain films and panoramic tomography.

In summary, as with most other imaging procedures, it is usually optimal to have views of the mandible in two planes oriented at 90 degrees to each another.

GENERAL PRINCIPLES IN THE TREATMENT OF MANDIBULAR FRACTURES 1. The patient’s general physical status should be carefully evaluated and monitor prior to any consideration of treating mandibular fractures.

It must be emphasized that any force great enough to cause a fractured mandible is capable of injuring any other organ system in the body. This fact is obvious when dealing with massive “crush” injuries of the face with concomitant multiple organ system involvement. However, it is all too easy for the clinical to focus on an obvious isolated mandibular fracture without noting a fractured cervical spine. The downward spiral to disaster can begin by not following this principle.

Banna also reported a case and reviewed the literature on posttraumatic thrombotic occlusion associated with an undisplaced body fracture of the mandible became apparent 48 hours after the injury. Gordon and colleagues described a patient with a unilateral body fracture of the mandible who developed symptoms of a ruptured spleen 5 day after the injury and 3 days after arch bars had been placed.

2.

Diagnosis and treatment of mandibular fractures should

approached methodically not with an “emergency-type�

be

mentality.

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

Diagnosis on the basis of the history and local physical and radio logic examination should be expedited in an orderly, efficient manner, and treatment should be instituted in a controlled environment and fashion. This is not, however, to condemn prolonged, unnecessary delay, which can increase the potential for infection and nonunion.

3.

Dental injuries should be evaluated and treated

treatment of mandibular fractures.

concurrently

Teeth are often injured with mandibular fractures, and although the teeth may not have to be restored immediately, dental knowledge is vitally important in determining which teeth can and should be maintained. (a) Fractured teeth can become infected and jeopardize bone union; however, an intact tooth in the line of fracture that is maintaining bone fragments can be intact tooth in the line of fracture that is maintaining bone fragments can be protected with antibiotic coverage. (b) A second molar on an otherwise edentuolus posterior fracture segment should be maintained to prevent superior displacement of the fragment in intermaxillary fixation. (c) Mandibular cuspids are the cornerstone of occlusion and should be maintained at all costs. (d) Some teeth are not critical to restoration and can be removed when their prognosis is doubtful and when maintenance may adversely affect fracture treatment. For example, a lone mandibular incisor adds little to future bridge or partial denture construction; however, a single molar tooth in an otherwise edentulous posterior quadrant can be critical to dental rehabilitation. (e) Some fractured teeth cannot be salvaged no matter how critical they may be. For example, a molar tooth may be split mesially and distally, so reconstruction would be impossible. Maintenance of this tooth during intermaxillary fixation may result in severe discomfort and perhaps infection.

4.

Re-establishment of occlusion is the primary goal in

the

treatment of mandibular fractures.

Probably because fo the mandible’s excellent blood supply, nonunion of mandibular fragments is rare, so it is apparent that bone fragments do not have to be in tight approximation to heal. In addition, in most cases, facial aesthetics will not be adversely affected by slight fragment displacement.

However, function can be seriously compromised when improper treatment results in malocclusion. Impressive-appearing radiographic bone adaptation should not be the primary treatment goal.

5. first.

With multiple facial fractures, mandibular fractures should be treated

The old adage “inside out and from bottom to top� applies to the proper sequence to follow when treating facial fractures. To build a foundation on which the facial bones can be laid, it is proper that the mandible be reconstructed first, although with the use of rigid fixation, deviation from this principle can be allowed. All intraoral surgery should be done prior to any extraoral open reductions or suturing of facial lacerations.

Too often, lip and skin wounds that have been meticulously closed in an emergency room are inadvertently, or ever necessarily, reopened during the treatment of mandiblular fractures. Gross debridement and control of hemorrhage should be combined with temporary measures to reapproximate extraoral wounds, thus allowing definitive treatment to be carried out after the intraoral procedures are completed.

6.

Intermaxillary fixation time should vary according to

the

type,

location, number, and severity of the mandibular fractures as well as the patient’s age and health and the method used for reduction and immobilization.

Historically, a period of 6 weeks of intermaxillary fixation has been used to occur. however, this time is only empirical and should vary with the patient and the clincial situation. A simple, nondisplaced greenstick mandibular fracture occurring in a healthy child would certainly require less intermaxillary fixation time than multiple, grossly comminuted, compound mandibular fractures occurring in an elderly, unhealthy patient. With the advent of rigid fixation techniques, intermaxillary fixation may be eliminated or maintained with light elastics for short periods.

7.

Prophylactic antibiotics should be used for compound

fractures.

Numerous studies in the literature demonstrate the advantages of antibiotics in the management of compound mandibular fractures, and despite the number of new antibiotics, penicillin remains the agent of choice.

8.

Nutritional needs should be closely monitor postoperatively.

Excellent reduction and fixation techniques may fail in a patient who

has undergone significant weight loss and a catabolic nutritional status.

9.

Most mandibular fractures can be treated by closed reduction.

With the current enthusiasm for open reduction and rigid fixation in the treatment of mandibular fractures, it is important to remember that closed reduction techniques have a long history of success. Although open techniques have advantages, such as more exacting bone fragment reapproximation and earlier return to function by the patient, significant disadvantages exist as well. They may subject the patient to prolonged anesthesia, may increase the risk of infection and metal rejection, may cause damage to adjacent teeth and nerves, may result in lntra oral or extraoral scarring, and may increase hospitalization time and cost.

Indications for Closed Reduction

Nondisplaced Favorable Fractues The simplest means possible should be used to reduce and fixate mandibular fractures. For the reasons specified previously, open reduction can carry an in creased risk of morbidity, so if possible, closed techniques should be use for treatment.

Grossly Comminuted Fractures

Because of the excellent blood supply to the face, small fragments of bones will coalesce and heal if the associated periosteum is not disturbed.

Comminuted fractures should be managed as a “bag of bones�, with the clinician utilizing closed techniques to establish normal occlusion without violating the integrity of the vascular supply to the bone fragments.

Fractures Exposed by Significant Loss of Overlying Soft Tissues Fracture repair is somewhat dependent on soft tissue coverage and vascular supply. Soft tissue coverage should be established by rotational flaps, micro vascular grafts, or (if the area is small) secondary granulation.

Wires, screws, and plates may decrease the chance of successful bone union by further disrupting the covering soft tissue.

Edentulous Mandibular Fractures

These fractures present a special challenge because the inferior alveolar vascular supply to the bone is severely compromised, there is little cancellous bone (with associated osteoblastic endosteum) for repair, and the fractures usually occur in the elderly, in whom the normal healing potential can be retarded. Open reduction requires stripping of the covering periosteum, which further inhibits osteogenesis. Closed reduction with the use of mandibular prosthesis held in place by circum-mandibular wire offers a more conservative approach. If delayed healing or nonunion occurs and open reduction is necessary, a supplemental bone graft across the fracture site should be considered. In severely atrophic edentulous ridges, open reduction with primary bone grafting may be indicated, since proper alinment of the fractured ends of bone may be impossible because of the small crosssectional diameter of the mandibular body.

Mandibular Fractures in Children With Developing Dentitions

Open reduction with or plates carries the risk of damage to the developing tooth buds, which occupy a major portion of the mandible in, children. If open reduction is necessary because of gross displacement of the fragments, fine wires should be placed at the most inferior border of the mandbile, engaging only the cortex Closed reduction is indicated with special special wiring technique (continuous loop) or fabricated acrylic splints maintained by circum-mandibular wiring. A special concern in children is fractures of the mandibular condyle. Damage to the condylar growth center can result in retarded

growth of the mandible and facial asymmetry.

Intracapsular condylar fractures in children can also lead to ankylosis of the joint, so early mobilization is indicated.

Coronoid Process Fractures : Fractures of the coronoid process are rarely isolated and are usually simple and linear with little displacement, although with extreme trauma the bone may be displaced into the temporal fossa. Isolated fractures of the coronoid process cause trismus and swelling in the region of the zygomatic arch. There may be swelling in the retromolar area and a lateral crossbite.

Treatment is usually instituted only if the occlusion is compromised or if the fractured coronoid process impinge on the zygomatic arch, inhibiting mandibular movement.

Condylar Fractures : Most condylar fractures can and should be treated via-clsoed techniques if the occlusion is compromised. Early jaw mobilization and physical therapy are indicated to prevent ankylosis or limited jaw movements.

Indications for Open Reduction Displaced Unfavorable Fractures Through the Angle of the Mandible Open reduction is indicated for this fracture when the proximal fragment is displaced superiorly

or medially and reduction cannot be

maintained without intraosseous wires, screws, or plating.

Displaced Unfavorable Fractures of the Body or the Parasymphyseal Region of the Mandible The mylohyoid, digastric, geniohyoid, and genioglossus muscles may further displace the fragments. When treated with closed reduction, parasympyseal fractures tend to open at the inferior border, with the superior aspects of the mandibular segments rotating medially at the point of fixation.

With medial rotation of the body of the mandible, the lingual cusps of all premolars and molars move out of occlusal contact. If the constriction is not corrected, masticatory inefficiency and negative periodontal changes occur.

Multiple Fractures of the Facial Bones :

In multiple fractures of the facial bones, open fixation of the mandibular segments provides a stable base for restoration.

Midface Fractures and Displaced Bilateral Condylar Fractures With midface fractures and displaced bilateral condylar fractures, one of the condylar fractures should be opened to establish the vertical dimension of the face. If this procedure is not done, any type of suspension wiring, such as that from th fronto zygomatic suture area to the mandible, would tend to collapse and telescope the fractures of the midface and condyles, resulting in a foreshortened facial appearance.

Fractures of an Edentulous Mandible With Severe Displacement of the Fracture Fragments

In fractures of an edentulous mandible with severe displacement of the fracture fragments, open reduction should be considered to re-establish continuity of the mandible. The technique is especially helpful with a nonatrophic mandible when there are no dentures, so the occlusion is not an immediate concern. In this situation, palting of the mandible without intermaxillary fixation should be a strong possiblity. As the mandible becomes extremely atrophic, consideration must be given to the status of blood supply to the bone and the effect of an open surgical procedure on the compromised vascularity. Supplemental bone grafts have to be considered in extremely atrophic mandibular fractures.

Edentulous Maxilla Opposing a Mandibular Fracture When a maxilla opposing a mandibular fracture is edentoulous or contains insufficient teeth to allow intermaxillary fixation, open reduction should be considered. Open reduction with rigid fixation of the mandibular fractures would eliminate the need for intermaxillary fixation, However, if the patient’s condition warrants closed reduction, a prosthesis could be constructed for the maxilla, it could be stabilized with palatal screws or circumzygomatic wires, and routine intermaxillary fixation could be utilized to treat th fractured mandible.

Delay of Tratment and Interposition of Soft Tissue Between Noncontacting Displaced Fracture Fragments When treatment has been delayed and soft tissue become interposed between noncontacting displaced fracture fragments, open reduction should be utilized. there are instances in which the treatment of mandibular fractures is delayed because of head injury or other serious medical problems, so withy time connective tissue grows between the bone fragments, inhibiting osteogenesis. When treatment is finally instituted, scar tissue must be removed, and treatment completed via an open approach.

Malunion When a poor result is obtained after mandibular fracture treatment, various types of osteotomies will have to be done via open surgical approaches to correct the deficiencies.

Special Systemic Conditions Contraindicating Intermaxillary There are situations in which mandibular functional

movement is

necessary, and open rigid fixation techniques can provide that option. For example, patients with difficult-to-control seizures, psychiatric or neurologic problems, compromised pulmonary function, and eating or gastrointestinal disorders could benefit from open rigid fixation techniques.

TREATMENT OF MANDIBULAR FRACTURES The foregoing classification is intended to be of assistance in distinguish the different patterns of fracture and understanding the causes of displacement. However, on a practical basis, mandibular fractures may be treated by one or more of the following basic methods.

CLOSED REDUCTION AND INDIRECT SKELETAL FIXATION : 1. Direct interdental wiring 2. Indirect interdental wiring (eyelet or Ivy loop) 3. Continuous or multiple loop wiring 4. Arch bars 5. Cap splints 6. Gunning type splints 7. Pin fixation.

OPEN REDUCTION AND DIRECT SKELETAL FIXATION : 1. Transosseous wiring (osteosynthesis) 2. Plating 3. Intramedullary pinning 4. Titanium mesh 5. Circumferential straps

6. Bone clamps 7. Bone staples and Bone screws.

In recent years there has been a progressive move away from the traditional use of predominantly closed or semiclosed indirect procedures in the management of facial fractures towards a greater use of direct fixation techniques.

CLOSED REDUCTION AND INDIRECT SKELETAL FIXATION : 1.

Direct Interdental Wiring : This technique provides a simple and rapid method of immobilisation

of the jaws. However, the wires tend to loosen and a broken wire cannot be replaced without first removing and then replacing all of the others.

2.

Interdental Eyelet Wiring (IVY Loop Method) : When the teeth of a fractured jaw are fixed in the correct occlusion, the

bone fragments supporting them will, in most cases, also be satisfactorily reduced.

Provided that teeth of a suitable number, shape and quality are present on each fragment, eyelet wiring is a simple and effective method of reduction and immobilization of such jaw fractures, and may control an edentulous posterior fragment if the fracture lines are favourable and displacement minimal. Alternative techniques, such as upper or lower border transosseous wiring, will be required if this is not the case.

Eyelet wires may also be used in combination with Gunning-type splints in an opposing edentulous jaw, and arch bars or cap splints in a partially dentate jaw.

Fractures of the ascending ramus or mandibular

condyle will not necessarily be reduced by this method nor will they be completley immobilised.

BUTTON WIRING : Leonard (1977) considers that eyelet wires have several drawbacks. • The simple eyelet was frequently drawn into the interdental space, making it difficult to use. • Elastic traction using eyelets, though possible, was time consuming to apply.

Leonard described the use of titanium buttons of 8mm diameter, inclusive of a 1mm rim, and 2mm deep.

3)

Continuous or Multiple Loop Wiring : Stout (1943) described a technique which permits blocks of tooth in

either jaw to be wired in such a manner that elastic traction can be used to reduce the fracture.

THE USE OF PARTIAL DENTURES :

If the patient wears a partial denture and this is available, it can be used not only to restore the occlusion but also as a point of anchorage for the wires or elastic bands to reinforce the intermaxillary fixation.

4)

Arch Bars : Basically there are two varieties of arch bars, those that are

commercially produced and those which are individually made for a given patient.

Barker (1986) described a precast arch bar for greater accuracy of occlusal reduction.

Indications for use : 1. When insufficient teeth remain to allow efficient eyelet wiring.

2. When the teeth present are so distributed that efficient intermaxillary fixation is otherwise impossible.

3. When there are simple dentoalveolar fractures, or where multiple toothbearing fragments in either jaw require reduction into an arch form before intermaxillary fixation is applied.

4. As an integral part of internal skeletal suspension in the treatment of fractures involving the middle third of the facial skeleton; alternatively, when external skeletal fixation is indicated, an anterior projection bar may be attached to an individually made arch bar.

5. Where laboratory and technical facilities are inadequate or non-existent.

6. To reduce the preoperative time which would otherwise be required for cap splint preparation.

Arch bars may be necessary in both jaws, or there may be sufficient teeth in one jaw for eyelet wiring whilst an arch bar is used in the other. The technique will not control separate edentulous fragments but may be used in conjunction with other techniques.

5)

Cap Splints :

Cast-Silver Cap Splints : Provided that an experienced maxillofacial technician and the necessary laboratory facilities and time are available, cap splints are of great assistance with fractures where standing teeth are present on one or all of the separate fragments.

Although arch bars are immediately available, fitting

them may considerably increase the operatingt ime and, as with eyelet wiring, buccolingual rotation is not prevented. Furthermore, during the period of immobilization, superficial dental caries may occur where there is plaque concentration. When combined with elastic traction, cap splints may obviate the need for a general anesthetic.

Acrylic splints : Acrylic resin cap splints are easily and more cheaply fabricated. They are particularly useful for the treatment of dislocated teeth and alveolar segmental fractures.

Impressions : Problems may be encountered in obtaining satisfactory impression because of : 1.

a)

Trismus resulting from muscle spasm

b)

Gagging of the posterior teeth which result either

the upward and medial movement of the mandibular fragment, or from a movement of the upper jaw 2.

form posterior

posterior and downward resulting from a middle third fracture.

Soft tissue injuries, burns or edema, especially in

relation

to

the lips. Lacerations of the tongue and adjacent soft tissues or hemorrhage from the fractures may produce blood clot and/or sufficient swelling to obscure much of the crowns of the posterior teeth.

3.

Dental injuries: fractures of the teeth, with or

pulps, or loose teeth may cause pain cooperation, 4.

without

exposed

and contribute to a lock of patient

especially in chi8ldre.

Cerebral irritation, alcoholism, drug addiction and apprehension also

produce special problems.

Impression technique : After the clinical and radiographic examination has determined the location of the fractures, and the position and condition of the teeth on the various fragments, the disposable trays are prepared. Blood clot and debris should be removed from the mouth using gauze moistened in sodium bicarbonate solution and, where necessary, exposed dental pulps should be covered by sedative dressings. Impression are taken of each separate tooth bearing fragment if it is impossible to obtain a satisfactory impression of all the teeth in the jaw in one tray. Any impression which loses its attachment to the tray should be repeated; however irritating this may be otherwise the splints will not fit correctly.

Splint dressings

:

The splint dressing and positioning of the hooks depends upon the overjet and overbite and the need or otherwise for extremely fixation.

Approximately three hooks are required on each quadrant unless an alternative anchorage of the tie wires is proposed, such as the locking plate or the connecting bar. The hooks should be positioned to allow the cross bracing in a zigzag pattern of the tie wires or elastic bands. If internal suspension is required, a loop or a reversed hook is sited on the buccal aspect of the upper splint in the first molar region.

Preoperative procedures: When possible, splints should be cemented on to the teeth an hour or two before the operation so that the material can mature and harder, before any stress is put upon it.

Cement media : 1.Black copper cement : Provided that the teeth are dry and the cement is correctly mixed, copper cement is the best long-term medium to use. The phosphoric acid etches the surface of the enamel, thereby achieving a good bond and is, in itself, bactericidal. Unfortunately the superficial enamel will be stained temporarily and synthetic restorations permanently. Porcelain crown should be protected by a thin smear of Vaseline to prevent cement from adhering to them. The patient’s lips and , if present, moustache and beard should be liberally coated with Vaseline.

It is advisable for the operator to wear surgeon’s gloves. If the fine black powder and the acid fluid penetrate under the nails and into any scratches or cuts they are difficult to remove.

The optimal working time for the cement is only 20-30 seconds. This calls for extreme efficiency and, particularly in warm climates, a chilled mixing slab to retard the setting time. The slab should be immersed in iced water or placed in a refrigerator before use. An excess of cement must be prepared each time so that all of the fitting surfaces of the splint are covered by one mix. The powder is added to the fluid in small quantities and mixed by rapid circular motions of the spatula until a light oily consistency is achieved.

Watery cement drips everywhere and thick cement will set before the splint safe seated. The situation calls for considerable manual dexterity and a little experience or guidance. Small splints may be difficult to manipulate and their placement is facilitated by the attachment of `orange sticks’ to the occlusal surface using beeswax. Once the splint is positioned, these stick’s are easily removed so that digital pressure can be applied to the splint to seat it properly.

The phosphoric acid solution is a strong irritant and some patients develop a considerable edema where the cement has come into contact with the mucous membrane. Care should, therefore, be exercised to prevent this.

2.

Cold-cure acrylic :

The working time for this material is much longer. Splint retention is achieved by the mechanical effect of the acrylic flowing into undercuts around the teeth. No cement/tooth bond is achieved, however, so that oral fluids will permeate into the interdental spaces and over the cervical margins of the teeth and superficial carious lesions can occur. If the patient do not complain of a fetor oris and foul tat during the period of splint wear, they certainly do for a short time after removal of the splint. Commonly, local areas of periodontal infection are found, usually associated with excess acrylic. These, however, clear in a few day without any permanent sequelae.

3.Polycarboxylate cement : This group of cements is considered by some surgeons to be cleaner than the copper cements. However, they suffer from one important disadvantage in that they do not etch the surface of the enamel and hence lack the adhesion achieved by copper cement.

Cementing the splint: When possible this should be done on the dental chair with good, illumination and compressed air available. If the patient is bedridden, mobile dental units are invaluable.

Reduction of the fracture:

Multiple fractures are more common in the lower jaw than the upper. A sectional splint does not possess the retentive properties of a complete unit and it is easy to dislodge it, even after the cement has completely hardened, when manipulating the fragments, when tightening tie wires or during periods of post anaesthetic nausea.

Postoperative care: When the patient’s general condition permits and the edema has subsided, the elastic bands, which become soggy, foul smelling and dirty, are replaced by tie wires. Patients should be instructed about oral hygiene at the earliest possible stage so that they can relieve the nursing staff of the task of thorough oral lavage as has already been described. The cap splints rapidly tarnish if oral hygiene is not satisfactory whereas, with reasonable care, the labiobuccal aspect of the splints will retain their bright polished appearance.

Hooks causing soft tissue trauma must be turned inwards, loose screws tightened and broken wires or elastics replaced. The sharp edges of splints, screws or locking plates, or areas of dissimilar metals which cause electrolytic ulceration in the first 2 or 3 days should be covered by softened pink wax or gutta-percha. Wire twists which have not been bent sufficiently, and therefore traumatize the soft tissue or catch the toothbrush, require adjustment.

Occasionally, a splint will become loose. This is of little consequence if it is retained by circumferential wiring. If not, and the stability of the fractures is not controlled by the remaining splints, it must be replaced after all the tie wires have been removed.

Splint removal : Provided the splint is not too thick, an upper premolar pattern dental extraction forceps, aligned parallel to the occlusal plane, is used with one blade on the occlusal surface and the other on the cervical margin of the splint. A slow outward rotation of the forceps will usually break the bond between cement and the splint in that are. This rotation is repeated elsewhere around the mouth as required until the splint can be lifted off.

Fractures of the edentulous mandible: GUNNING-TYPE SPLINTS: Intraoral control is achieved by `Gunning-type’ splints, retained by peralveolar and circumferential wiring or, occasionally, other methods. It is, therefore, a form of indirect, control of the bone fragments, transmitted through the mucoperiosteum.

Indications : For the reduction, fixation and immobilization of

unilateral and

bilateral fractures of the edentulous mandible, where the fractures lying proximal to these areas can be controlled by intermaxillary fixation.

Contraindications: Unfavourably displaced fractures lying outside the denturebearing areas, or severe posterior displacement of fractures of the anterior part of the mandible which will probably be inadequately controlled by this method alone and will require additional fixation, e.g. transosseous wiring.

Projectile injuries, involving grossly comminuted soft tissue and bone loss, may not be suitable for this technique unless posterior displacement can be prevented, although open reduction is facilitated by the lacerations.

Provided that the wound edges are correctly approximated without inversion and excess pressure is not applied, creations of the mucous membrane will heal normally under the gutta-percha lining of the splints.

Extreme atrophy of the maxillae or mandible complicates this technique. In the maxilla, per alveolar wires may cut out or be impossible to insert. However, piriform apperture, per nasal or circumzygomatic wires are suitable alternatives.

Splint technique: Gunning splints may be constructed from : • The patient’s existing dentures suitably modified. These are often left at the scent of the accident. They should be searched for and, even if broken, can be repaired before use. Many edentulous patients have a usable discarded set of dentures at home.

• Impressions from the patient’s mouth • Models cast from the fitting surface of the patient’s dentures • Prefabricated Gunning-type splints • Disposable, edentulous impression trays without their handles.

The patient’s dentures: Since these are likely to have a reasonable vertical dimension and occlusion, they are generally suitable for use. The incisors and canine teeth are removed from each denture together with the majority of the palate from the upper denture. Two or three hooks in each quadrant are embedded with cold-cure acrylic in the labiobuccal sufaces of both dentures.

Alternatively, groove of the appropriate width and depth is cut into the buccal flange of each denture into which a length of Erich arch bar is secured by quick-curing acrylic.

The depth of the flange periphery is reduced to allow for postoperative edema and, after being roughened, the fitting surfaces are lined with softened gutta-percha. Small grooves may by cut on the occlusal surfaces of the denture to accommodate the per alveolar and circumferential wires.

Imperssions from the mouth:

As these reproduce any fracture displacement and soft tissue damage of the alveolus, the technician will need to correct major misalignment of the bone after sectioning the models. Any minor discrepancy remaining will be compensated by the gutta-percha lining. Unless a suitable record of the vertical dimension and jaw relationship can be taken from the patient, provision for this is made at the time of operation by creating a trough on the occlusal surface of the acrylic blocks which occupy the molar areas of the lower splint. The maxillary blocks are ridged or grooved so that, when opposed after reduction of the fracture these fit into the softened guttapercha.

Models cast from the fitting surfaces of the dentures: If fracture displacement is minimal and the dentures are of recent construction, `Gunning-type’ splints can be made from models cast from their fitting surfaces after the elimination of any undercuts.

Prefabricated Gunning type splints: There are several varieties of `Gunning-type’ splints but these should combine the following properties if they are to be useful: a. There must be separate splints for each jaw which enable immobilization to be achieved in the correct relationship by means of hooks processed into the outer aspect.

b. The splints must be lined with guttapercha or other suitable materials such as soft acrylic or other polymers to prevent the ulceration which can occur, even if the patients own dentures are used for immobilization. c. There must be space anteriorly for feeding and breathing purposes.

Adaptation of old splints: In an extreme urgency, previously used splints may be used provided they are big enough and their fitting surfaces are thickly lined with gutta percha to compensate for the discrepancies of the recipient mouth.

Disposable trays: Under similar circumstances, after removal of the handles, these may be lined with gutta percha, the jaw relationship being obtained by the use of blocks of gutta percha placed in the buccal quadrants and allowed to harden in situ. These splints are held in the mouth by the usual circumferential or per alveolar wires, additional support being obtained if required from internal skeletal suspension.

Circumferential wiring: At this stage of the operation, the circumferential wires must be passed.

IF this procedure is carried out after the definitive reinsertion of the mandibular splints, manipulation of the wires will result in displacement of the bone ends. For this reason, the following sequence should be followed.

The point of a long curved awl is now placed externally in the desired position inferior to the lower border of the mandible, where it will remain remote from the fracture sites and will avoid injury to both the facial artery and the area of the mental foramen. The operators middle or index finger of the other hand lies in the lingual sulcus where it protects the submandibular duct and lingual nerve and facilitates, by proprioception, the correct passage of the instrument. The awl is then pushed through the skin until it reaches the lower border of the mandible. With the point remaining in contact with the bone throughout the procedure, the awl is advanced so that it emerges in withdrawn so that the point can traverse the lower border of the mandible and be pushed into the buccal sulcus, where the end of the wire is retrieved and detached. At least two such wires should be inserted, their positioning depending upon that of the fracture lines. The wire ends, secured by artery forceps, are pulled to and fro until the bone is contacted to ensure that no soft tissue remains between the wire and the bone. This procedure work-hardens that portion of wire in contact with the bone. It is necessary, therefore, to carry out this maneuver at one end of the wire before advancing it to the other end. The work-hardened action is cut off and the artery forceps is reapplied.

The lingual ends are allowed to hang outside the mouth. In this way, free access is provided for the next stage, which is reinsertion of the lower splint.

7. PIN FIXATION:

This technique was introduced during the Second World war for use with compound, comminuted and frequently infected jaw fractures as a means of controlling the fragments remote from the affected areas. Modern antibiotics and improved surgical technique have reduced the need for pin fixation but this method is still a valuable part of the armamentarium required for the treatment of jaw fractures. The concept has been updated by the `box frame’ method which was initially developed by Fordyce for the treatment of middle third fractures of the facial skeleton. It is now of great assistance in other problems of fixation involving the control of edentulous fragments when a bone graft is required. Pin fixation is of particular value in the control of bilateral edentulous posterior fragments, especially when the remainder of the mandible has been lost and is to be replaced with a bone graft.

Advantages of pins: a)

Control of the edentulous fragments without involving

the fracture

lines. b)

Can be applied under local analgesia if indicated.

c)

Reduction or avoidance of the need for surgery at the

fracture site,

thereby retaining the periosteal blood supply of the edentulous mandible. d)

Elimination of laboratory facilities, with minimum operative

time

required. e)

Light, portable apparatus requiring only a simple

surgical technique.

f)

Simultaneous treatment of middle third and mandibular

fractures by

relatively simple combined techniques. g)

Immobilization of the mandible may be less prolonged or even

avoided. The oral cavity is left free of apparatus, thus assisting feeding and minimizing the

risk of pulmonary complications.

Disadvantages of pins: a)

Conspicuous in daily life and uncomfortable while sleeping

of the projection of the pins which b)

because

may easily be knocked

Readily accessible to an interfering, uncooperative or

cerebrally

irritated patient. c)

The universal joints may require frequent tightening,

torsional forces may not be adequately controlled

since

by this means.

d)

Difficulty with washing and shaving.

e)

Soft tissue scars are caused by the pinholes and there

is

a

constant, although slight, risk of infection.

Indications for use: a) Pathologic fractures of gunshot injuries associated with gross bone loss, particularly when laboratory and operating facilities are limited and immediate control of the fragments is indicated. b) Osteomyelitis an edentulous fractures site.

c) Fractures associated with extreme atrophy of the edentulous jaw. d) Bone grafting of the mandible when there has been extensive bone loss. e) Fractures of the mandible associated with fractures of the middle third of the facial skeleton when a rapid and relatively simple fixation is indicated. f) Gross comminution and posterior displacement of the symphysis of the mandible in an edentulous patient.

General principles: Two pins, joined to each other by a transverse rod and two universal joints, are inserted into the principal anterior and posterior fragments of the jaw. Each pin assembly is then united by a further rod or rods held by universal joints attached to the transverse bars. If jaw immobilization is considered necessary and is not going to be provided intraorally, use may be made of a `box frame’, a Levant frame, a `head frame, or even a plaster of Paris head cap if these more sophisticated craniofacial fixations are not available. The pin fixation assembly in such cases is connected to this apparatus by further vertical rods and universal joints.

Several varieties of pins and universal joints are available. Generally, pins are 7 cm, long and 3mm wide, the length being sufficient to compensate for severe edema whilst the width of the pain provides adequate strength. One end of the pin is tapered obliquely to fit an Archimedean drill or hand

introducer, whilst the other is threaded and may have a cutting edge. Pins are constructed from inert metals to prevent local osteitis which could otherwise result from electrolytic action. Each operator usually prefers one of the several varieties of pin available, some of which included: a) Clouston-Walker pin-combines a spear point with a fine thread of approximately 15 turns per cm b) The East Grinstead pattern c) The MacGregor pin is trochar-pointed with a shoulder formed by reducing the diameter of the portion inserted into the bone to 2mm. Pins are available in three sizes of 8mm, 10mm and 16mm as measured from the point to the shoulder. d) Moule pins are coarse threaded, tapered screw pins of different lengths designed to be inserted by hand into a hole drilled by a 3 mm twist drill. e) Toller pin constructed from titanium.

Several type of universal joints exits, constructed of various metals.

Because of the hazards incurred by using dissimilar metals in the pins, universal joints and connecting pins, it is advisable to use joints made from Tufnol, which act as insulators to break the circuit and thus prevent electrolytic action.

Several

orthopaedic

hand

drills

are

available,

including an

Archimedean drill, Lane’s or a Swedish pattern bevel action drill, modified by

Toller to produce a 1:1 ratio. The latter is helpful, for it turns slowly and gives the operator a clear idea of the depth of penetration of the drill point.

Operative technique: Landmarks may be difficult to locate because of soft tissue edema. If this is severe, it is advisable for the operator to palpate the mandible intraorally while he marks its periphery on the surface with a skin pen.

Radiographs will indicate the position and angulations of the fracture, which is then drawn upon the skin and this gives an approximate guide to the position of the inferior dental nerve. The amount of forward movement of the posterior fragments should be carefully assessed. After this initial stage it is essential to change gloves before proceeding.

The skin must be thoroughly prepared before surgery. It is helpful for the fingers of one hand of the assistant to be placed within the mouth in order to support the fragments, whilst the other hand supports the symphysis.

The following description applies to Moule pins which have been found extremely satisfactory in use.

The posterior pins are first inserted into the area of the angle of the mandible while the skin is pushed upwards and forwards by the surgeon to restore the relationship between the displaced bone and undisplaced soft tissues. The lower and posterior border of the angle of the mandible is

defined by palpation and a horizontal stab incision at the proposed site of pin insertion is made with a No.15 scalpel blade.

As in the case of a carpenter inserting a screw into wood, so it is necessary to drill a pilot hole before inserting the pin so as to avoid the risk of splitting the bone. The diameter of the hole must be correctly matched to that of the pin to ensure that the threads grip the bone with maximum retention.

The tissues are bluntly dissected with the tips of a hemostat down to the surface of the bone and Moule’s tubular soft tissue retractor is inserted.

A twist drill of 2.25 mm (3/32�) diameter is inserted into the chuck of the drill and pushed down until the point comes into contact with the bone.

The drill point is moved about with its point in contact with the bone until the operator is convinced of its position relative to the lower border and the angle of the jaw. Having located a positioned approximately 1 cm from the angle, the drill is positioned at right angles to the surface of the mandible and drilling is commenced until the cortex is engaged. It is easy for the drill point to slip and, to prevent this, drilling is continued in this manner but the angulations is altered to 70° once the drill starts to penetrate. This is continued, without any oscillation around the long axis of the drill, until the inner cortex is just perforated. The revolutions of the drill must be slow enough to allow the heat generated to dissipate, which is assisted by saline being continuously applied to the drill shafts. Only light pressure should be

exerted, to avoid sudden uncontrolled penetration of the inner plate, in view of the proximity of adjacent vital structures.

The tubular soft tissue retractor or drill sleeve must be held securely against the bone by the assistant while the drill is withdrawn. The Mould pin is then inserted into the turnkey and the tip engaged in the drill hole. It may be necessary to search for this if the soft tissue has moved slightly, and the operator should be able to discern when the point catches the rim of the hole.

The original 70째 angulation must be maintained and two or three revolutions of the hand-operated turnkey will usually convince the operator as to whether the pin is correctly orientated. The pin is screwed in until it is tight, but caution should be exercised when the ramus is thin and atrophic to avoid over penetration.

In locating the position for the second pin, the operator must assess the soft tissue edema and the need to prevent the points of the pin shafts must not be too far apart, but sufficiently so to accommodate a universal joint on each shaft with

a further one placed between them. The hole is drilled in

converging direction to the first pin and the pin is inserted.

Pairs of holes are then drilled in the distal fragment. The fractures may be oblique, with a surrounding haematoma which could become infected, so it is essential to make a careful assessment from the radiographs and to place the nearest pin at least 2-3 cm away from the fracture line. With multiple

fractures it is important to prevent posterior collapse of the symphysis, and more than two pairs of pins may be required. Great care must be taken to avoid the inferior dental bundle, especially in the atrophic edentulous case, and to prevent the drill from slipping under the lower border of the mandible.

Very occasionally, screwing pins too tightly into an atrophic mandible will result in a split in the bone which joins the two holes.

It is easy to displace or traumatize the skin when inserting pins. This will result in skin necrosis, which continues if pressure of the skin against the pin is allowed to persist and results in unsightly scarring,. Care is, therefore, required to prevent skin distortion by inserting the pin to compensate for the final position of the underlying bony fragments after reduction of the fractures. Should some slight heaping up of the skin against the shaft persist after insertion, a minimal stab incision should be made to relieve the tension and allow the skin to adapt itself around the pin.

THE PIN SITES : The entry sites may be covered by a dressing such as tulle

or,

preferably, by 1.25 cm wide ribbon gauze soaked in Whitehead’s varnish (Pigmentum Iodoform Compound) and then squeeze-dried and wrapped in a figure-of-eight pattern around the base of the shaft. These dressings require renewal or repositioning when the entry wound becomes exposed as the o edema subsides. Although hey may be disturbed by the patient, the enry

wound and the underlying bone are rarely the caouse of troulbe Slight bone infection may occur, but as the discharge drains away down the pin shaft there is a minimum of symptoms. Surrounding whiskers must be cut by scissors, although normal shaving is permissible in those areas to which the patient ahs access.

Despite smoothing, the ends of the metal rods will still be prominent.

They may cause damage or injury or catch in materials but can be protected by commercially made acrylic covers or by short lengths of polythene or rubber tubing which is quite adequate.

COMPLICATIONS OF PIN FIXATION: a) Anesthesia of the lip commonly results from the initial fracture. Insertion of the pin into the inferior dental cancal will cause additional damage to the vessels and lessen the chances of nerve regeneration. Severe pain may result of the pin damages the nerve proximal to the fracture. b) Involvement of the fracture line or its surrounding haematoma by incorrect positioning of the pin may allow the entry of infection into the area. c) Pin insertion into an oblique fracture line will cause a widening of the fracture and the displacement of the lingula cortex despite the counter pressure of an assistant. The looseness of the pin so positioned requires its immediate resisting further away from the fracture.

d) Some areas of the ascending ramus are extremely thin and over penetration may occur. This usually does not matter, since the tip lies in the substance of the medial pterygoid muscle and no major vessel is in close proximity. Over penetration rarely occurs with a Moule pin and is less likely to occur with other varieties if the operator counts the revolutions of drill with a known ration as the pins are inserted. e) Damage to adjacent structures. The facial nerve and vessels are safe unless a stab incision is carried too deeply because the pins will tend to displace these structures rather than penetrate them.

The uncontrolled pin slipping beneath the lower border of the mandible or behind its posterior border constitute a hazard to major vessels. Pressure upon the drill should be increased slowly with the angulations of the pin kept at right angles to the bone until penetration of the outer cortex has occurred.

Drills must be sharp so that excessive pressure is not required. f)

Jaw movement will ultimately loosen the pins. While

movement appears to be beneficial in the late It is, therefore, sometimes weeks,

minimal

to malunion or infection.

advisable to immobilize the jaw for at least 3

or longer if necessary, before relying entirely on pin

fixation for support of the fracture. If intermaxillary

fixation

`Gunning-type’ splints in not possible, craniofacial fixation must be used.

by

g)

It is easy for the patient to strike objects or other

people

with

the

ends of the pins and connecting bars. Most patients adopt a pattern of behavior to prevent h)

this.

If acute infection develops around a pin and cannot be

by antibiotics, it is advisable to remove remaining one which

controlled

the affected pin, relying on the

may not be involved in the hope that sufficient

organization a the fracture site will have taken place. Leakage of parotid secretion does occasionally occur in the early days after the insertion of pin. In most cases this cease spontaneously before the pin removal and the fistula will usually repair itself once the pin has been removed.

PERSISTENCE OF INFECTION FOLLOWING REMOVAL: Rarely, purulent discharge may continue following the removal of the pin. This denotes the presence of a sequestering, sometimes in the form of a ring, which has resulted either from overheating during the insertion of the pin or a subsequent electrolytic reaction. If the discharge does not clear spontaneously within a week the area should be curetted using regional block analgesia or general anesthetic.

Treatment of mandibular fractures with teeth in one jaw only

A

number of patients present with facial fractures and other injuries which do not lend themselves to the sole use of the basic techniques previously described.

1. The edentulous maxilla with an adequate number of suitable mandibular teeth It the upper denture is available and in one piece, hooks are set into the buccal and labial aspect in cold-cure acrylic. The plate is either removed extensively as previously mentioned or holes 1 cm in diameter are cut in the palte for the passage of per alveolar wires. Undercuts shoul be removed from the fitting surface of the denture, which can then be relining in situ with a tissue conditioner, thus preventing the development of chronic moniliasis.

Gutta-percha is the alternative. If a denture is not available, `Gunning-type’ splints must be constructed. The splint or denture is wired in by per alveloar or piriform aperture wires, whilst the mandibular fractures are reduced and fixed.

2. Loss of maxillary bone : Standing lower teeth predispose to increased alveolar resorption in the opposing area of the edentulous upper jaw. Generalized atrophy of the maxilla is not uncommon in the elderly. The anterior area of the upper jaw may be extensively comminuted and, if any teeth are still present, they may be fractured and require extraction. Either of these situations will render

retention from per alveolar wire, ineffective. Although some mandibular fractures may be satisfactorily treated in such circumstances without jaw immobilization, e.g., by cap splints or arch bars, the majority of patients will have less discomfort and improved cahbes of bony union if jaw immobilization is provided. Under the circumstances, the alternative mehtods of upper splint retentiona are : a) Bone screws or a shot length of : Kirschner wire may be inserted in suitable undamaged areas through holes in the peripheral flanges or palate of the denture. b) Pinform aperture wires:

Even in the elderly, the lateral aspect of the

nasal aperture affords better retention than the surrounding bone. The nasal aperture is exposed through a mucoperiosteal incision and the periosteum and nasal mucosa is elevated from the area. The nasal mucosa is protected by the insertion of a Howarth’s nasal periosteal elevator. The wires are inserted as follows: i)

A hole is drilled through the thickest part of the bone down on to the

elevator and a. 0.5 mm soft stainless steel wire is passed and brought out through the pirifrorm aperture into the mouth. Both ends may then be twisted around hooks processed into the upper splint or a hook in the lower splint.

Preferably, the wires should be twisted together to from a loop. A separate wire can than be passed through the loop and attached to apparatus in either

the upper or the lower jaw or to a circumferential wire which is passed around the lower jaw. This has the advantage of allowing the jaws to be mobilized later without risking the fracture of either the circumferential or piriform aperture wires. ii)

Occasionally piriform aperture wires cut out, particularly in the elderly.

Improved distribution of the wire loading is obtained by passing one end of the wire back through the alveolus into the plate bt a straight wire introducer.

This wire is then brought forwards and twisted with the other end over the splint. iii)

Circumpalatal wiring may be use. The palate of the maxillary splint

should not be cut away and should incorporate a wire loop at the posterior border in the midline. A long curved awl is passed along the floor of the nose, above the mucosa, to the region along the floor of the nose, attached to the posterior border of the hard plate. The handle is then elevated, causing the point to penetrate the tissues and emerge in the mouth. A 10 cm length of 0.5 mm diameter soft stainless steel wire is passed through the loop processed into the posterior border and bent back on itself to form two 5 cm lengths.

The ends of these are passed through the eye at the tip of the awl which is then withdrawn to pull the wire ends forwards.

A finger placed in the labial sulcus palpates the anterior limit of the nasal fossa and the tip of the introducer is then passed inferiorly to emerge in

the labial sulcus. The wire is then detached and the introducer withdrawn.

The double length of wire now runs from the loop on the posterior edge of the splint along the floor of the nose and down into the labial sulcus. The two ends are then twisted been encountered. Removal is accomplished very easily by cutting the wire where it passes through the palatal loop and pulling both strands forwards into the labial sulcus. c)

Circumzygomatic or frontal suspension wires: The former may be used with intact zygomatic arches and the latter

when the zygomatic complex is fractured but the angular process and supraorbital ridges are intact. The wires may be attached to either the upper or lower jaw fixation but preferably they should be formed into a terminal loop which is attached to the apparatuses by a separate wire. This allows the jaw to be mobilized without untwisting the internal suspension wire and risking its fracture. d)

Extra skeletal retention : This may be achieved by fixation of either jaw to the cranium

employing a `halo’ frame (Royal Berkshire Hospital Pattem Downs Surgical Ltd), supraorbital bone pins, zygomatic bone pains or a plaster of Paris head cap. By comparison with this alternative’s the plaster head cap is uncomfortable and unhygienic and should only be used nowadays if other apparatus is not available.

The edentulous mandible and an adequate complement of maxillary teeth: The splint or denture secured by circumferential wires to the low jaw is joined to maxillary eyelet wires or arch bars by wires passed around the hooks of the denture or splint or through the circumferential wires. Further combinations of such problems will be met by the clinician, who will adapt the basic techniques described to fit the particular circumstances.

FRACTURES OF THE TOOTH-BEARING SECTION OF THE MANDIBLE : The general principles of treatment of fractures of the mandible do not differ essentially from the treatment of fractures elsewhere in the body. The fragments are reduced into a good position and are then immobilized until such time as bony union occurs. Traditionally immobilization of the mandible has involved linking it temporarily to the opposing jaw by some form of intermaxillary fixation (IMF). This has the considerable disadvantage to the patient of preventing normal jaw function and restricting the diet to a liquid or semi-solid consistency. Weight loss is common, oral hygiene is difficult to maintain and convalescence is prolonged. Leonard (1987) has drawn attention to a thesis by Bruksch at the University of Minnsota in which he demonstrated a 30% reduction of ventilatory volume in patients subjected to intermaxillary fixation.

For all these reasons, surgeons have looked for alternative methods of treatment which avoided or shortened the period of intermaxillary fixation.

The most significant contemporary change in the treatment of mandibular fractures, and in particular fractures of the dentate mandible, has been an

increasing trend towards rigid osteosynthesis by means of bone plates. In skilled hands, consistently successful results are now being reported (Cawood, 1985; Prein and Kellman, 1987; Raveh et al., 1987). However, because of the sheer number of mandibular fractures and the limitation of resources, such as operating theatre time, a considerable, proportion of these fractures will continue to be treated by traditional methods and a general overview is needed in a text such as this.

Reduction : Reduction of a fracture means the restoration of a functional alignment of the bone fragments. In certain situations this does not necessarily imply exact anatomical alignment, e.g. fracture of the clavicle. However, in the dentate mandible reduction must be anatomically precise when teeth are involved which were previously in good occlusion. Less precise reduction may be acceptable if part of the body of the mandible is edentulous or there are no opposing teeth.

The presence of teeth provides an accurate guide in most cases by which the related bony fragments can be aligned. The teeth are used to assist the reduction, check alignment of the fragments and assist in the immobilization. Whenever the occlusion is used as an index of accurate reduction it is important to recognize any pre-existing occlusal abnormalities such as an anterior or lateral open to previous contact areas. Teeth may on occasions be brought into contact during reduction and yet be occluding incorrectly owing to lingual inclination of the fractured segment.

Widely displaced, multiple or extensively comminuted fractures may be impossible to reduce by means of manipulation of the teeth alone, in which case open operative exploration becomes necessary.

In general, reduction and later immobilization is best effected under general anaesthesia, but occasionally it is possible to employ local analgesia

supplemented if necessary by sedation. If there is minimal displacement the reduction can sometimes be effected without an anaesthetic.

If a patient’s general medical condition precludes the administration of a general anaesthetic, gradual reduction of fractures can sometimes be carried out by elastic traction. Small elastic bands are applied to cap splints or wires fitted to teeth on the individual mandibular fragments and attached in turn to the intact maxilla. A satisfactory temporary reduction can usually be achieved pending an improvement in the patient’s general condition.

Teeth in the fracture line : Teeth in the fracture line are a potential impediment to healing for the following reasons : 1) The fracture is compound into the mouth via the opened periodontal membrane.

2) The tooth may be damaged structurally or lose its blood supply as a result of the trauma so that the pulp subsequently becomes necrotic.

3) The tooth may be affected by some pre-existing pathological process, such as an apical granuloma.

The fracture line can become infected as a result of any of the above; either from the oral cavity via the disrupted periodontium or directly from an infected pulp or apical granuloma. Infection of the fracture line will result in greatly protracted healing of the fracture or even non-union.

For these reasons in pre-antibiotic days all teeth in the line of the fracture were extracted. This practice was however, continued into the antibiotic era with unnecessary detriment to the patient. A tooth in the line of fracture which is structurally undamaged, potentially functional, and not subluxed should be retained and antibiotics administered. Its retention will tend to delay clinical union of the fracture by a short period, but this is acceptable in order to preserve the integrity of the dentition. Obviously teeth

in an intact dentition are more important than those in a partially edentulous jaw.

Without antibiotic therapy teeth in the line of fracture constitute a real risk of infection. As recently as 1978 Neal and co-workers reported a complication rate of 30% in a retrospective study of 207 mandibular fractures, where the average delay in treatment was 3-4 days, and the patients were generally from deprived social backgrounds and uncooperative. Thirtysix infections of the fracture site occurred, the incidence interestingly being unrelated to whether the involved tooth was removed at the time of treatment or after the complications had ensued.

In general the infection rate of manidbular fractures which involve teeth is much lower; around 5% (James et al., 1981). Kahnberg (1979) and Kahnberg and Ridell (1979) in a study of 185 teeth involved in the line of mandibular fractures have shown that the prognosis of the teeth they elected to conserve was good. Complete clinical and radiographic recovery was found in 59%, a figure similar to other studies (Fuhr and Setz, 1963; RoedPetersen and Andreasen, 1970; Ridell and Astrand, 1971). Careful follow-up of the retained teeth was necessary so that endodontic therapy could be instituted as soon as there were clinical indications. In Kahnberg and Ridell’s study 32 of the 185 involved teeth were extracted, 20 of which became necessary after initial fixation of the fracture because of loosening of the teeth or infection of the fracture site.

Considerable controversy exists with regard to functionless third molars involved in mandibular fractures. These teeth are a potential source of infection and, if left, will eventually need to be removed. They have little value in stabilizing the fracture which, if undisplaced, is retained in line by the attached periosteum. Furthermore, such a tooth will never be more easy to remove, because the fracture effectively disimpacts it and as a result it can be

elevated with minimal disturbance of bone and periosteum. On balance it would seem more sensible to remove a functionless, potentially troublesome tooth when an operative intervention has become necessary by virtue of the fracture.

Summary : Absolute indications for removal of a tooth from the fracture line : 1) Longitudinal fracture involving the root.

2) Dislocation or subluxation of the tooth from its socket.

3) Presence of periapical infection.

4) Infected fracture line.

5) Acute pericoronitis.

Relative indications for removal of a tooth from the fracture line : 1) Functionless tooth which would eventually be removed electively.

2) Advanced caries.

3) Advanced periodontal disease.

4) Doubtful teeth which could be added to existing dentures.

5) Teeth involved in untreated fractures presenting more than 3 days after injury.

It is desirable that all teeth not covered by these conditions should be retained.

Management of teeth retained in fracture line : 1) Good quality intra-oral periapical radiograph.

2) Institution of appropriate systemic antibiotic therapy.

3) Splinting of tooth if mobile.

4) Endodontic therapy if pulp is exposed.

5) Immediate extraction if pulp is exposed.

6) Follow-up for 1 year with endodontic therapy if there is demonstrable loss of vitality.

Immobilization : Following accurate reduction of the fragments, the fracture site must be immobilized to allow bone healing to occur. Orthopaedic surgeons have been concerned for some time with the process of fracture healing when either rigid or semi-rigid fixation is employed. The speed of repair of the weightbearing skeleton is of paramount importance in the eventual rehabilitation of an injured patient. When semi-rigid fixation is used a fracture heals by secondary intention which involves the formation and subsequent organization of callus. This is a relatively slow process and weight bearing must be delayed until full bone replacement has occurred. Even apparently rigid fixation by means of non-compression plating or pinning leaves a gap between the bone ends and bony union requires organization of a primary callus. Key (1932) noted that healing of the arthrodesed knee was accelerated when the opposing bony surfaces were compressed. Later experimental work (Schenk and Willenegger, 1967; Hutzschenreuter et al., 1969; Perren et al., 1969) has confirmed that compression osteosynthesis of both experimental osteotomies and clinical fractures results in primary bone healing without the formation of intermediate callus. This results in more rapid stabilization of the fracture site and much earlier restoration of the mechanical strength of the bone. Reitzik and Schoorl (1983) have compared rigid non-compression osteosynthesis and semi-rigid wired osteosynthesis on either side of the same mandible. Although non-compression plated osteotomies resulted in gap healing with the formation of a small amount of intermediate callus, this was still superior to semi-rigid osteosynthesis with demonstrably increased mechanical strength on the plated side 6 weeks after surgery.

The question arises as to how relevant are these findings to the treatment of mandibular fractures. Unlike a weight-bearing bone, it is only necessary to immobilize the mandible until a stable relationship between the

fragments has been achieved. This period is considerably less than would be required for full bony consolidation to take place. Some simple mandibular fractures need no immobilization at all, particularly if a lack of teeth means that precise restoration of the occlusion is not at a premium. Such fractures remain mobile for some time if they are forcibly manipulated but eventually proceed to full bony union. It is indeed difficult to prevent the fractured mandible uniting and malunion is a more frequent complication than nonunion.

The overwhelming advantage of rigid fixation is the avoidance of intermaxillary fixation. If that is not possible, bone plates offer no significant gain to the patient either during treatment or in the eventual outcome. In view of the fact that clinical union of mandibular fractures is much quicker than most other bones, compression osteosynthesis must have a very dubious place in any treatment plan.

Period of immobilization : The period of stable fixation required to ensure full restoration of function varies according to the site of fracture, the presence or otherwise of retained teeth in the line of fracture, the age of the patient and the presence or absence of infection. Juniper and Awty (1973) have shown that in favorable circumstances stable clinical union can on average regularly be achieved after 3 weeks at which time fixation can be released.

In fractures of the body of the mandible the blood supply to the fracture site is significant. Where endosteal vascularity is relatively poor as in the ageing jaw, and particularly in the symphysis region, healing tends to be prolonged. In contrast, the rich blood supply and exuberant osteoblastic activity of the child’s growing mandible ensures extremely rapid union.

A simple guide to the time of immobilization for fractures of the toothbearing area of the lower jaw is as follows :

Young adult With Fracture of the angle 3 weeks

receiving Early treatment in which Tooth removed from fracture line If : a)

Tooth retained in fracture line : add 1 week

b)

Fracture at the symphysis : add 1 week

c)

Age 40 years and over : add 1or 2 weeks

d)

Children and adolescents : subtract 1 week Applying this guide it follows that a fracture of the symphysis in a 40-

year-old patient where the tooth in the fracture line is retained requires 6 week’s immobilization (basic 3 weeks + 1 week for less favourable site + 1 week allowed for age + 1 week for tooth retained in the line of fracture).

Rules such as these are designed for guidance only, and it must be emphasized that the fracture must always be tested clinically before the mandible is finally released. The temporally attachments to the dentition should be retained for a further period so that reimmobilization can be carried out if the union of the fracture is found to be inadequate after function has been restored.

FRACTURES OF THE EDENTULOUS MANDIBLE : Introduction : The physical characteristics of the body of the mandible are altered considerably following the loss of the teeth. In effect from the point of view of treatment, the edentulous mandible becomes a different bone. Following resorption of the alveolar process, the vertical depth of the subsequent

denture-bearing area is reduced by approximately one-half and in some cases by considerably more. The resistance of the bone to trauma is further reduced by changes in the structure of the bone associated with the process of ageing.

The ageing process is also associated with significant changes in the vascular architecture (Cohen, 1960; Bradley, 1975). The endosteal blood supply from the inferior dental vessels begins to disappear and the bone becomes increasingly dependent on the periosteal network of vessels.

The denture-bearing area of the edentulous mandible is therefore not only more easily fractured, but also less well disposed to rapid and uneventful healing.

In addition, the smaller cross-sectional area of bone at the fracture site and the absence of the stabilizing influence of teeth means that the bone ends are more easily displaced, and even after reduction the area of contact between them may be insufficient for healing to occur easily. The more atrophic the mandible the more significant these factors become and Bruce and Strachen (1976), in a study of 146 fractures occurring in thin mandibles treated by a variety of methods, reported a 20% incidence of non-union.

The edentulous state confers a few advantages. Fractures are, for instance, much less frequently compound into the mouth than when teeth are present. As a result whenever closed reduction is possible the risk of subsequent infection of the fracture is negligible (Amaratunga, 1988). Again the absence of teeth means that precise reduction, such as would be required to restore the occlusion of natural teeth, is not necessary as any inaccuracy is easily compensated by adjustment of dentures. For these reasons many fractures in edentulous patients require no treatment at all. If the fracture is simple with little or no displacement it will heal satisfactorily if the patient refrains from unnecessary active movements and adjusts to a temporary soft

diet. Any subsequent discrepancy in the denture occlusion can be corrected in most cases by relining with or without occlusal adjustment.

Reduction : For the reasons already stated, precise anatomical reduction is not necessary in fractures of the denture-bearing area. This is fortunate because reduction is frequently difficult when there is over-riding of the bone ends.

Reduction and subsequent fixation become more difficult as the mandible atrophies. The dilemma which often faces the clinician has been well summarized by Marciani and Hill (1979). The reduced cross-section of bone fractures of thin mandibles means that displacement occurs more readily and in this situation open reduction may be the only way to restore adequate bone contact. However, operative open reduction involves further disruption of the periosteal attachment which interferes significantly with postoperative repair of bone. Mature clinical judgement is required, the objective being to achieve sufficient bone contact and alignment with the minimum direct operative interference at the fracture site.

Methods of immobilization : The fact that there is no uniformly accepted method of immobilizing edentulous fractures is indicative of the fact that no completely satisfactory method has yet been devised. There is no doubt, however, that the traditional treatment by means of Gunning-type splints has been largely superseded in recent years by methods which employ some form of direct or indirect skeletal fixation. In order patients intermaxillary fixation is even less desirable than in younger age groups. Nutritional requirements become difficult to maintain and oral candidiasis commonly affects the oral mucosa causing considerable discomfort during the active treatment period. The methods of treatment currently in common use are : 1)

Direct osteosynthesis :

a) Bone plates b) Transosseous wiring c) Circumferential wiring or straps d) Transfixation with Kirschner wires e) Fixation using cortico-cancellous bone graft.

2)

Indirect skeletal fixation : a) Pin fixation. b) Bone clamps.

3)

Intermaxillary fixation using Gunning-type splints : a) Used alone b) Combined with other methods.

Direct osteosynthesis : Bone plates : Bone plates are particularly useful for displaced fractures of the edentulous mandible, particularly those at the angle. They allow the fracture to be stabilized without immobilization of the jaw as a whole. The patient is, as a result, more comfortable during the period of healing of the fracture. The main mandibular plating systems described are in general applicable to edentulous fractures. The reduced depth of bone in the edentulous mandible favours the use of non-compression mini-plates rather than the bulkier compression plates in that the former are less likely to interfere with the edge of a future denture. Bone plates are easier to apply in the edentulous state than when teeth are present as there is no need to achieve the same degree of precision in the reduction of the fracture. Any discrepancy in the eventual occlusion of the pre-existing dentures is more easily corrected than when natural teeth are involved.

The surgical technique is, however, more time consuming and requires liberal exposure of the fracture site with extensive elevation of the

periosteum. Both compression and non-compression systems require an adequate blood supply to achieve uncomplicated bony union (Rhinelander, 1974) and elevation of periosteum in the thinner mandible seriously compromises the blood supply to the fracture site. It has been suggested that in these circumstances plates should be applied with an intervening layer of attached periosteum (Bradley, 1975), but in practice this is difficult to accomplish.

Plates related to the denture-bearing part of the mandible are much more likely to require removal at al later date than those used in the ramus or in dentate fracture sites. Nevertheless they are currently the preferred method of fixation for the majority of edentulous mandibular body fractures.

Transosseous wiring : Many simple edentulous fractures can be satisfactorily immobilized by direct transosseous wires but, in general, when a surgical exposure has been made it is just as easy to apply a mini-plate if available. Transosseous wires do not provide rigid osteosynthesis and supplementary fixation may be necessary. They are somewhat easier to apply from an intra-oral approach and, when placed near the upper border, are less likely to impinge on denture flanges at a later date. In general less periosteal stripping is required on each side of the fracture which may be advantageous when dealing with a very thin mandible. When the neurovascular bundle crosses the fracture site it is easier to avoid damage with a transosseous wire than a screwed plate.

The special instrumentation required for the application of miniaturized plates in not universally available in all parts of the world where fractures require treatment and wiring techniques continue to provide a simple and reliable alternative.

Circumferential wiring or straps :

Oblique fractures of the edentulous mandible can be most effectively and simply immobilized by circumferential wires. A modification of the method illustrated in is recommended in order to avoid placing the upper part of the wire immediately below the oral mucosa. Williams (1985) has described the use of miniaturized circumferential nylon straps as a useful alternative to wire.

Transfixation with Kirschner wires : This method of fixation employs a 2mm Kirschner wire inserted within the medullary cavity across the fracture site. When the edentulous mandible is reasonably thick the wire can be introduced through a stab incision in the overlying skin and a suitable point of insertion located on the cortex of the distal fragment. A hole is drilled through the cortex at this point and the wire directed into the medullary cavity and onwards across the reduced fracture site. The wire is cut off at the skin entry point from where it can be withdrawn when the fracture has healed.

In practice it is extremely difficult to insert a wire in this way without damaging the inferior dental vessels and nerve. The most satisfactory method of placing such a wire is to expose the fracture site by an external skin incision. The transfixing wire is passed first into the proximal or distal segment and drilled down the centre of the mandible to emerge through the cortex and skin at a point where the curvature of the jaw prevents further passage. The wire end attached to the drill will eventually come to lie opposite the fracture site at which point the inserting drill is detached and the direction of the wire reversed so that it is made to pass back down the other fragment transfixing the fracture (McDowell et al., 1954; Vero, 1968).

When the wire is inserted under direct vision, as in this latter technique, it can be usefully employed to immobilize fractures of the body of thin edentulous mandibles where a plate would be too bulky. It is not

possible, however, to employ the technique in the ultra-thin mandible because of the risk of damage to the inferior dental nerve.

Primary bone grafting : In 1973 Obwegeser and Sailer suggested primary bone grafting as a method of stabilizing and augmenting a fracture of the body of the ultra-thin edentulous mandible. Wood et al. (1979) successfully treated nine such fractures using autogenous rib grafts. A 5cm length of rib is obtained as an authogenous graft. The rib is split and the two pieces are placed one on each side of the fracture site in the manner of a first-aid splint applied to a limb.

The rib halves are lashed together by a series of circumferential wires sandwiching the fractured bone ends between them. Iliac bone can be employed in a similar fashion (James, 1976). Postoperative morbidity at the donor site can be considerably reduce by controlled infusion of bupivacaine through an epidural catheter.

Although the technique appears demanding for an elderly patient it is in practice often less time consuming than bone plating and does often an effective remedy for what is without doubt the most difficult of all jaw fractures.

Indirect skeletal fixation : A system of bone joined together by rods and universal joints can be used in edentulous mandibular fractures in the same manner as when teeth are present. The method is occasionally of practical use when there has been extensive comminution of a long segment particularly if this involves the symphysis.

Bone clamps such as the Brenthurst splint are theoretically of use to immobilize a fracture in a thin edentulous mandible avoiding direct surgical exposure of the fracture site. In view of the reported high incidence of nonunion following open reduction of fractures of the atrophic mandible

(Marciani and Hill, 1979), there would seem to be some merit in exploring the clinical usefulness of this method of fixation in the future.

Intermaxillary fixation using Gunning-type splints : The dental splint described originally by Gunning in 1866 was a vulcanite overlay of the natural teeth which he used as a splint for the fractured dentate mandible. A similar splint for the edentulous mandible consisted of a type of removable monobloc resembling two bite blocks joined together. The modern Gunning splint is therefore more correctly described as a Gunning-type splint. These splints take the form of modified dentures with bite blocks in place of the molar teeth and a space in the incisor area to facilitate feeding. They can be used when the patient is edentulous in one or both jaws. If the patient is completely edentulous immobilization is carried out by attaching the upper splint to the maxilla by peralveolar wires and the lower splint to the mandibular body by circumferential wires. intermaxillary fixation can then be effected by connecting the two splints with wire loops or elastic bands. When the patient is edentulous in one jaw intermaxillary fixation is achieved by attaching the Gunning splint to whatever type of splint is present in the opposing jaw.

Properly constructed Gunning-type splints should hold the jaws in a slightly over-closed relationship, as in this position fractures of the body of the mandible are more effectively reduced. The edges of the splints should be slightly over-extended around the sulcus in order to minimize food entry under the fitting surface. When the jaws are immobilized over-extension does not lead to ulceration of the mucosa as it would in a functioning denture.

Whenever possible the splints should be constructed on models from impressions of the patient’s mouth. The necessary degree of over-extension of the sulcus is achieved by using composition as an impression material which is superior to other impression material for this one purpose. It is, however, difficult to take an adequate impression when the mandible is badly fractured and the alveolar ridge distorted by displacement of the fragments. It may be possible to make use of the patient’s dentures if they are available but it should be stressed that models constructed from the fitting surface of dentures are usually inaccurate and under-extended.

The splints are constructed in acrylic resin and the fitting surface is lined with black gutta percha. If the correct vertical dimension of the bite is known or has been recorded the occluding surfaces can be made to fit together satisfactorily in a slightly over-closed relationship. Alternatively a trough can be cut in the occlusal surface of one splint and filled with gutta percha. The opposing occlusal surface is then shaped to fit into the trough and a satisfactory fit obtained at operation by softening the gutta percha and pressing the two splints together. Hooks are incorporated into each splint to allow intermaxillary fixation to be applied.

When the facilities of a maxillofacial laboratory are not easily available, splints can be made by modification of the patient’s dentures if

these have been preserved. The fitting surface is ground away to an even depth and replaced by a liberal lining of black gutta percha and pressing the two splints together. Hooks are incorporated into each splint to allow intermaxillary fixation to be applied.

When the facilities of a maxillofacial laboratory are not easily available, splints can be made by modification, of the patient’s dentures if these have been preserved. The fitting surface is black gutta percha. The anterior teeth are removed to provide a space for feeding and approximately positioned hooks are fitted using self-curing acrylic. The necessary materials for modifying dentures in this way should always be carried along with other fixation apparatus when called to treat a facial injury away from the main base.

At operation the splints are adapted to the alveolus of each jaw after reduction of the mandibular fracture. Gunning-type splints are frequently employed as an adjunct to some other form of fixation and it may not be possible to fit the lower splint until open reduction and other fixation has been applied. The upper splint is fixed to the alveolus by using an awl to pass a 0.45 mm soft stainless steel wire through the alveolus high up in the canine area on each side and then through an appropriately positioned hole in the palatal portion of the splint. The two free ends on each side are twisted together over the splint, cut short and bent in under one of the hooks or cleats.

The lower splint is attached to the reduced fractured mandible by means of circumferential wires. care must be taken to avoid passing a circumferential wire close to a fracture site as the wire may be pulled up into the fracture when it is tightened. The most satisfactory method of passing these wires it that described originally by Professor Obwegeser. A suitable curved awl is pushed through the skin beneath the mandible and directed into the mouth on the lingual side of the bone. One end of a length of 0.45 mm

soft stainless steel wire is passed through the tip of the awl which is then carefully withdrawn to the lower border of the mandible but not out through the skin. The tip of the awl with the attached wire is guided round the lower border and pushed up into the buccal sulcus where the wire end is detached.

The instrument is then withdrawn through the original puncture wound in the skin. The wire is applied close to the bone throughout its passage avoiding the necessity of ‘sawing’ it through the soft tissues.

After the splints have been attached to each jaw they are connected by elastic bands or wire loops utilizing the hooks on the buccal surfaces of each splint and intermaxillary fixation is established.

When treatment is completed, the peralveolar and circumferential wires are removed by cutting each wire close to the buccal sulcus and pulling firmly and rapidly. An anaesthetic is not required and if the wire is cut close to the point of mucosal entry this avoids a length of contaminated wire passing through the tissues. In spite of these precautions the passage of the wire during removal occasionally causes infection and it is wise to prescribe antibiotic cover for the procedure.

Gunning-type splints are still widely used as fixation for fractures of the edentulous mandible which justifies describing the technique in some detail. The method is useful for simple fractures treated by surgeons of limited experience. It is, however, a technique which is far from ideal. The splints become exceedingly foul during 4-6 weeks fixation as a result of food stagnation between the poorly fitting surface of the splint and the mucosa.

Apart from the Candida-induced stomatitis which results, there is a significant incidence of more serious infection of the wire track within the tissues. These splints are inefficient as a method of immobilization and provide poor control of mobile fractures, particularly when the mandible is very thin. They are

unfortunately least efficient in those case s where closed reduction is most desirable.

Selection of the method of fixation : 1)

In the edentulous mandible reduction and fixation is in the main required for fractures of the angle and body with a view to restoring an adequate denture-bearing area and avoiding facial deformity.

2)

Because of the risk of non-union resulting from interference with the periosteal blood supply, reduction should be accomplished with minimal exposure. Many undisplaced fractures require no active treatment.

3)

Although Gunning-type splints can be used to achieve fixation after closed reduction, their inherent disadvantages make other methods preferable in all cases requiring active treatment.

4)

In otherwise fit patients, open reduction and direct osteosnthesis is the method of choice. Intermaxillary fixation should be avoided wherever possible.

5)

The most effective form of osteosynthesis is by non-compression mini-plates. Compression plates offer theoretical advantages which are outweighed by their size in relation to the edentulous bone.

6)

When the mandibualr body is less than 10mm in depth, fracture treatment become difficult and non-union is more likely. It must be remembered that stable fibrous union may be an acceptable result in the very old or infirm patients. Although transfixation procedures utilizing Kirshner wires have their protagonists, the method is only occasionally used and the same may be said of systems employed bone clamps and pins. However when there is extensive comminution these method should be considered.

7)

The ultra-thin mandible will not usually unite satisfactorily with conventional methods of reduction and fixation and in these cases autogenous bone grafting as a primary procedure should be the method of choice where the patient’s general condition permits.

FRACTURE OF THE MANDIBLE IN CHILDREN Fractures of the mandible are uncommon in children owing to the fact that the bone is resilient at this age and considerable force is required to effect a fracture. The line of demarcation between the medulla and cortex is less

well defined than in adults whereas the ratio of bone to tooth substance is high (Khosla and Boren, 1971). Incomplete dysjunction in the form of a ‘greenstick’ fracture is therefore more likely and there is a greater risk of damage to developing teeth than in later years. Ranta and Ylipaavalniemi (1973) carried out a long-term investigation of teeth involved in mandibular fractures occurring before the age of 12 years, and observed disturbed formation in 72% of teeth directly involved in the line of fracture. They also noted from other surveys that between 25 and 48% of teeth involved in the fracture line in adults exhibited pulp necrosis.

Keniry (1971) in a survey of the literature found that between 8.3% and 15% of jaw fractures occurred in children under the age of 15 years.

According to MacLennan (1956) only 1% of the mandibular fractures happened before the age of 6 years.

The treatment of mandibular fractures in children before puberty is generally or a conservative nature because of the rapidity of healing and the adaptive potential of the bone and its contained dentition.

There are a few special factors which need to be taken into account in managing these injuries.

Interference with growth potential : The normal growth of the mandible will be disturbed if unerupted permanent teeth or teeth germs are lost, because the alveolus will not develop normally in the areas affected. Damage to the growth potential will be more severe in the event of infection of the fracture site.

McGuirt and Salisbury (1987) carried out a careful cephalometric analysis of 28 children who had experienced mandibular fractures at sites other than the condyle and found that mandibular unit length to be less than expected in 67%. One-third of the patients with fractures in the tooth-bearing portion of the mandible had specific dental complications.

The capacity for preferential growth in the sub-condylar region may be seriously compromised by high condylar fractures, particularly if function is restricted as a result of fibrous or bony ankylosis of the temporomandibular joint. The treatment of these injuries has been discussed in Chapter 8.

Fixation in the deciduous and mixed dentition period : If the severity and displacement of the fracture are of sufficient degree to warrant immobilization of the mandible, some modification of technique is required because of the presence of unerupted or partially erupted teeth of the permanent dentition and deciduous teeth of variable mobility.

Fixation independent of the teeth : 1. In the very young with uerupted or very few deciduous teeth MacLennan (1956) recommends the use of an overall Gunning-type splint for the lower jaw alone. This is constructed as a trough lined with black gutta percha and retained by two circumferential wires.

2. Where some occlusion is present but there is widespread caries or loose deciduous teeth the mandible may be suspended by circumferential wires on each side linked to circumzygomatic wires from above.

3. A simple elasticated bandage chin support may be used in cases with minimal displacement where jaw movement is nevertheless painful.

Fixation utilizing the teeth : 1. Cap splints can be constructed for the mixed dentition but retention tends to be inadequate, particularly if partially erupted teeth are present. It is necessary to reinforce the cement bond with circumsferential wires tied over the splint on each side.

2. Where there are sufficient firm erupted deciduous and permanent teeth, eyelet wires or arch bars can be used. It is often difficult to fix wires firmly to deciduous molars and canines but this task is made easier by

using thinner more flexible soft stainless steel wires of 0.35 mm diameter. Similarly, a light arch bar of German silver without hooks is more easily adapted

to the irregular dentition and this should be

attached to the teeth by similar 0.35mm diameter wire ligatures.

Orthodontic brackets bonded directly to the teeth may be used in simple fractures.

Unerupted teeth : In patients below the age of 9 or 10 yeas the body of the mandible is congested with developing teeth. It is unsafe to apply transosseous wires or to insert bone pins or plates in these circumstances. In exceptional instances such as gross displacement of a symphysis or angle fracture the lower border may be wired with caution – bone plates and pins are contraindicated.

Healing and remodeling : Mandibular fractures in children heal very rapidly and some fractures are stable within a week, and firmly united within 3 weeks. If at the time the fracture is first seen the fragments are firm, but not perfectly reduced, it is a s well to accept some slight imperfection in the reduction rather than refracture the mandible with possible damage to developing teeth. Similarly, some imperfection in reduction can be accepted when a fresh fracture is treated, as in each of the above circumstances containing growth and eruption of teeth will compensate in most cases for the imperfect alignment of the fragments.

Finally, it should be emphasized that a prolonged follow-up period is required following most fractures of the mandible in children in order to be sure that there are no long-term effects on both mandibular growth and the normal development of the permanent dentition. There are often damaged teeth associated with fractures in this age group and close cooperation with the paedodontist, orthodontist and the patient’s general dental practitioner is of vital importance.

Later complications : Malunion : Post reduction radiographs must always be taken and should these reveal an unacceptable malposition of the fragments, this should be corrected as soon as possible by a further operation if necessary.

When fixation is removed there should be no derangement of the occlusion. Unfortunately from time to time some disturbance is found to be present. Such minor malunion is more common after cap splits have been employed and results either from failure to seat the splints evenly when originally cemented into place, or from faulty laboratory technique producing variation in the thickness of the metal casting. If fixation is removed at the stage of clinical union when the callus is still soft, minor discrepancies in the occlusion will often correct themselves as the patient starts to use the jaws again. The process of readjustment may be helped by selective occlusal grinding.

Occasionally cases may be seen where inadequate reduction has resulted in gross derangement of the occlusion and deformity of the face. This situation may also arise when a patient has had no treatment at all for the fractured mandible, either because he did not seek treatment at the time of injury, or because other more serious injuries prevented treatment or diagnosis. The mandible has an impressive capacity to heal itself and providing some bone contact is present, malunion is more likely than nonunion. Gross occlusal derangement and facial deformity requires operative reconstruction usually in the form of refracture. Occasionally a formal planned osteotomy or ostectomy may be required. When the jaw is refractured to correct malunion it is wise to pack autogenous cancellous bone chips obtained from the iliac crest around the newly approximated bone ends.

If this is not done the diminished blood supply at the site of the original injury

may predispose to further delayed union. Occasionally alloplastic onlays may be indicated particularly when there is asymmetry.

Delayed and non-union Delayed union If the time taken for a mandibular fracture to unite is unduly protracted it is referred to as a case of ‘delayed union’. The term is difficult to define precisely as fractures heal at different rates, but if union is delayed beyond the expected time for that particular fracture (taking the site and the patient’s age into consideration) it must be assumed that the healing process has been disturbed. This may be the result of local factors such as infection, or general factors such as osteoporosis or nutritional deficiency. Providing the fracture site becomes stable so that jaw function can be resumed, no active intervention is necessary in the short term. A fracture in which fibrous union has occurred will frequently progress to slow bony consolidation during the ensuing 12 months after injury. Fibrous union may be an acceptable result in an elderly edentulous patient. However, in a younger dentate individual, prosthetic replacement of missing teeth is impractical if any mobility at a fracture site remains and at some point non-union has to be accepted and treated.

Non union : Non union means that the fracture is not only not united but will not unite on its own. Radiographs show rounding off and sclerosis of the bone ends, a condition referred to as eburnation. Non-union includes the condition of fibrous union referred to previously when there is a degree of stability.

Non-union may occur in a number of circumstances some of which are preventable. The theoretically preventable causes of non-union are as follows : 1. Infection of the fracture site.

2. Inadequate immobilization.

3. Unsatisfactory apposition of bone ends with interposition of soft tissue.

The remaining causes of non-union may be impossible or very difficult to overcome and are as follows : 1. The ultra-thin edentulous mandible in an elderly debilitated patient.

2. Loss of bone and soft tissue as a result of severe trauma, e.g., missile injury.

3. Inadequate blood supply to fracture site, e.g. after radiotherapy.

4. The presence of bone pathology, e.g. a malignant neoplasm.

5. General disease, e.g. osteoporosis, severe nutritional deficiency, disorders of calcium metabolism.

Treatment : A moderate delay in union is treated by prolonging the period of immobilization. Once non-union is accepted and if the bone ends are still approximated, the fracture line should be explored surgically and any obvious impediment to healing such as a sequestrum or devitalized tooth removed.

The bone ends are then freshened, the wound closed and the jaw is immobilized once again. If there is any doubt concerning the health of the bone ends autogenous cancellous bone chips should be obtained from the iliac crest and packed around the fracture site.

If radiographs of a non-union show marked eburnation of the bone ends or excessive bone loss, a formal bone graft of cortico-cancellous bone will be required. It is important to eliminate active infection from the site before employing a bone graft although if the obvious cause of the infection has been eliminated, a bone graft inserted at the same operation will usually be successful. In these circumstances metranidazole 500 mg every 8 hours given intravenously in an infusion is a most useful prophylactic antibiotic.

Derangement of the temporomandibular joint :

Conservative treatment of the fractured mandibular condyle frequently leaves

a

state

of

malunion at

the

fracture

site.

Post-traumatic

temporomandibular joint problems are not uncommon.

Late problems with transosseous wires and plates : Transosseous wires at the upper border may cause symptoms, particularly if covered by a denture. The wire is usually easily removed under local anaesthesia. Bone plates should not be placed near the oral mucosa as they will tend to become exposed.

Lower border wires sometimes give rise to pain and discomfort if the overlying skin is thin. In these circumstances they should be removed.

Bone plates, particularly the larger compression plates, may become infected some time after the fracture has healed. Surgical removal of the plate will lead to rapid resolution of the problem.

Sequestration of bone : Comminuted fractures of the mandible, particularly those caused by missile injuries, may be complicated by the formation of bone sequestra. A sequestrum may be a cause of delayed union but often the fracture consolidates satisfactorily and the sequestrum remains as an actual or potential source of infection. Sequestra may then be extruded spontaneously into the mouth with quite minimal symptoms but sometimes a localized abscess forms and surgical removal of the dead bone becomes necessary. It is important to be sure that a sequestrum has separated completely from the healthy adjacent bone before surgical removal is contemplated. Very often an infection can be treated with antibiotics and the dead bone allowed to extrude spontaneously without surgical intervention.

Limitation of opening : Prolonged immobilization of the mandible in intermaxillary fixation will result in weakening of the muscles of mastication. If there has been

substantial haemorrhage within muscles a considerable amount of organizing haematoma and early scar tissue may be present when fixation is released. All these factors combine to cause limitation of opening and a restricted mandibular excursion. In the majority of cases full movement is restored in time but as with other fractures, physiotherapy may accelerate the recovery period. Simple jaw exercises and mechanical exercises may be employed with advantage. Occasionally manipulation of the mandible under anaesthesia may assist the breakdown of scar tissue within muscles.

Fibrodysplasia ossificans involving the main muscles of mastication is a very rare complication of mandibular fractures. It is believed that a haematoma occurs in the muscle, which organizes and eventually becomes ossified. That view is supported by the finding of trabecular bone within the muscle mass at subsequent operation (Narang and Dixon, 1974). Treatment consist of excision of the ectopic bone but the condition will often recur. The complication is extremely rare considering the frequency of mandibular injury and systemic factors may play a part in the disorder.

Scars : Many mandibular fractures have associated soft-tissue injuries and providing these wounds are carefully cleaned and sutured minimal scarring occurs. At first all scars tend to be red and feel hard to the touch but during the first year they soften and fade. Massage of the scar by the patient and the application of lanoline are very helpful in this respect. Occasionally hypertrophic scarring or keloid occurs producing an ugly deformity. Unsightly scars also result from contamination of the original wound with dirt, especially tar products. In all these circumstances surgical revision may be beneficial but should not be contemplated until at least 1 year has elapsed.

Unsightly scars can largely be prevented by adequate wound toilet and careful suturing of the original laceration.

Fractures with gross comminution of bone and loss of hard and soft tissue : Although this type of mandibular fracture can occur in civilian practice from certain industrial injuries or injuries caused by fast-moving projectiles, it is more commonly associated with missiles employed in war or civil disturbance. The main differences between missile injuries of the mandible and the type seen in civilian practice can be enumerated as follows: 1. The fracture is usually extensively comminuted.

2. It is always compound and contaminated by foreign matter and bacteria.

3. The viability of the bone fragments and the extent of injury to teeth cannot be accurately evaluated preoperatively from clinical and radiographic examination.

4. Fracture treatment is complicated by soft-tissue injury or loss.

Bullets and other missiles traveling at high velocities cause this extensive damage because of the release of kinetic energy at the point of impact. Kinetic energy is proportional to the square of the velocity and it is therefore the impact velocity of the missile which is the most important factor. At impact there is deformation and sometimes fragmentation of the missile. The release of energy produces temporary cavitation within the tissues. These factors result in widespread damage adjacent to the missile tract and an ‘explosive’ exit wound although the entry wound may be comparatively small.

Such extensive injuries of the mandible require protracted treatment and the management can be divided into four main phases.

Immediate post-traumatic phase :

The patient is not particularly shocked as a result of a facial injury alone but haemorrhage may be severe. These patients are often fully conscious even after extensive injury and maintain surprisingly good control over their own airway as they are able to position themselves so that blood and debris do not obstruct respiration. If consciousness is depressed immediate steps must be taken to remove blood and debris from the mouth and to control the tongue by a suture if necessary. Care must be taken in transporting such patients to ensure they are not laid on their backs in which position they may rapidly suffocate. Stretcher cases should be laid face downward with their face over the end of the stretcher and their forehead supported on a bandage tied between the two handles of the stretcher, or they can be carried lying on their side. Either position ensures that the tongue falls forward and blood and saliva drain out of the mouth. Ambulatory patients will spontaneously hold their face downward and forward.

These patients suffer surprisingly little pain and powerful analgesics which depress the cough reflex should not be administered.

Primary surgery : The surgical treatment of the fracture is often an incidental stage in the management of the wound as a whole. Often extensive wounds can only be managed

after

preliminary tracheostomy to

ensue

immediate

and

postoperative control of the airway. The stages of treatment will be as follows : Wound toilet : A missile injury is always contaminated and intensive preliminary toilet is necessary in most cases, before formal surgical closure is undertaken.

Debridement : When the wound is ready for definitive surgery thorough debridement should be carried out to remove all devitalized tissue.

Management of involved teeth : Teeth are both a source of subsequent wound infection and a means of fixation. Their status in these two respects may only be determinable by inspection at the time of primary surgery. It is therefore very difficult to design fixation before the patient is under an anaesthetic. In general all extensively damaged and subluxed teeth should be removed. There are, however, occasions when temporary retention of damaged teeth may be necessary simply to control large loose alveolar fragments. Infection and delayed healing may result from such a decision in which case the involved teeth are removed at a later date by which time some consolidation of the bone fragments will have occurred.

Reduction and fixation : Ever attempt must be made to establish bone continuity especially in the symphysis region. This can sometimes be achieved by deliberately displacing fragments to compensate for bone loss. Where irretrievable bone loss has taken place the remaining portions of the mandible should be positioned in their normal relationship and separately immobilized. In general arch wires provide the most versatile form of fixation assisted by a minimal number of transosseous wires.

Closure of mucosa and skin : The oral mucosa is closed first after the fracture has been suitably reduced and every attempt should be made to ensure that this closure is watertight. The jaws are then temporarily immobilized and the overlying skin wound is sutured. When skin loss has occurred it is often possible to obtain closure by undermining the wound edges or by raising local flaps. The rich vascular supply to the face permits the raising local flaps. The rich vascular supply to the face permits the raising of local flaps from somewhat damaged tissue, whereas in other parts of the body similar flaps would undoubtedly

fail. Skin to mucosa suturing should only be used as a last resort as it condemns the patient to extensive secondary reconstruction. Every effort must be made to reconstitute the oral sphincter even if this results in some distortion or reduction in size of the mouth orifice.

Drainage : Comminuted bone within a sleeve of healthy periosteum will heal in continuity. If, however, the periosteal sleeve becomes infected the fragments of bone will necrose and sequestrate leading to non-union. For this reason drains should be used liberally in contaminated comminuted fractures of the mandible. Through and through drains which allow subsequent irrigation of the fracture site are often helpful in preventing or controlling infection. It must be remembered that all wounds of the ‘gunshot’ type are infected from the outset however ‘clean’ they may appear after debridement.

Immediate postoperative phase : Patients who have sustained severe facial injuries of this nature are very conscious of their actual and potential deformity. They require sympathetic nursing to bolster their confidence. Special feeding devices may be needed if there is soft-tissue loss involving the oral sphincter and sometimes some form of saliva shield may have to be constructed to prevent the constant escape of oral secretions. Oral hygiene is, of course, even more important than in simpler fractures and the patients usually require active assistance with mouth irrigation. Tracheostomy management and care of wound drains need specialized nursing care to avoid serious complications.

Reconstructive phase : There is no doubt that surgical expertise in treating the original injury can do much to reduce the amount of later reconstruction. If mandibular continuity is established even with considerable loss of mandibular thickness,

function is restored more quickly and the need for later bone grafting avoided.

Similarly, ingenuity in the use of local flaps during initial wound closure will minimize the effects of skin loss.

Nevertheless some reconstruction is usually necessary. Skin may have to be brought in and bone contour modified or re-established. Teeth need to be replaced and many patients require special prostheses. The reconstructive phase of treatment of these extensive disfiguring injuries may involve numerous hospital visits and further operations over a considerable period of time.

COMPLICATIONS : Serious complications arising as a result of a fracture of the mandible are rare providing the fracture has been competently treated. Minor complications are, however, more common than is generally accepted (Afzelius and Rosen, 1980). Complications may be considered under two headings : 1. Complications arising during primary treatment.

2. Late complications.

Complications arising during primary treatment Misapplied fixation The increased use of bone plates, particularly in the tooth-bearing portion of the mandible, has increased the complication rate during primary treatment. Compression plates demand screws of sufficient length to impinge on the inner cortex. Care is needed to avoid the inferior dental canal and to avoid damage to the roots of teeth. The risk of damage to structures within the body of the mandible is less when the screw engages only the outer cortex as is the case with non-compression mini-plates.

Rigid osteosynthesis can distort the anatomical alignment of the mandible leading to significant alteration of the occlusion. Should this occur a decision must be made as to whether the malalignment can be corrected by alter occlusal adjustment or whether a second corrective operation should be performed.

Osteosynthesis by transosseous wires is technically easier and damage to internal structures should be avoidable. Nevertheless ill-judged direction of drill holes can cause problems. Circumferential wires, particularly those used to retain Gunning-type splints, must be carefully located. If the circumferential wire is close to a fracture line it may inadvertently be drawn

up into the fracture giving rise to displacement of the bone fragments, damage to the inferior dental bundle and inadequate retention of the splint.

The correct insertion of pins fro external fixation is even more hazardous in unskilled hands. The pins have to be inserted without the advantage of direct exposure of the bone. They may impinge on nerves, blood vessels or teeth. They may split the bone fragment if inserted too near the lower border and they may fail to penetrate sufficient bone substance to remain secure during the required period of fixation.

Infection : Infection of the fracture site resulting in necrosis or osteomyelitis of the mandible is rare. When teeth are retained in the fracture line there is always some risk of infection and for this reason prophylactic antibiotic should be prescribed. Lowering of the patient’s local or general resistance will predispose to infection. Pathological fracture such as may be caused by the presence of a benign or malignant neoplasm is a good example of diminished local resistance to bacterial invasion. Debilitated patients, diabetics and patients on steroid therapy are more likely to develop infected fracture sites because of lowered general resistance.

Some of the most severe infections of fracture sites are seen as a result of injudicious surgical interference, such as transosseous wiring of a fracture already infected.

Nerve damage : Anaesthesia of the lower lip as a result of neuropraxia or neurotmesis of the inferior dental nerve is the most common complication of fracture of the body of the mandible. The recovery of sensation in the lower lip depends on the nature of the original damage to the nerve. While anaesthesia is present the patient should be warned of the danger of burning the lower lip with hot drinks or cigarettes.

Facial nerve damage may complicate some fractures of the ramus and condyle, either as a result of a penetrating injury severing branches of the nerve, or blunt trauma causing a neuropraxia. In the latter event recovery of the resultant nerve weakness usually takes place fairly rapidly. If the facial nerve is severed modern microsurgical techniques are often successful in restoring function but it is most important to perform the repair at the same time as the facial laceration is explored and sutured. It is much more difficult to restore continuity and function as a later secondary procedure.

Displaced teeth and foreign bodies : Teeth or portions of dentures are occasionally inhaled and, when missing, must be accounted for. If this is not possible the chest must be radiographed and if a foreign body is present it should be recovered by bronchoscopy.

Fragments of teeth or glass are not infrequently buried in the soft tissues of the lip. They may be difficult to locate in swollen tissues but may become infected if left. If an abscess does occur, the site of pus formation locates the foreign body which is ten usually removed easily when the abscess is opened and drained.

Pulpitis : Damaged teeth may develop pulpitis or apical infection during the period of fixation. Such teeth are relatively easy to treat if arch bars or eyelet wires have been employed. If a tooth becomes painful under a cap splint it is occasionally necessary to remove the root portion via a buccal transalveolar surgical approach. The tooth is sectioned at the cervical margin and the crown left within the cap splint.

Gingival and periodontal complications : Some degree of local gingivitis is inevitable when the fixation employed involves interdental wires or cap splints. The gingival reaction may

be very severe when acrylic resin is used to attach cup splints to the teeth.

Gingivitis is usually not a serious problem and responds to local measures.

A more serious periodontal problem can result from applying too much interdental force to individual teeth from eyelet wires or arch bars. The lower incisors are most vulnerable and may be partially extruded or even lost. The complication can be avoided by spreading the load more widely and evenly by additional eyelets or arch bar ligatures, and by avoiding the application of wires to suspect teeth.

Drug reactions : Allergic reactions occur from time to time usually to antibiotics. These are fortunately in the main fairly mild but the clinician must recognize the complication at an early stage, discontinue all drugs which might be incremented and prescribe an antihistamine such as oral chlorpheniramine maleate (Piriton) 4mg t.d.s.

Later complications : Malunion : Post reduction radiographs must always be taken and should these reveal an unacceptable malposition of the fragments, this should be corrected as soon as possible by a further operation if necessary.

When fixation is removed there should be no derangement of the occlusion. Unfrotunately form time to time some disturbance is found to be present. Such minor malunion is more common after cap splits have been employed and results either from failure to seat the splints evenly when originally cemented into place, or from faulty laboratory technique producing variation in the thickness of the metal casting. If fixation is removed at the stage of clinical union when the callus is still soft, minor discrepancies in the occlusion will often correct themselves as the patient starts to use the jaws

again. The process of readjustment may be helped by selective occlusal grinding.

Occasionally cases may be seen where inadequate reduction has resulted in gross derangement of the occlusion and deformity of the face. This situation may also arise when a patient has had no treatment at all for the fractured mandible, either because he did not seek treatment at the time of injury, or because other more serious injuries prevented treatment or diagnosis. The mandible has an impressive capacity to heal itself and providing some bone contact is present, malunion is more likely than nonunion. Gross occlusal derangement and facial deformity requires operative reconstruction usually in the form of refracture. Occasionally a formal planned osteotomy or ostectomy may be required. When the jaw is refractured to correct malunion it is wise to pack autogenous cancellous bone chips obtained from the iliac crest around the newly approximated bone ends.

If this is not done the diminished blood supply at the site of the original injury may predispose to further delayed union. Occasionally alloplastic onlays may be indicated particularly when there is asymmetry.

Delayed and non-union Delayed union If the time taken for a mandibular fracture to unite is unduly protracted it is referred to as a case of ‘delayed union’. The term is difficult to define precisely as fractures heal at different rates, but if union is delayed beyond the expected time for that particular fracture (taking the site and the patient’s age into consideration) it must be assumed that the healing process has been disturbed. This may be the result of local factors such as infection, or general

factors such as osteoporosis or nutritional deficiency. Providing the fracture site becomes stable so that jaw function can be resumed, no active intervention is necessary in the short term. A fracture in which fibrous union has occurred will frequently progress to slow bony consolidation during the ensuring 12 months after injury. Fibrous union may be an acceptable result in an elderly edentulous patient. However, in a younger dentate individual, prosthetic replacement of missing teeth is impractical if any mobility at a fracture site remains and at some point non-union has to be accepted and treated.

Non-union Non-union means that the fracture is not only not united but will not unite on its own. Radiographs show rounding off and sclerosis of the bone ends, a condition referred to as eburnation. Non-union includes the condition of fibrous union referred to previously when there is a degree of stability.

Non union may occur in a number of circumstances some of which are preventable. The theoretically preventable causes of non-union are as follows : 1. Infection of the fracture site.

2. Inadequate immobilization.

3. Unsatisfactory apposition of bone ends with interposition of soft tissue.

The remaining causes of non-union may be impossible or very difficult to overcome and are as follows : 1. The ultra-thin edentulous mandible in an elderly debilitated patient.

2. Loss of bone and soft tissue as a result of severe trauma, e.g. missile injury.

3. Inadequate blood supply to fracture site, e.g., after radiotherapy.

4. The presence of bone pathology, e..g a malignant neoplasm.

5. General disease, e.g. osteoporosis, severe nutritional deficiency, disorders of calcium metabolism.

Treatment : A moderate delay in union is treated by prolonging the period of immobilization. Once non-union is accepted and if the bone ends are still approximated, the fracture lien should be explored surgically and any obvious impediment to healing such as a sequestrum or devitalized tooth removed.

The bone ends are then freshened, the wound closed and the jaw is immobilized once again. If there is any doubt concerning the health of the bone ends autogenous cancellous bone chips should be obtained from the iliac crest and packed around the fracture site.

If radiographs of a non-union show marked eburnation of the bone ends or excessive bone loss, a formal bone graft of cortico-cancellous bone will be required. It is important to eliminate active infection from the site before employing a bone graft although if the obvious cause of the infection has been eliminated, a bone graft inserted at the same operation will usually be successful. In these circumstances metronidazole 500mg every 8 hours given intravenously in an infusion is a most useful prophylactic antibiotic.

Derangement of the temporomandibular joint : Conservative treatment of the fractured mandibular condyle frequently leaves

a

state

of

malunion at

the

fracture

site.

Post-traumatic

temporomandibular joint problems are not uncommon.

Late problems with transosseous wires and plates : Transossous wires at the upper border may cause symptoms, particularly if covered by a denture. The wire is usually easily removed under local anesthesia. Bone plates should not be placed near the oral mucosa as they will tend to become exposed.

Lower border wires sometimes give rise to pain and discomfort if the overlying skin is thin. In these circumstances they should be removed.

Bone plates, particularly the larger compression plates, may become infected some time after the fracture has healed. Surgical removal of the plate will lead to rapid resolution of the problem.

Sequestration of bone : Comminuted fractures of the mandible, particularly those caused by missile injuries, may be complicated by the formation of bone sequestra. A sequestrum may be a cause of delayed union but often the fracture consolidates satisfactorily and the sequestrum remains as an actual or potential source of infection. Sequestra may then be extruded spontaneously into the mouth with quite minimal symptoms but sometimes a localized abscess forms and surgical removal of the dead bone becomes necessary. It is important to be sure that a sequestrum has separated completely from the healthy adjacent bone before surgical removal is contemplated. Very often an infection can be treated with antibiotics and the dead bone allowed to extrude spontaneously without surgical intervention.

Limitation of opening : Prolonged immobilization of the mandible in intermaxillary fixation will result in weakening of the muscles of mastication. If there has been substantial haemorrhage within muscles a considerable amount of organizing haematoma and early scar tissue ay be present when fixation is released. All these factors combine to cause limitation of opening and a restricted mandibular excursion. In the majority of cases full movement is restored in time but as with other fractures, physiotherapy may accelerate the recovery period. Simple jaw exercises and mechanical exercises may be employed with advantage. Occasionally manipulation of the mandible under anaesthesia may assist the breakdown of scar tissue within muscles.

Fibrodysplasia ossificans involving the main muscles of mastication is a very rare complication of mandibular fractures. It is believed that a haematoma occurs in the muscle, which organizes and eventually becomes ossified. That view is supported by the finding of trabecular bone within the muscle mass at subsequent operation (Narang and Dixon, 1974). Treatment consists of excision of the ectopic bone but the condition will often recur. The complication is extremely rare considering the frequency of mandibular injury and systemic factors may play a part in the disorder.

Scars : Many mandibular fractures have associated soft-tissue injuries and providing these wounds are carefully cleaned and sutured minimal scaring occurs. At first all scars tend to be red and feel hard to the touch but during the first year they soften and fade. Massage of the scar by the patient and the application of lanoline are very helpful in this respect. Occasionally hypertrophic scarring or keloid occurs producing an ugly deformity. Unsightly scars also result from contamination of the original wound with dirt, especially tar products. In all these circumstances surgical revision may be beneficial but should not be contemplated until at least 1 year has elapsed.

Unsightly scars can largely be prevented by adequate wound toilet and careful suturing of the original laceration.

REFERENCES

• MAXILLOFACIAL INJURIES - ROWE & WILLIAMS. VOL- 1 • ORAL MAXILLORFACIAL TRAUMA- RAYMOND-J.FONSECA. VOL-1 • ORAL MAXILLOFACIAL SURGERY- PETER WARDBOOTH. VOL-1 • MANDIBULAR FRACTURES - KILLEY & KAY. • MAXILLOFACIAL TRAUMA – ROBERT H MATHOG. • TEXT

BOOK

OF

PLASTIC

,

MAXILLOFACIAL

RECONSTRUCTIVE SURGERY – GREGORY S GEORGIADE

AND