TMJ Pain May Be Aggravated by Free Radicals,
Relieved Partly by Antioxidants

By Jack Challem
Copyright © 1998 by Jack Challem, The Nutrition Reporter™
All rights reserved.

Temporomandibular joint (TMJ) disease affects an estimated 10 million Americans. The joint, located on each side of the head where the temporal bone of the skull meets the lower jaw (mandible), is considered the most complicated joint in the body. It moves backward and forward, opens and closes like a hinge, and is subject to enormous pressure during chewing. Not surprisingly, then, the cause of TMJ disease is often mechanical, the result of malocclusion (bad bite). TMJ disease can also be a manifestation of arthritic inflammation.

For someone with TMJ disease, chewing food causes pain, which can radiate outward and affect nearby tissues, resulting in toothache, headache, muscle tightness in the face, clicking or popping noises, and neck and shoulder pain. Conventional treatments can include bite plates, orthodontics, and prescription muscle relaxants.

Free radicals - the same molecules implicated as a cause of cancer and heart disease - may play a major role in exacerbating TMJ disease symptoms, according to a recent article by Stephen B. Milam, DDS, PhD, and his colleagues at the University of Texas Health Sciences Center, San Antonio, Texas. If free radicals do contribute to TMJ disease, then antioxidants may provide a therapeutic option.

Milam believes that the mechanical stress of the TMJ generates free radicals through a number of mechanisms, triggering a cascade of biochemical reactions. The end result amplifies the tissue damage and pain associated with TMJ disease.

"One can envision that a disease state could result from an accumulation of such radicals by either increased production of such radicals, overwhelming local antioxidant defenses, or by a deficient production of free radical scavengers," he wrote.

• Physical and mechanical stresses, such as shearing, can generate free radicals. This, wrote Milam, has been demonstrated in blood cells and fingernails exposed to shearing stresses. Grinding and shearing may occur with movement of the temporomandibular joint.
  

• Hypoxia-reperfusion injury can also generate free radicals. Unbalanced joint pressure can temporarily induce localized oxygen starvation. When oxygen is restored, cell metabolism can shift and increase production of free radicals.
  

• Hemoglobin, the iron-containing protein in blood is a potent source of free radicals and inflammation. Microbleeding can deposit hemoglobin into joint tissues, enabling its iron to generate hydroxyl radicals, which can damage collagen, elastin, and other types of tissues, Milam wrote.
  

• Breakdown of arachidonic acid, an essential fatty acid, increases production of free radicals that attack cell membranes. Some cytokines (peptide hormones) can also generate free radicals.
  

"Free radicals generated by these mechanisms in normal TMJs may not lead to a pathologic state if endogenous free radical scavenging mechanisms prevent their accumulation," Milam wrote. "However, if the scavenging capacity of affected articular tissues is exceeded by an overwhelming production of free radicals, significant tissue damage could occur. Also, if the scavenging capacity of the affected tissue is compromised (eg, genetic deficiency, nutritional deficiency, compromised synthesis by mechanically stressed cells), then tissue damage could result from a modest production of free radicals."

Milam and his colleagues cautiously approached the use of antioxidants in ameliorating TMJ disease symptoms - dentistry has been slower than medicine to recognize the therapeutic potential of antioxidants. Milam cited one study showing that superoxide dismutase (an antioxidant enzyme produced by the body) reduced TMJ disease symptoms. Other antioxidants, including glutathione, vitamins C and E, and melatonin are well established as free radical scavengers.

Reference: Milam SB, Zardeneta G, Schmitz JP, "Oxidative stress and degenerative temporomandibular joint disease: a proposed hypothesis," Journal of Oral and Maxillofacial Surgery, 1998;56:214-223.

This article originally appeared in The Nutrition Reporter™ newsletter. The information provided by Jack Challem and The Nutrition Reporter™ newsletter is strictly educational and not intended as medical advice. For diagnosis and treatment, consult your physician.