The Dental Blog

Treatment of Motor Vehicle Accident (MVA) Related Chronic Myofacial Pain

The American Headache Society estimates that 23 million people older than 12 years of age suffer from severe migraine headaches. However this condition is under-treated and under-diagnosed world wide. Additionally tension-type headaches effect from 22% to 69% of males and from 35% to 88% of females. Only 45% of tension-type headache sufferers have ever sought medical care, specifically for headache, and some 90% have used over-the-counter drugs. The cover of New York Times Health Section from July 2002 stated that bite related / associated pain issues rank among the top 4 women’s pain issues, including tension headaches, migraine headaches, TMJ pain, and fibromyalgia. Compilations of data from the Nation Institute of Dental and Craniofacial Research of the National Institutes of Health indicate that 10.8 million people in the United States suffer from TMJ problems at any given time. While more specific data from a survey of 677 Canadian subjects (validity testing yielded a sensitivity of 81.4% and a specificity of 48.3%) found that symptoms were reported by 63.5% and signs were found in 88.1%.

Recent research has expanded beyond the belief that migraine is primarily a vascular phenomenon. Additionally current research links migraine suffers to larger massater and medial pterygoid muscle volumes, and greater bite forces than the controls, which could not be explained by any change in craniofacial morphology. It is also essential to note that chronic muscle tenderness is a characteristic of young patients with tension-type headache and migraine sufferers while absent in controls.

A new theory, central sensitization, considers changes that occur in the brain in response to repeated stimulation by signals either inside or outside the body. Levels of neurotransmitters and brain signals change as the brain develops a memory for responding to those signals. The brain is activated or “sensitized” by repeated signals from stimulation either inside or outside the body.

This has lead to the belief that headaches should be viewed on a continuum including primary and secondary migraine, tension, stress and sinus headaches as well as chronic fatigue and pain in the face, neck and shoulders rather than as separate distinct entities. Tooth interferences can stimulate hyperactivity in muscles. The possible origins of these pain triggering interferences include the organic development of the teeth, restorations, iatrogenic tooth movement, micro trauma, such as tooth clenching and grinding or significant force or trauma to the body.

A common cause of head, neck, and facial pain are motor vehicle accidents (MVA) that result in cervical whip lash trauma to the occupants. This can result from either trauma to the TM Joint structures, changes to the occlusion or from primary muscle injury. The descriptive term, “whiplash” is taken from the action of the lion trainer as they crack their whip to make a loud sound. The handle of the whip is swung forward causing the end of the whip to move forward and accelerate much faster than the handle in the lion trainer’s hand. Then suddenly the handle stops moving and the end of the whip, which had been accelerating is brought to a sudden stop and snaps back, making that cracking sound we are all familiar with.

A victim in a MVA often unfortunately has the same experience. The human head weighs 8 to 10 pounds and is precariously perched on the small cervical vertebrae. The head is supported by a complex system of muscles that attach from the neck and shoulders to the skull and jaws. In a whip lash scenario, caused by a front end impact, the torso begins to accelerate like the lion trainers whip and the head, at the outer most point, accelerates even faster. When the torso stops as a result of a seat belt or hitting another object such as the steering wheel, the head will continue moving forward until it reaches the maximum stretching point of the neck and shoulder muscles. At that point, the muscles rapidly contract followed by extension snapping the head forward and back until the energy is dispersed. Additionally it is important to note that since the condyles are suspended on the skull they move somewhat independently of the rest of the skull but are subject to similar forces. As a result, it is very common to suffer TMJ ds, neck and shoulder strain from this type of injury.

• In front impact collisions, the head continues to move forward after the torso has been restrained by a seat belt or the steering wheel. In an effort to maintain the structural integrity of the system significant muscle contraction occurs. Muscle contraction pain as well as damage to the retrodiscal tissues may be a primary site of injury. As a result the skull accelerates into the jaw. The primary injury is damage to the jaw joint as a result is compression of the condyles against the retrodiscal tissues.
• Rear impact collisions cause the neck to be stretched back first and then bounce forward. Typically the unsupported neck tends to lag behind in the initial impact because the torso is thrust forward. When the muscles in the front of the neck reach maximum extension they will rapidly contract causing the head to lurch forward. In a rear impact collision, the skull, due to its weight, moves first and the lighter, independent and later moving jaw is stretched forward. The primary jaw injury is stretched and possibly torn muscles and ligaments.
• Oblique angle collisions cause a combination injury of compression on the impact side and stretching on the opposite side.

In addition to this acute injury, many people have underlying chronic jaw joint pathology such as muscle fatigue, strain or spasm due to occlusal interference as well as prior damage to the jaw joint ligaments and discs from prior macro trauma (a previous injury) or micro trauma (due to muscle strain from occlusal interference). Often these MVA events not only create new trauma but also exacerbate the underlying pathology. As a result, the underlying pathology may prevent the new damage from healing, or the new damage might heal but leave the underlying pathology in a more acute stage.

Bite problems resulting from and independent of whiplash injuries can manifest in three unique and often co-existent ways: muscle pain, dental damage and/or damage to the jaw joint structures. The most important step in developing a treatment plan to for these disorders is to determine which, if any, of the three components a patient is experiencing. While techniques to center the jaw joints and relax the muscles to assist in the diagnostic process have been used in dentistry for decades they our outside the expertise of the medical doctor. Often when the accident victim suffers severe trauma, the jaws are understandably not the very first priority. In most cases if the team does not have a trained TMJ practitioner this part of the assessment is often over looked. Sometimes after the primary injuries from the major trauma subside, the victim continues to have head, neck and facial pain that does not respond to standard therapeutic approaches, such as physical therapy. In some cases cause of the continuing pain is the undetected conflict between the teeth and the jaw joints and the underlying muscle and ligament damage that prevents the acute accident related trauma from healing.

Case Study

The following is a case report of a generally healthy 35 year old female patient who had recently moved to the area and was referred to the practice for a new patient exam and cleaning. Upon reviewing the patient’s history it was brought to my attention that she had been in a severe car accident two years prior and sustained significant injuries to her abdomen as well as a significant whip lash injury. Since the accident she experienced chronic headaches and facial pain, typically 2-3 “events” a month that would require bed rest for up to several hours. Prior to the accident she experienced “moderate” headaches but they were not nearly as severe so she never brought them to her doctor’s attention because she assumed “headaches were a normal part of life.”

Here post accident treatment plan defined by her internist included muscle relaxants (cyclobenzaprine hydrochloride, Flexeril), non-steroidal anti-inflamatory pain relievers (800mg, Ibuprofen), prescription pain relievers (oxycodone hcl, acetaminophen, Percocet) at night and as needed and over the counter pain relievers for day time use. Additionally she underwent 3 months of physical therapy (1x per week) followed by 9 months of chiropractic treatment (3-4x per month). While these treatments did offer significant short-term relief typically within several days following a session the discomfort would return.

When I explained that her pain might be from her occlusion and muscles as a result of the accident she expressed significant doubt as she had seen seven different doctors each with a different diagnosis and no long-term solution since the accident. I explained that if you have back pain and go to a physical therapist or a chiropractor, and they recognize that it is a muscle problem and they work on your muscles, but they never notice that you have one high heel shoe and one low heel shoe on, forcing you to walk crooked all the time, is it not unlikely that their treatment would not have any long term success. She agreed. Then I asked, “Is there difference between your shoes throwing your hip joints off and your teeth throwing your jaw joints off”? “Not very much”, she replied.

At the time of my examination, she had acutely painful temporalis muscles on both sides as well a pain during palpation in her massater, temporalis and sternomastoid muscles. To capture an accurate measurement of her muscle activity surface electromyography (BioEMG,Myotronics Inc.) of the massater, temporalis, lateral pyerygoid and sternomastoid was recorded while the muscles were at rest and the patient was seated upright in the dental chair. The current headache pain on the visual analogue scale (VAS) was 4 out of 10. Occlusal examination revealed first contact on the right side and then the teeth had to shift forward and to the right for maximal intercuspation. It is likely that this occlusal conflict existed prior to the MVA and was the stimulus of her prior pain. The MVA took the moderate chronic pain and escalated it to a whole new level of acute pain.

The first step in the differential diagnostic process is to evaluate the status of the jaw joints and muscles to determine if there is an underlying jaw joint and/or muscle problem that is preventing the macro injury from healing. The patient did not have any history of “popping” or “clicking” of the jaw joint. The jaw joint was also not sensitive to firm palpation. When the Doppler (Mini Dopplex, HNE Health Care) was used to listen to the internal structures of the jaw joint, minimal sounds indicated a healthy joints and supporting structures.

An anterior deprogrammer (Discluder, Best-Bite Inc.) was utilized to disclude the posterior teeth which enabled the lower incisors to move freely anterior-posterior and inferior-superior without tooth interference which in turn allows the condyles to move to the centered position in the fossa. Once the condyles were centered, the muscles no longer needed to brace the condyles in an unstable position.

In some cases relieving the influence of occlusal interferences on the muscles can produce a remarkably rapid reduction in symptoms, both in cases where muscles are the primary cause of pain or a trigger for a secondary pain, such as migraines. The jaw muscle fatigue, strains and spasms were released, reducing the patient’s pain to zero on the VAS. A second sEMG was recorded to document the significant reduction in muscle activity, particularly in the right side temporalis and sternomastoid. For further confirmation the device was removed and the patient was instructed to close her teeth together and swallow several times which allowed the occlusal interference to un-center the jaw joints allowing the pain to return as well as increase the levels of muscle activity as evidenced by the sEMG. The patient was again fitted with the device and the pain was quickly relieved and the muscles relaxed.

The immediate effect of the anterior deprogrammer in conjunction with the additional information from my examination confirmed that underlying occlusal muscle pain, secondary to occlusal interferences may have been exacerbated by the recent trauma from the accident. The immediate pain relief from this experience allowed the patient to confidently proceed with occlusal treatment for their headaches and face pain.

Once the patient was again comfortable a bite record was taken so that occlusal relationship with the condyles centered and muscles relaxed could be captured and transferred to the articulator for further study. A dab of polyvinyl adhesive was placed on the underside of the Discluder where the lower incisors line up. Next a small amount of bite registration material is dispensed on the under side of the Discluder and the patient passively, with totally relaxed muscles, closes against the flat surface to capture the anterior position. The last step is to inject a bolus of custom liner material in between the upper and lower posterior teeth and let it passively set. The result is a confirmed, passive, accurate, stable and repeatable bite record.

A facebow recording (Waterpik Technologies Slidematic] was taken to capture the relationship of the upper teeth to the jaw joints and transfer that relationship to a suitable articulating instrument for further study and treatment planning. The anterior discluder and posterior bite records are used to mount the casts on the semi adjustable articulator (WaterPik Technologies Denar Combi). Marking ribbion showing first contact verifies accurate transfer of the occlusal relationship from the mouth the to the articulator.

The first step of the treatment plan was to custom fabricate a long term hard acrylic bite splint that the patient could wear every night and for large portions of the day at first to stabilize her jaws in this centered and comfortable position. This gave the patient the opportunity to “test drive” her new bite for an extended period of time prior to additional long term treatment. Upper and lower alginate impressions were taken to make casts that were then mounted and sent to the laboratory for bite splint fabrication.

Prior to fitting the bite splint the deprogrammer was used to release the muscles and to re-center the jaw joints to ensure it was equilibrated in a centered jaw position, free of occlusal interference and with relaxed muscles.

The bite splint was designed with a stable occlusion pattern emphasizing Dr. Peter E. Dawson’s objectives of bite splint therapy:

1. Full and simultaneous contact of the teeth at the same time that the jaw joint is centered in the glenoid fossa.
2. Full and simultaneous contact of all of the teeth in the position of maximal intercuspation
3. Anterior guidance so that there is full and immediate disclusion of the posterior teeth on the working side
4. Full and complete disclusion of the posterior teeth on the non-working side
5. Full and complete disclusion of the posterior teeth in protrusive

Over several visits and adjustment sessions the patient became comfortable and free of pain with the full coverage bite splint. That confirmed that the long term bite splint was adjusted to a stable centered jaw position. Often bite splints fail to achieve success, not because the bite splint was not the proper treatment, but because it was never adjusted to the proper end point.

Twelve weeks of wearing the bite splint and maintaining a position which did not continue to require further adjustments confirmed that the bite was stable. Based on this result, we decided that I could confidently go ahead and reshape the teeth to alter the pattern of occlusal contacts to the same standards that have been achieved with a bite splint, commonly known as equilibration.

The process of reshaping her teeth was carried out over several sessions and the patient was allowed to slowly wean herself off of the long term full coverage bite splint as progress was made with the tooth adjustments. The figures show the occlusal contact pattern prior to and following the equilibration. The goal of duplicating the occlusal contact pattern that was originally determined with the Discluder and then maintained with the bite splint was accomplished ensuring comfort and stability.

Summary

In the eighteen months since the start of treatment there has not been a reoccurrence of pain. This case highlights two important issues. First, dentists have a great opportunity to help a great number of people who suffer from head, neck and facial pain from a variety of causes, such as whip lash due to MVA. Second we all need to do our part in raising awareness as to the relationship of occlusal interference and chronic head, neck and facial pain. This includes the public and the medical personnel who are the first to see accident victims. This unfortunate woman saw seven medical personnel since the accident and suffered needlessly for over a decade with pain due to her bite and muscles even before the accident. The only thing separating her from the treatment she needed was knowledge. Please do your part in raising awareness among your staff, patients and the medical community.