Low translational and rotational movements with 2-point stainless-steel retainers over aperiod of 1and 3years.

Abstract

Long-term stabilization of orthodontic treatment outcomes is an everyday challenge in orthodontics. The use of permanently attached lingual retainers has become gold standard. However, in some cases, patients with fixed lingual retainers show retainer-associated side effects. Aiming to reduce these side effects, clinical knowledge about how tooth and arch form stability adaption takes place over time is important to improve long-term retention protocols. Therefore, the present study aimed to investigate occlusion stability and risks for anewly developing malocclusion in atime-dependent manner in patients being treated with permanent 2‑point steel retainers. In this retrospective cohort study, atotal of 66consecutive patients with round stainless-steel retainers were analyzed for postorthodontic occlusion changes after 1year (group1, n = 33) and 3years (group2, n = 33). Digital Standard Tessellation Language (STL) datasets of the lower jaw were obtained before retainer insertion (T0), and after a1-(T1) or 3‑year (T2) retention period. Using superimposition software, T1and T2 situations were compared to T0 regarding rotational and translational changes in tooth positions in all three dimensions. Occlusion changes were low in both groups. The investigated lower canines were nearly stable in the 1‑ and 3‑year group, although aretention-time-dependent increase in tooth position change of the central and lateral incisors could be observed. The present data provide evidence for time-dependent development of posttherapeutic occlusal adaption limited to central and lateral incisors in patients treated with a2-point retainer. The observed occlusal changes should be interpreted as an occlusal adaption process rather than severe posttreatment changes associated with the orthodontic retainer.