One-year comparative assessment of retention of arch width increases between modified vacuum-formed and Hawley retainers: A multicenter randomized clinical trial

Abstract

Objectives: To compare the clinical effectiveness of Hawley retainers (HRs) and modified vacuumformed retainers (mVFRs) with palatal coverage in maintaining transverse expansion during a 12- month retention period. Materials and Methods: Data were collected from postorthodontic treatment patients who met the inclusion criteria. A total of 35 patients were randomly allocated using a centralized randomization technique into either mVFR (n=18) or HR group (n=17). The outcome assessor and data analyst were blinded to the retention method. Dental casts of patients were evaluated at debond, 3 months, 6 months, and 12 months of retention. Intercanine width (ICW), interpremolar width (IPMW), interfirst molar mesiobuccal cusp width 1 (IFMW1), and interfirst molar distobuccal cusp width 2 (IFMW2) were compared between groups over time using mixed analysis of variance. Results: No statistically significant differences were found between the two groups for ICW (P = .76), IPMW (P=.63), IFMW1 (P=.16), and IFMW2 (P=.40) during the 12-month retention period. Conclusions: The null hypothesis could not be rejected. HR and mVFR had similar clinical effectiveness in the retention of transverse expansion cases during a 12-month retention period.