Part-time versus full-time retainer wear following fixed appliance therapy: a randomized prospective controlled trial.

Aim: To compare part-time and full-time Essix-type retainer wear regimens following fixed appliance treatment, with respect to dental alignment and occlusal changes.

Methods: In this prospective study, 60 patients were randomly allocated to either full-time or part-time Essix retainer wear following fixed appliance therapy. Study casts were taken before treatment, at debonding, and 6 months following debonding. Little's irregularity index, the intercanine width, intermolar width, overjet, and overbite were measured blindly on both the maxillary and mandibular casts.

Results: Both groups showed pretreatment equivalence for start age, duration of fixed appliance treatment, Little's index, intercanine width, intermolar width, overjet, and overbite. The number of patients completing the trial was 29 (1 dropout) in the part-time group and 28 in the full-time group (2 dropouts). There was a significant reduction in both the maxillary and mandibular Little's index and mandibular intermolar width in both groups during active treatment. There was a significant reduction in overjet and overbite in only the part-time retention group during fixed appliance treatment. Between debonding and 6 months after debonding, there was no significant change in any of the intra- or intergroup study cast measurements.

Conclusions: Night-time-only Essix retainer wear may be an acceptable retention regimen following the use of fixed appliances.