Aim: This study aimed to compare the efficiency of self-ligating (SL) and conventionally ligated (CL) brackets in extraction cases during initial alignment.

Methods: Study models were included from consecutive patients who had premolar extractions followed by fixed appliance treatment with 0.022" x 0.028" slot brackets and similar archwire sequences. Twenty-three patients received CL brackets (Victory Series brackets, 3M Unitek or Mini-Diamond brackets, Ormco) and seventeen patients received SL brackets (Damon 3MX brackets, Ormco). Anterior arch alignment, extraction spaces and arch dimensions were evaluated at pre-treatment, 10 weeks (T1) and 20 weeks (T2).

Results: Mean irregularity scores in the SL group decreased from 11.98 to 4.37 in the maxillary arch and 10.88 to 2.84 in the mandibular arch. Scores in the CL group decreased from 12.53 to 4.16 in the maxillary arch and 12.52 to 2.45 in the mandibular arch. At T2 there were no significant differences in irregularity between the two groups in the maxillary (p = 0.81) or mandibular (p = 0.54) arches. There were also no significant differences in the mean residual extraction spaces between the SL and CL groups in the maxillary (T0-T2: p = 0.33) or mandibular (T0-T2: p = 0.85) arches. Mandibular intercanine widths increased from T0 to T2 by 1.96 mm in the SL group and 2.86 mm in the CL group.

Conclusions: There were no differences between SL and CL brackets in alignment efficiency or passive extraction space closure during initial alignment. Changes in arch dimensions were comparable in both bracket groups.