Dr. J. Travell and Dr. S.H. Rinzler (1952) were among first scientists who pointed on tension and spasm in the masticatory muscles as a major contributing factor to TMJ dysfunction. Despite that, other theories were also proposed, but the muscular origin of TMJ is considered as one of the leading causes of this joint dysfunction.
According to Travel and Simmons (1983): “The trigger points (in the masticatory muscles cause increased tension and shortening of local muscle fibers, but in the absence of motor unit activity.” Let’s decode this sentence. As a result of chronic tension the resting muscle tone of the masticatory muscles increases but the threshold of the muscle spindle receptors activation drops and combination of these events triggers a condition of hyperirritability of the masticatory muscles (Kotani, et al., 1980).
Now we need shortly discuss the concepts of resting muscle tone and condition of hyperirritability of muscle spindle receptors. The resting muscle tone is residual tension which each muscle carries during state of complete rest and relaxation. One of the first signs of future muscle spasm and tension is slow rise in the resting muscle tone without the patient be aware of this process. When resting muscle tone rises it increases peripheral vascular resistance in the affected muscle with consequential decrease in the arterial blood supply and venous and lymph drainage. Thus the increase of the resting muscle tone is first clinical step in the future development of acute muscle spasm and formation of active trigger points.
The muscle spindle receptors control degree of the muscle tension including the resting muscle tone. As a result of various factors (see below) affecting TMJ function the masticatory muscles start to work under the greater pressure and they slowly reset to the new, lower threshold of their activation. Such changes in the threshold of any peripheral receptors including muscle spindle receptors are called condition of hyperirritability. This is a main cause of the increase in the resting muscle tone.
Thus the condition of the hyperirritability of muscle spindle receptors and increase in the resting muscle tone greatly contribute to the development of tension in the TMJ itself, even during resting hours. As a result, articular disk wears and tears first and Osteoarthritis of TMJ develops later.
There are many factors which contribute to the tension build up in TMJ: chewing gum and eating hard food, toothache on the opposite side, incorrectly placed bridge, bruxism, hereditary factor, etc.
One of the frequent contributing factors of TMJ dysfunction I would like to mention separately is bruxism. Bruxism is a especially prevalent among women and it is clinching and grinding the teeth at night. Excessive compression of the disk in the combination with grinding movements of the lower jaw, sometimes during entire night, smash and in many cases dislocate articular disk causing severe TMJ dysfunction (Nagamatsu-Sakaguchi, et al. 2008). Degeneration of the TMJ triggers additional spasm in masticatory muscles and as a result the vicious cycle of TMJ dysfunction is formed and it affects the patient’s everyday life.
Temporalis muscle, especially its posterior portion, is primarily activated during bruxism. Also people may have bruxism periodically during the day as a body response to chronic stress.
Patients with TMJ dysfunction complain of dull pain anteriorly to the ear and on the same side of the face. The pain becomes sharp when the mouth is wide open and during chewing especially hard food. Pain also increases if the patient sleeps on the affected side because of the pressure on the TMJ against the pillow.
If the articular disk is under the pressure, clicking sounds appear with every mandibular movement and patients may report about periodic ‘locking’ of the joint.
Frequently pain from the affected joint radiates to the temporal and occipital areas, and it may trigger chronic headaches which are usually located in the temporal area (Ciancaglini et al. 2001; Ballegaard.et al., 2008) Any patient with temporal headache must be examined for TMJ dysfunction even of he or she doesn’t complain about any uncomfortable sensations in the area of TMJ.
Some patients complain about ear pain, dizziness and even tinnitus (Rubinstein et al. 1990). These side effects of TMJ dysfunction were initially described by Dr. Costen (1934) and they constitute so called Costen’s Syndrome.
VISUAL TEST (VT)
The first simple test is VT. Position yourself in the front of the patient that your eyes are on the level of his or her mouth. Now ask the patient to clinch teeth while open lips. What you see is the patient bite which is way upper and lower teeth are positioned in respect to each other. You may observe it from the lateral and frontal views.
The bite is a very individual and it changes during lifetime as a result of lost teeth, bridges or crowns. The bite of the patient with TMJ is always pathologically changed. It can change in two major ways: anterior-posterior and lateral.
If examiner looks on position of upper and lower teeth from a side he or she may noticed that in some patients the upper and lower teeth positioned exactly against each other (insial bite). In some patients the lower teeth go slightly forward in regard to the upper teeth (maxillar protrusion) and finally in some patients lower teeth are slightly behind the upper teeth (mandibular protrusion). See Fig. 1 presents three types of the bite.
Fig. 1. Variants of the normal bite
a – mandibular protrusion bite
b – maxillar protrusion bite
c – insial bite
In many cases there is no previous records of the bite before the patient stated to suffer from TMJ dysfunction. This is why the lateral view of the bite is less informative in the regard to the current treatment protocol but it can be very important subject during and at the end of the treatment.
Ask the patient permission to make photo of the bite from the lateral view (you don’t need to take picture of entire face) before the treatment begins, during the treatment and after the treatment ends. In many cases comparison of these pictures will shows positive changes in the bite from the lateral view which reflect normalization of the anterior-posterior relationship between upper and lower jaw.
These restorative changes documented by pictures can be also very helpful for the dentist if night guard is needed. They also shows the patient how much changes your therapy did to restore the normal bite.
The lateral changes of the bite are very important, because they are definite sign of the TMJ dysfunction. Ask the patient to slightly clinch upper and lower teeth and observe if there is any differences between position of the upper and lower teeth on each side of the mouth. In the patients with TMJ dysfunction the spasm in the masticatory muscles pulls the lower jaw superiorly on the same side and it changes bite in the way that gap between upper and lower teeth form on the opposite unaffected side. Very frequently the patients noticed this crooked position of the lower jaw on their own and they mentioned it even before the examination starts.
This simple test helps to confirm the diagnosis of TMJ and it can be used during the treatment to observe its effectiveness. As a result of the therapy the lateral deviations of the bite must be completely eliminated. Fig. 2 illustrates the anterior view of the pathological and normal bite of the patient with TMJ dysfunction.
Fig. 2. Anterior view of the pathological (a) and restored normal bite (b) of the patient with TMJ dysfunction
THREE KNUCKLES TEST (TKT)
The simplest and the most effective way to examine TMJ and to find out if there is any tension in the masticatory muscles is Three Knuckles Test (Travell and Simons, 1983). This test must be conducted just before any palpatory evaluation of the TMJ and masticatory muscles. Normally we suppose to fit three knuckles of 2nd-4th fingers compressed together into wide open mouth. Ask the patient to open the mouth and try to fit his or her three compressed knuckles between the upper and lower teeth. If pain or stiffness prevent the patient from fitting three knuckles into the open mouth, he or she has spasm and shortening of the masticatory muscles with following pathological changes in the TMJ.
Fig. 3 illustrates results of TKT on patient with severe TMJ dysfunction before first session and at the end of treatment course.
Fig. 3. Results of TKT used on patient with severe TMJ dysfunction before first session (a) and at the end of treatment course (b)
LATERAL MOVEMENT TEST (LaMT)
LaMT is also observation test which allows to detect degree of tension in lateral pterygoid muscles responsible for the lateral or grinding movements in TMJ.
Ask the patient’s permission to mark spot on the middle of the chin and hold ruler under the chin with the similar mark. The mark on the ruler must be precisely under the mark on the chin. Fig. 4 illustrates the application of the LaMT in case of the tension in the left lateral pterygoid muscle.
Fig. 4. LaMT in case of the tension in the left pterygoid muscleFig. 4a illustrates the initial position of the lower jaw before application of the test. Now ask the patient to move lower jaw laterally first to the direction of affected joint until he or she feels pain (see Fig. 4b). Notice the distance the marked point on the chin travels during the lateral movement. For the next part of the test ask the patient to move lower jaw laterally in the direction opposite to the affected joint. Usually this movement is more painful and restricted if tension in the lateral pterygoid muscle is present (see Fig. 4c). Notice and record the difference between lateral movement to each side.
Please notice that during lateral movement to the left the marked point on the chin moved more than inch along the ruler while during lateral movement to the right the patient was able to move lower jaw only slightly because he feels pain in the left TMJ.
PALPATION TEST (PT)
PT is the first touch contact with the affected TMJ and it gives the practitioner a lot of important information. First of all be sure that the patient relaxes masticatory muscles and mouth slightly opens. Now palpate both temporal areas, TMJ areas as well as along both lower jaws. Apply moderate pressure and try to feel if there are any abnormalities in the tension and structure on the affected side compared to the normal side.
The practitioner needs to examine and compare these abnormalcies in each of three areas separately: temporal, TMJ and along the lower jaw. Video below presents the application of the PT in each area.
DYNAMIC TEST FOR LATERAL PTERYGOID MUSCLE (DT)
The DT allows us to examine the position of the condyloid process inside of the TMJ and also tension in the lateral pterygoid muscle (LPM). The video below illustrates the application of DT. Pay attention to the position of the fingertips in the external auditory passages.
Place tips of the index or small fingers in both external auditory passages (Part 1 of the video) so that the padded parts of both fingertips are pressed against the anterior walls of the passages. In Part 2 of the video you see that the practitioner’s index fingers are pushing upward on the anterior wall of the ears. Now ask your patient slowly to open and close mouth and concentrate on the sensation in your fingertips (Part 3 of the video). You will feel that bony resistance (i.e. condyloid process) your fingertips are pressed against moves forward while the patient continues to open his or her mouth. If you compare sensations from both sides you may notice that on the affected side this movement of the condyloid process forward you will feel as a decrease of bony resistance and it appears earlier. This is a sign of the increased tension in the LPM.
There is another important tip for the correct execution of DT. Basically all patients with TMJ dysfunction feel a clicking in the joint while the mouth opens. The moment of click will significantly impair your ability to examine the LPM using this test. To eliminate this distracting factor you should ask the patient to slide the tip of the tongue all way backward along the roof of the mouth before he or she opens their mouth and keeps it in this position while DT is applied. Pay attention to the position of the tongue during the application of DT (see Part 3 of the video).
TRIGGER POINT TEST (TPT)
A palpatory examination will reveal several trigger points in the masticatory muscles.
1. Temporalis muscle
The trigger point in temporalis muscle are located above zygomatic arch in the temporal area. Video below shows the examination of the active trigger points in the temporalis muscle. The dashed line in the video indicates the lower edge of zygomatic arch white dots indicate the location of trigger points.
During examination be sure that the patient relaxes all masticatory muscles and don’t clinch teeth. The best way to control this matter is to observe if the patient maintain small gap between upper and lower teeth (see video of masseter muscle examination).
Two trigger points in the temporalis muscle just above the ear are especially active in cases of Costen’s Syndrome or directly associated with the temporal headache as a result of TMJ.
2. Masseter muscle
Trigger points in the masseter muscle are located on the lateral side of the face below the zygomatic arch (dashed line in the video). Video below shows the examination of the active trigger points in the masseter muscle.
During examination be sure that the patient relaxes all masticatory muscles and don’t clinch teeth. The best way to control this matter is to observe if the patient maintain small gap between lower and upper teeth during the examination.
3. Lateral Pterygoid Muscle (LPM)
The LPM should be examined below the zygomatic arch and in front of the TMJ. The video below shows the examination of the active trigger point in the LPM. The dashed line in the video indicates the lower edge of the zygomatic arch. Pay attention to the position of the thumb in the video.
4. Digastric muscle
The digastric muscle should be examined just below the chin as it is shown on the video below. White arrow in the video indicates the direction of the pressure.
EVALUATION OF THE POSTERIOR NECK
Evaluation of the patient with TMJ dysfunction must be combined with the evaluation of the posterior cervical muscles. There is great number of publications which link TMJ dysfucnction with chronic tension and spasm of the posterior cervical muscles (Nicolakis 2000, Sonnesen et al., 2001, Wiesinger et al., 2007, etc.). It is also worth to remember that one in three people who are exposed to whiplash trauma is at risk of developing delayed TMJ symptoms that may require clinical management (Sale, 2007) and 53 % of patients with Fibromyalgia have TMJ pain of different intensity (Balasubramaniam et al., 2007) .
The clinical correlation between TMJ dysfunction and tension in posterior cervical muscles was noticed long ago. Halbert’s (1958) statement may explain this phenomenon: “…there is a close anatomo-functional relationship between the masticatory system and the cervical region and scapular centric, and the postural alteration of the head leads to a disadvantage to muscular biomechanics.”
Unfortunately the obvious clinical correlation between TMJ dysfunction and chronic tension and pain on the posterior neck created incorrect assumption that adjustments and manipulations of the cervical vertebrae will help the patients with TMJ. There are countless clinics where TMJ is treated using series of quick cervical adjustments despite that all research data confirm its muscular origin. As it was correctly pointed by Matheus, et al., (2009): “The relationship between craniocervical disorder and TMJ dysfunction may be stronger related to the muscular component rather than the articular component.”
We won’t discuss here the evaluation of the posterior cervical muscles but I would like to make it clear to all practitioners who work on TMJ cases that this is a must component of patient’s examination and treatment protocol.
OTHER PATHOLOGICAL CONDITIONS WHICH MIMIC TMJ DYSFUNCTION
This is a very important issue for patients who suffer from TMJ dysfunction. On weekly basis we see patients in our clinic who were misdiagnosed and consequently incorrectly treated for TMJ dysfunction while real problem was triggered by completely different cause. Expensive day guards and night guards were made, medication with severe side effects were prescribed and even surgeries were performed on patients who were incorrectly diagnosed with TMJ dysfunction. This is why I would like to discuss this important subject separately.
First of all I would like to emphasize that clicking and even occasional locking of the jaw isn’t the ground for the intensive therapy. Only if the patient experience pain in the area of TMJ and/or restriction of the movement of the lower jaw the practitioner or physician should consider the treatment options. In all other scenarios stretching during the day and before meals, avoiding hard food usually enough.
It is a very common mistake when clicking in the TMJ during mouth opening in the combination with headache or tinnitus immediately leads to the diagnosis of TMJ dysfunction. Yes, every patient with temporal headache should be examined for the TMJ dysfunction. However the temporal headache even in the combination with joint clicking is irrelevant if there is no pain and restriction of mouth opening (TKTest) or lateral movement.(LaMT). If TMJ examination we discussed above didn’t confirm preliminary diagnosis of TMJ dysfunction other causes for the headache should be considered first.
So, what pathological conditions can mimic TMJ dysfunction and send even experienced health practitioner on the wrong path?
Greater Occipital Nerve Neuralgia (GONN) and/or Minor Occipital Nerve Neuralgia (MONN)
These pathological conditions, especially MONN are very frequent causes of wrongly diagnosed TMJ dysfunction. Minor occipital nerve innervates the temporal area and outer ear. Even slightest irritation of the minor occipital nerve on the lateral part of the occipital ridge will trigger temporal headache and if the patient has clicking in the TMJ incorrect diagnosis of TMJ dysfunction frequently established.
Greater occipital nerve innervates the scalp on the top of the head and less frequently is associated with temporal headache. However in severe cases of GONN the tension in the cranial aponeurosis and scalp spreads to the temporal area and it may trigger temporal headache secondarily. The tension in the posterior cervical muscles is direct cause of GONN and MONN.
The major differences of temporal headache as a result of MONN are:
1. In case of temporal headache as a result MONN the pain frequently originates on the back of the head and radiates to the temporal area.
2. Frequently the patients have other sensory abnormalities in the temporal area: tingling, burning pain, local numbness.
3. There is no increase in the intensity of headache during or after chewing.
4. Three Knuckles Test and Lateral Movement Tests are negative.
Temporal Arteritis (TA)
TA is inflammation, narrowing and loss of elasticity in temporal arteries. TA may also mimic TMJ dysfunction because it causes temporal headache as well as restriction of movements in TMJ.
The major differences of TA are:
1. TA affects only patients after 55.
2. TA accompanies by mild fever and fatigue.
3. Temporal headache is constant and it may got worse during chewing.
4. TA accompanies by stiffness and pain in the neck, shoulders, back and legs.
5. TA also accompanied by visual abnormalities.
6. Patients with TA exhibit weakness of masticatory muscles and may exhibit pain in the area of TMJ. They chew food slowly and have difficulties with hard food.
Trigeminal Nerve Neuralgia (TNT)
Patients with TNT may also mimic TMJ dysfunction because this pathological condition may also trigger temporal headache.
Trigeminal nerve is cranial nerve and doesn’t innervate temporal area but TNN may trigger pain radiation there and also be responsible in the tension developed in the cranial aponeurosis.
The major differences of temporal headache as a result of TNN are:
1. Initially pain originated on the face and it still mainly affects the face.
2. The pain is much more intense and it combines with burning or itching.
3. Pain may increase its intensity during chewing but major difference is its constant character. Pain bothers patients 24 hours and very frequently dramatically increases its intensity at night.
4. Three Knuckles Test and Lateral Movement Tests can be positive. However restrictions of mouth opening or lateral movements of the lower jaw are results of intense facial pain rather of the pain in the TMJ area.
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Dr. Bipar has an unusual background for a physician. He graduated in engineering from Lousiana State University in 1981 and worked as an engineer for Exxon Mobil. In 1989, he enrolled in the Dental School of the University of Texas and graduated in 1993 as a Doctor of Dental Surgery. He later obtained degrees as a Doctor of Periodontics and Implant Surgery, and Plastic and Reconstructive Surgery.
Dr. Bipar’s unique combination of medical and engineering backgrounds helped him to become one of the world’s most recognized dentists and oral reconstructive surgeons. In 2009, the American Research Council recognized him as among the top ten dental surgeons in the United States.
Dr. Bipar is a member of the American Dental Association, as well as the International Academy of Periodontics. He teaches at the Arizona Dental School and actively lectures worldwide on behalf of the International Academy of Periodontics.
Dr. Bipar uses many modalities for his patients, including medical massage, as a part of an integrative protocol in the treatment of temporomandibular dysfunction, neuralgia of cranial and peripheral nerves, etc.
He lives in North Scottsdale, Arizona, with his wife and two children. His hobbies are sports, cars and travel.
Category: Medical Massage