Temporomandibular Joint Disorder - Cause

Cause

There are many external factors that place undue strain on the TMJ. These include but are not limited to the following:

Bruxism has been shown to be a contributory factor in the majority of TMD cases. Over-opening the jaw beyond its range for the individual or unusually aggressive or repetitive sliding of the jaw sideways (laterally) or forward (protrusive). These movements may also be due to parafunctional habits or a malalignment of the jaw or dentition. This may be due to:

1. Bruxism (repetitive unconscious clenching or grinding of teeth, often at night).
2. Loss of bite height (bite collapse), leading to an unnatural position of the lower jaw while chewing. Often occurs in patients over the age of 40 due to the natural aging process and/or bruxism. Overzealous equilibration by inexperienced staff or the improper use of air abrasion can also lead to the loss tooth height.
3. Trauma (e.g. sports related injuries; whiplash from any automobile accident; accidental injuries from any source to one's chin to cause ones chin to move in an upward/backward direction)
4. Mal-alignment of the occlusal surfaces of the teeth due to genetics, defective crowns, restorative procedures, lack of cooperation during orthodontic treatment.
5. The controversial practice of extracting 4 bicuspids in orthodontic treatment of patients with small jaws and overcrowding, which has been shown to lead to joint dysfunction. It is now discouraged in favor of a palate expander based treatment plan.
6. Jaw thrusting (causing unusual speech and chewing habits).
7. Parafunctional habits other than bruxism: excessive gum chewing, nail biting, eating very hard foods.
8. Exaggerated opening of mouth, when eating large sized foods, excessive opening during yawning/sneezing and in difficult cases of third molar (wisdom tooth) extraction.
9. Degenerative joint disease, such as osteoarthritis or organic degeneration of the articular surfaces, recurrent fibrous and/or bony ankylosis, developmental abnormality, or pathologic lesions within the TMJ
10. Myofascial pain syndrome
11. Lack of overbite or cuspid protected occlusion will result in excessive forces directed to posterior teeth and hence, more stress to muscles of mastication
12. Clenching from stress or anger and this will result in a common complaint of "sore jaws" noticed when one first awakens in morning.

Patients with TMD often experience pain such as migraines or headaches, and consider this pain TMJ-related. There is some evidence that some people who use a biofeedback headband to reduce nighttime clenching experience a reduction in TMD. The dentist must ensure a correct diagnosis does not mistake trigeminal neuralgia as a temporomandibular disorder. Oromandibular dystonia is another rare diagnosis which might cause some confusion