Effectiveness of part-time vs full-time wear protocols of Twin-block appliance on dental and skeletal changes: A randomized controlled trial.

Introduction: The aim of this 2-arm parallel study was to compare the dentoalveolar and skeletal changes achieved with Twin-block appliance therapy prescribed on either a part- or full-time basis for 12 months.

Methods: Sixty-two 10- to 14-year-old patients were randomly allocated to either full-time (FT, 22 hours daily) or part-time (PT, 12 hours daily) wear of a modified Twin-block appliance. Participants were recruited from the Institute of Dentistry, Barts and the London School of Medicine and Dentistry, London, United Kingdom, and recalled at 6- to 8-week intervals. Electronic randomization was undertaken, with group allocation concealed using opaque, sealed envelopes. The outcome assessor was blinded; however, it was not feasible to blind either operator or patients. Study models and cephalograms were taken at baseline and after 12 months of treatment.

Results: Data from 55 of the 62 participants were analyzed. Overjets were reduced by 7 mm (SD, 2.92) in the PT group and 6.5 mm (SD, 2.62) in the FT group, with no statistical difference between the groups (P = 0.587; 95% CI, -1.01, 1.78). Similarly, no clinical or statistical differences were noted for skeletal changes: ANB angle (PT, -1.51°; FT, -1.25°; P = 0.828; 95% CI, -0.68, 0.849), pogonion-sella vertical (PT, 3.25 mm; FT, 3.35 mm) or A-sella vertical (PT, 1.28 mm; FT, 1.06 mm). Mean wear durations were 8.78 hours a day in the PT group and 12.38 hours in the FT group.

Conclusions: There was no difference in either dental or skeletal changes achieved with PT or FT wear of a Twin-block appliance over 12 months. Less onerous PT wear regimens may therefore be a viable alternative to FT wear of removable functional appliances.

Registration: NCT02190630.

Protocol: The protocol was not published before trial commencement.