Clinical Evaluation and Management of Direct Jaw Trauma in Adults
Direct temporomandibular joint (TMJ) trauma is identified as a causal factor in many patients with temporomandibular disorders (TMDs) who then need clinical management.
Approximately 20-25% of people with chronic TMDs have a history of direct TMJ trauma . Furthermore, TMD patients with a history of trauma suffer more severe symptoms than those with no trauma history .
Direct jaw trauma occurs frequently because of the prominence of the mandible in the cranium. This explains why fractures of the mandible represent around 70% of all facial fractures. By implication, non-fracture traumatic injury to the temporomandibular joint (TMJ) complex occurs even more frequently.
TMJ trauma without fracture can still initiate pathological changes. Several preclinical and human studies have established that there are substantial changes in the joint space after direct trauma to the jaw, even in the absence of a mandible fracture.
TMJ injuries without fracture are under-treated in acute care settings. Once a mandible fracture is ruled out, the treatment plan for patients with jaw joint complaints is typically limited to a soft diet recommendation. This oversight is critical, as many of these injuries develop into chronic TMD conditions.
The following is a review of the pathophysiology and clinical management of direct jaw trauma. There is a narrow window of time when prompt treatment of jaw injuries may prevent a chronic disorder from developing. This paper provides a rational clinical approach to achieve this goal.
Pathophysiology of Direct Trauma to the TMJ Complex
How direct jaw trauma can lead to TMD
Direct trauma to the jaw causes predictable patterns of injury to the temporomandibular complex. Blunt force applied to the joint space can produces a variety of histological changes, including:
- Cartilage degeneration
- Disc enlargement
- Fibrous adhesions
Synovitis, hemorrhage, and collagen deformation are all present after direct jaw joint trauma of sufficient force. Because inflammatory mediators or blood in the joint space are implicated in joint ankylosis and fibrosis, early mobilization after an injury is recommended.
Aside from damage to the joint space, the ligaments and muscles of the TMJ complex can be affected by direct jaw trauma. These are referred to as Jaw and Muscle Sprain/Strain (JAMSS) injuries and can occur with indirect blows to the jaw, where stretching of the ligamentous tissues can occur.
Even Mild Facial Trauma to the TMJ Complex can Trigger Myofascial TMD Development
Central sensitization is the most widely accepted theory of the pathogenesis of chronic myofacial pain and occurs when there is prolonged excitation of neurons in central pain pathways, resulting in self-perpetuating perception of pain in the form of hyperalgesia, allodynia, and referred pain .
How might acute jaw trauma lead to a chronic TMD?
The proposed sequence for central sensitization is as follows:
- Jaw trauma triggers a guarding reflex in the muscles of mastication.
- onstant tension of these muscles causes a decrease in tissue oxygenation and muscle fatigue, leading to the release of proinflammatory cytokines in the tissue.
- Inflammation and fatigue trigger peripheral sensitization by increasing the excitability of masticatory muscle trigeminal afferents.
- Tonic pain signals ultimately lead to central sensitization, the neurophysiologic hallmark of chronic pain syndromes.
Psychological factors are also important in TMD pathogenesis. Blunt force injuries can be both physically and psychologically traumatic, such as with car accidents or physical violence. In terms of TMD pathogenesis, psychological stress amplifies central sensitization and stabilizes pain signaling circuits, a process that is mediated through the neuroendocrine system. The contribution of heightened stress from jaw trauma pathogenesis can be seen clinically in the strong association between PTSD and TMD pain.
Clinical Aspects of Direct Jaw Trauma
Blunt jaw trauma involves a direct or lateral blow to the jaw from an external source. The causes of direct jaw trauma vary by demographics, age group, and ethnicity. Regardless of the cause, it may trigger orofacial pain thata requires treatment. You may be asking, “What are common causes of jaw injury?”
Common causes of direct jaw trauma include:
- Sports injuries
- Motor vehicle and bicycle accidents
- Physical violence
The prevalence of at least moderate TMD symptoms in athletes is around 60%, with the number for boxers approaching 80% . There is also a significantly higher prevalence of TMD symptoms in competitive vs. recreational athletes, suggesting that the psychological stress of competition contributes to TMD development .
Typical cases of direct trauma to the TMJ complex in sports include an elbow to the jaw, a ball to the face, or a direct blow with boxing or martial arts. These types of injuries may never be seen at the acute care level, but they are significant possible causes of JAMSS injuries and subsequent TMD development. The adoption of early preventive measures in athletes to avoid the burden of chronic TMJ dysfunction is recommended .
Injuries to the temporomandibular complex from motor vehicle accidents can occur as direct jaw trauma, from airbag deployment, or indirectly via whiplash associated injuries. If the force of direct trauma is sufficient to cause a mandible fracture, the incidence of having an associated injury is over 99%.
Bicycle accidents are a common cause of mandible fracture and TMJ trauma. Surprisingly, the use of a bicycle helmet increases the incidence of jaw injury, likely because the impact force becomes concentrated on the jaw instead of distributed across the whole cranium .
Interpersonal violence is common cause of TMJ injuries. The mandible is the most commonly fractured facial bone in cases of assault. Notably, a single punch in an assault can be just as dangerous as an assault with multiple blows . There is an association between intimate partner violence and TMD incidence in women .
Falls can be accidental or associated with interpersonal violence. In some urban settings, falls are the most common cause of mandible fractures. Of patients with mandible fractures from falls, roughly 1/3 are associated with alcohol consumption. Around 50% of physical assaults are associated with a fall due to the assault .
Clinical Presentation of Jaw Trauma
When a patient presents with a suspected jaw joint injury from blunt trauma, a complete TMJ complex examination should be performed.
|The clinical workup for jaw joint injury from blunt trauma|
|Focused history to assess for prior TMJ issues.||Perform intra- and extraoral palpation of the muscles of mastication.|
|Focused history to check for anxiety, depression, or somatic illness.||Palpate to discover soft tissue point tenderness.|
|Ask about pain in the TMJ are or TMJ “sounds”.||Check for crepitus over the joint with jaw movement.|
|Ask for a subjective assessment of occlusion.||Evaluate the full range of motion of the mandible, including assessment for symmetry.|
|Evaluate for any soft tissue injuries in the face and neck region.||Evaluate and palpate the cervical muscles.|
|Check dentition for dentoalveolar trauma.||Perform a cranial nerve exam.|
|Objectively assess occlusion.|
|Note any of the following findings from examination|
|Dentoalveolar trauma.||Altered occlusion.|
|Soft tissue avulsion.||Jaw joint crepitus.|
|TMJ dislocation.||Trigeminal paresthesia.|
|Trismus or decreased range of jaw movement.||Mandible fracture.|
|Jaw joint soreness or pain|
Source: Epstein JB, Klasser GD, Kolbinson DA, Mehta SA. Orofacial injuries due to trauma following motor vehicle collisions: part 2. Temporomandibular disorders. J Can Dent Assoc. 2010;76: a172.
The clinical workup for jaw joint injury from blunt trauma
Focused history to assess for prior TMJ issues. Perform intra- and extraoral palpation of the muscles of mastication
Focused history to check for anxiety, depression, or somatic illness Palpate to discover soft tissue point tenderness
Ask about pain in the TMJ area or TMJ “sounds” Check for crepitus over the joint with jaw movement
Ask for a subjective assessment of occlusion Evaluate the full range of motion of the mandible, including assessment for symmetry
Evaluate for any soft tissue injuries in the face and neck region Evaluate and palpate the cervical muscles
Check dentition for dentoalveolar trauma Perform a cranial nerve exam
Objectively assess occlusion
Note any of the following findings from examination
Dentoalveolar trauma Altered occlusion
Soft tissue avulsion Jaw joint crepitus
TMJ dislocation Trigeminal paresthesia
Trismus or decreased range of jaw movement Mandible fracture
Jaw joint soreness or pain
Note any of the following findings from a jaw trauma examination:
- Dentoalveolar trauma.
- Soft tissue avulsion.
- TMJ dislocation.
- Trismus or decreased range of jaw movement.
- TMJ soreness or pain.
- Altered occlusion.
- TMJ crepitus.
- rigeminal paresthesia.
- Mandible fracture.
Acute care protocols call for imaging studies whenever mandibular fractures are suspected. These studies evaluate mandible fracture, disc displacement, and TMJ derangement. When a fracture is ruled out by radiographic studies, but clinical findings persist, comprehensive conservative management for acute TMJ injury should be started.
Dentoalveolar trauma is a common presentation in the acute care setting, accounting for 15% of all emergency room visits. Any time dental fractures are seen, a comprehensive exam of the temporomandibular complex should be performed. If any signs of TMJ injury are present, conservative measures should be started.
Treatment of Direct Jaw Trauma
Treatment of direct TMJ trauma is determined by the presence or absence of a mandible fracture. While management of mandible fractures is outside the scope of this article, it is important to note that they are frequently treated with interdental wire fixation, either alone or in support of open reduction internal fixation (ORIF). This necessarily precludes and delays many of the rehabilitation therapies for TMJ trauma outlined below.
In non-fracture TMJ injuries, a comprehensive treatment approach is optimal. The goal of therapy is to address the factors that lead to chronic disorders such as arthropathies, ankylosis, and myofascial pain disorders. These predisposing factors include histologic changes in the joint space, joint and muscle inflammation, masticatory muscle guarding, and subjective pain.
Since there are multiple targets that may help prevent chronic TMD development, a multimodal approach to therapy is optimal.
A multimodal approach to jaw trauma therapy should include the following:
- Cryotherapy: Cold therapy causes peripheral vasoconstriction, which is critical to help slow any bleeding into the joint space. This decreased circulation also reduces inflammation, has an analgesic effect, and decreases muscle tension. Cryotherapy is most important in the first 72 hours after injury.
- Thermotherapy: Because heat therapy causes vasodilation, it should be used only 3-5 days after the time of injury (depending on the severity of the trauma) to minimize bleeding into the joint space. Thermotherapy increases circulation, tissue oxygenation, and waste elimination. It is soothing, promotes muscle relaxation, and facilitates mobility.
- Physical Therapy: Mobility exercises are critical in cases of blunt jaw trauma to help prevent ankylosis and fibrosis of the joint. Mobility also serves to help circulate synovial fluid and remove metabolic waste. Prompt mobility exercises also interrupt peripheral sensitization.
- Behavioral Pain Management: Guiding patients to use behavioral pain management techniques helps increase patient resilience to anxiety and stress from pain, both factors that contribute to chronic TMD development.
- Oral appliance therapy: Oral appliances use is dependent on the nature of the injury. If there is dentoalveolar injury, splint use should be coordinated with the patient’s dental health professional. In cases of muscle guarding and TMJ pain, the goal is bite inhibition and joint unloading. Anterior bite plane splints are ideal for this purpose.
The therapeutic window for conservative measures to prevent of TMD development is from the time of injury to 4 weeks after injury, according to both clinical data and models of TMD pathogenesis . The inference is that prompt treatment with a multimodal approach to therapy represents the best chance of preventing TMD development.
Dr. Brad Eli, DMD, MSis a graduate of UCLA’s post-doctoral Orofacial Pain program. The field of orofacial pain, temporomandibular disorders, and treatment of sleep disorders became the 12th specialty of dentistry in 2020. Over the past 29 years of clinical practice specializing in orofacial pain and sleep, Dr. Eli has also been on the educational staff at university hospitals, pain centers, and the clinical staff of Southern California hospitals.
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