The signs and symptoms of TMJ

The trials and tribulations of TMD patients

Murphy's law of dentistry states quite simply; "If any complication can arise from any dental procedure, patients who exhibit the symptoms of TMD will probably have that complication!"

• If a bruxer has a tooth extracted, he WILL get a dry socket.
• If a patient who bruxes does not clean his teeth thoroughly, his periodontal disease will progress much faster than those who do not brux.
• If a bruxer has a sugar habit, he will tend to get more recurrent decay under his fillings or other restorations than someone who does not brux. The mechanism here is that the constant pressure on the fillings causes tiny micro cracking in the tooth structure underneath the fillings, thus allowing sugar and bacteria to seep under them.
• TMD patients frequently present at dental offices with pain that mimics the pain of a dead or dying nerve. When a tooth has symptoms that suggest it needs a root canal, but shows no testable signs of needing one, we say that the tooth is suffering phantom pain. In many cases, the pain is really caused by the nervous habit of grinding on that tooth to the exclusion of others. More unnecessary root canal procedures are performed on otherwise healthy teeth for this reason than any other.
• If it really becomes necessary for a dentist to perform a root canal on a tooth (for any reason), patients who display the symptoms of TMD generally have a really miserable time with pain between visits. Root canals (endodontic treatment) generally proceed without much pain from beginning to end for most patients. But persons who unconsciously grind and clench their teeth tend to cause themselves severe, prolonged pain which is really the result of the bruxing habit and only secondarily due to the endodontic procedure itself. This is well explained on my page concerning root canals.
• Even denture patients who tend to have these habits get constant denture sores, and sometimes cannot even wear their dentures, no matter how well they fit. Each time the dentist removes one denture sore, another crops up.
• Serious bruxing causes attrition of the teeth. Attrition is the simple wearing down of the tops of the back teeth and the top edges of the front teeth. This can become very pronounced in older people who have stressful occupations or men who do a lot of heavy lifting. It can also be quite serious among ravers who make extensive use of Ecstasy. In the image to the left the cusps of the molars have been worn down exposing the yellow dentin underneath. The image on the right shows how serious attrition can be. This is a 76 year old man who has been bruxing all his life. Click on this image to see it full size.
• Very hard pressure on the teeth causes the teeth to deform and bend on a microscopic level. This can cause an erosion of the enamel that protects the teeth on the outside, near the gum line. This phenomenon is called abfraction, and it is partly responsible for chronic sensitivity of the teeth to cold foods and liquids. Damage like that seen in the images below is difficult to repair with fillings because the repair tends to pop off after a while due to the constant deformation of the tooth caused by bruxing.

More often, toothbrush abrasion works in combination with bruxing to create some fairly bizarre effects on teeth. The image on the right shows a tooth which has been worked, over time, by these combined forces into the shape of a Coca Cola bottle. You are viewing the back of the tooth in a mirror. Click the image to enlarge it. The yellow arrow emphasizes the area of concern. On the enlarged image, you can see that the damage stops at the gum line, leaving a shelf of unaffected root about even with the level of the gums. The fact that this tooth is the last in the arch makes it more vulnerable to abrasion by toothbrush bristles, as it does not have another tooth behind it to "protect" it. Constant pressure from bruxing causes the tooth to flex at the level of the gum line loosening molecular sized chips of tooth structure over time. These loosened chips are easily abraded away by overzealous tooth brushing. The image below shows a similar 360 degree lesion surrounding both central incisors. Even though it is not visible in the image, the damage continues on the lingual (tongue) side of the tooth.

Note that abfraction is different than toothbrush abrasion with which it is often confused. Toothbrush abrasion (image on left) is caused by overbrushing with a hard bristle toothbrush, while abfraction is caused by excessive pressure applied to the teeth by severe bruxing habits. Abfraction can involve both the enamel and the root surface, but toothbrush abrasion almost always involves only the root surface below the level of the enamel. The shape of the defects are quite different as well. While abfraction tends to be a "dished out" defect, toothbrush abrasion tends to be a "notch" in the tooth surface just above the gum line. Click on either to see very serious toothbrush abrasion which caused the death of the nerve.

• Various categories of Cracked tooth syndrome can be caused by the pressure of bruxing. Cracked teeth do not appear to be broken or decayed, but cause sharp pain when pressure is applied to them. Cracked teeth are serious problems because the long term prognosis for these teeth is not always good.
• The constant pressure on the teeth presses on the periodontal ligament which in turn causes the majority of the extreme sensitivity to cold that many people experience. It is probably the most common reason for cold sensitive teeth that do not respond to Sensodyne or other sensitivity relieving toothpastes.
• Constant bruxing overworks the chewing muscles and causes them to get "cramps". Because of the way these muscles are leveraged, these cramps manifest as headaches and neckaches, and sometimes earaches. These symptoms tend to occur at the times these habits are most active. Hence, if your symptoms occur in the morning on waking up, you are probably bruxing in your sleep. If they happen while working on a computer, then the headaches are caused by bruxing while concentrating, and not by rays emitted by the CRT. These habits are especially active when angry at your spouse or children, or during times of personal or family crisis.
  • Headaches are associated with muscular hyperactivity principally in the temporalis muscle and secondarily in the masseter and medial pterygoid muscles. These muscles are responsible for closing the jaw. The temporalis muscle is particularly involved in producing headache pain. The activity most associated with the stimulation of this type of muscular headache is clenching. Clenching is defined as placing the teeth together with heavy force without lateral (side to side) movement of the lower jaw.
  • Neckaches are associated with the trapezius muscle. The trapezius originates along the shoulders and the vertebrae and inserts into the base of the skull. This muscle apparently becomes active during bruxing, although the reason for this is not especially apparent. The trapezius is responsible for keeping the head upright. (ie. it keeps the head from falling forward allowing the chin to come to rest on the chest.)
  • Earaches due to bruxing are due to muscle cramping from overuse of the lateral pterygoid muscle which is responsible for drawing the lower jaw forward. These little muscles are located directly in front of the ear, and pain associated with them refers to the ear itself. When they work out of synchronization, the lateral pterygoids are responsible for lateral movements of the lower jaw and hence are heavily active during grinding of the teeth. Spastic activity in one or both lateral pterygoid muscles is responsible for the clicking and popping patients experience when the internal anatomy of the joint itself has been damaged. (See my page on occlusion.)
• People who are chronic bruxers have a very difficult time keeping their mouths open at the dentist's office. The reason for this is that the muscles that close the jaws are paired with others that open them. When the muscles that close the jaws are active, it causes a reflexive relaxation of the opposing opening muscles. These opening muscles are so used to being in a relaxed state because of the constant grinding that they are not used to being in the contracted state demanded by the dental situation. This causes these muscle to cramp, which is why so many people have such an awful time in the dental chair. (Note: If you have this problem in the dentist's chair, simply ask for a "mouth prop". This is a rubber block that is placed between the upper and lower back teeth on the opposite side of the mouth from where the dentist is working. As the name implies, it props the mouth open taking the stress off the muscles that make it so painful to stay open. As a matter of fact, if you actually put extra pressure on the prop, biting down with some force, it can relieve muscle spasm and the attendant pain of staying open for long periods.)
• An inability to open the mouth, or a limitation in opening is called trismus. It may be very severe in which case it may be impossible to open the teeth more than a few millimeters. This condition is most often caused by spasm of the muscles which close the lower jaw. Whenever the patient tries to open wider than this amount, the muscles reach a "trigger point" at which they go into spasm and refuse to relax.
• Bruxing puts constant pressure on the joint, and can stretch the ligaments that hold the joint together. These ligaments are supposed to limit the joint's movement to its normal boundaries, and when they are stretched out too much, they cannot do that job properly. And since that angry little muscle attached to the ball joint in front of the ear must contract to open the jaw, it may cramp when opening the mouth wide pulling the ball too far forward. Thus, people with these habits tend to be prone to dislocating their jaws when opening wide to take a bite of a large sandwich like a grinder ("submarine sandwich" for those who live in New England).
• In very extreme cases of the disorder, long term abuse of the joints can cause the separate bones to fuse together. This is most usually due to severe bruxing, or as a response to severe joint trauma. The technical term for this is ankylosis, and it may severely limit the patient's ability to open the mouth at all. This is a VERY rare occurrence. In 22 years of practice, I have never seen such a case, but the existence of this phenomenon shows just how serious this disease can become.