White spot lesions are defined as enamel surface and sub surface demineralisation, although these lesions can be reversed and do not form cavities. Infiltration using fluid resin proved to be a valid micro-invasive alternative compared with traditional conservative therapy. This has allowed treatment without any trauma (no use of local anaesthesia and cavity preparation) of numerous lesions in only one session with stable clinical (mechanical stability, enamel hardness, conservation of sound tissue) and aesthetic results (disappearance of lesions) over the time. The present report evaluates the effectiveness of Icon infiltration resin on postorthodontic white spots at 6 months, 1 and 4 years.