A preventive dentistry delivery system was developed for maximum effectiveness in private practice. Four new pit or fissure carious lesions developed in 20 patients who were 10 to 20 years old at the start of a two-year exploratory test; there were no new lesions of smooth surfaces. Of the incipient lesions that were under observation, no increase was observed in 23 of 26 pit or fissure lesions, 24 to 25 proximal and all of 26 buccal or lingual smooth surface lesions. In 33 patients 21 to 30 years old at the start of the test, no new lesions appeared and growth of the 142 incipient lesions appeared to be arrested. A low level of gingivitis was maintained in all patients who were tested.