In the United States, the demand for straight white teeth has never been more important to patients. Crowded, poorly aligned teeth are not esthetically pleasing and are difficult to keep clean. However, until recently, the process of straightening the teeth typically has involved appliances involving bands, brackets and wires that also can be difficult to clean. The desire for a cosmetic solution to misaligned teeth has led to an increase in the number of patients seeking veneers, crowns and other laboratory-fabricated cosmetic restorations. Some clinicians are not aware that there are other ways to align teeth without either significant enamel reduction or conspicuous fixed orthodontic appliances.An alternative method of treatment, involving a series of clear removable appliances, circumvents this shortcoming and enables tooth alignment while avoiding deterioration in the cosmetics of the smile during treatment. This article describes a method of treatment, Invisalign (Align Technology, Santa Clara, Calif.), that clinicians can use in conjunction with 3-D computer models to accomplish the esthetic and oral hygiene objectives during and after treatment.The authors present three case reports, all involving a chief concern of crowding. The first case involved treatment of both arches by interproximal reduction, alignment of teeth and leveling the curve of Spee. The second case involved treatment of both arches by proclination, expansion and minor interproximal reduction. The final case shows relief of lower-arch crowding via lower-incisor extraction.In addition to satisfying the patient's chief concern of desiring straight teeth, this method of treatment satisfies additional objectives of esthetic treatment and esthetic results with significant oral hygiene benefits. Clinicians can address a patient's chief concern effectively without requiring an inventory of appliances (such as bands, brackets, wires and instruments). Furthermore, the use of 3-D computer models can give clinicians additional information to make more complete decisions regarding treatment.