Initial Assessment - History

The diagnostic work-up of mandible fractures begins with a thorough primary survey as outlined by the Advanced Trauma Life Support (ATLS) protocols.

Life-threatening injuries, when present, need to be recognized and managed early before fracture assessment can begin (eg. Bucket Handle Fractures which may require tracheostomy)

A thorough history of present illness and past medical and surgical history will highlight any relevant medical conditions, previous trauma, bone disease, nutritional and metabolic disorders, and psychiatric conditions that may influence timing and management of the fracture.In addition, the patient's premorbid dental history and occlusion needs should be accounted for. When available, photographs can aid in reduction of the patient's fracture to re-establish the premorbid occlusion.

Initial Assessment - Clinical Examination

Focused evaluation of the head and neck is a part of the secondary survey outlined by ATLS protocols

Examination should begin with inspection and palpation. The classical signs of inflammation, pain, swelling, and erythema will help guide the physician in thorough identification of potential injuries. After examining for any lacerations or sources bleeding that needs to be addressed urgently, the clinician should perform an in- depth fracture assessment.

Extra- and intra-oral findings, in addition to a neurosensory examination, will help the physician in identification of fractures or fractures patterns that may be present.

Extra-oral Examination:

1.      An extra-oral assessment should begin by examining the face and mandible for any abnormal contours or step defects.

2.      Changes to the patient's facial profile and mandibular movements will cue the physician for types of fractures. For instance, a flattened facial profile may be due to a fractured mandibular body, angle, or ramus. A retruded chin may be caused by bilateral parasymphyseal fractures. An elongated face may be the result of bilateral subcondylar, angle, or body fractures.

3.      Trismus or limited mouth opening, and deviation on opening may be due to guarding of the muscles of mastication, non-functioning of muscles, or bony impingements. Deviation upon opening may signify a mandibular condylar fracture due to unopposed contraction of the contralateral lateral pterygoid muscle. Inability to fully open may be due to impingement of the coronoid process on the zygomatic arch when fractures of the ramus and coronoid process or depression of the zygomatic arch is present. On the other hand, inability to fully close may signify dentoalveolar process, angle, ramus, or symphysis fractures. Inability to fully bring one's teeth together may be due to an open bite that was present pre-injury; the presence of mammelons on the incisal edges of the anterior dentition may be a clue to determining a premorbid anterior open bite

Intra-oral Examination:

1.      This includes assessment of the mandibular arch form and occlusion and identification of gingival lacerations, hematomas, or ecchymosis, and injuries to the teeth. The mandible is unique in that it is a continuous, U-shaped bone that crosses midline; deviations from this arch form may indicate a fracture. Any change in occlusion is highly suggestive of a mandible fracture. The mandible should be palpated bimanually to assess for fracture mobility.

2.      The patient should be asked if their bite feels different. This can identify injuries to the teeth, dentoalveolar process, mandible, or temporomandibular joint (TMJ). Premature posterior contacts between the maxillary and mandibular dentition can result from bilateral mandible fractures of the angles or ramus-condyle units or signify the presence of a displaced maxillary fracture. Asking for premorbid photographs of the patient's premorbid occlusion can help to ensure accurate reduction of fractures based upon the occlusion.

3.      Gingival lacerations, hematomas, or ecchymosis may indicate injury to the mandible For instance, sublingual ecchymosis is a pathognomonic sign for symphysial, parasymphyseal, or body fractures. In addition, retromolar trigone ecchymosis can signify angle fractures. Segments of fractured teeth may indicate fractures to the dentoalveolar process or mandible itself. Fractured teeth, mobile teeth, and any grossly carious teeth in the line of fracture may require extraction for reduction and to prevent aspiration. Missing teeth should that have not been accounted for should be considered swallowed, aspirated, or displaced into soft tissue. Radiography and operative exploration may help identify lost teeth and may require removal to prevent infection or airway issues.

Neurosensory Deficits should be accurately documented. Paresthesia, dysesthesia, or anesthesia of the lower lip indicates injury to the inferior alveolar nerve distal to the mandibular foramen. Most injuries are neuropraxic in nature and related to transient ischemia, inflammation, and traction.

Initial Assessment - Radiographic Examination

Most patients with mandible fractures, undergo radiographic assessment with computed tomographic (CT) imaging of the head and cervical spine (C-spine). Although CT imaging is now considered the gold standard, various other imaging studies can be helpful when CT is not available. These include plain films with Reverse Towne, Caldwell posteroanterior, lateral oblique, or occlusal views or panoramic radiograph (panorex). Panorex (OPG) is advantageous in allowing visualization of the entire mandible including the subcondylar unit/TMJ unit; however, its availability may be limited in the acute setting. In addition, certain fracture patterns, particularly in the posterior mandible, may be missed on single-view panoramic radiography. When evaluating a patient with mandibular injury with only plain film imaging it is prudent to obtain atleast two views

Surgical Anatomy

The osteology of the mandible, various muscle attachments and their influence, and presence of developing or permanent dentition, or lack of dentition, need to be understood for accurate treatment of mandible fractures. A full description of a mandibular fracture should include an assessment of its relationship to the external environment (ie, simple/closed, compound/open), type (ie, incomplete, greenstick, complete, comminuted), dentition (ie, primary, mixed, permanent, or lack of dentition), displacement, favorability, and location.

Bony Anatomy of the Mandible

The mandible is a U-shaped bone that crosses anatomical midline. The mandible has thirteen muscle attachments. Organized by function, these are jaw closers (temporalis, masseter, medial pterygoid), openers (digastric, lateral pterygoid), and glottic attachments (genioglossus and geniohyoid). The remaining muscles can influence displacement of fractures and may be involved in soft tissue closure (buccinator, platysma, mentalis, mylohyoid, depressor labii inferiorius, and depressor anguli oris).

The major vascular supply to the mandible during development is from the inferior alveolar artery, but transitions to the involved periosteum and muscle attachments as the body ages. During fixation of comminuted or atrophic mandible fractures, areas with poor blood supply, such as the body, careful soft tissue management is mandatory, as the blood supply to these regions is periosteal, rather than endosteal. Periosteal stripping in these areas should be minimized and done only to the extent necessary to apply fixation. Supra-periosteal placement of hardware has been studied in this context, but bears no discernable advantage for healing. The course of the facial artery and vein around the mandible in the antegonial notch should also be appreciated when treatment requires a transcervical approach.

The mandibular branch of the trigeminal nerve includes the auriculotemporal, buccal, inferior alveolar, and lingual nerves. Innervation of the mandible is supplied by the inferior alveolar nerve (IAN) and its branches, the mylohyoid, dental, incisive, and mental branches. The IAN enters the mandibular foramen on the medial aspect of the ramus behind the lingula, travels within a bony canal, and exits the mental foramen of the mandible near the apex of the first and second premolars. IAN injuries in the setting of mandible fractures have been reported to range from 5.7 to 58.5%.

Definition of Sites of Fracture

As defined by Dingman and Natvig, the mandible can be subdivided as follows symphysis, bounded by vertical lines distal to canine; parasymphysis, distal aspect of the roots of lateral incisors to distal of roots of canine teeth; body, from distal roots of canine to line corresponding to anterior border of the masseter muscle (usually coincides with third molar); angle, bounded by anterior and posterior borders of the masseter muscle; ramus, bounded by superior aspect of the angle to sigmoid notch; condylar process, area superior to ramus; coronoid process, and alveolar process, the area that normally contains teeth.

Favorable versus Unfavorable Fractures

Mandibular angle and body fractures can be classified as vertically favorable or unfavorable or horizontally favorable or unfavorable. Favorability is determined by the direction of a fracture line and its relationship to muscle action on the fracture segments. Vertically favorable fractures resist the medial pull of the medial pterygoid muscle on the proximal segment in the vertical plane. Horizontally favorable fractures resist upward the vertical pull of the masseter, temporalis, and medial pterygoid muscles on the proximal segment in the horizontal plane. The more forward a fracture occurs in the body the more the upward displacement is counteracted by the downward pull of the mylohyoid muscles.

Fracture Fixation Principles

The mandible is the only moveable, load bearing bone of the skull. To properly treat mandible fractures, one must first understand basic fracture fixation principles. These can be grouped into tension versus compression and load-bearing versus load- sharing principles

Tension versus Compression

At any time, there are counteracting forces of tension and compression on the mandible influenced by muscular attachments and loading. At rest, these forces are equal. While an oversimplification, forces of tension generally separate a fracture and forces of compression bring a fracture together. Under compression, fractures generally undergo rapid healing and a greater resistance to separation. However, without addressing tension forces, overcompression can compromise ideal bony healing leading to nonunion.

Studies have shown that in the region of the mandibular body tension exists along the alveolar border while compression exists along the inferior border of the mandible. Moving toward the symphysis and parasymphysis, these two opposing forces become mixed or even inverted due to the introduction of torsional, or rotational, forces.

Biomechanically, it is most advantageous to apply bicortical rigid fixation along the zone of tension. Bicortical rigid fixation along the alveolar border is not feasible due to the presence of tooth roots, thin cortical bone, and thin gingival tissue. The inferior border of the mandible is not constrained by these limitations, with the notable exception of pediatric patients in the primary or mixed dentition. Bicortical screw fixation in this region is extremely stable and then only requires placement of a tension band at the alveolar level (either a continuous arch bar at the dentition or a small plate with monocortical screws) to resist tensile forces.

Load Bearing versus Load Sharing

Fracture fixation can be divided into either load bearing or load sharing. Choosing which type depends on the bone quality, location of the fracture, comminution, or bone loss. With load bearing osteosynthesis, the plate bears 100% of all of the forces of function at the fracture site. Load bearing osteosynthesis is indicated in comminuted mandible fractures, segmental defects, complex fracture patterns, or fractures with compromised bone such as atrophic mandibles or patients with metabolic or endocrine disorders. Fixation is accomplished with 2.3mm-2.7mm diameter locking reconstruction plates

Various methods exist for obtaining rigid fixation of mandibular fractures. In high energy injuries, such as this comminuted mandibular fracture secondary to a gunshot wound , interfragmentary fixation use can be used to align the different segments of the mandibular and rigid fixation was achieved with the addition of a locking plate along the inferior border. In edentulous patients, reconstruction plates with bicortical screws should be placed as laterally and inferiorly as possible, to avoid interference with denture fabrication.

When using load sharing osteosynthesis, stability at the fracture site is shared between the plate and well-buttressed bone. Depending on the location, the functional load is either shared equally between bone and plate (e.g., angle fractures), or in more ideal situations the bone assumes a greater share of the functional load than the plate (e.g., body fractures in dentate mandibles). Here, fixation can be accomplished with 2.0mm diameter miniplate systems. Examples of load-sharing fixation include a single miniplate along the oblique ridge for angle fractures (ie, Champy technique), or a single miniplate and an arch bar (providing tension) for body or symphysial fractures, and lag screw fixation.

Lag Screw Fixation

The use of lag screws was popularized by Niederdellmann et al. in 1976.Lag screws can be use in simple fractures where there is well-buttressed bone such as in symphysis or parasymphysis fractures. A lag screw has threads on only half the shaft so that the portion below the screw head is smooth and will not engage bone. Thus, the threads only engage the inner segment of bone and compress it against the outer segment. Typically, the two screws are placed, with minimal divergence between their long axes.

Rigid versus Non-rigid Fixation

Fixation can be grouped into rigid fixation, nonrigid fixation, or semirigid fixation. With rigid fixation, no bony callus if formed during healing and fracture segments are completely immobilized. In nonrigid fixation, micro-mobility of the fracture segments occurs and the fracture cap undergoes callus formation. Rigid fixation techniques include the use of plates and screws (miniplate and tension band with two screws on each side of the fracture), two lag screws, or reconstruction plates with three screws on each side of the fracture.

 Fracture Management Techniques by Anatomic Site                                                                                                                                     

Symphysis/Parasymphysis

Fractures of the anterior mandible can be addressed using either closed reduction, open reduction and internal fixation (ORIF), lag screws, or a combination of lag screws and miniplates. Closed reduction of fractures is most commonly achieved by applying Erich arch bars with circumdental stainless steel wires or hybrid arch bars. The patient is then placed into maxillomandibular fixation using stainless steel wires loops or heavy elastics. While still acceptable for simple fractures, ORIF is the standard of care for management of most displaced mandibular injuries.

ORIF can be achieved using a variety of techniques. Semi-rigid fixation using application of transoral mini-plates can be applied in simple, non-displaced fractures. Rigid fixation with the use of a reconstruction plate and bicortical screws may be required in severely comminuted or displaced fractures. In severely comminuted fractures, a transcervical approach may be required for adequate reduction of fracture segments; simultaneous bone grafting may be considered for fractures with segmental bone loss.

Body

As with anterior mandible fractures, body fractures can be treated with either a closed approach using MMF or ORIF. MMF can only be used in the presence of reliable, reproducible occlusion, using either the patient's own teeth or a mandibular prosthesis. It may be indicated in nondisplaced, favorable fractures, comminuted fractures, fractures in children with mixed dentition, or edentulous fractures (e.g., using dentures or gunning splints). This technique is generally contraindicated in displaced, unfavorable fractures, multiple fractures, or instances of malunion. In addition, certain systemic conditions such as psychiatric disease, neurologic problems like seizures disorders, pulmonary disease, or gastrointestinal disorders where aspiration of emesis is a concern preclude prolonged intermaxillary fixation.

In most clinical circumstances, management of displaced mandibular injuries necessitates. Fixation can be achieved solely via an intraoral approach with a single reconstruction plate (2.3 to 2.5mm at the inferior border of the mandible or two miniplates (superior and inferior border plate) along zones of tension and compression. A transbuccal puncture for screw fixation may be required to access more posterior body fractures. A review by Ellis of 682 patients treated with ORIF of body and/or symphysial fractures with two miniplates was associated with more postoperative complications (wound dehiscence, plate exposure, need for plate removal, and tooth root damage) compared with the use of a single, larger diameter plate.

Angle

Management of angle fractures is especially complex given the distracting forces of the muscles of mastication, lack of tooth-bearing segments, and possible presence of the third molar. If the fracture is unfavorable, treatment with only MMF would be contraindicated as the proximal segment may rotate.

Ramus-Condyle Unit

Classification and management of condylar fractures is a controversial topic in craniomaxillofacial trauma. The two commonly used classification system are Lindahl and Spiessl. Lindahl's classification is based on three factors: level of fracture, amount of displacement, and relationship of the condylar head to the glenoid fossa. The three levels of fracture are condylar head (located within the joint capsule), condylar neck (inferior to the joint capsule and inferior attachment of the lateral pterygoid muscle), and subcondylar fracture (between the sigmoid notch and posterior aspect of the ramus). Spiessl's classification is based on the degree of displacement of fracture segments and dislocation of the condylar head from the fossa.

Treatment includes observation, closed reduction, ORIF by either transfacial or intraoral approaches. Current absolute indications include bilateral fractures, severe dislocation, cases where closed reduction doesn't re-establish occlusion, concomitant fractures of other areas of the face that compromise occlusion, foreign bodies, or dislocation of the condyle into the middle cranial fossa.

Regardless of treatment choice early mobilization and physical therapy has been shown to decrease risk of ankylosis and trismus.Decision-making for condylar injuries should prioritize early mobilization. In patients with intracapsular injuries and associated malocclusion, a short course of intermaxillary fixation (no longer than 7 days) can be considered, followed by aggressive mobilization to prevent ankylosis.

In patients with displaced condylar or subcondylar injuries, treatment with open or closed approaches is valid .When considering closed management, our approach is to re-establish occlusion with closed reduction and placement of intermaxillary fixation. This is followed by a period of tight intermaxillary fixation for 2 weeks, then 2 weeks of elastic (4–6 oz) fixation with jaw stretching exercises at meal times (3–5 minutes), and then 2 weeks of elastics use only at night, with jaw stretching exercises at meal times. The use of oral muscle relaxants during the subacute healing period may help patients with jaw stretching exercises.

Special Populations Atrophic Mandible

Atrophic, edentulous mandibular fractures represent 1% of all facial fractures. Although thought to be associated with advanced age, mandibular atrophy is more related to the duration of edentulism. The presence of tooth roots and forces of mastication send signals to inhibit bony resorption. To be classified atrophic, the remaining bone height must be 15mm or less. Severe atrophy is classified as 10mm in height or less. Decreased bony height correlates to increased incidence of nonunion, malunion, recurrent fractures, hardware failure, postoperative infection, and osteomyelitis. The incidence of these complications is between 10–20%.

ORIF has largely replaced other reduction techniques such as gunning splints, circum-mandibular wires around dentures, and external fixators. Load bearing osteosynthesis with a reconstruction plate for anatomic reduction provides a solid construct for atrophic mandible fractures. In some cases, a large inferior border plate on the lateral border, coupled with a shallow vestibule may make wearing a denture less feasible. In these circumstances, placement of the reconstruction plate on the underside of the mandible, with screws oriented vertically or near vertically, may allow a patient to continue to wear a denture. This technique may also avoid potential intraoral hardware dehiscence. With any open approach, periosteal detachment should be limited to the buccal tissues to minimize devascularization. Autologous grafting can also be undertaken concurrently to aid in fracture healing and anticipation of dental rehabilitation.

Mandibular Injuries in Children

Mandible fractures in children follow different patterns than those observed in adults. In children, up to 50 to 80% of mandible fractures involve the condyle, subcondylar, or angle. The next most common are symphysis and parasymphysis fractures. Body fractures are relatively rare. Management must take into account eventual mandibular growth, presence of tooth buds, and eruption of permanent teeth. The main goals of treatment of pediatric mandible fractures are to obtain bony union, restore occlusion, and prevent growth disturbances.

Treatment modalities for pediatric mandible fractures include physical therapy without MMF, a short period of MMF (7–14 days) followed by physical therapy, and ORIF. When considering intermaxillary fixation in children in the primary or mixed dentition, screw-retained devices should not be used, due to the risk of injury to the developing permanent dentition. Ivy loops, Risdon cables, Erich arch bars, sutures, and dental splints are all potential options for achieving intermaxillary fixation in children. Similarly, placement of internal fixation should account for the presence of the developing permanent teeth .In the dentate regions of the mandible, plates should be placed at or near the inferior border, with monocortical screws. If titanium fixation is used, it is prudent to consider removal at 2–3 months post-operatively in growing patients. Resorbable fixation in this population remains under investigation, but appears to result in stable healing when appropriately utilized.

Similar to management in adults, treatment of pediatric condylar fractures remains controversial. Long-term favorable facial growth outcomes have been described with closed treatment of condylar fractures. Early mobilization is crucial to prevent hemarthrosis and ankylosis. TMJ ankylosis can be very difficult to treat and can children can result in profound facial deformities, particularly in growing children.

Management of odontogenic infections and sepsis:

Odontogenic infections can lead to sepsis, a potentially life-threatening condition caused by the body's immune system responding abnormally. This can lead to tissue damage, organ failure and death. A patient with non-odontogenic-related infection could also present with sepsis at a dental practice.

Odontogenic infections pass through three key stages:

·       Stage 1: 1-3 days; soft and mildly tender swelling

·       Stage 2: 2-5 days; hard, red and severely sore swelling

·       Stage 3: 5-7 days; abscess formation.

Seven principles have been proposed to achieve the best outcome in managing odontogenic infections

·       Establish the severity of the infection

·       Assess host defences

·       Elect the setting of care

·       Surgical intervention

·       Medical support

·       Antibiotic therapy

·       Frequently evaluate the patient.

Establish the severity of infection

A careful history and thorough clinical examinations are essential to determine the severity of any infection. History-taking will highlight factors like immune system competence and the level of systemic reserves to fight infections. A physical examination can identify clinical observations outside normal limits. C-reactive protein (CRP), fever and anatomical locations have been investigated for the assessment of the extent of odontogenic infections and presumed duration of hospital stay.

Additional factors must be considered to establish the infection severity:

·       Anatomical location

·       Airway compromise.

Ludwig's angina

A compromised airway is synonymous with Ludwig's angina and the initial assessment of a patient with Ludwig's angina should follow the familiar 'Airway, Breathing, Circulation, Disability, Exposure' (ABCDE) approach. Signs of a compromised airway in these patients could include noisy (gurgling) breathing with drooling saliva, stridor, dyspnoea, tachypnoea, tachycardia, dysphagia and trismus. The initial immediate management usually includes positioning the patient in an upright position and administering oxygen 15 litres/minute

Assess host defences

A healthy immune system is essential to the maintenance of host defence against infection

·       Factors that can compromise the immune system

1.      Diabetes steroid therapy

2.      Organ transplants

3.      Malignancy

4.      Chemotherapy

5.      Chronic renal disease malnutrition

6.      Alcoholism.

Elect the setting of care

Severe neck infection in an immunocompromised elderly person warrants treatment in a secondary care setting.

Criteria for referral to secondary care

1.       Difficulty in swallowing and dehydration

2.       Threat to the airway or vital structures

3.       Infection in moderate- or high-severity anatomic spaces

4.       Involvement of orbital contents

5.       Need for general anaesthesia

6.       Need for inpatient control of systemic disease.

Surgical intervention

Five principles must be followed:

·       Elimination of the source of the infection. This can be achieved by either removing the tooth or commencing root canal treatment

·       Incisions to be made on healthy skin or mucosa

·       Blunt dissection to explore the abscess cavity without damaging vital structures A microbiology swab should be obtained

·       Copious irrigations will ensure the dilution of the bacterial load

·       Drainage is maintained by placement of a drain to keep the abscess cavity open.

Blunt dissection is achieved by inserting a closed haemostat, then open it at a depth of penetration and remove the instrument while it is still open. A haemostat should never be closed while it is inside the wound. Different surgical drains are available to use and should be removed when the drainage ceases, usually between 48-72 hours.

Although abscess formation takes place between the fifth and seventh days, early elimination of the infection source and surgical intervention will decompress the involved anatomical spaces. Relying on antibiotics only in relieving dental infection is likely to be less effective and can cause antimicrobial resistance

Two of the challenges to performing adequate drainage of any odontogenic infection in dental practice are:

·       Achieving adequate local anaesthesia

·       Risk of spreading the infection to other anatomical spaces.

The ability to deliver safe, adequate local anaesthesia is essential for any dental procedure. The mechanism of action of the local anaesthetic solution depends on the tissue pH. In the presence of infection, tissue pH becomes more acidic, which slows down the degree of ionisation, resulting in less optimal or failed anaesthesia.

To overcome this problem, the injection of the anaesthetic solution at a distance from the inflammatory site is required (nerve blocks). It will also avoid infection spread to different tissue spaces.

Medical support

Medical support has a critical role in controlling the disease. Adequate hydration, nutrition and control of fever are essential to optimise the medical care for patients presenting with odontogenic infections. Stabilisation of any underlying systemic disease (for example, uncontrolled diabetes) is extremely important.

Antibiotic therapy

Odontogenic infections are multi-microbial with a combination of facultative and anaerobes species. Facultative Streptococcus viridans group are commensal Gram-positive bacteria and include S. anginosus, S. intermedius and S. constellatus. These organisms are abundant in the mouth and most frequently associated with orofacial cellulitis and abscess. After a few days, the anaerobes (Prevotella and Porphyromonas) predominate. The majority of the facultative streptococci that cause odontogenic infections are sensitive to penicillin. Approximately a quarter of strains of Prevotella and Porphyromonas are penicillin- resistant.

Penicillin-based antibiotics remain the first line for the treatment of odontogenic infections. Metronidazole is effective against anaerobic bacteria.

Recommended antibiotics and doses

Frequently evaluate the patient

The last principle, but as vital as the previous ones, is the periodic re-evaluation of these patients. In outpatient settings, the recommended follow-up is after two days. Forty-eight hours will allow the drainage to cease and the immune system to overcome the initial insult from the infection. If no improvement or deterioration of symptoms is noted, further escalation in care must be provided. The review interval, however, depends on the clinical course of the infection. A patient with a rapidly developing swelling and mild temperature may need review within 24 hours, but a patient with a chronic abscess and no systemic symptoms will need to be reviewed at the end of the antibiotic treatment.

Causes of treatment failure include:

·        Failure to remove the source of infection

·        Underlying systemic disease; for example, uncontrolled diabetes

·        Antibiotic-related factors - patient non-compliance, drug not reaching site secondary to inadequate drainage, wrong antibiotic choice or incorrect dose.