Mandible Fracture

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Mandible Fracture

Trauma
Author Credentials 

José E. Barrera, MD
Texas Facial Plastic Surgery and ENT
San Antonio, Texas 78230
Facialplasticsurgerytexas.com

Module Summary

As with any trauma, the fundamentals of good trauma care must be followed. The airway must be secure and breathing and circulation must be confirmed. Possible cervical spine (C-spine) injury needs to be ruled out. With mandible fractures, earlier reduction is associated with better outcomes. Although, if other injuries dictate, repair may be delayed 5-7 days, surgical correction is recommended as soon as possible. Current concepts include early intervention with wide surgical exposure to allow for precise alignment and rigid fixation.
Knowledge of the anatomy of the mandible and the muscular forces applied to it is the key to proper reduction of mandible fractures. The goal in reduction is to restore pre morbid occlusion, allowing patients to resume masticatory functions. Prior to repair, patients must be thoroughly evaluated.

Module Learning Objectives 
  1. Describe the mechanism of a mandible fracture.
  2. Identify the important anatomical structures and areas of the mandible.
  3. State the location of tensile and compressive forces.
  4. Review the standard trauma protocol of Airway, Breathing and Circulation.
  5. Summarize the signs and symptoms which suggest a fracture of the mandible as a primary or contributing factor in common trauma scenarios in otolaryngology.
  6. Explain the principles of closed versus open reduction and stabilization of a fracture site, as well as the treatment options that are available in the reduction of a fracture.
  7. Recognize the signs and symptoms of a mandible fracture, and formulate a logical work up and treatment plan.
  8. Explain that the treatment goals are to restore function and the pre-morbid occlusion. Mastication, speech, and normal range of oral motion should be achieved. Contour defects must be corrected. Early treatment curtails the possibility of infection.

Embryology

Learning Objectives 

Understand the development of the mandible:

  1. The mandible is derived from the first branchial arch.
  2. Its bone is membranous in nature.
  3. Ossification is by direct mineral deposition into the organic matrix of mesenchyme or connective tissue.
  4. Bone matrix is 35% organic and 65% inorganic, and 90% of the organic component is type I collagen. Hydroxyapatite makes up most of the inorganic portion of bone.
References 
  1. Bailey BJ, Dierks EJ: Mandibular fractures. In: Bailey BJ, et al, eds. Head and Neck Surgery-Otolaryngology. Vol 1. Philadelphia: JB Lippincott; 1993:961-972.

Anatomy

Learning Objectives 

Understand the unique design of the mandible and fracture patterns seen in trauma cases. Knowledge of the anatomy of the mandible and the muscular forces applied to it is key to proper reduction of mandible fractures.

  1. The mandible is divided into the condylar, subcondylar, ramus, angle, body, parasymphyseal, symphyseal, coronoid, and dental alveolar regions.
  2. The structure of the mandible is such that masticatory force trajectories are transmitted to the skull base, but the mandible usually fractures prior to penetration of the middle cranial fossa. This design permits great forces on the mandible to be distributed along its frame.
  3. The third division of the trigeminal nerve enters the mandible, at the lingula, as the inferior alveolar nerve (IAN). The IAN gives off dental branches before exiting the mental foramen. The distal mental nerve is located between the first and second premolar teeth.
  4. Knowledge of the path of the nerve and the length of the teeth is important in planning the placement of titanium plates and screws.
  5. Dental occlusion is determined by the opposition of teeth of the upper and lower arches.
  6. Primary dentition starts with the incisors at 6 months of age, and all 20 teeth are present by age 2.5 years.
  7. The permanent teeth start with the eruption of the first molars around age 6 years, and the completion of the dentition takes place at age 16-20 years.
  8. The surfaces of the teeth help determine the pre morbid occlusion. Wear facets can be identified and guide the surgeon to the proper occlusion.
  9. The mandibular anatomy not only helps in the planning and execution of surgery, but it also is useful in communicating with other members of the surgical team.
References 
  1. Chang EW, Lam SM, Karen M, Donlevy JL: Sliding genioplasty for correction of chin abnormalities. Arch Facial Plast Surg. 2001 Jan-Mar;3(1):8-15[Medline].
  2. Chang EW, Lam SM, Farrior EH: Mandible Fractures - General Principles and Occlusion, E - medicine, March 2002
  3. Seckel BR: Facial Danger Zones: Avoiding Nerve Injury in Facial PLastic Surgery. St. Louis: Quality Medical Publishing; 1994:1-48.
  4. Kane AA, Lo LJ, Chen YR, et al: The course of the inferior alveolar nerve in the normal human mandibular ramus and in patients presenting for cosmetic reduction of the mandibular angles. Plast Reconstr Surg. 2000 Oct;106(5):1162-74; discussion 1175-6[Medline].
  5. Barrera JE. “Contemporary Management of Facial Fractures.” Otolaryngology Lifelong Learning Manual, Chapter 107:711-718, 2015.

Pathogenesis

Learning Objectives 

Understand the mode of injury and patterns of fracture.

  1. Although a single blow to the mandible can yield an isolated fracture, more commonly, 2 sites are involved. The surgeon should always be wary if only one fracture site is identified. For example, trauma to the side usually yields an ipsilateral body fracture and a contra lateral subcondylar fracture. A classic severe blow to the symphysis may produce a symphyseal fracture and bilateral subcondylar fractures.
  2. With bilateral mandible fractures, parasymphyseal or body, always protect the airway from obstruction caused by the retro displacement of the tongue.
  3. In a motor vehicle accident or a gunshot wound, multiple fractures should be suspected along with injuries to the soft tissue, C-spine, and central nervous system. These concomitant injuries are seen in as many as 30% of facial trauma cases.
  4. These injuries may be life threatening and should be dealt with as a high priority. As in all patients with traumatic injuries, the airway should be secured, the patient should be breathing, and the circulation should be stabilized. The C-spine should always be assessed radiologically and clinically, and injuries here should be ruled out prior to manipulation of the neck. Some C-spine injuries can be asymptomatic. Appropriate consultations should be made to assess the patient. The secondary survey can then be performed, including a full head and neck examination.
  5. Airway compromise often accompanies mandible fracture. Causes can include intraoral bleeding, edema, loose teeth or dentures, and posterior displacement of the mandible and/or tongue due to a flailed segment of the mandible. Consider an emergent tracheotomy or a cricothyrotomy when an obstruction persists despite use of basic cardiopulmonary resuscitation (CPR) and Advanced Trauma Life Support (ATLS).
References 
  1. Coleman JA, Johnson JT, Myers EN: Treatment of Mandibular Fractures. SIPAC; 1995:13-109.
  2. Ellis E: Advances in maxillofacial trauma surgery. In: Oral and Maxillofacial Trauma. Vol 2. WB Saunders Co; 1997.

Basic Science

Learning Objectives 

Understand the mode of injury and patterns of fracture.

  1. Although a single blow to the mandible can yield an isolated fracture, more commonly, 2 sites are involved. The surgeon should always be wary if only one fracture site is identified. For example, trauma to the side usually yields an ipsilateral body fracture and a contra lateral subcondylar fracture. A classic severe blow to the symphysis may produce a symphyseal fracture and bilateral subcondylar fractures.
  2. With bilateral mandible fractures, parasymphyseal or body, always protect the airway from obstruction caused by the retro displacement of the tongue.
  3. In a motor vehicle accident or a gunshot wound, multiple fractures should be suspected along with injuries to the soft tissue, C-spine, and central nervous system. These concomitant injuries are seen in as many as 30% of facial trauma cases.
  4. These injuries may be life threatening and should be dealt with as a high priority. As in all patients with traumatic injuries, the airway should be secured, the patient should be breathing, and the circulation should be stabilized. The C-spine should always be assessed radiologically and clinically, and injuries here should be ruled out prior to manipulation of the neck. Some C-spine injuries can be asymptomatic. Appropriate consultations should be made to assess the patient. The secondary survey can then be performed, including a full head and neck examination.
  5. Airway compromise often accompanies mandible fracture. Causes can include intraoral bleeding, edema, loose teeth or dentures, and posterior displacement of the mandible and/or tongue due to a flailed segment of the mandible. Consider an emergent tracheotomy or a cricothyrotomy when an obstruction persists despite use of basic cardiopulmonary resuscitation (CPR) and Advanced Trauma Life Support (ATLS).
References 
  1. Coleman JA, Johnson JT, Myers EN: Treatment of Mandibular Fractures. SIPAC; 1995:13-109.
  2. Ellis E: Advances in maxillofacial trauma surgery. In: Oral and Maxillofacial Trauma. Vol 2. WB Saunders Co; 1997.

Incidence

Learning Objectives 

Recognize that the areas of the mandible most commonly fractured include the condylar/subcondylar region, body, and angle.

  1. Location of the fractures and associated frequency are as follows:
    1. Condyle - 29%
    2. Angle - 24%
    3. Symphysis - 22%
    4. Body - 16%
    5. Ramus - 1.7%
    6. Coronoid - 1.3%
  2. The types of fractures commonly seen due to motor vehicular accident have decreased significantly with the use of restraint devices. The symphyseal and bilateral parasymphyseal fractures caused by the mandible striking the steering wheel or dashboard are rarely seen in patients using a seat belt.
  3. The average number of mandibular fractures per patient is 1.5-1.8 per patient. Ten percent of patients have more than 2 fractures.
  4. Children younger than 6 years make up only 1% of the total number of cases. Of note, children with mandibular fractures often have other associated injuries.
  5. The incidence of maxillofacial trauma resulting from motor vehicle accidents has been on the decline. On the other hand, the number of mandibular fractures resulting from assault has risen. Other causes include injury from a fall, sports-related injuries, and bicycle accidents. Causes are summarized as follows:
    1. Vehicular accidents - 43%
    2. Assaults - 34%
    3. Work related - 7%
    4. Fall - 7%
    5. Sporting accidents - 4%
    6. Miscellaneous - %5
References 
  1. Chang EW, Lam SM, Farrior EH: Mandible Fractures - General Principles and Occlusion, E - medicine, March 2002.
  2. Barrera JE. “Contemporary Management of Facial Fractures.” Otolaryngology Lifelong Learning Manual, Chapter 107:711-718, 2015.

Patient Evaluation

Learning Objectives 

Understand that the history and physical examination is crucial in determining the proper treatment plan.

  1. Underlying bone disorders and previous mandibular trauma may predispose a patient to traumatic fractures.
  2. The type and direction of force are important, as is the object causing the fracture.
  3. Symptoms often described include pain, trismus, difficulty chewing, and anesthesia or paresthesia of the lower lip and chin.
  4. On examination, findings include abnormal mandibular movements, malocclusion, change in facial contour and mandibular arch form, tenderness, swelling, redness, lacerations, hematoma, and ecchymosis.
  5. Loose and fractured teeth should be evaluated and counted. If teeth are missing, consider a chest radiograph to rule out aspiration.
  6. Premorbid occlusion can be confirmed by examining the wear facets on the surfaces of the opposing teeth. Patients are quite sensitive to changes in their occlusion and can appreciate displacements smaller than 1 mm. It must be remembered that not all patients have ideal occlusion (i.e., only 74% of the population have an angle class I bite). The remainder has either retrognathia (angle class II, 24%) or prognathia (angle class III, 1%).
  7. Angle classification is based on the relationship of the mesial-buccal cusp of the maxillary first molar to the buccal groove of the mandibular first molar.
  8. Class I occlusion refers to the mesial-buccal cusp of the maxillary first molar's contact with the mandibular first molar's buccal groove.
  9. The mesial-buccal cusp lies in front of (or mesial to) the groove in class II occlusion.
  10. In angle class III occlusion, the mesial-buccal cusp of the maxillary first molar falls behind (or distal to) the groove.
  11. Fractures that occur in the region of the teeth are considered to be compound fractures, which can be predisposed to bacterial contamination from the oral cavity. An open laceration and bleeding from the site also may be evident with compound fractures. These types of fractures should, therefore, be prophylactically treated with antibiotics. If the mucosa has not been violated, then clinical findings can be limited to ecchymosis.
  12. If the third division of the trigeminal nerve (the inferior alveolar or mental nerve) has been injured, the patient may have paresthesia or anesthesia of the chin. Documenting this and the function of the marginal mandibular nerve (branch of cranial nerve VII) is important prior to surgical intervention.
  13. Spasm of the muscles of mastication due to trauma can result in trismus, limiting a proper oral examination. Facial edema, erythema, and pain are also associated with mandibular fractures. Bilateral parasymphyseal/body and, at times, subcondylar fractures can result in the posterior displacement of the tongue, leading to airway compromise. In accordance with the tenets of trauma care, the airway should always be addressed first.
References 
  1. Rowe NL, Williams JL, Heslop IH: Mandibular fractures: treatment by open reduction and direct skeletal fixation. In: Rowe NL, Williams JL, eds. Maxillofacial Injuries. Vol 1. NY: Churchill Livingstone; 1985:293-336.

Measurement of Functional Status

Learning Objectives 

Know that return of normal masticatory, speech and respiratory functions are expected after treatment of a mandible fracture.

  1. Occlusion should be the same as before the injury
  2. The range of oral opening or maximal incisive opening (MIO) should be greater than 40 mm
  3. There should be no speech or airway compromise
References 
  1. Chang EW, Lam SM, Farrior EH: Mandible Fractures - General Principles and Occlusion, E - medicine, March 2002

Imaging

Learning Objectives 

Know the diagnostic test that will be of use in fracture reduction.

  1. A CT scan is extremely useful in maxillofacial trauma. Obtain images in both the axial and coronal planes. Addition, the current 3-D reconstruction views have excellent detail are very helpful when available.
  2. A panoramic radiograph (Panorex) affords an excellent 2-dimensional representation of the mandible. The entire mandible and the dentoalveolar structures can be viewed with the Panorex. Several types of plain films add to the evaluation of mandibular fractures.
    1. The dental periapical view gives fine detail to the teeth and their roots.
    2. The dental occlusal view helps determine whether the fracture is vertically favorable or unfavorable.
    3. The mandibular series includes several views to help identify the fracture.
    4. The Caldwell is a coronal view that shows displacement in the horizontal plane.
    5. The oblique views highlight the ramus angle and posterior body.
    6. The reverse Towne view depicts the condylar/subcondylar region well.
  3. Obtain a chest radiograph when evidence of a broken denture or missing tooth is present.
References 
  1. Chang EW, Lam SM, Farrior EH: Mandible Fractures - General Principles and Occlusion, E - medicine, March 2002

Treatment

Learning Objectives 
  1. Medical therapy: Nonoperative therapy is reserved for minimally displaced favorable fractures. Children often incur an incomplete fracture called a greenstick fracture, which is amenable to conservative therapy. Elderly edentulous patients with minimal displacements can be treated in a similar manner. Dressings help relieve the discomfort of the fracture. Minimal occlusal load is recommended when this mode of therapy is used.
  2. Surgical therapy: Goals of treatment include anatomic reduction of fracture segments, restoration of premorbid occlusion, and avoidance of complications. Ideally, treatment should be instituted within 7 days. Options to consider include closed or open reduction. Closed reduction maintains the segments by maxillomandibular fixation. Open reduction allows for direct evaluation of the mandibular segments and further for internal or external fixation. Internal fixation can be accomplished by wire (used more historically and in children), titanium plate, and screw fixation.
  3. The Joe-Hall-Morris appliance is an example of an external-pin fixation device. It was used extensively in World War II but has dropped out of favor. It is particularly useful in edentulous patients with a comminuted fracture.
  4. Oblique fractures, especially in the parasymphyseal region, are amenable to lag screws or to the lag technique, in which the proximal segment is drawn towards the distal segment.
  5. When determining the mode of therapy, consideration must be given to patient age, general health, and reliability, as well as position, stability, and severity of the fracture. One must not overlook the patient' s dental and periodontal status, the availability of materials and instrumentation for repair, availability of dental consultation, and the skill and experience of the surgeon.
  6. Preoperative details: Perioperative antibiotics are recommended, especially in fractures that go through areas with teeth. These are considered compound fractures, and should be treated as such.
  7. It is important to obtain appropriate diagnostic studies to aid in the localization of fractures. A dental evaluation helps to determine the condition of the teeth and allows appropriate fabrication of a dental appliance when needed.
  8. Intraoperative details: Occlusion is always set first. The occlusion can be maintained by maxillomandibular fixation (MMF) with Erich arch bars. Intermaxillary fixation (IMF) screws can simply be placed using four titanium screws, 1 in each dental quadrant, to permit wire fixation of the upper and lower arches. Stainless steel ligatures with eyelets can be passed interdentally to be used for MMF.
  9. More commonly, Erich arch bars are placed and secured with wire. Erich arch bars are outfitted with prongs that permit the upper and lower bars to be held together with looped wires. An alternative for attaching the arch bar to the mandible and maxilla other than wires involves light-cured resin composites. One caveat, if a subcondylar fracture is present, immobilization must not exceed 2 weeks. Physiotherapy is instituted to prevent ankylosis of the condyle.
  10. Open reduction necessitates a mucosal or skin incision for direct access to the fracture site. Fixation can then be accomplished with either wires or titanium plates and screws. Open reduction is used when closed reduction is insufficient to achieve anatomic alignment and immobilization. It should also be considered when contraindications to MMF arise.
  11. The condyle can be approached intraorally with a sulcus incision or extraorally through a preauricular incision.
  12. The angle can be addressed with a sulcus incision, percutaneous access, and/or a posterior angle incision.
  13. Sometimes a combination of access is needed, especially at the angle of the mandible. The body and parasymphyseal area is generally easily approached intraorally with a sulcus incision.
  14. With any incision, the surgeon must be cognizant of the course of the marginal mandibular branch of cranial nerve VII. The nerve is more at risk from an external access incision rather than through percutaneous access.
  15. Once the fracture is localized, some important concepts must be kept in mind. Mandibular tensile forces exist superiorly at the dentoalveolar area, and compressive forces exist at the inferior border.
  16. To combat the distraction of the segments, place a tension band superiorly along with an inferior plate. The tension band can take the form of an arch bar if teeth are present proximal and distal to the fracture line. If no teeth are found proximally, a small plate may be placed on the external oblique ridge of the mandible to act as a tension band. This concept is exemplified in Champy's technique. Ellis has had great success with noncompression, monocortical plates, fashioned in 2 planes at the external oblique ridge, for nondisplaced angle fractures. The 2-dimensional bend counteracts forces in both horizontal and vertical planes.
  17. For the inferior aspect of the mandible, a compression plate may be used. The medial screws are placed laterally in the screw hole and, as they engage the bone, they slide medially, compressing the mandibular segments together. An eccentric compression plate also exists, in which the medial screws bring the inferior portion of the mandible together while the lateral screws draw the superior aspect of the mandible together. Various sizes of plates and screws exist, and newer resorbable plates are currently under investigation. At present, the resorbable plates are being used in non–load-bearing areas, such as the periocular area. The surgeon should be familiar with the many plate sizes as well as the specifications of the different companies' products. Resorbable plates have not been found to promote osteointegration in the mandible.
  18. Teeth in the line of fracture should be removed if carious, fractured below the crown, or in an infected area. Otherwise leave in with a warning to the patient that extraction may be needed later on.
  19. Postoperative details: Patients left in MMF should have a nasal trumpet until fully awake. Wire cutters should be taped to the head of the bed, and a tracheotomy tray should be in the room.
  20. Teach patients to use a 60-cc syringe, with a 3-inch trimmed red rubber catheter attached at the end of the syringe, for feeding. The catheter is placed into the sulcus adjacent to the fixated arches so liquids and pureed food can then be easily delivered from the syringe.
  21. Patients must practice strict oral hygiene. Chlorhexidine (Peridex) oral rinses after meals and at bedtime should be prescribed if an intraoral incision is used.
  22. Follow-up care: Patients should be seen on a weekly basis. The condition of the arch bars, as well as the tension on the MMF wires, can be checked and tightened as necessary. Maximal time in MMF for Children is 4 weeks, adults no longer than 6 weeks, and elderly patients no longer than 8 weeks. Patients with condylar fractures must be taken out of MMF by 2 weeks, and aggressive physiotherapy must be instituted to prevent ankylosis. Measure the oral opening on each follow-up visit. Normal MIO is 40 mm. If open reduction and internal fixation is performed, many feel that MMF is not needed. By not having the patient in MMF, the ill effects are avoided and the patient's comfort level is increased.
References 
  1. Ellis E 3rd, Walker LR: Treatment of mandibular angle fractures using one noncompression miniplate. J Oral Maxillofac Surg. 1996 Jul;54(7):864-71;discussion 871-2[Medline].
  2. Schneider AM, et.al: Use of Specialized Bone Screws for Intermaxillary Fixation. Annals of Plastic Surgery. 2000 Feb;44(2):154-157.
  3. Assael LA, Buchbinder D: Use of rigid internal fixation in the treatment of mandibular fractures. Oral Maxillofac Clin North Am. 1990;2(1):41-54.
  4. Assael LA, Prein J, Beyer M: Management of infection and nonunion in mandibular fractures. Oral Maxillofac Clin North Am. 1990;2(1):187-194.
  5. Assael LA, Schwimmer AM: Lag screw fixation in maxillofacial trauma. Oral Maxillofac Clin North Am. 1990;2(1):195-204.
  6. Berg S, Pape HD: Teeth in the fracture line. Int J Oral Maxillofac Surg 1992 Jun; 21(3): 145-6[Medline].
  7. Chang EW, Lam SM, Farrior EH: Mandible Fractures - General Principles and Occlusion, E - medicine, March 2002
  8. Davies BW, Cederna JP, Guyuron B: Noncompression unicortical miniplate osteosynthesis of mandibular fractures. Ann Plast Surg. 1992 May;28(5):414-9[Medline].
  9. Ellis E 3rd, Zide MF: Transfacial approaches to the mandible. In: Surgical Approaches to the Facial Skeleton. Baltimore: Lippincott Williams & Wilkins; 1995:121-160.
  10. Garza JR: Mandible Fractures, Facial Plastic and Reconstructive Surgery, pp. 769-781, Second Edition-2002.
  11. Barrera JE. “Contemporary Management of Facial Fractures.” Otolaryngology Lifelong Learning Manual, Chapter 107:711-718, 2015.

Rehabilitation

Learning Objectives 

The surgeon realizes that oral physiotherapy is almost always beneficial. Especially with condylar/subcondylar fractures.

  1. Condylar/subcondylar fractures should not be kept immobilized for greater than 14 days. Thereafter, aggressive oral physiotherapy should be instituted.

Staging

Learning Objectives 

Mandible fractures are not staged, but are classified according to location.

  1. The fracture may be classified as simple, greenstick, compound, comminuted, or pathologic.
  2. Furthermore, classification can take into account forces influenced by muscular distraction.
  3. Muscular force can act favorably (nondisplaced fracture) or unfavorably (displaced fracture).
  4. Displacement can occur in either the horizontal or the vertical plane.

Case Studies

References 
  1. A 20 year old male has severe jaw pain after falling forward off of his mountain bike. He did not have LOC and remembers that his face hit the ground first. His exam shows a full compliment of teeth with no missing teeth and stability of the jaws. In an attempt to check his occlusion, there is marked pain and an anterior open bite. What injury is suspected?
    • Most likely, a bilateral condylar/subcondylar fracture.
  2. A 45 year old male was struck in the jaw with a baseball bat. There was LOC and the patient had airway compromise and was orally intubated in the field. What injuries do you suspect, and what interventions should you be prepared for?
    • One should always rule out c-spine injury first after the ABC protocol.
    • Most likely the patient has a flailed jaw, causing retro flexion of the tongue and anterior jaw segment. This is commonly seen in bilateral body or parasymphyseal fractures.
    • One must be prepared to perform a tracheotomy on this patient.

Complications

Learning Objectives 

Understand that complications can arise with delayed treatment, inadequate treatment, poor patient constitution, or poor postoperative care.

  1. Acute complications are the result of trauma itself. Intermediate complications are caused during MMF, and late ones occur after MMF. The overall complication rate is 3 times as high if the fracture is treated more than 10 days after initial injury.
  2. The greatest potential for respiratory distress occurs with bilateral body, parasymphyseal, or condylar fractures. Muscular action pulls the distal mandible segment posterior, causing the tongue to obstruct the oropharynx. Depending on the degree of neural injury, nerve function may or may not return. In neuropraxia, function returns in 4-6 weeks, whereas in neurotmesis, function may or may not return for approximately 18 months.
  3. An infection increases the chance of delayed union, nonunion, osteomyelitis, and loss of teeth and bone structure. Infection prolongs hospitalization and disability and increases the financial burden. With any open fracture or fractures involving teeth, antibiotics are recommended.
  4. A bony union is expected to result within 4-8 weeks with proper reduction and immobilization. Any time longer than 8 weeks is considered a delayed union and is seen when MMF is released prematurely. Pain and mobility require MMF to be reinstituted and within 8 weeks, a union is eventually formed.
  5. Nonunion occurs when no future potential exists for the bone to ultimately heal. Usually, a pseudoarthrosis is present, in which surgery is required to allow for union. Approximately 2.4% of fractures result in nonunion. Malunion occurs when the bone heals with improper alignment.
  6. Ankylosis is seen with an interincisal opening smaller than 5 mm. The normal oral opening is 40 mm, measured from incisal edge to incisal edge of the anterior teeth. The ankylosis is either fibrous or bony. Aggressive physiotherapy may release a fibrous ankylosis, but surgery is required in the latter case.
References 
  1. Rowe NL, Williams JL, Heslop IH: Mandibular fractures: treatment by open reduction and direct skeletal fixation. In: Rowe NL, Williams JL, eds. Maxillofacial Injuries. Vol 1. NY: Churchill Livingstone; 1985:293-336.
  2. Schilli W, Stoll P, Prein J: Mandibular fractures. In: Pren J, ed. Manual of Internal Fixation in the Cranio-Facial Skeleton. NY: Springer-Verlag; 1998:57-92.

Review

Review Questions 
  1. In planning for the reduction of a mandible fracture, which of the following is the most reliable way to restore function?
  2. When can conservative therapy be used for the treatment of mandible fractures?
  3. In patients with multiple traumatic injuries, should the treatment of mandible fractures takes precedence over life-threatening injuries?
  4. What fractures should be immobilized for only 2 weeks, followed by aggressive physiotherapy?
  5. Bone is 65% inorganic, does hydroxyapatite makes up most of the inorganic portion?
  6. When mandible fractures are treated conservatively, is there a lower incidence of infection than fractures that are treated with rigid fixation?
References 
  1. Assael LA, Buchbinder D: Use of rigid internal fixation in the treatment of mandibular fractures. Oral Maxillofac Clin North Am. 1990;2(1):41-54.
  2. Assael LA, Prein J, Beyer M: Management of infection and nonunion in mandibular fractures. Oral Maxillofac Clin North Am. 1990; 2(1):187-194.
  3. Assael LA, Schwimmer AM: Lag screw fixation in maxillofacial trauma. Oral Maxillofac Clin North Am. 1990;2(1):195-204.
  4. Bailey BJ, Dierks EJ: Mandibular fractures. In: Bailey BJ, et al, eds. Head and Neck Surgery-Otolaryngology. Vol 1. Philadelphia: JB Lippincott; 1993:961-972.
  5. Berg S, Pape HD: Teeth in the fracture line. Int J Oral Maxillofac Surg. 1992 Jun;21(3):145-6[Medline].
  6. Chang EW, Lam SM, Farrior EH: Mandible Fractures - General Principles and Occlusion, E - medicine, March 2002
  7. Chang EW, Lam SM, Karen M, Donlevy JL: Sliding genioplasty for correction of chin abnormalities. Arch Facial Plast Surg. 2001 Jan-Mar;3(1):8-15[Medline].
  8. Coleman JA, Johnson JT, Myers EN: Treatment of Mandibular Fractures. SIPAC; 1995:13-109.
  9. Davies BW, Cederna JP, Guyuron B: Noncompression unicortical miniplate osteosynthesis of mandibular fractures. Ann Plast Surg. 1992 May;28(5):414-9[Medline].
  10. Ellis E: Advances in maxillofacial trauma surgery. In: Oral and Maxillofacial Trauma. Vol 2. WB Saunders Co; 1997.
  11. Ellis E 3rd, Zide MF: Transfacial approaches to the mandible. In: Surgical Approaches to the Facial Skeleton. Baltimore: Lippincott Williams & Wilkins; 1995:121-160.
  12. Ellis E 3rd, Walker LR: Treatment of mandibular angle fractures using one noncompression miniplate. J Oral Maxillofac Surg. 1996 Jul;54(7):864-71;discussion 871-2[Medline].
  13. Garza JR: Mandible Fractures, Facial Plastic and Reconstructive Surgery, pp. 769-781, Second Edition-2002
  14. Kane AA, Lo LJ, Chen YR, et al: The course of the inferior alveolar nerve in the normal human mandibular ramus and in patients presenting for cosmetic reduction of the mandibular angles. Plast Reconstr Surg. 2000 Oct;106(5):1162-74;discussion 1175-6[Medline].
  15. Rowe NL, Williams JL, Hopkins R: Mandibular fractures: treatment by closed reduction and indirect skeletal fixation. In: Rowe NL, Williams JL, eds. Maxillofacial Injuries. Vol 1. NY: Churchill Livingstone; 1985:232-292.
  16. Rowe NL, Williams JL, Heslop IH: Mandibular fractures: treatment by open reduction and direct skeletal fixation. In: Rowe NL, Williams JL, eds. Maxillofacial Injuries. Vol 1. NY: Churchill Livingstone; 1985:293-336.
  17. Schilli W, Stoll P, Prein J: Mandibular fractures. In: Pren J, ed. Manual of Internal Fixation in the Cranio-Facial Skeleton. NY: Springer-Verlag; 1998:57-92.
  18. Seckel BR: Facial Danger Zones: Avoiding Nerve Injury in Facial PLastic Surgery. St. Louis: Quality Medical Publishing; 1994:1-48.
  19. Schneider AM, et.al: Use of Specialized Bone Screws for Intermaxillary Fixation. Annals of Plastic Surgery. 2000 Feb;44(2):154-157.
  20. Barrera JE. “Contemporary Management of Facial Fractures.” Otolaryngology Lifelong Learning Manual, Chapter 107:711-718, 2015.
Resources 

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