Long-term postretention assessment of orthodontically treated cases has been of interest for 5 decades; however, extraction versus nonextraction follow-up studies are difficult to compare without regard to sample structure, therapy concept und different parameters. The results of selected studies- extraction of 1 or 2 incisors, of premolars and of second and third molars, early and late extraction therapy and serial extraction-showed that long-term postretention stability is not a realistic treatment goal. The Cologne long-term records allow optimistic prediction: relative stability has been found in the majority of former patients, irrespective of the kind of treatment and treatment time. Original anomaly, type (extraction/nonextraction) and amount of treatment, and end-of-treatment alignment were found to be major factors influencing dentoalveolar and skeletal post-treatment changes. The conclusion is that therapy-induced post-treatment changes can be reduced by having a treatment goal within the anatomic limits.
