Every May our office sees an increase in the number of phone calls from patients worried because their jaws have begun to pop or click. They want to be seen by the orthodontist assuming this is related to their bite. What is the real relationship between the TMJ and orthodontics?
Following a landmark lawsuit in 1987 where a Michigan patient received a legal judgment against her orthodontist for giving her “TMJ,” hundreds of studies and millions of dollars have been spent by the scientific community to find if there really is a relationship between orthodontic treatment and the health of the temporomandibular joint (TMJ). Obviously this would be an important finding for doctors and patients alike. These studies have examined the different types of bad bite as well as the various approaches to treatment to show any cause and effect relationships.
Time and time again scientific studies have supported the conclusion that orthodontics neither causes nor cures TMJ disorders. Except for two exceptions, malocclusion in general cannot be linked to a higher prevalence of joint problems. The two exceptions are a posterior cross bite that causes the jaw to shift to one side upon closure, and an anterior open bite where all the biting force is on the back teeth only and the front teeth do not touch at all. Scientific studies have been unable to uncover any links between the use of headgear, extractions, rubber bands, oral surgery, or any other treatments and TMJ problems.
There are many conditions that can cause pain in the area of the TMJ that are not related to the teeth at all. Some are serious like degenerative arthritis and cancer. Others are related to functional habits (like clenching and grinding). While cross bites and open bites may be linked to joint problems, not all bad bites result in TMJ pain. Most patients who come into an orthodontic office have “bad bites,” and yet very few report TMJ pain. On the other hand, many patients who report severe TMJ pain often have ideal bites. This simple observation supports the scientific studies that have separated the fields of TMJ and orthodontics. If all bad bites had TMJ symptoms and all great bites never had any pain, a direct relationship would be defendable.
Jaw joint issues can involve muscles, ligaments, tendons, and/or the cartilages associated with the joints. Many times these problems are due to the anatomy of the patient’s joints. Some folks’ joints just make noises or move roughly because of their shape and size. It is not uncommon for patients’ ankles to pop when they stand up, but rarely do they seek treatment for that noise. A pop in the jaw joint however is much more noticeable because it occurs close to the ear where the patient can hear it.
If the ligament is loose so that it doesn’t hold the disc in the right place however, the disc travels a little too far upon opening and then suddenly pop back into place when the ligament finally applies enough tension. If the muscle pulls too hard on the front of the disc, it can also hold it too far forward until the ligament ultimately pulls it back into place. Ligaments can be naturally loose, get loose during childbirth (when all the ligaments in the body relax), or become damaged by trauma. The muscles pull too much if they have been busy chewing (gum, bagels, etc.), clenching, or grinding. Clenching or grinding can actually cause spasms in the chewing muscles which can be painful as well as pull the disc forward.
Nearly half of American women report they have had a pop or a click in their jaws while about one-fourth of the men report the same. While some popping may not be related to an identifiable event, many patients know exactly what sets it off. Studies have indicated that more than 50% of TMJ symptoms are attributable to stress alone. That helps explain the rise in calls we get during the last two weeks of the school year. Almost without fail our patients identify that their symptoms arrived about the same time as their finals and associated end-of-year projects. While there definitely are TMJ conditions that warrant treatment, most popping and clicking is not serious. Sometimes just recognizing the relationship between these noises and their stress level is all that is needed to get a patient on the road to recovery.