One hundred thirty-two extracted premolar teeth were selected and divided into four equal groups. The first group of thirty-three teeth received a topical application of acidulated phosphate fluoride; the second group, a topical application of stannous fluoride; the third group, an application of a polymeric adhesive coating; the fourth group was left untreated to serve as a control. On each tooth a loosely fitted orthodontic band was cemented to place. After cementation, the band was broken to simulate a loose orthodontic band in vivo. The four groups of teeth were simultaneously immersed in a decalcifying gelatin and were left undisturbed for 11 weeks. The teeth were then removed and a record was made of the decalcification produced. A chi-square test was used to compare the teeth in each group to those in every other group. Compared to a control group of teeth, those teeth treated with polymeric adhesive coating, acidulated phosphate fluoride, or stannous fluoride produced a statistically significant reduction in decalcification of the tooth surfaces beneath loose orthodontic bands. For a one-application technique, the polymeric adhesive coating provided more protection against decalcification of teeth under loose orthondontic bands than did either acidulated phosphate fluoride or stannous flouride.