Self-ligating brackets do not increase treatment efficiency

The Oxford English Dictionary defines efficiency as “achieving maximum productivity with minimum wasted effort or expense.” Orthodontic pioneers have continuously sought methods of enhancing treatment efficiency by attempting to reduce the duration of orthodontic treatment and the length of orthodontic appointments. Although mean treatment times of 1 to 2 years are now typical, the drive to reduce orthodontic treatment duration persists. Many techniques and appliances, including surgical techniques, vibratory stimulation, increased customization of wires and brackets, eschewal of integral treatment phases, and routine avoidance of extractions, continue to be proposed with the expressed aim of furthering this progression. The most high profile of these developments has been self-ligating brackets. Unfortunately, the marketing of self-ligating brackets has courted controversy, with some advocates overly optimistic about the potential effects and, consequently, overlooking or ignoring the findings from clinical research studies. In this article, we will review the evidence for many of the claims made by those who promote self-ligating brackets, even in the face of recently published clinical research.

Chair-side efficiency and ease of use

Evidence indicating that self-ligating systems result in a consistent but modest reduction in chair-side time compared with conventional appliances is plentiful ( Table I ). In a meta-analysis, results from 2 comparable studies reported mean time savings of 20 seconds per arch with slide opening compared with ligature removal. No significant time difference was noted, however, for slide closure and replacement of ligatures. Proponents have suggested that the saved time could be used to schedule more patients, increase efficiency, improve patient relations, or allow oral hygiene reinforcement. However, it could also be suggested that a saving of 40 seconds per patient is insignificant and would not make many operators change their practice.

Table I
Comparative studies of chair-side time differences with self-ligating and conventional brackets
Study Self-ligating Conventional ligation Time savings
Maijer and Smith (1990) SPEED Elastomerics 7 min
Shivapuja and Berger (1994) Activa, Edgelok (Ormco), SPEED Elastomerics
Steel ligatures
1 min
12 min
Voudouris (1997) Interactwin (Ormco) Elastomerics 2.5 min
Harradine (2001) Damon SL Elastomerics 25 s
Berger and Byloff (2001) SPEED Elastomerics 2-3 min
Turnbull and Birnie (2007) Damon 2 Elastomerics 1.5 min

SPEED System Orthodontics; Strite Industries, Cambridge, Ontario, Canada

“A” Company Orthodontics, San Diego, Calif.

Efficiency of treatment

Early research examining the relationship between self-ligating brackets and overall treatment time was observational. These studies were invariably compromised by the compelling possibilities of selection bias, observer bias, and confounding, including susceptibility to uncontrolled factors such as varying operator experience and preference, differing archwires and sequences, and inconsistent appointment intervals. These studies were most notable for large reported discrepancies in treatment durations, with mean treatment times for conventional brackets ranging from 23.5 to 31 months. This inconsistency suggests that any advantage attributable to bracket type is likely to be dwarfed by extraneous factors, including the skills, standards, and ability of the operator. Nevertheless, the enduring message from these studies was that self-ligating brackets were responsible for significantly reducing treatment times and visits without impairing the occlusal outcomes. This assumption remained unchallenged until more robust prospective research began to emerge 4 years later. This prospective research was initially restricted to efficiency during a snapshot of treatment, including the efficiency of the initial orthodontic alignment and the rate of orthodontic space closure ; however, prospective studies encompassing treatment in its entirety have been published more recently.

Efficiency of treatment

Early research examining the relationship between self-ligating brackets and overall treatment time was observational. These studies were invariably compromised by the compelling possibilities of selection bias, observer bias, and confounding, including susceptibility to uncontrolled factors such as varying operator experience and preference, differing archwires and sequences, and inconsistent appointment intervals. These studies were most notable for large reported discrepancies in treatment durations, with mean treatment times for conventional brackets ranging from 23.5 to 31 months. This inconsistency suggests that any advantage attributable to bracket type is likely to be dwarfed by extraneous factors, including the skills, standards, and ability of the operator. Nevertheless, the enduring message from these studies was that self-ligating brackets were responsible for significantly reducing treatment times and visits without impairing the occlusal outcomes. This assumption remained unchallenged until more robust prospective research began to emerge 4 years later. This prospective research was initially restricted to efficiency during a snapshot of treatment, including the efficiency of the initial orthodontic alignment and the rate of orthodontic space closure ; however, prospective studies encompassing treatment in its entirety have been published more recently.

Efficiency of arch alignment

A number of prospective studies have investigated the efficiency of initial orthodontic alignment over periods up to 20 weeks. The results from these trials have consistently indicated that despite their associated costs, self-ligating brackets might offer no advantage with respect to treatment efficiency ( Table II ).

Table II
Comparative studies of the rate of initial orthodontic alignment with self-ligating and conventional brackets
Study Method Subjects Interventions Outcomes
Miles (2005) CCT, observed at 10 and 20 weeks 48 patients; mean age, 17.1 years; 26 male, 32 female Group 1: 24 patients with SmartClip
Group 2: 24 patients with Victory
Rate of initial alignment mandibular 3-3
Miles et al (2006) CCT, split-mouth design, observed at 10 and 20 weeks 58 consecutive patients; mean age, 16.3 years; 18 male, 40 female Lower appliance with Damon 2 or Victory brackets in alternate quadrants Rate of initial alignment mandibular 3-3
Pandis et al (2007) CCT, observed until alignment achieved 54 patients; mean age, 13.7 (SD 1.38) years; 11 male, 43 female Group 1: 27 patients with Damon 2
Group 2: 27 patients with MicroArch
Time taken (days) to align mandibular 3-3
Scott et al (2008) RCT, observed at 8 weeks and after mandibular alignment 62 patients recruited; mean age, 16.27 (SD 4.47) years; 32 male, 30 female Group 1: 33 patients with Damon 3
Group 2: 29 patients with Synthesis (Ormco)
Rate of initial alignment mandibular 3-3
Time taken (days) to align mandibular arch in 0.019 × 0.025-in SSW
Fleming et al (2009) RCT, observed at 8 weeks 65 patients; mean age, 16.28 (SD 2.68) years; 22 male, 43 female Group 1: 32 patients with SmartClip
Group 2: 33 patients with Victory
Rate of initial alignment mandibular 6-6
Miles and Weyant (2010) RCT, observed at 10.7 weeks 60 patients; 22 male, 38 female Group 1: 30 patients with In-Ovation C (Dentsply)
Group 2: 30 patients with Clarity (3M Unitek)
Rate of initial alignment maxillary 3-3
Ong et al (2010) CCT, observed at 10 and 20 weeks 50 patients; 20 male, 30 female Group 1: 40 arches with Damon 3
Group 2: 44 arches with conventional brackets (26 Victory, 18 Mini Diamond [Ormco])
Rate of initial alignment maxillary and mandibular 3-3
Pandis et al (2011) RCT, observed at 10 and 20 weeks 50 patients; 17 male, 33 female Group 1: 25 arches with Damon 3
Group 2: 25 arches with MicroArch
Rate of initial alignment mandibular 3-3
CCT , Controlled clinical trial; RCT , randomized controlled trial; 3-3 , canine to canine; SSW , stainless steel wire; 6-6 , first molar to first molar.
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Apr 8, 2017 | Posted by in Orthodontics | Comments Off on Self-ligating brackets do not increase treatment efficiency
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