Objectives

To compare the clinical effectiveness of Hawley retainers (HRs) and modified vacuum-formed 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.

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Author notes

a

Clinical Lecturer in Orthodontics, Faculty of Dentistry, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia.

b

Master Student, Faculty of Dentistry, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia.

c

Associate Professor in Orthodontics, Faculty of Dentistry, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia.

d

Professor in Orthodontics, Faculty of Dentistry, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia.

e

Orthodontist and Head of Unit, Orthodontic Specialist Unit, Klinik Pergigian Sungai Chua, Ministry of Health, Selangor, Malaysia.

f

Orthodontist and Head of Unit, Orthodontic Specialist Unit, Klinik Pergigian Bandar Botanik, Ministry of Health, Selangor, Malaysia.

g

Dental Officer, Orthodontic Specialist Unit, Klinik Pergigian Bandar Botanik, Ministry of Health, Selangor, Malaysia.