OBJECTIVE To evaluate the efficacy of weekly supervised tooth-brushing with a toothpaste and a 1.23% acidulated phosphate fluoride gel (APF) gel on white lesion reversal to treat incipient enamel lesions. METHODS A double-blind and randomized controlled trial. METHODS Three-hundred seven to 12-year-old Brazilian schoolchildren who presented with white spots on the buccal surfaces of permanent upper incisors were randomly allocated to three groups. In group I, children underwent supervised tooth-brushing and APF gel (1.23%) for one minute once a week. In group II, children were subjected to a weekly supervised tooth-brushing and a topical application of placebo, whereas group III (control) received no intervention. An expert dental examiner performed all intra-oral examinations for dental caries (DMF-s and dmf-s) and oral hygiene (Visible Plaque Index, Gingival Blood Index). RESULTS After three months, 258 children and 460 lesions were analyzed. The results of the clinical evaluation of arrested white spots did not differ significantly (p = 0.95) between the two experimental groups (57.9% in group I and 56.8% in group II) but differed significantly between them and the control group (p = 0.022). Logistic regression analysis identified gingival blood index (OR = 1.70, CI = 1.13 -2.55), DMF-s2 (OR = 1.61, CI = 1.07-2.43) and number of white spot lesions (OR = 1.76, CI = 1.04 to 2.98) as independent 'risk' factors for white spot lesion activities. On the other hand, supervised tooth-brushing with APF (OR = 0.55, CI = 0.34-0.91) or without APF (OR = 0.58, CI = 0.35-0.94) was a protective factor. CONCLUSIONS These results suggest that the weekly supervised tooth-brushing was able to arrest enamel white spots and that poor oral hygiene increases the probability of keeping white spots active.