Long-term assessment of orthodontic relapse.

The long-term stability of orthodontic treatment was evaluated in a group of ninety-six former patients who were treated between 12 and 35 years previously. Dental relationships were recorded on study models taken prior to orthodontic treatment, at the end of active treatment, and at long-term follow-up. A malocclusion score was developed for this study, and the over-all static occlusal relationships were categorized by defining an ideal range for eleven variables. Ninety of the ninety-six cases were within the ideal range at the end of treatment. Most of the cases showed an improvement of their malocclusions in the long-term stage. However, of the ninety-six subjects, sixty-nine (72 percent) had at least one variable outside our ideal range in the long-term follow-up. A moderately increased overjet and overbite was responsible in most instances for the result being outside the ideal range in the long term. The long-term result as compared to the original malocclusion exhibited increased overbite in 16 percent of the cases, increased mandibular anterior crowding in 9 percent of the cases, and increased overjet in 5 percent of the cases. The range of ideal, considering only the variables used in this study, will to some extent vary with the eye of the beholder. Therefore, the results of this study need to be interpreted accordingly. It is suggested that orthodontists be well aware of long-term changes in dental relationships many years after treatment and take this into account when advising patients as to the potential benefits of orthodontic treatment.