Posttreatment tooth movement: for better or for worse.

P osttreatment tooth movement is inevitable, but its degree depends on a variety of factors that are both iatrogenic and innate to each patient. Although various retention techniques have been developed to minimize posttreatment movement, it is unrealistic to believe that the entire dentition can be retained in all dimensions. Relapse is usually considered an adverse phenomenon, but some dimensions of posttreatment tooth movement might actually enhance occlusal function and esthetics. Favorable movement is often considered as ‘‘settling’’ if that aspect of the occlusion is improved over time. In 1998, the American Board of Orthodontics (ABO) published an objective method of evaluating posttreatment results by using 7 cast measurements and 1 radiographic measurement. Formerly called the Objective Grading System, the ABO now refers to this as the Cast Radiograph Evaluation (C-R Eval). This evaluation technique is used to score final casts and the panoramic radiograph produced within 12 months of debanding. The 8 scoring parameters are alignment/rotations, marginal ridges, buccolingual inclination, overjet, occlusal contacts, occlusal relationships, interproximal contacts, and root angulation. The C-R Eval was developed to increase objectivity in evaluation of treatment results; it uses a point system with precise criteria for cast and radiographic grading to score the case result in terms of finishing and detailing. Each case is scored after individual and group calibration of examiners in an effort to secure equity in grading among all examiners. Hence, 8 aspects of the