In a double-blind study, evaluations for changes in cervical hypersensitivity in 20 subjects were made at 30 and 60 days by a thermoelectric tooth stimulator and by a mechanical stimulating device. Ten of the subjects used Thermodent dentifrice for 60 days, whereas the other ten sub­ jects used placebo of Thermodent for 30 days and then the active dentifrice for 30 days. There were no significant altera­ tions o f cervical hypersensitivity to m e­ chanical or thermal stimuli after the use of Therm odent for 30 or 60 days.