Comparison of treatment stability among maxillary round multi-strand wire, chairside rectangular chain and vacuum formed retainers: a randomized clinical trial

Objectives To compare the effect of three different maxillary retainers: round multi-strand stainless steel (SS), rectangular white gold-plated SS, and vacuum-formed (VF) retainers on treatment stability, retainer integrity, and gingival health over 12 months. Materials and Methods Seventy subjects who finished fixed orthodontic treatment and required orthodontic retainers in the upper arch were randomly divided into three groups. The first group (mean age: 21.0 years) received bonded three multi-strand round (0.0175-inch) SS retainer, the second group (mean age: 20.4 years) received bonded rectangular (0.038 × 0.016-inch) white gold-plated SS retainer, the third group (mean age: 20.0 years) received removable VF retainer. Bonded retainers were extended from lateral to lateral incisor while VF retainer was extended to the most distal molar. After 1 year, all subjects were recalled. The primary outcome was to assess relapse in upper labial segment alignment. The secondary outcome was to evaluate the plaque index (PI) and gingival index (GI) of the upper labial segment teeth and retainer failure rate. Results There was no statistical difference in the average irregularity index (IRI), PI, and GI among the three groups ( P = .667, P = .781, P = .487, respectively). Retainer failure rate was significantly higher in Group III (60.9%) compared to Group I (20.8%) and Group II (34.8%, P = .017). Conclusions After 1 year, anterior tooth alignment stability and gingival health parameters were not different between bonded and VF retainers. However, the VF retainer exhibited a higher failure rate compared to bonded retainers.