Summary of findings 1. Fixed appliances and auxiliaries to prevent or correct dental crowding in children.
| Fixed appliances and auxiliaries versus other treatment or no treatment to prevent or correct dental crowding in children | ||||||
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Population: children or adolescents, or both (age ≤ 16 years) having treatment to prevent or correct dental crowding Settings: Australia, Brazil, Finland, India, Turkey, UK, USA Intervention: fixed appliances and auxiliaries (lip bumper, headgear, lower lingual arch, brackets, archwires, lacebacks, vibrational appliances) Comparison: control (brackets, archwires, fixed appliances only, minor interceptive procedures, no active treatment) | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) |
Relative effect
(95% CI) |
Number of participants (studies) | Certainty of the evidence (GRADE) | Comments | |
| Assumed risk | Corresponding risk | |||||
| Control | Fixed appliances and auxiliaries | |||||
| Lower lip bumper ‐ lower lip bumper versus no active treatment (control) | ||||||
| Change in the amount of crowding at 6 months | Mean change −0.7 mm | Mean change −5.09 mm ± 0.97 mm | 34 (1) | ⊕⊝⊝⊝ Very lowa,b |
There was less crowding in the lip bumper group (MD −4.39 mm, 95% CI −5.07 to −3.71). | |
| Headgear ‐ cervical pull headgear versus minor interceptive procedures (control) | ||||||
| Amount of crowding at 2 years | Mean change 2.45 mm | Mean change 2.78 mm ± 1.91 mm | 64 (1) | ⊕⊝⊝⊝ Very lowa,b |
There was no difference between groups in the amount of crowding at 2 years (MD 0.33 mm (95% CI −0.60 to 1.26). There was also no difference at 13 years follow‐up of the remaining 34 participants (MD 0.26, 95% CI −1.35 to 1.87). |
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| Lower lingual arch ‐ lower lingual arch versus no active treatment (control) | ||||||
| Amount of crowding | Not measured | |||||
| Brackets ‐ self‐ligating brackets versus conventional brackets | ||||||
| Amount of crowding at 10 weeks | Mean amount of crowding 2.7 mm | Mean amount of crowding was 0.40 mm less (0.93 mm less to 0.13 mm more) | 60 (1) | ⊕⊝⊝⊝ Very lowa,b |
There was no difference between groups in the amount of crowding. | |
| Archwires ‐ coaxial nickel‐titanium archwire versus nickel‐titanium archwire | ||||||
| Amount of tooth movement at 12 weeks | Mean amount of tooth movement 3.1 mm | Mean amount of tooth movement was 6.77 mm more (5.55 mm to 7.99 mm more) | 24 (1) | ⊕⊝⊝⊝ Very lowa,b |
There was more tooth movement with the coaxial nickel‐titanium archwire than the nickel‐titanium archwire. | |
| Archwires ‐ copper nickel‐titanium archwire versus nickel‐titanium archwire | ||||||
| Amount of crowding at 12 weeks | Mean amount of crowding 6.33 mm | Mean amount of crowding was 0.49 mm more (0.35 mm to 0.63 mm more) | 66 (1) | ⊕⊝⊝⊝ Very lowa,b |
There was less residual crowding with the nickel‐titanium archwire than the copper‐nickel titanium archwire. | |
| Archwires ‐ Titanol versus Nitinol | ||||||
| Change in the amount of crowding up to 37 weeks | Mean change 1.42 mm ± 0.79 mm | Mean change 1.7 mm ± 1.15 mm | 40 (1) | ⊕⊝⊝⊝ Very lowa,b |
There was no difference between groups in the change in the amount of crowding (MD −0.28 mm, 95% CI −0.89 to 0.33). | |
| Archwires ‐ nickel‐titanium archwire versus multistranded stainless steel archwire | ||||||
| Change in the amount of crowding at 8 weeks | Mean change −29.2 mm | Mean change −27.6 mm ± 26.5 mm | 25 (1) | ⊕⊝⊝⊝ Very lowa,b |
There was no difference between groups in the overall change in the amount of crowding (MD 1.60 mm, 95% CI −22.16 to 25.36). | |
| Archwires ‐ nickel‐titanium archwire versus stainless steel archwire | ||||||
| Change in the amount of crowding at 8 weeks | Mean change −10.8 mm | Mean change −27.6 mm ± 26.5 mm | 24 (1) | ⊕⊝⊝⊝ Very lowa,b |
There was no difference between groups in the overall change in the amount of crowding (MD 16.80 mm, 95% CI −42.79 to 9.19). | |
| Archwires ‐ multistranded stainless steel archwire versus stainless steel archwire | ||||||
| Change in the amount of crowding at 8 weeks | Mean change −10.8 mm | Mean change −29.2 mm ± 33.4 mm | 23 (1) | ⊕⊝⊝⊝ Very lowa,b |
There was no difference between groups in the overall change in the amount of crowding (MD −18.40 mm, 95% CI −47.12 to 10.32). | |
| Lacebacks ‐ lacebacks and fixed appliances versus fixed appliances only (control) | ||||||
| Change in the amount of crowding at 6 months | Mean change −2.67 mm | Mean change −3.00 mm ± 8.94 mm | 62 (1) | ⊕⊝⊝⊝ Very lowa,b |
There was no difference between groups in the change in the amount of crowding (MD −0.33 mm, 95% CI −5.90 to 5.24). | |
| Vibrational appliances ‐ vibrational appliances with fixed appliances versus fixed appliances only (control) | ||||||
| Change in the amount of crowding at 10 to 30 weeks | Mean change −0.7 mm | Mean change ranged from 4.0 mm to 5.5 mm | 119 (2) | ⊕⊝⊝⊝ Very lowc,d |
There was no difference between groups in the change in the amount of crowding (MD 0.24, 95% CI −0.81 to 1.30). | |
| *The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; MD: mean difference; mm: millimetre | ||||||
| GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate; the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited; the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate; the true effect is likely to be substantially different from the estimate of effect. | ||||||
aDowngraded one level as study at high risk of bias. bDowngraded twice as only one small study reported on this. cDowngraded twice as both studies at high risk of bias. dDowngraded one level as studies were potentially underpowered.