This study investigated the use of iontophoresis in altering the sensitivity level of teeth that displayed thermal and tactile hypersensitivity. A total of 95 teeth were treated with an iontophoresis instrument. Forty-eight of these teeth were treated with a placebo of deionized water, and 47 were treated with a 2% sodium fluoride solution. Two of the 47 teeth receiving sodium fluoride had identical pretreatment and posttreatment sensitivity ratings, while 40 teeth (85.1%) demonstrated a reduction in sensitivity. Twenty-nine of the 48 teeth receiving the plac ebo demonstrated no change in sensitivity. All teeth receiving the placebo were re-treated with soidum fluoride. Forty-seven (97.9%) responded with reduced levels of sensitivity.