Introduction
The aim of this study was to compare the efficiency of self-ligating (SL) and conventionally ligated (CL) brackets during the first 20 weeks of extraction treatment.
Methods
Study models of 50 consecutive patients who had premolar extractions in the maxillary or mandibular arch, 0.022 × 0.028-in slot brackets, and similar archwire sequences were examined. Forty-four arches received SL Damon 3MX brackets (Ormco, Glendora, Calif), and 40 arches received either CL Victory Series (3M Unitek, Monrovia, Calif) or Mini-Diamond (Ormco) brackets. The models were evaluated for anterior arch alignment, extraction spaces, and arch dimensions at pretreatment (T0), 10 weeks (T1), and 20 weeks (T2).
Results
There were no significant differences between the SL and CL groups at 20 weeks in irregularity scores (mandibular arch, P = 0.54; maxillary arch, P = 0.81). There were no significant differences in passive extraction space closures between the SL and CL groups (mandibular arch, T0-T2, P = 0.85; maxillary arch, T0-T2, P = 0.33). Mandibular intercanine widths increased from T0 to T2: 1.96 and 2.86 mm in the SL and CL groups, respectively. This was not significant between the groups ( P = 0.31). Logistic regression did not show a difference between the SL and CL bracket groups.
Conclusions
SL brackets were no more efficient than CL brackets in anterior alignment or passive extraction space closure during the first 20 weeks of treatment. Ligation technique is only one of many factors that can influence the efficiency of treatment. Similar changes in arch dimensions occurred, irrespective of bracket type, that might be attributed to the archform of the archwires.
Editor’s comment
Lately, the efficiency of SL brackets as assessed in clinical trials has received wide attention from investigators; as a result, there is a growing body of evidence that contributes crucial information on this topic. This Australian team studied the efficiency of CL and SL brackets in extraction patients during the first 20 weeks of treatment. They collected study models of consecutive patients who had premolar extractions in either arch, 0.022-in slot brackets, and similar archwire sequences. Forty-four arches received SL Damon 3MX brackets and 44 received either Victory Series or Mini-Diamond CL brackets. The models were evaluated for anterior arch alignment, extraction spaces, and arch dimensions at pretreatment (T0), 10 weeks (T1), and 20 weeks (T2). There were no significant differences between the SL and CL bracket groups at 20 weeks in irregularity scores (mandibular arch, P = 0.54; maxillary arch, P = 0.81), and no significant differences in passive extraction space closure (mandibular arch, T0-T2, P = 0.85; maxillary arch, T0-T2, P = 0.33). Mandibular intercanine widths increased from T0 to T2: 1.96 and 2.86 mm in the SL and CL groups, respectively. This was not significant between the groups ( P = 0.31), and logistic regression showed no difference. This study confirms the wide array of clinical trials indicating that the laboratory-studied variables of SL brackets are not transferred to the clinical situation, since these brackets were no more efficient than CL brackets in anterior alignment or passive extraction space closure during the first 20 weeks of treatment. Moreover, these authors found similar changes in arch dimensions, regardless of bracket type—a main outcome in many other studies.
Theodore Eliades
| Mandibular arch | Maxillary arch | |||
|---|---|---|---|---|
| SL | CL | SL | CL | |
| T0 | 19 | 18 | 25 | 22 |
| T1 | 19 | 18 | 25 | 22 |
| T2 | 19 | 14 | 25 | 16 |
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