Which orthodontic appliance is best for oral hygiene? A randomized clinical trial

Introduction Clear aligners and to a lesser extent self-ligated brackets are considered to facilitate better oral hygiene than traditional fixed orthodontic appliances. This 3-arm parallel-group prospective randomized clinical trial compared the long-term and short-term effects of clear aligners, self-ligated brackets, and conventional (elastomeric-ligated) brackets on patients' oral hygiene during active orthodontic treatment. Methods Seventy-one participants (41 boys, 30 girls; mean age, 15.6 years) undergoing orthodontic treatment were randomly allocated through a computer-generated randomization schedule to one of the groups based on the choice of intervention: Clear Aligners (CLA) (Align Technology, San Jose, Calif) (n = 27), preadjusted edgewise fixed appliance with self-ligated brackets (SLB) (Carriere, Carlsbad, Calif (n = 22), or preadjusted edgewise fixed appliance with elastomeric ligated brackets (ELB) (Ortho Organizers Inc., Carlsbad, CA) (n = 22). For each participant, the primary outcome, plaque index (PI), and secondary outcomes, gingival Index (GI) and periodontal bleeding index (PBI), were measured at baseline (T0), after 9 months of treatment (T1), and after 18 months of treatment (T2). Blinding of the clinicians and the patients to the intervention was impossible. It was only done for outcome assessment and for the statistician. Ten participants did not receive the allocated intervention for various reasons. Results The means and standard deviations of PI at T0 (CLA, 0.50 ± 0.51; SLB, 0.65 ± 0.49; ELB, 0.70 ± 0.73), T1 (CLA, 0.83 ± 0.48; SLB, 1.38 ± 0.72; ELB, 1.32 ± 0.67), and T2 (CLA, 0.92 ± 0.58; SLB, 1.07 ± 0.59; ELB, 1.32 ± 0.67) were similar. The odds ratio (OR) for plaque index (0 or ≥1) comparing SLB or CLA to ELB was not significant. OR for SLB vs ELB = 1.54 at T0 (95% CI, 0.39-6.27), 0.88 at T1 (95% CI, 0.03-24.69), and 0.83 at T2 (95% CI, 0.02-27.70); OR for CLA vs ELB = 1.07 at T0 (95% CI, 0.30-3.88), 0.24 at T1 (95% CI, 0.01-1.98), and 0.17 at T2 (95% CI, 0.01-1.71). However, the odds ratios comparing CLA with ELB for GI (OR = 0.14; P  = 0.015) and PBI (OR = 0.10; P  = 0.012) were statistically significant at T1. Conclusions In this prospective randomized clinical trial, we found no evidence of differences in oral hygiene levels among clear aligners, self-ligated brackets, and conventional elastomeric ligated brackets after 18 months of active orthodontic treatment. Registration The trial is registered at ClinicalTrials.gov ( NCT02745626 ). Protocol The protocol was not published before trial commencement.