[Long-term stability of orthodontic treatment].

Aim of this study was to assess long-term stability of orthodontic treatment in a sample of 1016 patients until 10 years postretention. Treatment outcome was measured with the PAR-index at 6 different stages. The mean age of the patients was 12.0 +/- 3.1 year at the start of treatment to 26.3 +/- 2.9 year 10 years postretention. The results show that 67% of the orthodontic treatment result, as measured with the PAR-index, was maintained 10 years postretention. The PAR-scores for the midline and the open bite remained about the same over the years. However, the scores for the lateral occlusion, overjet, reversed overjet, overbite, and contact point displacement of the upper and lower front teeth increased gradually over time. Nearly 50% of the total relapse took place the first two years after retention. The largest change was found for the position of the lower incisors. Ten years postretention their position was even worse than at the start of treatment.