Mandibular incisor alignment in untreated subjects compared with long-term changes after orthodontic treatment with or without retainers.

INTRODUCTION: The aim of this work was to analyze the dental and skeletal changes in patients treated with fixed orthodontic appliances with or without retention appliances, and to compare the changes with untreated subjects. Specifically, mandibular incisor irregularity was analyzed.

METHODS: A total of 105 children who had undergone orthodontic treatment with fixed appliances in both jaws were examined in 2 groups: 64 had a lingual mandibular retainer and 41 had no retainer. Retention time was 2.7 ± 1.5 years. The untreated group consisted of 25 subjects. Measurements were done on study casts and lateral head radiographs before and after treatment and 6 and 12 years after treatment. The Little irregularity index (LII) was the most important variable.

RESULTS: No differences were found in LII 12 years after treatment between the group that had a retainer and the group without a retainer after treatment. In the untreated group, LII was increased over time, but not to the same extent as in the treated groups. Correction of overjet and overbite was stable long-term. At the last examination, the amount of overjet was almost the same in all 3 groups.

CONCLUSIONS: The routine use of mandibular retainers for 2 to 3 years does not appear to prevent long-term relapse. If the patient wants to constrain natural development and changes, lifelong retainers are needed.