Does low-frequency vibration have an effect on aligner treatment? A single-centre, randomized controlled trial.

Background: Low-frequency vibrations have been proposed as a means of accelerating tooth movement and reducing orthodontic treatment times.

Objective: To determine any differences in the accuracy of dental movement in patients treated with a low-frequency vibration aligner protocol and/or by reducing the aligner replacement interval with respect to a conventional protocol.

Design: This trial was designed as a single-centre, randomized controlled clinical trial.

Methods: Participants: Patients (aged 27.1 ± 9.0 years) who required orthodontic treatment with aligners. Randomization: Patients were randomly allocated to three arms as determined by a computer-randomization scheme. Group A were assigned a conventional protocol (aligners replaced every 14 days); group B also used a low-frequency vibration device for 20 minutes per day; group C followed the same vibration protocol but replaced their aligners every 7 days. Blinding: The operator who performed the set-up and the one who analysed the data were blinded to the group of the patients. Outcome: Pre- and post-treatment digital models were analysed using VAM software to identify the accuracy/imprecision of dental movements. One-way analysis of variance (P < 0.05) and the Bonferroni post hoc test were used to identify any statistically significant differences between the three arms in terms of the accuracy of tooth movement versus the prescription.

Results: Numbers analysed: A total of 45 patients (15 for group) were analysed (i.e. 2286 dental movements). Outcome: No statistically significant differences emerged between groups A and C in the upper arch, or among groups A, B, and C in the lower. Group B displayed significantly greater accuracy with respect to group A in upper incisor rotation (P = 0.016), and to group C in vestibulolingual (P = 0.007) and mesiodistal tipping (P = 0.029) of the upper canines, and vestibulolingual tipping of the upper molars (P = 0.0001). Harms: No adverse events or side-effects were registered.

Conclusions: Considering all tooth and movement types of the 45 participants, the mean total imprecision was 2.1 ± 0.9 degrees, with respect to a mean prescription of 5.7 ± 2.2 degrees. There was no difference in accuracy between replacing the aligners accompanied by low-frequency vibration every 7 days and replacing them every 14 days without vibration. Moreover, low-frequency vibration seemed to improve the accuracy of a conventional protocol in terms of upper incisor rotation.

Trial Registration: The German Clinical Trials Register (DRK00015613).