The Shocking Tooth About Trigeminal Neuralgia

Your Mouth and Other Illness
The New England Journal of Medicine
June 29, 2000, Vol. 342, No. 26
To the Editor:

A 66-year-old woman with a two-year history of right-sided Trigeminal neuralgia (involving the second Trigeminal division) presented with severe exacerbation of her typical sharp pain after a root-canal procedure in a right upper incisor. The procedure had slightly repositioned a mercury-amalgam restoration, nudging it closer to the adjacent tooth, which bore a gold-alloy crown.

Thereafter, and until the mercury amalgam was replaced by a porcelain restoration, tomatoes or certain other acidic foods would produce intense jolts, described as being like those of an “electrical battery,” in the right palate, boosting the pain in the same division of the Trigeminal nerve to an excruciating level. Lightly touching the right cheek also triggered paroxysms of neuralgia, which subsequently resolved with use of gabapentin.

Adjacent dental amalgams that are composed of dissimilar metals in contact with saliva can :

Form a galvanic cell that generates localized electrical currents with potentials as high as several hundred millivolts
Such currents usually cause no symptoms
Some patients report a metallic or battery-like taste
Many patients with Trigeminal neuralgia describe their pain in terms of electricity. This patient’s oral galvanism produced genuine electrical currents that potentially triggered the neuralgia.

William P. Cheshire, Jr., M.D.
Mayo Clinic Jacksonville
Jacksonville, FL 32224


  1. Certosimo AJ, O’Connor RP. Oral electricity. Gen Dent 1996;44:324-6. (8957826)
  2. Bergman M, Ginstrup O, Nilsson B. Potentials of and currents between dental metallic restorations. Scand J Dent Res 1982;90:404-8 (6758103)
  3. Muller AW, Van Loon LA, Davidson CL. Electrical potentials of restorations in subjects without oral complaints. J Oral Rehabil 1990;17:419-24. (2231160)
  4. Hugoson A. Results obtained from patients referred for the investigation of complaints related to oral galvanism. Swed Dent J 1986;10:15-28.