TMJ and Jaw Injuries After a Car Accident

Temporomandibular Joint Anatomy

Each person has two temporomandibular joints, one on each side of the jaw, and the National Institute of Dental and Craniofacial Research (NIDCR) notes that they can be felt by placing the fingers in front of the ears and opening the mouth. These are the joints that connect the lower jaw to the skull, MedlinePlus explains, and MedlinePlus adds that the abbreviation TMJ names the joint itself even though people often use it to mean any disorder or symptom of the region.

An articular disc separates each joint into two synovial cavities with distinct movement patterns, according to StatPearls. Gliding movement happens in the upper compartment, between the disc and the glenoid fossa of the temporal bone, and StatPearls places hinge movement in the lower compartment, between the disc and the mandibular condyle at the top of the lower jawbone.

Problems in this region go by the name TMD. NIDCR defines temporomandibular disorders as a group of more than 30 conditions that cause pain and dysfunction in the jaw joint and in the muscles that control jaw movement. NIDCR sorts them into disorders of the joints, including disc disorders, disorders of the chewing muscles, and headaches associated with a TMD, and a person may have more than one at the same time.

TMD affects about 5% of adults in the United States, NIDCR reports, though the figure can vary depending on who is studied and how the condition is assessed. NIDCR also says TMDs are twice as common in women as in men, especially women between 35 and 44 years old.

Collision Forces and the Jaw

Injury to the temporomandibular joint can lead to some TMDs, according to NIDCR, but in most cases the exact cause is not clear. NIDCR adds that research suggests a combination of genes, psychological and life stressors, and how someone perceives pain may play a part.

Trauma sits on the list of problems inside the joint. StatPearls names trauma among the intraarticular causes of TMD, alongside capsular inflammation, osteoarthritis, hypermobility, and inflammatory diseases. For derangement of the condyle-disc complex, a breakdown in the rotational function of the disc, StatPearls lists micro- or macro-trauma among the contributing factors.

Jaw injury, such as a break or dislocation, appears among the reasons TMD can happen in the Cleveland Clinic overview. MedlinePlus likewise names fractures and dislocations among the other possible causes of TMJ-related symptoms.

The crash type shapes the break. Studies vary in reported fracture frequencies, the StatPearls review of mandible fractures notes, but in automobile accidents the condyle was the most common fracture site, while the symphysis was most commonly fractured in motorcycle accidents. The same StatPearls review says a patient in a motor vehicle accident usually suffers multiple or compound mandibular fractures.

Whiplash and Posttraumatic TMD

A 2009 narrative review in the Journal of Chiropractic Medicine examined 32 studies, published from 1966 onward, on the relationship between whiplash injury and temporomandibular disorders. The review’s authors wrote that the best evidence from prospective studies indicates a low to moderate incidence and prevalence of posttraumatic TMD.

Most studies of clinical findings suggest significant differences between posttraumatic TMD and TMD with no traumatic cause, the Journal of Chiropractic Medicine review reports. On outcome, most of the studies it examined suggest that posttraumatic TMD carries a poorer prognosis.

The question is still open. The review’s authors found conflicting evidence regarding the effects of whiplash on the development of TMD, and they wrote that differences between study populations, along with a lack of standard data collection and outcome measures, kept the review from conclusively resolving the controversy.

MedlinePlus observes that many conditions can cause TMJ symptoms, from arthritis to whiplash injuries.

Symptoms After a Jaw Injury

Pain in the chewing muscles or the jaw joint is the most common symptom, according to NIDCR. Other symptoms that may signal a TMD on the NIDCR list include pain that spreads to the face or neck; jaw stiffness; limited movement or locking of the jaw; painful clicking, popping, or grating when the mouth opens or closes; ringing in the ears, hearing loss, or dizziness; and a change in the way the upper and lower teeth fit together.

Some of the pain shows up away from the joint. MedlinePlus lists earache, headache, dull aching pain in the face, and difficulty or discomfort with biting or chewing, and Cleveland Clinic adds tooth pain and neck or shoulder pain.

MedlinePlus traces part of that spread to trigger points, which it describes as contracted muscles in the jaw, head, and neck that can refer pain to other areas, causing a headache, earache, or toothache.

A broken jaw is a medical emergency regardless of what part of the jawbone is broken, according to Cleveland Clinic, which treats a dislocated jaw as a medical emergency as well. The signs below come from that Cleveland Clinic page. MedlinePlus separately advises contacting a provider right away for trouble eating or opening the mouth.

Clicking, Popping, and Locking

Clicking or popping sounds in the TMJs without pain are common, are considered normal, and do not require treatment, according to NIDCR. Painful clicking, popping, or grating is different: NIDCR places it among the symptoms that may signal a TMD.

Many clicks trace back to the disc. In disc displacement with reduction, StatPearls explains, the disc sits in front of the condyle when the mouth is closed and moves back onto it when the mouth opens. StatPearls says this on-and-off disc movement explains the click, snap, or pop sound in the joint, and that the sound does not occur with every jaw movement.

Sometimes the disc fails to slide back into place. StatPearls calls that pattern disc displacement with reduction and intermittent locking, because the failed reduction limits mouth opening. When the disc fails to reduce repeatedly and opening stays limited, StatPearls says the diagnosis becomes disc displacement without reduction.

Dislocation of the Lower Jaw

A jaw dislocation is a displacement of the mandibular condyle from the glenoid fossa of the temporal bone, on one side or both, according to StatPearls. Anterior dislocations, in which the condyle moves forward of the articular eminence, are the most common type, and StatPearls says they usually come from atraumatic causes such as laughing or yawning.

Acute facial trauma is also one of the most common causes of dislocation, the StatPearls review notes. In an acute dislocation, StatPearls says patients often present with pain in front of the ear and difficulty closing the mouth, which may lead to garbled speech and drooling.

For a traumatic dislocation, an unclear diagnosis, or concern for fracture, StatPearls names a CT scan as the imaging test of choice and says imaging should be performed before reduction to check for a fracture. Closed reduction can often treat the dislocation, though it may require anesthesia or muscle relaxants, and StatPearls adds that some acute dislocations carry an increased risk of recurrence despite proper treatment.

A dislocation differs from a break. A dislocated jaw does not involve a broken jawbone, Cleveland Clinic explains, and happens when the lower jawbone pulls away from the temporomandibular joints.

Condyle and Mandible Fractures

Broken jawbones are the second most common facial fracture, according to Cleveland Clinic, which puts fractured noses at 40% to 50% of all facial fractures. Cleveland Clinic names interpersonal violence as the most common cause of broken jaws, followed by vehicle accidents.

Depending on the fracture locations, a patient can present with trismus, dental malocclusion, swelling, and tenderness inside and outside the mouth, the StatPearls review of mandible fractures reports. Damage to the inferior alveolar nerve may result in loss of sensation in the lower lip and chin, StatPearls adds.

Other injuries come into the picture too. StatPearls says it is critical to evaluate patients with mandible fractures for other associated trauma, including cervical spine and traumatic brain injuries.

Treatment depends on severity. For a mild fracture, a provider may prescribe a liquid diet for four to six weeks, Cleveland Clinic explains, while a severe fracture may call for surgery to place metal plates or bars that hold the bone in place, sometimes with the jaw held closed by wires or elastics.

Three Conditions Side by Side

Muscle and disc disorders, dislocations, and fractures can overlap in the symptoms they cause, yet they differ in what happened inside the joint, in which imaging answers the question, and in what care comes first. The table below lines up the three using the NIDCR, StatPearls, and Cleveland Clinic descriptions cited on this page.

Other conditions can mimic a TMD as well. StatPearls lists trigeminal neuralgia, sinusitis, and salivary gland disorders among common causes of facial pain, dental caries and dental abscess among causes of orofacial pain, migraines and cluster headaches among causes of headache, and middle ear infections and Eustachian tube dysfunction among causes of ear pain.

Examination and Imaging Tests

There is no widely accepted, standard test to diagnose TMDs, according to NIDCR, and because TMDs can have different causes and symptoms that overlap with other conditions, diagnosis can be difficult. NIDCR says a doctor or dentist will note the symptoms, take a detailed medical history, and may examine the head, neck, face, and jaw for tenderness, clicking or popping, or difficulty with movement.

The exam described by MedlinePlus involves a dental exam for bite alignment, feeling the joints and muscles for tenderness, sliding the teeth from side to side, and watching, feeling, and listening to the jaw open and shut. MedlinePlus cautions that the physical exam results may sometimes be normal and that a provider also needs to consider infections, nerve-related problems, and headaches.

MRI is the preferred imaging modality for assessing the TMJ because it can accurately depict joint effusion, disc displacement, and soft tissues, according to StatPearls. A simple panoramic x-ray can rapidly evaluate the teeth and the joint and is often the initial investigation, StatPearls notes, while plain radiographs and CT scans can show severe joint degeneration, fractures, and dislocations.

For a suspected break, the StatPearls review of mandible fractures lists a mandibular series, a dental panoramic view called a panorex, and CT, and says a CT scan is indicated if associated facial fractures are suspected.

Conservative and Reversible Care

Because evidence for many TMD treatments is limited, NIDCR says the recommended course is conservative treatment that avoids anything that permanently changes the jaw joints, teeth, or bite, or that involves surgery. NIDCR also notes that many jaw joint and muscle problems are temporary and do not get worse.

The first steps a doctor or dentist may suggest, according to NIDCR, include eating soft foods, applying heat or cold to the face along with exercises that gently stretch and strengthen the jaw muscles, taking over-the-counter pain medicine such as NSAIDs, and cutting back on habits such as jaw clenching, gum chewing, or nail biting.

Conservative treatment reduces symptoms in 50% to 90% of patients and should be the first line of treatment, according to StatPearls, which lists patient reassurance and education, a soft diet, jaw rest, warm compresses, and passive stretching among those methods.

There is not a lot of evidence on whether oral splints improve TMD pain, NIDCR says, and a splint a dentist or doctor suggests should not be designed to permanently change the bite. MedlinePlus says mouth or bite guards may or may not help, that some people feel worse pain while wearing one, and that use should stop if a guard causes any change in the bite.

Injections, Procedures, and Surgery

Nonsurgical options on the Cleveland Clinic list include custom mouth guards or splints, jaw exercises through physical therapy, trigger point injections, ultrasound therapy to relax muscles, and TENS. MedlinePlus adds medicines a provider may discuss, including muscle relaxants, botulinum toxin injections, and, rarely, corticosteroid shots in the TMJ to treat inflammation.

If other treatments do not help, Cleveland Clinic says a provider may suggest surgery such as arthrocentesis to flush the joint, TMJ arthroscopy, or open-joint surgery for more serious problems.

MedlinePlus advises caution with treatment methods that cannot be reversed, such as orthodontics or surgery that permanently changes the bite. A failed course of conservative care does not automatically mean more aggressive treatment is needed, MedlinePlus says, and reconstructive surgery of the jaw, or joint replacement, is rarely required, with results that are often worse than before surgery.

Recovery Time Ranges

TMD can be short-term or last longer, according to Cleveland Clinic, with some people feeling better in a week or two and others needing ongoing care.

Many TMDs last only a short time and go away on their own, NIDCR says, but in some cases they can become chronic, or long-lasting. Up to 40% of patients report remission of symptoms without intervention, StatPearls reports, and most respond favorably to conservative treatment, though a small number develop refractory or persistent TMD.

Relief is not always permanent. MedlinePlus notes that TMJ-related pain may return in the future.

A fracture follows its own timeline. After surgery, it may be a month or more before the jawbone heals completely, according to Cleveland Clinic, and Cleveland Clinic says a full recovery from a broken jaw may take a few months.

Complications That Can Linger

Chronic face pain and chronic headaches are the possible complications MedlinePlus lists for TMJ disorders. Cleveland Clinic adds that TMD can lead to long-term pain, chewing problems, or damage from grinding the teeth.

TMDs may also occur on their own or together with other conditions such as headaches, back pain, sleep problems, irritable bowel syndrome, and fibromyalgia, NIDCR notes.

Recurrent dislocation can damage the joint ligaments and joint capsule and lead to degenerative joint disease, according to StatPearls. After a mandible fracture, malocclusion is the most common complication of the fracture and its treatment, the StatPearls review of mandible fractures reports, and reduced sensation in the lower lip and chin is also extremely common.

Dental, Medical, and Therapy Records

Care for a jaw injury often crosses several offices. A person may need to see more than one medical specialist for TMJ pain and symptoms, MedlinePlus says, including a health care provider, a dentist, or an ear, nose, and throat (ENT) doctor, depending on the symptoms.

Records from before the injury matter in fracture repair. The StatPearls review of mandible fractures says it is often difficult to determine a patient’s dental occlusion before surgery, and that dental records, when available, are useful as a reference for surgical reduction of the fracture.

Each office writes down a different part of the injury. A dental chart describes the teeth and bite, an imaging report describes the bone, disc, and joint, and therapy notes describe movement and function from one visit to the next.