Comparative assessment of alignment efficiency and space closure of active and passive self-ligating vs conventional appliances in adolescents: A single-center randomized controlled trial

Goldie Songra, Matthew Clover, Nicola E Atack, Paul D Ewings, Martyn Sherriff, Jonathan R Sandy, Anthony J Ireland

Research output: Contribution to journalArticle (Academic Journal)peer-review

35 Citations (Scopus)


Introduction: The aim of this study was to compare the time to initial alignment and extraction space closure using conventional brackets and active and passive self-ligating brackets. Methods: One hundred adolescent patients 11 to 18 years of age undergoing maxillary and mandibular fixed appliance therapy after the extraction of 4 premolars were randomized with stratification of 2 age ranges (11-14 and 15-18 years) and 3 maxillomandibular plane angles (high, medium, and low) with an allocation ratio of 1:2:2. Restrictions were applied using a block size of 10. Allocation was to 1 of 3 treatment groups: conventional brackets, active self-ligating, or passive self-ligating brackets. All subjects were treated with the same archwire sequence and space-closing mechanics in a district general hospital setting. The trial was a 3-arm parallel design. Labial-segment alignment and space closure were measured on study models taken every 12 weeks throughout treatment. All measurements were made by 1 operator who was blinded to bracket type. The patients and other operators were not blinded to bracket type during treatment. Results: Ninety-eight patients were followed to completion of treatment (conventional, n = 20; active self-ligating brackets, n = 37; passive self-ligating brackets, n = 41). The data were analyzed using linear mixed models and demonstrated a significant effect of bracket type on the time to initial alignment (P = 0.001), which was shorter with the conventional brackets than either of the self-ligating brackets. Sidak's adjustment showed no significant difference in effect size (the difference in average response in millimeters) between the active and passive self-ligating brackets (the results are presented as effect size, 95% confidence intervals, probabilities, and intraclass correlation coefficients) (-0.42 [-1.32, 0.48], 0.600, 0.15), but the conventional bracket was significantly different from both of these (-1.98 [-3.19, -0.76], 0.001, 0.15; and -1.56 [-2.79, -0.32], 0.001, 0.15). There was no statistically significant difference between any of the 3 bracket types with respect to space closure. Space-closure times were shorter in the mandible, except for the Damon 3MX bracket (Ormco, Orange, Calif), where active and total space-closure times were shorter in the maxilla. No adverse events were recorded in the trial. Conclusions: Time to initial alignment was significantly shorter for the conventional bracket than for either the active or passive self-ligating brackets. There was no statistically significant difference in passive, active, or total space-closure times among the 3 brackets under investigation.

Original languageEnglish
Pages (from-to)569-578
Number of pages10
JournalAmerican Journal of Orthodontics and Dentofacial Orthopedics
Issue number5
Early online date6 May 2014
Publication statusPublished - May 2014


  • Adolescent
  • Bicuspid
  • Cephalometry
  • Child
  • Copper
  • Dental Alloys
  • Elastomers
  • Female
  • Follow-Up Studies
  • Humans
  • Male
  • Mandible
  • Maxilla
  • Nickel
  • Orthodontic Appliance Design
  • Orthodontic Brackets
  • Orthodontic Space Closure
  • Orthodontic Wires
  • Stainless Steel
  • Time Factors
  • Titanium
  • Tooth Extraction
  • Tooth Movement


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