The aim of this study is to evaluate intra- and interarch changes over the year following active treatment appliance removal, and to analyze the impact of anterior fixed retention on these changes.

This study is based on casts taken at appliance removal (T1) and one year after removal (T2) in two groups of 15 privately-treated adolescent patients. One group received anterior fixed retention (G2), and the other did not (G1). We applied the seven criteria of the American Board of Orthodontics Objective Grading System: alignment (anterior/posterior), vertical positioning of the posterior marginal ridges, interproximal contacts, buccolingual inclination of the posterior teeth, posterior occlusal contacts, sagittal occlusal relationships, and overjet (anterior/posterior).

G1 and G2 together showed significant improvement in occlusal contacts, interproximal contacts, marginal ridges, and maxillary posterior alignment, but also a deterioration in anterior alignment, anterior overjet, and sagittal occlusal relationships. However, significant differences were found between the two groups, notably in terms of anterior alignment, which deteriorated more in G1.

The relapse observed in anterior overjet and sagittal relationships seems independent of the retention modality, whereas the deterioration in anterior alignment was specific to the group without fixed retention. At the same time, there were spontaneous adjustments in posterior occlusion, favorable to treatment stability.