Background
Methods
Focused question
Population: patients with dental malocclusion.Intervention: orthodontic treatment with clear aligners.Comparison: orthodontic treatment with fixed appliances.Outcomes: the primary outcome was treatment effectiveness: the outcome assessment of the treatment, included arch width, occlusal contacts, alignment, derotation and inclination of teeth; the secondary outcome was treatment duration.Study design: clinical comparative trials.
Search strategies
#1 (orthodont* OR clear OR removable) AND aligner*#2 Invisalign#3 #1 or #2#4 conventional orthodontic treatment OR traditional orthodontic treatment OR brace* OR bracket* OR fixed appliance*#5 #3 AND #4
Eligibility criteria
Study selection and data extraction
Quality assessment
Data analysis
Results
Literature search
Study characteristics
Author (Year) | Country | Study design | Clinicians | Inclusion criteria | Patients number (male/female) | Mean age | Intervention | Comparison | ||
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Aligner | Brace | Aligner | Brace | |||||||
Djeu (2005) [10] | America | Retrospective cohort study | Certified orthodontists | Nonextraction patients. Two groups had similar discrepancy index scores before treatment. | 48 (UK) | 48 (UK) | 33.6 ± 11.8 | 23.7 ± 11.0 | Invisalign® | Tip-edge braces |
Kuncio (2007) [13] | America | Retrospective cohort study | Certified orthodontists | Nonextraction patients. Two groups had similar distributions of gender, ethnicity, age, retainer wear, treatment, and posttreatment length. | 11 (1/10) | 11 (1/10) | 33.97± 8.98 | 26.79 ± 12.12 | Invisalign® | Tip-edge braces |
Pavoni (2011) [15] | Italy | Prospective cohort study | Orthodontists | Nonextraction patients. Class I malocclusion; mild crowding; vertebral maturation. | 20 (8/12) | 20 (11/9) | 18.33 | 15.50 | Invisalign® | Self-ligation braces |
Li (2015) [17] | China | Randomized controlled trial | Orthodontists | Extraction patients. Class I malocclusion; severity in complexity with discrepancy index score of 25. | 76 (27/45) | 76 (27/45) | 35.2±7.3 | 32.2 ± 8.3 | Invisalign® | 3 M Unitek braces |
Grunheid [14] | America | Retrospective cohort study | Orthodontic specialists | Nonextraction patients. Class I malocclusion; no periodontal attachment loss. | 30 (8/22) | 30 (8/22) | 25.0± 11.8 | 26.3 ± 13.5 | Invisalign® | Preadjusted edgewise braces |
Hennessy (2016) [16] | Ireland | Randomized controlled trial | Postgraduate students | Nonextraction patients. Mild crowding; skeletal class I malocclusion. | 20 (6/14) | 20 (7/13) | 29.1± 7.5 | 23.7 ± 7.0 | Invisalign® | Preadjusted edgewise braces |
Gu (2017) [12] | America | Retrospective cohort study | Orthodontic faculty and residents | Nonextraction patients. | 48 (16/32) | 48 (18/30) | 26.0± 9.7 | 22.1 ± 7.9 | Invisalign® | Straight-wire edgewise braces |
Lanteri (2018) [11] | Italy | Retrospective cohort study | UK | Nonextraction patients. Two groups had similar dental crowding and PAR index scores before treatment. | 100 (30/70) | 100 (30/70) | 28± 10 | 25± 10 | Invisalign® | Straight-wire edgewise braces (MBT prescription) |
Treatment effectiveness
Treatment efficiency
Reference | Outcomes | Treatment duration (month) | Conclusion | ||||||
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Measurements | Aligner | Brace | P value | Aligner | Brace | P value | |||
Djeu 2005 | OGS score immediately after appliance removal | 45.35± 15.56 | 32.21± 11.73 | 0.000 | 16.8 | 20.4 | 0.0138 | Invisalign® did not treat malocclusions as well as braces in occlusal contacts and correcting large anteroposterior discrepancies. Invisalign® was able to close space, correct anterior rotations and marginal ridge heights. | |
Number of cases receiving passing score (≤30 points lost on OGS) | 10 (20.8%) | 23 (47.9%) | 0.005 | ||||||
Kuncio 2007 | OGS score change between posttreatment and postretention | −0.73± 5.58 | 2.55 ± 7.30 | 0.1208 | 20.9 ± 10 | 28.1 ± 9.2 | 0.0941 | Patients treated with Invisalign® relapsed more than those treated with braces in alignment. | |
Pavoni 2011 | Maxillary intercanine width (cusp) change between pretreatment and posttreatment | 0.50 ± 1.10 mm | 3.15 ± 2.30 mm | 0.000 | 21.6 | 21.6 | >0.05 | Low friction self-ligating system produced significantly more transverse dento-alveolar width and perimeter of maxillary arch compared to Invisalign®. | |
Maxillary first interpremolar width (fossa) change | 0.05 ± 0.51 mm | 3.40 ± 1.96 mm | 0.000 | ||||||
Maxillary second interpremolar width (fossa) change | 0.45 ± 0.51 mm | 2.50 ± 2.16 mm | 0.000 | ||||||
Maxillary intemolar width (fossa) change | 0.50 ± 0.51 mm | 0.90 ± 2.45 mm | 0.479 | ||||||
Maxillary arch depth change | 0.00 ± 1.17 mm | 1.90 ± 11.40 mm | 0.463 | ||||||
Maxillary arch perimeter change | −0.05± 1.61 mm | 1.30 ± 2.23 mm | 0.034 | ||||||
Li 2015 | OGS score immediately after appliance removal | 24.49± 7.45 | 20.11 ± 6.24 | / | 31.5 | 22 | < 0.05 | Invisalign® scores were consistently lower than braces scores for buccolingual inclination and occlusal contacts. However, the similar overall improvement in OGS scores indicated that both Invisalign® and braces were successful in treating Class I adult extraction cases. | |
Number of cases receiving passing score (≤30 points lost on OGS) | 48 (66.67%) | 60 (75%) | 0.52 | ||||||
Grunheid 2016 | Buccolingual inclination of lower canines | Pretreatment | 6.6 ± 3.2° | 6.6 ± 3.4° | > 0.05 | 13.4± 6.8 | 20.2± 5.3 | < 0.05 | Orthodontic treatment with Invisalign® tended to increase the mandibular intercanine width with little change in inclination in contrast to treatment with braces, which left the intercanine width unchanged but leaded to more upright canines. |
Posttreatment | 7.3 ± 2.8° | 4.7 ± 4.8° | < 0.05 | ||||||
Mandibular intercanine width (cusp) | Pretreatment | 24.8 ± 1.9 mm | 25.3 ± 2.3 mm | > 0.05 | |||||
Posttreatment | 25.4 ± 1.3 mm | 25.2 ± 1.5 mm | > 0.05 | ||||||
Hennessy 2016 | Increase of mandibular incisor proclination during alignment | 3.4 ± 3.2° | 5.3 ± 4.3° | 0.14 | 10.2 | 11.3 | > 0.05 | Braces could produce more mandibular incisor proclination during alignment than Invisalign® did in mild crowding cases, but no statistically significant difference was found between two groups. | |
Gu 2017 | Weighted PAR score reduction | 16.73± 6.78 | 20.1 ± 8.06 | 0.457 | 13.35 ± 8.63 | 19.08 ± 5.92 | 0.004 | Both Invisalign® and braces were able to improve the malocclusion. However, Invisalign® may not be as effective as braces in achieving great improvement. | |
Number of cases receiving great improvement (a reduction of 22 PAR score) | 11 (22.9%) | 22 (45.8%) | 0.015 | ||||||
Lanteri 2018 | The percentage of improvement of the weighted PAR score | 80.9% | 91.0% | > 0.05 | 14 | 19 | < 0.05 | Invisalign® can achieve great outcomes with appropriate patients, especially in patients with anterior crowding. | |
Percentage of cases receiving great improvement | 42% | 46% | > 0.05 |
Quality assessment
Reference | Selection | Comparability | Outcome | Total score | |||||
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Representativeness of the exposed cohort | Selection of the non-exposed cohort | Ascertainment of exposure | Demonstration that outcome of interest was not present at start of study | Comparability of cohorts on the basis of the design or analysis | Assessment of outcome | Was follow-up long enough for outcomes to occur | Adequacy of follow up of cohorts | ||
Djeu2005 |
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Kuncio2007 |
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Pavoni2011 |
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Grunheid2016 |
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Gu2017 |
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Lanteri2018 |
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Reference | Random sequence generation | Allocation concealment | Blinding of participants and personnel | Blinding of outcomes assessment | Incomplete outcome data | Selective reporting | Other bias |
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Li2015 | Low risk | Low risk | High risk | Low risk | Low risk | Low risk | Low risk |
Hennessy2016 | Low risk | Low risk | High risk | Unclear risk | Low risk | Low risk | Low risk |