Comparison of Alignment Efficiency, Arch Dimensional Changes, and Passive Extraction Space Closure Between Self-Ligating and Conventional Brackets

This prospective, randomized controlled trial was conducted to evaluate the clinical effects of self-ligating brackets (SLBs) versus conventional brackets (CBs) in patients requiring premolar extractions. The study included 70 participants aged 13-30 years with moderate to severe crowding and skeletal Class I or mild-to-moderate Class II malocclusions.

Participants were randomly assigned to either the SLB or CB group (35 participants each) using computer-generated random numbers and allocation concealment through sequentially numbered, opaque, sealed envelopes. Blinding of the operator and participants was not possible due to the nature of the interventions; however, outcome assessors were blinded by covering brackets on dental casts with beading wax.

The study assessed alignment efficiency, arch dimensional changes, and passive extraction space closure over a 9-month period. Dental impressions and study casts were collected at baseline, 3, 6, and 9 months. Alignment was quantified using Little's Irregularity Index, while intercanine and intermolar widths and passive extraction space closure were measured using digital calipers. No active space-closing auxiliaries, such as power chains or springs, were used during the observation period.

All treatments were performed by trained orthodontic residents with calibration to ensure consistency in bonding procedures, archwire sequence, and ligation methods. Linear mixed-effects models with repeated measures and covariates (age, gender, and malocclusion type) were used for statistical analysis, and regression coefficients with 95% confidence intervals were reported.

The trial aims to determine whether SLBs differ from conventional brackets in terms of alignment speed, arch dimensional changes, and passive space closure in extraction cases. Findings from this study can inform evidence-based bracket selection and clinical decision-making in orthodontic practice.

Inclusion criteria

Age 13-30 years, any gender Moderate (4-8 mm) or severe (>8 mm) dental crowding Skeletal Class I (ANB 0-20) or mild-to-moderate Class II (ANB 3-50) Normal or vertical growth pattern (FMA 22-280) Good oral hygiene (plaque index ≤1) Require extraction-based orthodontic treatment

Exclusion criteria

Previous orthodontic treatment Asymmetric extractions Systemic diseases or medications affecting bone metabolism Cleft lip/palate or other craniofacial anomalies Congenital absence of teeth (except third molars) Low-angle (hypodivergent) growth pattern Inability to comply with treatment/follow-up