Stability and relapse of mandibular anterior alignment-first premolar extraction cases treated by traditional...

Assessment at least 10 years postretention of sixty-five cases previously treated in the permanent-dentition stage with first-premolar extractions, traditional edgewise mechanics, and retention revealed considerable variation among patients. The long-term response to mandibular anterior alignment was unpredictable; no variables, such as degree of initial crowding, age, sex, Angle classification, etc., were useful in establishing a prognosis. Typically, arch width and length decreased after retention, regardless of treatment expansion or constriction. Two thirds of the patients had unsatisfactory lower anterior alignment after retention. Cases that were minimally crowded before treatment usually became more crowded, while initially severe crowding cases usually moderated.