Influence of Electrical Potential on Ion Migration in Teeth 2. Quantitative Measurements of 1-131 Penetration by an Acid-Leaching Technique

Abstract

Radioactive NaI-I131 penetrated wax-covered extracted human teeth through a window in the enamel. When the tooth was immersed in successive portions of 3 N HCl, radioactivity levels in the acid extracts were used to evaluate penetration. When a positive potential between 1 and 12.5 volts was applied through a wire in the root canal, penetration was invariably greater than in controls. The mean ratio of activities of 2.9 did not depend upon voltage, current carried or duration of iontophoresis between 15 min. and 24 hrs. The effect of potential may be due more to depolarization of the negative surface charge than to iontophoresis. With potential, penetration towards the pulp was deeper, but the concentration gradients were not noticeably changed. An average of more than 90% of the radioactivity could be removed by 4 water rinses, whether or not a potential had been applied.