A total of 78 orthodontic patients participated in a study of the degree of decalcification inhibition induced by daily treatment with 0.4% SnF2 gel. Control patients (n = 39) were managed exactly as were the test patients (n = 39) except that the latter were instructed to brush at bedtime each day with the gel. In the nongel users, 24 (64.1%) developed decalcification after 18-24 months bandin...