Electromotive Forces and Electric Currents Caused by Metallic Dental Fillings

E LECTRICAL phenomena in oral cavities have been described and discussed in many papers published between 1878 and the present time. Solomon, Reinhard, and Goodale1 abstracted the 24 most important papers published before June, 1933. The papers up to late 1933 describe different cases and suggest explanations of the observed symptoms. Cases are described in which certain pathologic conditions in the oral cavity were relieved when the metallic restorations were changed so that all were made of one kind of metal, or were completely removed. Lain and Caughron2 reported their use of a Weston Model No. 440 micro-ammeter having a range of 75 microamperes, and stated that in only a few cases did they require an instrument having a greater range. They also state correctly that the potential difference of the tw6 restorations could be calculated by taking the product of the observed current and the resistance of the micro-ammeter. They state neither the resistance of the meter nor the magnitude of a potential difference. The chief concerns of the paper are case histories and