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Mandibular fractures / Oral surgery courses


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Mandibular fractures / Oral surgery courses

  1. 1. SEMINAR on Mandibular fractures CONTENTS
  3. 3. 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
  4. 4. 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 :
  5. 5. • 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
  6. 6. 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 1st 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
  7. 7. 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.
  8. 8. 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
  9. 9. 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
  10. 10. 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
  11. 11. 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
  12. 12. 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.
  13. 13. 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.
  14. 14. 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:
  15. 15. 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.
  16. 16. 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:
  17. 17. 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.
  18. 18. 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 :
  19. 19. 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. Statistics- related 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.
  20. 20. 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.
  21. 21. 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.
  22. 22. 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.
  23. 23. 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)
  24. 24. 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.
  25. 25. 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:
  26. 26. I. Relation the External Environment A. Simple or closed B. Compound or open II. Type of Fractures A. Incomplete B. Greenstick C. Complete D. Comminuted. III. 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 IV. 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. Fractures of the angle of the mandible in the third molar region
  27. 27. 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:
  28. 28. 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, well- defined object (hammer or pipe) may cause a single comminuted fracture, since the impact of the force is concentrated in a smaller area.
  29. 29. 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 :
  30. 30. 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:
  31. 31. 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:
  32. 32. 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
  33. 33. 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 :
  34. 34. 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.
  35. 35. 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.
  36. 36. 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.
  37. 37. 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
  38. 38. 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.
  39. 39. Banna also reported a case and reviewed the literature on post- traumatic 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 be approached methodically not with an “emergency-type” 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 concurrently treatment of mandibular fractures.
  40. 40. 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.
  41. 41. 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. With multiple facial fractures, mandibular fractures should be treated first.
  42. 42. 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.
  43. 43. 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.
  44. 44. 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
  45. 45. 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
  46. 46. 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 cross- sectional diameter of the mandibular body. Mandibular Fractures in Children With Developing Dentitions
  47. 47. 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.
  48. 48. 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 :
  49. 49. 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
  50. 50. 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.
  51. 51. 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.
  52. 52. 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
  53. 53. 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.
  54. 54. 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 :
  55. 55. 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.
  56. 56. 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 :
  57. 57. 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
  58. 58. b) Gagging of the posterior teeth which result either form the upward and medial movement of the posterior mandibular fragment, or from a posterior and downward movement of the upper jaw resulting from a middle third fracture. 2. 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 without exposed pulps, or loose teeth may cause pain and contribute to a lock of patient cooperation, especially in chi8ldre. 4. Cerebral irritation, alcoholism, drug addiction and apprehension also produce special problems. Impression technique :
  59. 59. 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:
  60. 60. 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.
  61. 61. 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.
  62. 62. 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 :
  63. 63. 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:
  64. 64. 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.
  65. 65. 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.
  66. 66. 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.
  67. 67. • 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:
  68. 68. 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 gutta- percha. 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.
  69. 69. 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.
  70. 70. 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:
  71. 71. 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.
  72. 72. 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 because of the projection of the pins which may easily be knocked b) Readily accessible to an interfering, uncooperative or cerebrally irritated patient. c) The universal joints may require frequent tightening, since torsional forces may not be adequately controlled 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.
  73. 73. 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
  74. 74. 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
  75. 75. 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
  76. 76. 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
  77. 77. 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 70° 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
  78. 78. 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
  79. 79. 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.
  80. 80. 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 minimal movement appears to be beneficial in the late to malunion or infection. It is, therefore, sometimes advisable to immobilize the jaw for at least 3 weeks, or longer if necessary, before relying entirely on pin fixation for support of the fracture. If intermaxillary fixation by `Gunning-type’ splints in not possible, craniofacial fixation must be used.
  81. 81. 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 this. h) If acute infection develops around a pin and cannot be controlled by antibiotics, it is advisable to remove the affected pin, relying on the remaining one which 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.
  82. 82. 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
  83. 83. 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
  84. 84. 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
  85. 85. 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.
  86. 86. 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
  87. 87. 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