The decision to restore a smooth surface carious lesion should be based on whether the lesion has cavitated. All non-cavitated lesions should receive preventive therapy aimed at arresting and remineralizing the lesion. Dental caries is a disease based on an imbalance in the equilibrium of ion exchange between the tooth and dental plaque, resulting in a net mineral loss. This equilibrium often can be reversed prior to cavitation, eliminating the need for treating the tooth surgically. Dentists in the U.S. often are apt to restore all lesions that have radiographically penetrated the dentinoenamel junction; however, most of these lesions have not cavitated and can be treated with preventive therapy. Restorations have a limited lifespan and the preparation is enlarged every time a restoration is replaced; as a result, a surgical approach can lead to unnecessary removal of tooth structure and eventually lead to more extensive treatment such as root canal therapy. This article reviews the rationale for deciding when to restore or remineralize non-cavitated lesions on the smooth tooth surfaces in the permanent dentition (and when to provide no treatment at all), what preventive treatment should be administered, and how to determine if the disease has been arrested.