Non-Cochrane · intervention · PM34874143
Impact of Aligners and Fixed Appliances on Oral Health during Orthodontic Treatment: A Systematic Review and Meta-Analysis.
Oikonomou Elissaios, Foros Petros, Tagkli Aikaterini, et al. · Oral health & preventive dentistry · 2021 · PubMed · doi:10.3290/j.ohpd.b2403661
Full textEvery question was extracted from the full text, figures and supplements by two independent LLM extractors, disagreements adjudicated. Rows cite where in the review the value comes from.
Questions
20
current version
GRADE rated
7
No studies
0
Included studies
21
linked below
No studies 0 · 0%Ungraded 13 · 65%Very low 3 · 15%Low 4 · 20%Moderate 0 · 0%High 0 · 0%
Ungraded means an effect was reported without a GRADE rating; it is not a gap. No studies means the review found nothing to answer the question. The six categories are a display order, not a score.
Review question
| Element | Planned (methods) | Found (results) |
|---|---|---|
| Population | Patients undergoing orthodontic treatment (clear aligners or fixed appliances) | 21 studies included (882 unique records screened); 15 studies in adults (1 with chronic periodontitis), 4 in teens/adolescents, 2 mixed ages; 4 studies pooled in meta-analyses |
| Intervention | Clear/orthodontic aligners | Clear aligners (Invisalign in 13/21 studies; thermoformed aligners in the remainder) |
| Comparison | Fixed appliances | Fixed appliances (labial in 20/21 studies; lingual in some; self-ligating/elastomeric brackets in one) |
| Outcomes | Oral hygiene / periodontal parameters (plaque, bleeding, probing/pocket depth, gingival indices), microbiological/cariogenic parameters (S. mutans, lactobacilli) and incipient caries / white spot lesions | Periodontal (plaque index, BOP, pocket depth, gingival index); microbiological (S. mutans, lactobacilli); caries (white spot lesions, fluorescence loss, lesion area) |
| Study designs | Randomised controlled trials and non-randomised studies (controlled trials and observational studies); risk of bias via Cochrane RoB 2.0 (RCTs) and ROBINS-I (non-randomised) | 6 RCTs, 11 prospective clinical trials, 3 retrospective cohorts, 1 cross-sectional study |
| Timing | Not restricted (any follow-up during or after orthodontic treatment) | Follow-up 1-18 months (two retrospective studies covered the whole treatment duration); meta-analyses limited to <=6 months (periodontal 6-12 weeks; microbiological 3-6 months) |
Search date: 31 May 2021 (updated; initial search 21 August 2020). Databases: MEDLINE via PubMed, Scopus, Cochrane Central (CENTRAL), Cochrane Database of Systematic Reviews; grey literature via ClinicalTrials.gov, OpenGrey and ISRCTN; hand-searching of retrieved full texts
Questions and results
Clear aligners (Invisalign / thermoformed aligners) vs Fixed appliances
Population: Adults undergoing orthodontic treatment
| Outcome | Effect | Evidence | Status / GRADE |
|---|---|---|---|
Lactobacilli presence (CFU > 10^5) 3 months · Adults Aligners probably lower the risk of high lactobacilli counts versus fixed appliances in adults at 3 months (RR 0.09, 95% CI 0.02 to 0.47; low certainty). Source: Table 5 (Adults, lactobacilli 3 months); Fig 3 (GRADE SoF); Results · same question in other reviews | RR 0.09 [0.02, 0.47] | 2 studies · 140 participants | Low Downgraded: risk of bias |
Gingival index (GI) 6 to 12 weeks · Adults A single study found no significant difference in gingival index between aligners and fixed appliances in adults at 6-12 weeks (MD -0.10, 95% CI -0.35 to 0.15; ungraded). Source: Table 4 (Adults, GI 6-12 weeks); Results · same question in other reviews | MD -0.10 [-0.35, 0.15] | 1 study | Ungraded |
Bleeding on probing (BOP) 6 to 12 weeks · Adults No clear difference in bleeding on probing between aligners and fixed appliances in adults at 6-12 weeks (MD -0.26, 95% CI -0.77 to 0.26; very low certainty). Source: Table 4 (Adults, BOP 6-12 weeks); Fig 3 (GRADE SoF); Results · same question in other reviews | MD -0.26 [-0.77, 0.26] | 2 studies · 62 participants | Very low Downgraded: risk of bias, inconsistency |
Lactobacilli presence (CFU > 10^5) 6 months · Adults Aligners probably lower the risk of high lactobacilli counts versus fixed appliances in adults at 6 months (RR 0.19, 95% CI 0.08 to 0.45; low certainty). Source: Table 5 (Adults, lactobacilli 6 months); Fig 3 (GRADE SoF); Results · same question in other reviews | RR 0.19 [0.08, 0.45] | 2 studies · 140 participants | Low Downgraded: risk of bias |
Pocket/probing depth (PD) 6 to 12 weeks · Adults Aligners may reduce pocket depth compared with fixed appliances in adults at 6-12 weeks (MD -0.42 mm, 95% CI -0.71 to -0.12; very low certainty). Source: Table 4 (Adults, PD 6-12 weeks); Fig 3 (GRADE SoF); Results · same question in other reviews | MD -0.42 [-0.71, -0.12] | 2 studies · 62 participants | Very low Downgraded: risk of bias |
Plaque index (PI) 6 to 12 weeks · Adults Aligners may reduce plaque index compared with fixed appliances in adults at 6-12 weeks (MD -0.58, 95% CI -0.82 to -0.34; very low certainty). Source: Table 4 (Adults, PI 6-12 weeks); Fig 2 (forest plot); Fig 3 (GRADE SoF); Results (Effects of Interventions) · same question in other reviews | MD -0.58 [-0.82, -0.34] | 4 studies · 202 participants | Very low Downgraded: risk of bias |
Average fluorescence loss (dF%) 3 months · Adults A single study reported lower average fluorescence (mineral) loss with aligners versus fixed appliances in adults at 3 months (MD -1.40, 95% CI -2.15 to -0.65; ungraded). Source: Table 6 (Adults, average fluorescence loss 3 months); Results · same question in other reviews | MD -1.40 [-2.15, -0.65] | 1 study | Ungraded |
White spot lesions (WSLs), tooth level 3 months · Adults A single study reported a lower risk of white spot lesions (tooth level) with aligners versus fixed appliances in adults at 3 months (RR 0.72, 95% CI 0.60 to 0.86; ungraded). Source: Table 6 (Adults, WSLs tooth level 3 months); Results · same question in other reviews | RR 0.72 [0.60, 0.86] | 1 study | Ungraded |
S. mutans presence (CFU > 10^5) 3 months · Adults Aligners probably lower the risk of high S. mutans counts versus fixed appliances in adults at 3 months (RR 0.07, 95% CI 0.01 to 0.49; low certainty). Source: Table 5 (Adults, S. mutans 3 months); Fig 3 (GRADE SoF); Results · same question in other reviews | RR 0.07 [0.01, 0.49] | 2 studies · 140 participants | Low Downgraded: risk of bias |
S. mutans presence (CFU > 10^5) 6 months · Adults Aligners probably lower the risk of high S. mutans counts versus fixed appliances in adults at 6 months (RR 0.22, 95% CI 0.10 to 0.51; low certainty). Source: Table 5 (Adults, S. mutans 6 months); Fig 3 (GRADE SoF); Results · same question in other reviews | RR 0.22 [0.10, 0.51] | 2 studies · 140 participants | Low Downgraded: risk of bias |
Lesion area (decalcification area, pixels) 3 months · Adults A single study reported a larger decalcification lesion area with aligners versus fixed appliances in adults at 3 months (MD 80.50 pixels, 95% CI 60.52 to 100.48; ungraded). Source: Table 6 (Adults, lesion area 3 months); Results · same question in other reviews | MD 80.50 [60.52, 100.48] | 1 study | Ungraded |
Clear aligners (Invisalign / thermoformed aligners) vs Fixed appliances
Population: Adolescents/teenagers undergoing orthodontic treatment
| Outcome | Effect | Evidence | Status / GRADE |
|---|---|---|---|
Plaque index (PI) 18 months · Adolescents A single study reported lower plaque index with aligners versus fixed appliances in adolescents at 18 months (MD -0.40, 95% CI -0.77 to -0.03; ungraded). Source: Table 4 (Adolescents, PI 18 months); Results · same question in other reviews | MD -0.40 [-0.77, -0.03] | 1 study | Ungraded |
Simplified gingival index (s-GI) 1 month · Adolescents A single study reported lower simplified gingival index with aligners versus fixed appliances in adolescents at 1 month (MD -8.46, 95% CI -10.47 to -6.45; ungraded). Source: Table 4 (Adolescents, s-GI 1 month); Results · same question in other reviews | MD -8.46 [-10.47, -6.45] | 1 study | Ungraded |
S. mutans presence 1 month · Adolescents A single study found no significant difference in S. mutans presence between aligners and fixed appliances in adolescents at 1 month (RR 0.86, 95% CI 0.64 to 1.14; ungraded). Source: Table 5 (Adolescents, S. mutans presence 1 month); Results · same question in other reviews | RR 0.86 [0.64, 1.14] | 1 study | Ungraded |
Gingival index (GI) 18 months · Adolescents A single study reported lower gingival index with aligners versus fixed appliances in adolescents at 18 months (MD -0.57, 95% CI -0.93 to -0.21; ungraded). Source: Table 4 (Adolescents, GI 18 months); Results · same question in other reviews | MD -0.57 [-0.93, -0.21] | 1 study | Ungraded |
White spot lesions (WSLs), patient level 9 months · Adolescents A single study found no significant difference in white spot lesion formation (patient level) between aligners and fixed appliances in adolescents at 9 months (RR 0.33, 95% CI 0.10 to 1.04; ungraded). Source: Table 6 (Adolescents, WSLs patient level 9 months); Results · same question in other reviews | RR 0.33 [0.10, 1.04] | 1 study | Ungraded |
Full-mouth plaque score (FMPS) 12 months · Adolescents A single study reported a lower full-mouth plaque score with aligners versus fixed appliances in adolescents at 12 months (MD -43.48, 95% CI -47.65 to -39.31; ungraded). Source: Table 4 (Adolescents, FMPS 12 months); Results · same question in other reviews | MD -43.48 [-47.65, -39.31] | 1 study | Ungraded |
Full-mouth bleeding score (FMBS) 12 months · Adolescents A single study reported a lower full-mouth bleeding score with aligners versus fixed appliances in adolescents at 12 months (MD -20.44, 95% CI -22.98 to -17.90; ungraded). Source: Table 4 (Adolescents, FMBS 12 months); Results · same question in other reviews | MD -20.44 [-22.98, -17.90] | 1 study | Ungraded |
Simplified plaque index (s-PI) 1 month · Adolescents A single study reported lower simplified plaque index with aligners versus fixed appliances in adolescents at 1 month (MD -14.78, 95% CI -16.74 to -12.82; ungraded). Source: Table 4 (Adolescents, s-PI 1 month); Results · same question in other reviews | MD -14.78 [-16.74, -12.82] | 1 study | Ungraded |
S. mutans counts (5th-root transformed) 1 month · Adolescents A single study found no significant difference in S. mutans counts between aligners and fixed appliances in adolescents at 1 month (MD -2.22, 95% CI -6.82 to 2.38; ungraded). Source: Table 5 (Adolescents, S. mutans counts 1 month); Results · same question in other reviews | MD -2.22 [-6.82, 2.38] | 1 study | Ungraded |
AMSTAR 2 appraisal
Two independent extractors rated each item. Their ratings are shown side by side because they have not been reconciled yet. The overall rating follows Shea et al. 2017: one critical flaw gives Low, more than one gives Critically Low.
| Item | Extractor A | Extractor B | Agree |
|---|---|---|---|
| 1Research question includes PICO components | Yes | Yes | yes |
| 2Protocol established before the reviewcritical | Partial Yes | Partial Yes | yes |
| 3Choice of study designs explained | No | No | yes |
| 4Comprehensive literature searchcritical | Yes | Yes | yes |
| 5Study selection in duplicate | Yes | Yes | yes |
| 6Data extraction in duplicate | Yes | Yes | yes |
| 7List of excluded studies with reasonscritical | No | No | yes |
| 8Included studies described in detail | Partial Yes | Yes | no |
| 9Risk of bias assessed satisfactorilycritical | RCT: Yes · NRSI: Yes | NRSI: Yes · RCT: Yes | no |
| 10Funding of included studies reported | No | No | yes |
| 11Appropriate meta-analysis methodscritical | RCT: Yes · NRSI: No | NRSI: Yes · RCT: Yes | no |
| 12Impact of risk of bias on the pooled results | No | No | yes |
| 13Risk of bias accounted for in interpretationcritical | Yes | Yes | yes |
| 14Heterogeneity explained | Yes | Yes | yes |
| 15Publication bias investigatedcritical | No | No | yes |
| 16Conflicts of interest reported | No | No | yes |
| Overall | Critically Low | Critically Low | yes |
Included primary studies 21
Open as a trial list| Study | Also included by | Outcomes it informs here | Trial PICO | Results |
|---|---|---|---|---|
| Buschang et al. 2018 Incidence of white spot lesions among patients treated with clear aligners and traditional braces. PMID:30556747 | 1 other review | not stated | not extracted yet | not extracted yet |
| Dallel et al. 2020 Influence of orthodontic appliance type on salivary parameters during treatment. PMID:33378497 | 1 other review | White spot lesions (WSLs), patient level | not extracted yet | not extracted yet |
| Karkhanechi et al. 2013 Periodontal status of adult patients treated with fixed buccal appliances and removable aligners over one year of active orthodontic… PMID:22725616 | 1 other review | Plaque index (PI) | not extracted yet | not extracted yet |
| Levrini et al. 2015 Periodontal health status in patients treated with the Invisalign(®) system and fixed orthodontic appliances: A 3 months clinical and… PMID:26430371 | 1 other review | not stated | not extracted yet | not extracted yet |
| Madariaga et al. 2020 Impact of Fixed Orthodontic Appliance and Clear Aligners on the Periodontal Health: A Prospective Clinical Study. PMID:31906577 | 1 other review | not stated | not extracted yet | not extracted yet |
| Mummolo et al. 2020a Salivary levels of Streptococcus mutans and Lactobacilli and other salivary indices in patients wearing clear aligners versus fixed… PMID:32330172 | 1 other review | S. mutans presence (CFU > 10^5) | not extracted yet | not extracted yet |
| Mummolo et al. 2020b Salivary concentrations of Streptococcus mutans and Lactobacilli during an orthodontic treatment. An observational study comparing fixed… PMID:32250562 | 1 other review | S. mutans presence (CFU > 10^5) | not extracted yet | not extracted yet |
| Abbate et al. 2015 Periodontal health in teenagers treated with removable aligners and fixed orthodontic appliances DOI:10.1007/s00056-015-0285-5 | this review only | Full-mouth plaque score (FMPS) | not extracted yet | not extracted yet |
| Albhaisi et al. 2020 Enamel demineralization during clear aligner orthodontic treatment compared with fixed appliance therapy, evaluated with quantitative… DOI:10.1016/j.ajodo.2020.01.004 | this review only | White spot lesions (WSLs), tooth level | not extracted yet | not extracted yet |
| Azaripour et al. 2015 Braces versus Invisalign®: gingival parameters and patients' satisfaction during treatment: a cross-sectional study. PMID:26104387 | this review only | not stated | not extracted yet | not extracted yet |
| Chhibber et al. 2018 Which orthodontic appliance is best for oral hygiene? A randomized clinical trial DOI:10.1016/j.ajodo.2017.10.009 | this review only | Plaque index (PI) | not extracted yet | not extracted yet |
| Gujar et al. 2019 Cytokine levels in gingival crevicular fluid during orthodontic treatment with aligners compared to conventional labial fixed appliances:… DOI:10.1080/00016357.2019.1607548 | this review only | not stated | not extracted yet | not extracted yet |
| Gujar et al. 2020 Microbial profile in different orthodontic appliances by checkerboard DNA-DNA hybridization: An in-vivo study DOI:10.1016/j.ajodo.2019.01.026 | this review only | not stated | not extracted yet | not extracted yet |
| Han et al. 2015 A comparative study of combined periodontal and orthodontic treatment with fixed appliances and clear aligners in patients with… PMID:26734489 | this review only | not stated | not extracted yet | not extracted yet |
| Levrini et al. 2013 matched by author and year (probable) | this review only | Plaque index (PI) | not extracted yet | not extracted yet |
| Miethke & Brauner 2007 A Comparison of the Periodontal Health of Patients during Treatment with the Invisalign® System and with Fixed Lingual Appliances DOI:10.1007/s00056-007-0655-8 | this review only | not stated | not extracted yet | not extracted yet |
| Miethke & Vogt 2005 A Comparison of the Periodontal Health of Patients during Treatment with the Invisalign® System and with Fixed Orthodontic Appliances DOI:10.1007/s00056-005-0436-1 | this review only | not stated | not extracted yet | not extracted yet |
| Mulla Issa et al. 2020 Periodontal parameters in adult patients with clear aligners orthodontics treatment versus three other types of brackets: A… PMID:32166083 | this review only | not stated | not extracted yet | not extracted yet |
| Sifakakis et al. 2018 Salivary levels of cariogenic bacterial species during orthodontic treatment with thermoplastic aligners or fixed appliances: a… PMID:30066184 | this review only | Simplified plaque index (s-PI) | not extracted yet | not extracted yet |
| Srinath et al. 2016 matched by author and year (probable) | this review only | not stated | not extracted yet | not extracted yet |
| Wang et al. 2019 Alterations of the oral microbiome in patients treated with the Invisalign system or with fixed appliances DOI:10.1016/j.ajodo.2018.11.017 | this review only | not stated | not extracted yet | not extracted yet |
Overlap with other reviews
Reviews that include the same primary studies are not independent evidence. Shared counts match studies by PMID, DOI or NCT, and otherwise by author and year (a probable match).
| Review | Shared studies | Jaccard |
|---|---|---|
| White spot lesions, plaque accumulation and salivary caries-associated bacteria in clear aligners compared to fixed orthodontic treatment.… (2023) | 7 | 0.25 |