Sample characteristics
Initially, 90 patients (54 females and 36 males) with a mean age of 13.9 years agreed to participate in the trial. After 2 years of retention, all the patients were asked to remove the retainers in the maxilla. Eleven patients refused removal: seven in group A (bonded retainer 13–23) and four in group B (bonded retainer 12–22). Further, one patient in group A, two in group B, and one in group C (VFR) moved during the 1-year follow-up. According to the Intention-to-treat (ITT) principle, all patients who kept the retainers or moved location remained within their allocated groups. Baseline demographic data. Consort flow chart.