by William P. Cheshire, Jr., M.D.
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 (1)
with potentials as high as several hundred millivolts. (2)
Such currents usually cause no symptoms, (3)
although some patients report a metallic or battery-like
taste. (4) 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.
2. Bergman M, Ginstrup O,
Nilsson B. Potentials of and currents between dental
metallic restorations. Scand J Dent Res 1982;90:404-8.
3. Muller AW, Van Loon LA,
Davidson CL. Electrical potentials of restorations in
subjects without oral complaints. J Oral Rehabil
4. Hugoson A. Results
obtained from patients referred for the investigation of
complaints related to oral galvanism. Swed Dent J