Oral fluoride retention with thixotropic and APF gels and foam-lined and unlined trays.

Ten child volunteers each received four topical fluoride applications using different techniques. The amounts of fluoride applied, recovered from the mouth, and retained in the mouth were calculated for each treatment. The value of patient expectoration following topical F treatment was also evaluated. The tray system with an absorptive liner significantly reduced the amount of gross oral-retained fluoride (p less than 0.01). Expectoration following topical treatment with either an APF or thixotropic gel was a significant adjunct in reducing the net oral-retained F dose (p less than 0.01). When expectoration is done following a topical F treatment, a thixotropic gel may be an added advantage in reducing oral F retention and ingestion. We recommend that suction devices be used during a topical F treatment, but most importantly that the patient be requested to expectorate thoroughly following topical treatment.