Molar Extraction in Orthodontics: An Umbrella Review of Cochrane Systematic Reviews

Molar Extraction in Orthodontics: An Umbrella Review of Cochrane Systematic Reviews | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Systematic Review Molar Extraction in Orthodontics: An Umbrella Review of Cochrane Systematic Reviews Maen Mahfouz, Eman Alzaben This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9503209/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background: Molar extraction in orthodontics is used to manage severe crowding, correct Class II and Class III malocclusions, address compromised teeth, and facilitate alveolar realignment. An umbrella review synthesizes evidence from systematic reviews and meta-analyses, representing the highest level of evidence. Methods: This umbrella review followed PRIOR guidelines. The Cochrane Database of Systematic Reviews was searched (2010–2025), with the final search conducted in January 2026. Only systematic reviews and meta-analyses were included. Ten Cochrane reviews met inclusion criteria. Methodological quality was assessed using AMSTAR-2, and certainty of evidence was evaluated using GRADE. Results: High-certainty evidence (AMSTAR-2 high; GRADE high) from two RCTs (n = 190) indicates that molar bands have lower failure rates than bonded tubes (HR 2.92, 95% CI 1.80–4.72; NNT = 3.1). Moderate-certainty evidence (GRADE moderate) from 15 studies (n = 561) shows that surgical anchorage results in 1.68 mm less mesial movement of molars (95% CI −2.27 to −1.09). Low-certainty evidence suggests intraoral distalizers are more effective than headgear (MD −1.45 mm) but with greater anchorage loss (MD 1.82 mm). Very low-certainty evidence is insufficient to support routine prophylactic removal of asymptomatic third molars. No umbrella-level evidence was identified for first or second molar extraction. Conclusion: High-certainty evidence supports the use of molar bands over bonded tubes. Moderate-certainty evidence supports surgical anchorage. Evidence for prophylactic third molar removal is insufficient. Major evidence gaps exist for first and second molar extraction. Dentistry umbrella review molar extraction orthodontics Cochrane review GRADE Figures Figure 1 Figure 2 1. Introduction 1.1. Rationale Molar extraction in orthodontics is a treatment strategy used for managing severe crowding, correcting Class II and Class III malocclusions, addressing compromised teeth, and facilitating alveolar realignment [1,2]. An umbrella review (also called a review of reviews or overview of reviews) synthesizes evidence exclusively from systematic reviews and meta-analyses – the highest level of evidence in the evidence hierarchy [3]. The methodological distinction between umbrella reviews, systematic reviews, narrative reviews, and protocols has been described previously [4]. Unlike scoping or systematic reviews, umbrella reviews do not include primary studies (RCTs, cohort studies, cross-sectional studies). Instead, they identify, appraise, and synthesize findings from existing systematic reviews to provide a high-level summary of evidence for clinical decision-making and guideline development [5]. 1.2. Objectives This umbrella review aims to: 1. Identify all systematic reviews and meta-analyses on molar extraction in orthodontics 2. Appraise the quality of included reviews using AMSTAR-2 3. Synthesize findings using GRADE to determine certainty of evidence 4. Identify evidence gaps at the systematic review level 2. Methods 2.1. Protocol and Registration This umbrella review was conducted according to PRIOR (Preferred Reporting Items for Overviews of Reviews) guidelines [6]. A protocol was developed a priori but was not formally registered. 2.2. Eligibility Criteria Inclusion Criteria: · Cochrane Systematic Reviews published between 2010 and 2025 · Reviews addressing orthodontic treatment involving molars, extractions, anchorage, or related topics · Reviews including at least one outcome relevant to molar extraction decisions · English language Exclusion Criteria: · Primary studies (RCTs, cohort studies, cross-sectional studies) · Narrative reviews · Non-Cochrane systematic reviews (to ensure methodological consistency and high-quality standards across all synthesized evidence) 2.3. Information Sources and Search Strategy The Cochrane Database of Systematic Reviews was searched for reviews published between January 2010 and January 2025. The final search was conducted on 12 January 2026. Search terms included: ("molar extraction" OR "second molar" OR "third molar" OR "wisdom teeth" OR "anchorage" OR "distalization") AND ("orthodontic" OR "orthodontics"). 2.4. Selection Process Two reviewers (MM, EA) independently screened titles and abstracts. Disagreements were resolved by discussion. Full texts were assessed against eligibility criteria. 2.5. Quality Assessment AMSTAR-2 (A MeaSurement Tool to Assess systematic Reviews) was used to assess the quality of included systematic reviews [7]. AMSTAR-2 provides an overall rating of confidence in the results of each review: high, moderate, low, or critically low. 2.6. Data Extraction The following data were extracted from each included review: · Review title and year · Number and design of included primary studies · Total sample size · Key findings with effect estimates (HR, MD, OR, RR) · 95% confidence intervals · Authors' reported certainty of evidence (where available) 2.7. Certainty Assessment (GRADE) GRADE principles were applied to assess overall certainty of evidence for each domain [8], considering: · Study design (RCTs start as high certainty; observational studies as low certainty) · Risk of bias · Inconsistency (unexplained heterogeneity) · Indirectness · Imprecision (wide confidence intervals) · Publication bias GRADE certainty levels: · High: Further research is very unlikely to change confidence in the estimate of effect · Moderate: Further research is likely to have an important impact on confidence and may change the estimate · Low: Further research is very likely to have an important impact on confidence and is likely to change the estimate · Very low: Any estimate of effect is very uncertain 2.8. Synthesis Findings were organized by clinical domain based on the focus of each systematic review. Due to heterogeneity in interventions, populations, and outcome measures across included reviews, a quantitative re-analysis was not performed. 3. Results 3.1. Study Selection The study selection process is illustrated in Figure 1 . The search covered reviews published between January 2010 and January 2025, with the final search conducted on 12 January 2026. Initial searching identified 24 Cochrane Systematic Reviews. After title and abstract screening, 10 reviews met inclusion criteria. Fourteen reviews were excluded as they did not address molar extraction, extractions, or relevant orthodontic anchorage decisions. 3.2. Characteristics of Included Reviews Table 1 summarizes the ten included Cochrane Systematic Reviews, including: review title and year, number and design of included primary studies, total sample size, AMSTAR-2 quality rating, and key findings with effect estimates. Table 1: Characteristics of Included Cochrane Systematic Reviews Review (Year) Primary Studies (n) Total N AMSTAR-2 Key Finding Millett 2017 [1] 2 RCTs 190 High HR 2.92 favouring bands Jambi 2014 [2] 15 561 Moderate 1.68 mm less mesial movement Jambi 2013 [3] 10 354 Low MD −1.45 mm distalization Ghaeminia 2020 [4] 2 493 Low Insufficient evidence Ugolini 2021 [5] 31 1410 High Expansion effective Benson 2021 [6] 4 199 Low RR 2.87 (very uncertain) Millett 2016 [7] 8 Not reported Critically low Insufficient evidence Mandall 2018 [8] 3 Not reported Critically low No clear evidence Millett 2018 [9] 0 0 Critically low No evidence identified Turner 2021 [10] 24 1512 Low Very low certainty 3.3. Quality Assessment (AMSTAR-2) Review (Year) AMSTAR-2 Rating Confidence Millett 2017 (adhesives for bonded molar tubes) [9] High High confidence Jambi 2014 (reinforcement of anchorage) [10] Moderate Moderate confidence Jambi 2013 (distalising upper first molars) [11] Low Low confidence Ghaeminia 2020 (asymptomatic wisdom teeth) [12] Low Low confidence Ugolini 2021 (posterior crossbites) [13] High High confidence Benson 2021 (palatally displaced canines) [14] Low Low confidence Millett 2016 (adhesives for orthodontic bands) [15] Critically low Very low confidence Mandall 2018 (adhesives for orthodontic brackets) [16] Critically low Very low confidence Millett 2018 (deep bite and retroclined incisors) [17] Critically low No evidence identified Turner 2021 (crowded teeth in children) [18] Low Low confidence 3.4. Domain 1: Molar Attachment Selection Included Review: Millett et al. (2017) [9] – Adhesives for bonded molar tubes during fixed brace treatment Characteristics: Two parallel-group randomized controlled trials with low risk of bias. Total n = 190 participants. Both trials compared bonded molar tubes to molar bands. Outcomes assessed at 6, 12, and 24 months. Key Findings: · Bonded tubes failure rate: 57% event rate · Molar bands failure rate: 25% event rate · Hazard ratio: 2.92 (95% CI 1.80–4.72) favouring molar bands · Number needed to treat (NNT) to prevent one failure: 3.1 · One trial showed less decalcification with molar bands (OR 0.32, 95% CI 0.12–0.86) Quality Assessment: · AMSTAR-2: High confidence · GRADE certainty: High (consistent findings from two low-risk-of-bias RCTs) Conclusion: High-certainty evidence demonstrates that molar bands have substantially lower failure rates than bonded tubes. 3.5. Domain 2: Anchorage Control Included Review: Jambi et al. (2014) [10] – Reinforcement of anchorage during orthodontic brace treatment with implants or other surgical methods Characteristics: Fifteen studies with 561 randomised patients. Studies compared surgical anchorage (mini-screws, orthodontic implants, onplants) to conventional anchorage (headgear, transpalatal arches, Nance buttons). Key Findings: · Mean difference of 1.68 mm less mesial movement of molars with surgical anchorage (95% CI −2.27 to −1.09) · No significant difference in overall treatment duration (mean difference −0.15 years, 95% CI −0.37 to 0.07) · Subgroup analysis suggested mini-screws showed the most promising results · No included studies reported on adverse effects of surgical anchorage · Limited and inconclusive data on patient-reported outcomes Quality Assessment: · AMSTAR-2: Moderate confidence · GRADE certainty: Moderate (consistent findings from 15 studies, but heterogeneity present) Conclusion: Moderate-certainty evidence supports that surgical anchorage provides clinically meaningful anchorage reinforcement. 3.6. Domain 3: Distalization as an Alternative to Extraction Included Review: Jambi et al. (2013) [11] – Orthodontic treatment for distalising upper first molars in children and adolescents Characteristics: Ten studies with 354 participants. Study quality generally poor (seven at high risk of bias, three unclear, none low risk). Key Findings: · Intraoral appliances more effective than headgear for distalising upper first molars: mean difference −1.45 mm (95% CI −2.74 to −0.15) · However, intraoral appliances associated with significant loss of anterior anchorage: mesial incisor movement MD 1.82 mm (95% CI 1.39–2.24) · Headgear showed less anchorage loss and better overjet control (MD 1.64 mm favouring headgear, 95% CI 1.26–2.02) · No studies reported on adverse effects, attendance, or compliance Quality Assessment: · AMSTAR-2: Low confidence · GRADE certainty: Low (poor study quality, heterogeneity) Conclusion: Low-certainty evidence suggests distalization is effective but associated with anterior anchorage loss. 3.7. Domain 4: Third Molar Management Included Review: Ghaeminia et al. (2020) [12] – Surgical removal versus retention for the management of asymptomatic disease-free impacted wisdom teeth Characteristics: Two studies (one RCT, one prospective cohort) with 493 participants. This review updated previous versions (2005, 2012, 2016). Key Findings: · Insufficient evidence to determine whether asymptomatic disease-free impacted wisdom teeth should be removed or retained · Very low-certainty evidence suggests retention may be associated with increased risk of periodontitis affecting adjacent second molars in the long term (OR 2.3, 95% CI 1.1–4.8) · No evidence to support the claim that prophylactic removal prevents late incisor crowding · No eligible studies reported on health-related quality of life or cost-effectiveness Quality Assessment: · AMSTAR-2: Low confidence · GRADE certainty: Very low (feasibility constraints for RCTs) Conclusion: Very low-certainty evidence is insufficient to support routine prophylactic removal of asymptomatic impacted wisdom teeth. 3.8. Domain 5: Posterior Crossbite (Context for Extraction vs Expansion) Included Review: Ugolini et al. (2021) [13] – Orthodontic treatment for posterior crossbites Characteristics: 31 studies with approximately 1410 participants. Eight studies at low risk of bias, 15 at high risk, eight at unclear risk. Key Findings: · Quad-helix and expansion plates effective for posterior crossbite correction in children (high-certainty evidence) · Quad-helix more effective and faster than expansion plates (RR 1.29, 95% CI 1.13–1.46; MD −3.15 months, 95% CI −4.04 to −2.25) · For patients with both transverse deficiency and crowding, expansion should be considered before extraction as first-line treatment Quality Assessment: · AMSTAR-2: High confidence · GRADE certainty: High for main comparisons Conclusion: High-certainty evidence supports expansion over extraction for posterior crossbite correction. 3.9. Domain 6: Palatally Displaced Canines (Extraction Context) Included Review: Benson et al. (2021) [14] – Interventions for promoting eruption of palatally displaced permanent canine teeth without surgical exposure Characteristics: Four studies with 199 randomised participants (164 analysed). All studies at high or unclear risk of bias. Key Findings: · Very low-certainty evidence that extraction of the primary canine may increase the proportion of successfully erupted palatally displaced canines at 12 months (RR 2.87, 95% CI 0.90–9.23) · No evidence that double extraction of primary teeth increases eruption compared to single extraction Quality Assessment: · AMSTAR-2: Low confidence · GRADE certainty: Very low (small sample sizes, heterogeneity) Conclusion: Evidence for primary canine extraction in palatally displaced canines is very uncertain. 3.10. Domains with No Umbrella-Level Evidence The following domains had no systematic reviews meeting inclusion criteria: Domain Evidence Status Second molar extraction No systematic reviews identified First molar extraction No systematic reviews identified Extraction techniques (Physics Forceps, etc.) No systematic reviews identified Adhesives for bands/brackets Reviews exist but critically low quality (no useful evidence) 4. Major Evidence Gaps at Umbrella Level Gap Area Description Priority Second molar extraction No systematic reviews exist Critical First molar extraction No systematic reviews exist Critical Extraction techniques No systematic reviews exist High Premolar extraction effects on third molars No systematic reviews exist High Adhesive selection Existing reviews are critically low quality Moderate 5. Discussion 5.1. Summary of Evidence This umbrella review synthesizes evidence exclusively from Cochrane systematic reviews – the highest level of evidence available. Figure 2 summarizes the certainty of evidence across all domains using GRADE levels. Key findings include: Domain Certainty Key Finding Molar attachment selection High Molar bands have lower failure rates than bonded tubes (HR 2.92) Anchorage control Moderate Surgical anchorage provides 1.68 mm less mesial movement of molars Distalization Low Effective but associated with anchorage loss Third molar management Very low Insufficient evidence for prophylactic removal Posterior crossbite High Expansion preferred over extraction Second molar extraction No evidence No systematic reviews exist First molar extraction No evidence No systematic reviews exist 5.2. Strengths This umbrella review has several strengths. It exclusively included Cochrane systematic reviews, ensuring high methodological rigor and consistency. The use of AMSTAR-2 and GRADE provides a transparent and robust assessment of both review quality and certainty of evidence. Furthermore, the domain-based synthesis allows clinically meaningful interpretation of findings relevant to orthodontic decision-making. 5.3. Comparison with Previous Literature Previous narrative reviews have discussed second molar extraction from clinical perspectives [19,20]. However, this umbrella review reveals a critical gap: no systematic reviews exist on second or first molar extraction . Consequently, clinical decision-making in these areas is currently based on observational studies and expert opinion, not high-level evidence synthesis. The absence of systematic reviews on first and second molar extraction represents a critical gap in evidence-based orthodontics, highlighting a disconnect between clinical practice and high-level evidence synthesis. 5.4. Limitations This umbrella review has several limitations: · Only Cochrane reviews were included; non-Cochrane systematic reviews may exist but were excluded for quality consistency · Several included reviews had low or critically low AMSTAR-2 ratings · No systematic reviews exist for key domains (second molar extraction, first molar extraction) · Publication bias cannot be excluded 5.5. Implications for Clinical Practice Based on umbrella-level evidence: 1. Molar attachments: Molar bands are recommended over bonded tubes (high-certainty evidence) 2. Anchorage control: Surgical anchorage (mini-screws, implants) is recommended when maximum anchorage reinforcement is required (moderate-certainty evidence) 3. Posterior crossbite: Expansion is preferred over extraction (high-certainty evidence) 4. Asymptomatic wisdom teeth: Routine prophylactic removal is not supported by high-quality evidence (very low-certainty evidence) 5. Second and first molar extraction: No umbrella-level evidence exists to guide clinical decisions 5.6. Implications for Research This umbrella review identifies critical research priorities at the systematic review level: 1. Conduct systematic reviews on second molar extraction – No systematic review currently exists despite clinical prevalence 2. Conduct systematic reviews on first molar extraction – No systematic review currently exists 3. Update low-quality Cochrane reviews – Several reviews have low or critically low AMSTAR-2 ratings 4. Conduct systematic reviews on extraction techniques – Including Physics Forceps and other minimally invasive methods 6. Conclusions At the umbrella review level (synthesizing evidence exclusively from systematic reviews and meta-analyses): 1. High-certainty evidence (GRADE High) supports that molar bands have lower failure rates than bonded tubes (HR 2.92, 95% CI 1.80–4.72). 2. Moderate-certainty evidence (GRADE Moderate) supports that surgical anchorage provides 1.68 mm less mesial movement of molars (95% CI −2.27 to −1.09) compared to conventional anchorage. 3. High-certainty evidence (GRADE High) supports expansion over extraction for posterior crossbite correction. 4. Very low-certainty evidence (GRADE Very low) is insufficient to support routine prophylactic removal of asymptomatic impacted wisdom teeth. 5. Importantly, no systematic reviews were identified for second molar extraction, first molar extraction, or extraction techniques. These represent major evidence gaps at the highest level of evidence synthesis. Until systematic reviews are conducted in these domains, clinical decisions regarding second and first molar extraction must rely on observational studies and clinical expertise rather than umbrella-level evidence. Declarations 7. Acknowledgements The authors thank the Cochrane Oral Health Group for producing the systematic reviews that made this umbrella review possible. We acknowledge the foundational work of Professor William Proffit, Professor Samir Bishara, and Professor Bjørn Zachrisson. 8. Conflicts of Interest The authors declare no conflicts of interest related to this study. 9. Funding This research received no external funding. 10. Ethical Approval This study is a review of previously published systematic reviews and did not involve human participants or animals. Ethical approval was therefore not required. 11. Data Availability Statement All data analysed in this study are available from the published Cochrane reviews cited in the reference list. References Included Cochrane Reviews (n=10) 1. Millett DT, Mandall NA, Mattick RCR, Hickman J, Glenny AM. Adhesives for bonded molar tubes during fixed brace treatment. Cochrane Database Syst Rev. 2017;(2):CD008236. 2. Jambi S, Walsh T, Sandler J, Benson PE, Skeggs RM, O'Brien KD. Reinforcement of anchorage during orthodontic brace treatment with implants or other surgical methods. Cochrane Database Syst Rev. 2014;(8):CD005098. 3. Jambi S, Thiruvenkatachari B, O'Brien KD, Walsh T. Orthodontic treatment for distalising upper first molars in children and adolescents. Cochrane Database Syst Rev. 2013;(10):CD008375. 4. Ghaeminia H, Perry J, Nienhuijs ME, et al. Surgical removal versus retention for the management of asymptomatic disease-free impacted wisdom teeth. Cochrane Database Syst Rev. 2020;5:CD003879. 5. Ugolini A, Doldo T, Ghislanzoni LTH, Mapelli A, Giorgetti R. Orthodontic treatment for posterior crossbites. Cochrane Database Syst Rev. 2021;12:CD000979. 6. Benson PE, Parkin N, Dyer F, et al. Interventions for promoting eruption of palatally displaced permanent canine teeth without surgical exposure. Cochrane Database Syst Rev. 2021;2:CD012248. 7. Millett DT, Glenny AM, Mattick RCR, Hickman J, Mandall NA. Adhesives for fixed orthodontic bands. Cochrane Database Syst Rev. 2016;(10):CD004485. 8. Mandall NA, Hickman J, Macfarlane TV, Mattick RCR, Millett DT, Worthington HV. Adhesives for fixed orthodontic brackets. Cochrane Database Syst Rev. 2018;(4):CD002282. 9. Millett DT, Cunningham SJ, O'Brien KD, Benson PE, de Oliveira CM. Orthodontic treatment for deep bite and retroclined upper front teeth in children. Cochrane Database Syst Rev. 2018;(2):CD005972. 10. Turner S, Harrison JE, Sharif FNJ, Owens D, Millett DT. Orthodontic treatment for crowded teeth in children. Cochrane Database Syst Rev. 2021;(12):CD003453. Methodological References 11. Mahfouz M. Protocol Versus Narrative Review Versus Systematic Review Versus Umbrella Review: A Comparative Methodological Analysis for Evidence Synthesis. Preprints. 2026;2026041300. doi:10.20944/preprints202604.1300.v1 12. Pollock M, Fernandes RM, Pieper D, et al. Preferred Reporting Items for Overviews of Reviews (PRIOR): a protocol for development of a reporting guideline for reviews of reviews. BMJ Open. 2019;9(11):e031278. 13. Shea BJ, Reeves BC, Wells G, et al. AMSTAR 2: a critical appraisal tool for systematic reviews that include randomised or non-randomised studies of healthcare interventions, or both. BMJ. 2017;358:j4008. 14. Guyatt GH, Oxman AD, Vist GE, et al. GRADE: an emerging consensus on rating quality of evidence and strength of recommendations. BMJ. 2008;336(7650):924-926. 15. Proffit WR, Fields HW, Larson B, Sarver DM. Contemporary Orthodontics. 6th ed. Elsevier; 2018. 16. Bishara SE. Third molars: A dilemma! Or is it? Am J Orthod Dentofacial Orthop. 1999;115(6):628-633. 17. De-la-Rosa-Gay C, Valmaseda-Castellón E, Gay-Escoda C. Spontaneous third molar eruption after second molar extraction in orthodontic patients. Am J Orthod Dentofacial Orthop. 2006;129:337-344. 18. Færøvig LF, Pandis N, Johal A, Vandevska-Radunovic V. Mandibular second molar extraction: A retrospective cohort study of spontaneous occlusal changes in adolescent patients. Orthod Craniofac Res. 2024;27(4):606-614. 19. Montasser ZM, Montasser MA. Therapeutic extraction of second molars in orthodontics: a scoping review. BMC Oral Health. 2025;25(1):26. 20. Türköz C, Ulusoy C. Effect of premolar extraction on mandibular third molar impaction in young adults. Angle Orthod. 2013;83(4):572-577. Additional Declarations The authors declare no competing interests. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9503209","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Systematic Review","associatedPublications":[],"authors":[{"id":628177985,"identity":"51f948b0-8186-4642-8d11-0fd820e2d61d","order_by":0,"name":"Maen Mahfouz","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABE0lEQVRIie2Qz0rDQBCHZxnYXEZzzZL6DpFAT9K+SkLAU/FSEMRCC4XkEvTqk+wLLKQX0avQS6KQsz0I9eb0D5XSBOtNZD+W2WGZj93fAlgsfxFHTCACIG7legGCKHmj0zYFdwpuFELAYKXIVuW72ypcPdhc2og7xbQsR72O6z8X5fv1xVXfwfrmY9DrSMDq9eVQ8YzIgqhISN0lzvnD0+WQUHbnZzrhh8kwHBwqAYrUiydIwSNK/yQ1cY4k50pz5Th+uzLeV4ZKj39SzL4iFtq0Kpwl9aJiRirHruIscW5k6As9I4nNWdwsq9VydNt3SdQe/1ic3Ztq8an5xJlWbw1KM0jreuz4CrH8zbTFYrH8d74AvOhQot3tM+4AAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0001-9669-9984","institution":"Private Orthodontic Practice, Ramallah, Palestine.","correspondingAuthor":true,"prefix":"","firstName":"Maen","middleName":"","lastName":"Mahfouz","suffix":""},{"id":628177986,"identity":"f155d84d-6103-4ad6-8efa-6172ae3bce39","order_by":1,"name":"Eman Alzaben","email":"","orcid":"https://orcid.org/0009-0000-2829-6833","institution":"Private Dental Clinic, Jerusalem","correspondingAuthor":false,"prefix":"","firstName":"Eman","middleName":"","lastName":"Alzaben","suffix":""}],"badges":[],"createdAt":"2026-04-23 07:04:35","currentVersionCode":1,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-9503209/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9503209/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":107692358,"identity":"bf83d8f0-7986-435a-a29a-6f24c3f11ed5","added_by":"auto","created_at":"2026-04-24 06:22:57","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1625828,"visible":true,"origin":"","legend":"\u003cp\u003eFigure legend not provided with this version\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-9503209/v1/ca8a7e3ed792c70f05e6143d.png"},{"id":107707674,"identity":"b215baf9-5b12-47bd-a039-579cbffc88ea","added_by":"auto","created_at":"2026-04-24 09:20:53","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":3421427,"visible":true,"origin":"","legend":"\u003cp\u003eFigure legend not provided with this version\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-9503209/v1/5871d2deae4040cdeb399712.png"},{"id":107709399,"identity":"7aa7947e-0de0-4078-b24e-e5ae5804e25d","added_by":"auto","created_at":"2026-04-24 09:35:39","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4711149,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9503209/v1/dec9d8a0-0687-4fe5-90e2-194109d188ce.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003eMolar Extraction in Orthodontics: An Umbrella Review of Cochrane Systematic Reviews\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003ch3\u003e\u003cstrong\u003e1.1. Rationale\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003eMolar extraction in orthodontics is a treatment strategy used for managing severe crowding, correcting Class II and Class III malocclusions, addressing compromised teeth, and facilitating alveolar realignment [1,2]. An umbrella review (also called a review of reviews or overview of reviews) synthesizes evidence exclusively from systematic reviews and meta-analyses – the highest level of evidence in the evidence hierarchy [3]. The methodological distinction between umbrella reviews, systematic reviews, narrative reviews, and protocols has been described previously [4].\u003c/p\u003e\n\u003cp\u003eUnlike scoping or systematic reviews, umbrella reviews do not include primary studies (RCTs, cohort studies, cross-sectional studies). Instead, they identify, appraise, and synthesize findings from existing systematic reviews to provide a high-level summary of evidence for clinical decision-making and guideline development [5].\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e1.2. Objectives\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003eThis umbrella review aims to:\u003c/p\u003e\n\u003cp\u003e1.\u0026nbsp; \u0026nbsp;Identify all systematic reviews and meta-analyses on molar extraction in orthodontics\u003c/p\u003e\n\u003cp\u003e2.\u0026nbsp; \u0026nbsp;Appraise the quality of included reviews using AMSTAR-2\u003c/p\u003e\n\u003cp\u003e3.\u0026nbsp; \u0026nbsp;Synthesize findings using GRADE to determine certainty of evidence\u003c/p\u003e\n\u003cp\u003e4.\u0026nbsp; \u0026nbsp;Identify evidence gaps at the systematic review level\u003c/p\u003e"},{"header":"2. Methods","content":"\u003ch3\u003e\u003cstrong\u003e2.1. Protocol and Registration\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003eThis umbrella review was conducted according to PRIOR (Preferred Reporting Items for Overviews of Reviews) guidelines [6]. A protocol was developed a priori but was not formally registered.\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e2.2. Eligibility Criteria\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003e\u003cstrong\u003eInclusion Criteria:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026middot; Cochrane Systematic Reviews published between 2010 and 2025\u003c/p\u003e\n\u003cp\u003e\u0026middot; Reviews addressing orthodontic treatment involving molars, extractions, anchorage, or related topics\u003c/p\u003e\n\u003cp\u003e\u0026middot; Reviews including at least one outcome relevant to molar extraction decisions\u003c/p\u003e\n\u003cp\u003e\u0026middot; English language\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eExclusion Criteria:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026middot; Primary studies (RCTs, cohort studies, cross-sectional studies)\u003c/p\u003e\n\u003cp\u003e\u0026middot; Narrative reviews\u003c/p\u003e\n\u003cp\u003e\u0026middot; Non-Cochrane systematic reviews (to ensure methodological consistency and high-quality standards across all synthesized evidence)\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e2.3. Information Sources and Search Strategy\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003eThe Cochrane Database of Systematic Reviews was searched for reviews published between January 2010 and January 2025. The final search was conducted on 12 January 2026.\u003c/p\u003e\n\u003cp\u003eSearch terms included:\u003cbr\u003e\u0026nbsp;(\u0026quot;molar extraction\u0026quot; OR \u0026quot;second molar\u0026quot; OR \u0026quot;third molar\u0026quot; OR \u0026quot;wisdom teeth\u0026quot; OR \u0026quot;anchorage\u0026quot; OR \u0026quot;distalization\u0026quot;) AND (\u0026quot;orthodontic\u0026quot; OR \u0026quot;orthodontics\u0026quot;).\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e2.4. Selection Process\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003eTwo reviewers (MM, EA) independently screened titles and abstracts. Disagreements were resolved by discussion. Full texts were assessed against eligibility criteria.\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e2.5. Quality Assessment\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003eAMSTAR-2 (A MeaSurement Tool to Assess systematic Reviews) was used to assess the quality of included systematic reviews [7]. AMSTAR-2 provides an overall rating of confidence in the results of each review: high, moderate, low, or critically low.\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e2.6. Data Extraction\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003eThe following data were extracted from each included review:\u003c/p\u003e\n\u003cp\u003e\u0026middot; Review title and year\u003c/p\u003e\n\u003cp\u003e\u0026middot; Number and design of included primary studies\u003c/p\u003e\n\u003cp\u003e\u0026middot; Total sample size\u003c/p\u003e\n\u003cp\u003e\u0026middot; Key findings with effect estimates (HR, MD, OR, RR)\u003c/p\u003e\n\u003cp\u003e\u0026middot; 95% confidence intervals\u003c/p\u003e\n\u003cp\u003e\u0026middot; Authors\u0026apos; reported certainty of evidence (where available)\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e2.7. Certainty Assessment (GRADE)\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003eGRADE principles were applied to assess overall certainty of evidence for each domain [8], considering:\u003c/p\u003e\n\u003cp\u003e\u0026middot; Study design (RCTs start as high certainty; observational studies as low certainty)\u003c/p\u003e\n\u003cp\u003e\u0026middot; Risk of bias\u003c/p\u003e\n\u003cp\u003e\u0026middot; Inconsistency (unexplained heterogeneity)\u003c/p\u003e\n\u003cp\u003e\u0026middot; Indirectness\u003c/p\u003e\n\u003cp\u003e\u0026middot; Imprecision (wide confidence intervals)\u003c/p\u003e\n\u003cp\u003e\u0026middot; Publication bias\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eGRADE certainty levels:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026middot; \u003cstrong\u003eHigh:\u003c/strong\u003e Further research is very unlikely to change confidence in the estimate of effect\u003c/p\u003e\n\u003cp\u003e\u0026middot; \u003cstrong\u003eModerate:\u003c/strong\u003e Further research is likely to have an important impact on confidence and may change the estimate\u003c/p\u003e\n\u003cp\u003e\u0026middot; \u003cstrong\u003eLow:\u003c/strong\u003e Further research is very likely to have an important impact on confidence and is likely to change the estimate\u003c/p\u003e\n\u003cp\u003e\u0026middot; \u003cstrong\u003eVery low:\u003c/strong\u003e Any estimate of effect is very uncertain\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e2.8. Synthesis\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003eFindings were organized by clinical domain based on the focus of each systematic review. Due to heterogeneity in interventions, populations, and outcome measures across included reviews, a quantitative re-analysis was not performed.\u003c/p\u003e"},{"header":"3. Results","content":"\u003ch3\u003e\u003cstrong\u003e3.1. Study Selection\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003eThe study selection process is illustrated in \u003cstrong\u003eFigure 1\u003c/strong\u003e. The search covered reviews published between January 2010 and January 2025, with the final search conducted on 12 January 2026. Initial searching identified 24 Cochrane Systematic Reviews. After title and abstract screening, 10 reviews met inclusion criteria. Fourteen reviews were excluded as they did not address molar extraction, extractions, or relevant orthodontic anchorage decisions.\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e3.2. Characteristics of Included Reviews\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1\u003c/strong\u003e summarizes the ten included Cochrane Systematic Reviews, including: review title and year, number and design of included primary studies, total sample size, AMSTAR-2 quality rating, and key findings with effect estimates.\u003c/p\u003e\n\u003ch3\u003eTable 1: Characteristics of Included Cochrane Systematic Reviews\u003c/h3\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 137px;\"\u003e\n \u003cp\u003eReview (Year)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 135px;\"\u003e\n \u003cp\u003ePrimary Studies (n)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003eTotal N\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003eAMSTAR-2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 213px;\"\u003e\n \u003cp\u003eKey Finding\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 137px;\"\u003e\n \u003cp\u003eMillett 2017 [1]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 135px;\"\u003e\n \u003cp\u003e2 RCTs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e190\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003eHigh\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 213px;\"\u003e\n \u003cp\u003eHR 2.92 favouring bands\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 137px;\"\u003e\n \u003cp\u003eJambi 2014 [2]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 135px;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e561\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003eModerate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 213px;\"\u003e\n \u003cp\u003e1.68 mm less mesial movement\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 137px;\"\u003e\n \u003cp\u003eJambi 2013 [3]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 135px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e354\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003eLow\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 213px;\"\u003e\n \u003cp\u003eMD \u0026minus;1.45 mm distalization\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 137px;\"\u003e\n \u003cp\u003eGhaeminia 2020 [4]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 135px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e493\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003eLow\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 213px;\"\u003e\n \u003cp\u003eInsufficient evidence\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 137px;\"\u003e\n \u003cp\u003eUgolini 2021 [5]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 135px;\"\u003e\n \u003cp\u003e31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e1410\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003eHigh\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 213px;\"\u003e\n \u003cp\u003eExpansion effective\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 137px;\"\u003e\n \u003cp\u003eBenson 2021 [6]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 135px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e199\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003eLow\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 213px;\"\u003e\n \u003cp\u003eRR 2.87 (very uncertain)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 137px;\"\u003e\n \u003cp\u003eMillett 2016 [7]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 135px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003eNot reported\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003eCritically low\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 213px;\"\u003e\n \u003cp\u003eInsufficient evidence\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 137px;\"\u003e\n \u003cp\u003eMandall 2018 [8]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 135px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003eNot reported\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003eCritically low\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 213px;\"\u003e\n \u003cp\u003eNo clear evidence\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 137px;\"\u003e\n \u003cp\u003eMillett 2018 [9]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 135px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003eCritically low\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 213px;\"\u003e\n \u003cp\u003eNo evidence identified\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 137px;\"\u003e\n \u003cp\u003eTurner 2021 [10]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 135px;\"\u003e\n \u003cp\u003e24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e1512\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003eLow\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 213px;\"\u003e\n \u003cp\u003eVery low certainty\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e3.3. Quality Assessment (AMSTAR-2)\u003c/strong\u003e\u003c/h3\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 365px;\"\u003e\n \u003cp\u003eReview (Year)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 147px;\"\u003e\n \u003cp\u003eAMSTAR-2 Rating\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 176px;\"\u003e\n \u003cp\u003eConfidence\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 365px;\"\u003e\n \u003cp\u003eMillett 2017 (adhesives for bonded molar tubes) [9]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 147px;\"\u003e\n \u003cp\u003eHigh\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 176px;\"\u003e\n \u003cp\u003eHigh confidence\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 365px;\"\u003e\n \u003cp\u003eJambi 2014 (reinforcement of anchorage) [10]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 147px;\"\u003e\n \u003cp\u003eModerate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 176px;\"\u003e\n \u003cp\u003eModerate confidence\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 365px;\"\u003e\n \u003cp\u003eJambi 2013 (distalising upper first molars) [11]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 147px;\"\u003e\n \u003cp\u003eLow\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 176px;\"\u003e\n \u003cp\u003eLow confidence\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 365px;\"\u003e\n \u003cp\u003eGhaeminia 2020 (asymptomatic wisdom teeth) [12]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 147px;\"\u003e\n \u003cp\u003eLow\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 176px;\"\u003e\n \u003cp\u003eLow confidence\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 365px;\"\u003e\n \u003cp\u003eUgolini 2021 (posterior crossbites) [13]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 147px;\"\u003e\n \u003cp\u003eHigh\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 176px;\"\u003e\n \u003cp\u003eHigh confidence\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 365px;\"\u003e\n \u003cp\u003eBenson 2021 (palatally displaced canines) [14]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 147px;\"\u003e\n \u003cp\u003eLow\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 176px;\"\u003e\n \u003cp\u003eLow confidence\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 365px;\"\u003e\n \u003cp\u003eMillett 2016 (adhesives for orthodontic bands) [15]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 147px;\"\u003e\n \u003cp\u003eCritically low\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 176px;\"\u003e\n \u003cp\u003eVery low confidence\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 365px;\"\u003e\n \u003cp\u003eMandall 2018 (adhesives for orthodontic brackets) [16]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 147px;\"\u003e\n \u003cp\u003eCritically low\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 176px;\"\u003e\n \u003cp\u003eVery low confidence\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 365px;\"\u003e\n \u003cp\u003eMillett 2018 (deep bite and retroclined incisors) [17]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 147px;\"\u003e\n \u003cp\u003eCritically low\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 176px;\"\u003e\n \u003cp\u003eNo evidence identified\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 365px;\"\u003e\n \u003cp\u003eTurner 2021 (crowded teeth in children) [18]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 147px;\"\u003e\n \u003cp\u003eLow\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 176px;\"\u003e\n \u003cp\u003eLow confidence\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003ch3\u003e\u003cstrong\u003e3.4. Domain 1: Molar Attachment Selection\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003e\u003cstrong\u003eIncluded Review:\u003c/strong\u003e Millett et al. (2017) [9] \u0026ndash; \u003cem\u003eAdhesives for bonded molar tubes during fixed brace treatment\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCharacteristics:\u003c/strong\u003e Two parallel-group randomized controlled trials with low risk of bias. Total n = 190 participants. Both trials compared bonded molar tubes to molar bands. Outcomes assessed at 6, 12, and 24 months.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eKey Findings:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026middot; Bonded tubes failure rate: 57% event rate\u003c/p\u003e\n\u003cp\u003e\u0026middot; Molar bands failure rate: 25% event rate\u003c/p\u003e\n\u003cp\u003e\u0026middot; Hazard ratio: \u003cstrong\u003e2.92\u003c/strong\u003e (95% CI 1.80\u0026ndash;4.72) favouring molar bands\u003c/p\u003e\n\u003cp\u003e\u0026middot; Number needed to treat (NNT) to prevent one failure: 3.1\u003c/p\u003e\n\u003cp\u003e\u0026middot; One trial showed less decalcification with molar bands (OR 0.32, 95% CI 0.12\u0026ndash;0.86)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eQuality Assessment:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026middot; AMSTAR-2: High confidence\u003c/p\u003e\n\u003cp\u003e\u0026middot; GRADE certainty: \u003cstrong\u003eHigh\u003c/strong\u003e (consistent findings from two low-risk-of-bias RCTs)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e High-certainty evidence demonstrates that molar bands have substantially lower failure rates than bonded tubes.\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e3.5. Domain 2: Anchorage Control\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003e\u003cstrong\u003eIncluded Review:\u003c/strong\u003e Jambi et al. (2014) [10] \u0026ndash; \u003cem\u003eReinforcement of anchorage during orthodontic brace treatment with implants or other surgical methods\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCharacteristics:\u003c/strong\u003e Fifteen studies with 561 randomised patients. Studies compared surgical anchorage (mini-screws, orthodontic implants, onplants) to conventional anchorage (headgear, transpalatal arches, Nance buttons).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eKey Findings:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026middot; Mean difference of \u003cstrong\u003e1.68 mm less mesial movement of molars\u003c/strong\u003e with surgical anchorage (95% CI \u0026minus;2.27 to \u0026minus;1.09)\u003c/p\u003e\n\u003cp\u003e\u0026middot; No significant difference in overall treatment duration (mean difference \u0026minus;0.15 years, 95% CI \u0026minus;0.37 to 0.07)\u003c/p\u003e\n\u003cp\u003e\u0026middot; Subgroup analysis suggested mini-screws showed the most promising results\u003c/p\u003e\n\u003cp\u003e\u0026middot; No included studies reported on adverse effects of surgical anchorage\u003c/p\u003e\n\u003cp\u003e\u0026middot; Limited and inconclusive data on patient-reported outcomes\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eQuality Assessment:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026middot; AMSTAR-2: Moderate confidence\u003c/p\u003e\n\u003cp\u003e\u0026middot; GRADE certainty: \u003cstrong\u003eModerate\u003c/strong\u003e (consistent findings from 15 studies, but heterogeneity present)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e Moderate-certainty evidence supports that surgical anchorage provides clinically meaningful anchorage reinforcement.\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e3.6. Domain 3: Distalization as an Alternative to Extraction\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003e\u003cstrong\u003eIncluded Review:\u003c/strong\u003e Jambi et al. (2013) [11] \u0026ndash; \u003cem\u003eOrthodontic treatment for distalising upper first molars in children and adolescents\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCharacteristics:\u003c/strong\u003e Ten studies with 354 participants. Study quality generally poor (seven at high risk of bias, three unclear, none low risk).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eKey Findings:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026middot; Intraoral appliances more effective than headgear for distalising upper first molars: mean difference \u003cstrong\u003e\u0026minus;1.45 mm\u003c/strong\u003e (95% CI \u0026minus;2.74 to \u0026minus;0.15)\u003c/p\u003e\n\u003cp\u003e\u0026middot; However, intraoral appliances associated with significant loss of anterior anchorage: mesial incisor movement MD \u003cstrong\u003e1.82 mm\u003c/strong\u003e (95% CI 1.39\u0026ndash;2.24)\u003c/p\u003e\n\u003cp\u003e\u0026middot; Headgear showed less anchorage loss and better overjet control (MD 1.64 mm favouring headgear, 95% CI 1.26\u0026ndash;2.02)\u003c/p\u003e\n\u003cp\u003e\u0026middot; No studies reported on adverse effects, attendance, or compliance\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eQuality Assessment:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026middot; AMSTAR-2: Low confidence\u003c/p\u003e\n\u003cp\u003e\u0026middot; GRADE certainty: \u003cstrong\u003eLow\u003c/strong\u003e (poor study quality, heterogeneity)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e Low-certainty evidence suggests distalization is effective but associated with anterior anchorage loss.\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e3.7. Domain 4: Third Molar Management\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003e\u003cstrong\u003eIncluded Review:\u003c/strong\u003e Ghaeminia et al. (2020) [12] \u0026ndash; \u003cem\u003eSurgical removal versus retention for the management of asymptomatic disease-free impacted wisdom teeth\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCharacteristics:\u003c/strong\u003e Two studies (one RCT, one prospective cohort) with 493 participants. This review updated previous versions (2005, 2012, 2016).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eKey Findings:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026middot; \u003cstrong\u003eInsufficient evidence\u003c/strong\u003e to determine whether asymptomatic disease-free impacted wisdom teeth should be removed or retained\u003c/p\u003e\n\u003cp\u003e\u0026middot; Very low-certainty evidence suggests retention may be associated with increased risk of periodontitis affecting adjacent second molars in the long term (OR 2.3, 95% CI 1.1\u0026ndash;4.8)\u003c/p\u003e\n\u003cp\u003e\u0026middot; No evidence to support the claim that prophylactic removal prevents late incisor crowding\u003c/p\u003e\n\u003cp\u003e\u0026middot; No eligible studies reported on health-related quality of life or cost-effectiveness\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eQuality Assessment:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026middot; AMSTAR-2: Low confidence\u003c/p\u003e\n\u003cp\u003e\u0026middot; GRADE certainty: \u003cstrong\u003eVery low\u003c/strong\u003e (feasibility constraints for RCTs)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e Very low-certainty evidence is insufficient to support routine prophylactic removal of asymptomatic impacted wisdom teeth.\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e3.8. Domain 5: Posterior Crossbite (Context for Extraction vs Expansion)\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003e\u003cstrong\u003eIncluded Review:\u003c/strong\u003e Ugolini et al. (2021) [13] \u0026ndash; \u003cem\u003eOrthodontic treatment for posterior crossbites\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCharacteristics:\u003c/strong\u003e 31 studies with approximately 1410 participants. Eight studies at low risk of bias, 15 at high risk, eight at unclear risk.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eKey Findings:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026middot; Quad-helix and expansion plates effective for posterior crossbite correction in children (high-certainty evidence)\u003c/p\u003e\n\u003cp\u003e\u0026middot; Quad-helix more effective and faster than expansion plates (RR 1.29, 95% CI 1.13\u0026ndash;1.46; MD \u0026minus;3.15 months, 95% CI \u0026minus;4.04 to \u0026minus;2.25)\u003c/p\u003e\n\u003cp\u003e\u0026middot; For patients with both transverse deficiency and crowding, expansion should be considered before extraction as first-line treatment\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eQuality Assessment:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026middot; AMSTAR-2: High confidence\u003c/p\u003e\n\u003cp\u003e\u0026middot; GRADE certainty: \u003cstrong\u003eHigh\u003c/strong\u003e for main comparisons\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e High-certainty evidence supports expansion over extraction for posterior crossbite correction.\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e3.9. Domain 6: Palatally Displaced Canines (Extraction Context)\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003e\u003cstrong\u003eIncluded Review:\u003c/strong\u003e Benson et al. (2021) [14] \u0026ndash; \u003cem\u003eInterventions for promoting eruption of palatally displaced permanent canine teeth without surgical exposure\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCharacteristics:\u003c/strong\u003e Four studies with 199 randomised participants (164 analysed). All studies at high or unclear risk of bias.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eKey Findings:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026middot; Very low-certainty evidence that extraction of the primary canine may increase the proportion of successfully erupted palatally displaced canines at 12 months (RR 2.87, 95% CI 0.90\u0026ndash;9.23)\u003c/p\u003e\n\u003cp\u003e\u0026middot; No evidence that double extraction of primary teeth increases eruption compared to single extraction\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eQuality Assessment:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026middot; AMSTAR-2: Low confidence\u003c/p\u003e\n\u003cp\u003e\u0026middot; GRADE certainty: \u003cstrong\u003eVery low\u003c/strong\u003e (small sample sizes, heterogeneity)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e Evidence for primary canine extraction in palatally displaced canines is very uncertain.\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e3.10. Domains with No Umbrella-Level Evidence\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003eThe following domains had \u003cstrong\u003eno systematic reviews\u003c/strong\u003e meeting inclusion criteria:\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003eDomain\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 366px;\"\u003e\n \u003cp\u003eEvidence Status\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003eSecond molar extraction\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 366px;\"\u003e\n \u003cp\u003eNo systematic reviews identified\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003eFirst molar extraction\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 366px;\"\u003e\n \u003cp\u003eNo systematic reviews identified\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003eExtraction techniques (Physics Forceps, etc.)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 366px;\"\u003e\n \u003cp\u003eNo systematic reviews identified\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 354px;\"\u003e\n \u003cp\u003eAdhesives for bands/brackets\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 366px;\"\u003e\n \u003cp\u003eReviews exist but critically low quality (no useful evidence)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"4. Major Evidence Gaps at Umbrella Level","content":"\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 302px;\"\u003e\n \u003cp\u003eGap Area\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 282px;\"\u003e\n \u003cp\u003eDescription\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003ePriority\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 302px;\"\u003e\n \u003cp\u003eSecond molar extraction\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 282px;\"\u003e\n \u003cp\u003eNo systematic reviews exist\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eCritical\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 302px;\"\u003e\n \u003cp\u003eFirst molar extraction\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 282px;\"\u003e\n \u003cp\u003eNo systematic reviews exist\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eCritical\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 302px;\"\u003e\n \u003cp\u003eExtraction techniques\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 282px;\"\u003e\n \u003cp\u003eNo systematic reviews exist\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eHigh\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 302px;\"\u003e\n \u003cp\u003ePremolar extraction effects on third molars\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 282px;\"\u003e\n \u003cp\u003eNo systematic reviews exist\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eHigh\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 302px;\"\u003e\n \u003cp\u003eAdhesive selection\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 282px;\"\u003e\n \u003cp\u003eExisting reviews are critically low quality\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eModerate\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"5. Discussion","content":"\u003ch3\u003e\u003cstrong\u003e5.1. Summary of Evidence\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003eThis umbrella review synthesizes evidence exclusively from Cochrane systematic reviews \u0026ndash; the highest level of evidence available. \u003cstrong\u003eFigure 2\u003c/strong\u003e summarizes the certainty of evidence across all domains using GRADE levels. Key findings include:\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 211px;\"\u003e\n \u003cp\u003eDomain\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003eCertainty\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 361px;\"\u003e\n \u003cp\u003eKey Finding\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 211px;\"\u003e\n \u003cp\u003eMolar attachment selection\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHigh\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 361px;\"\u003e\n \u003cp\u003eMolar bands have lower failure rates than bonded tubes (HR 2.92)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 211px;\"\u003e\n \u003cp\u003eAnchorage control\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eModerate\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 361px;\"\u003e\n \u003cp\u003eSurgical anchorage provides 1.68 mm less mesial movement of molars\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 211px;\"\u003e\n \u003cp\u003eDistalization\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLow\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 361px;\"\u003e\n \u003cp\u003eEffective but associated with anchorage loss\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 211px;\"\u003e\n \u003cp\u003eThird molar management\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eVery low\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 361px;\"\u003e\n \u003cp\u003eInsufficient evidence for prophylactic removal\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 211px;\"\u003e\n \u003cp\u003ePosterior crossbite\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHigh\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 361px;\"\u003e\n \u003cp\u003eExpansion preferred over extraction\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 211px;\"\u003e\n \u003cp\u003eSecond molar extraction\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNo evidence\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 361px;\"\u003e\n \u003cp\u003eNo systematic reviews exist\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 211px;\"\u003e\n \u003cp\u003eFirst molar extraction\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNo evidence\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 361px;\"\u003e\n \u003cp\u003eNo systematic reviews exist\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003ch3\u003e\u003cstrong\u003e5.2. Strengths\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003eThis umbrella review has several strengths. It exclusively included Cochrane systematic reviews, ensuring high methodological rigor and consistency. The use of AMSTAR-2 and GRADE provides a transparent and robust assessment of both review quality and certainty of evidence. Furthermore, the domain-based synthesis allows clinically meaningful interpretation of findings relevant to orthodontic decision-making.\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e5.3. Comparison with Previous Literature\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003ePrevious narrative reviews have discussed second molar extraction from clinical perspectives [19,20]. However, this umbrella review reveals a critical gap: \u003cstrong\u003eno systematic reviews exist on second or first molar extraction\u003c/strong\u003e. Consequently, clinical decision-making in these areas is currently based on observational studies and expert opinion, not high-level evidence synthesis. The absence of systematic reviews on first and second molar extraction represents a critical gap in evidence-based orthodontics, highlighting a disconnect between clinical practice and high-level evidence synthesis.\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e5.4. Limitations\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003eThis umbrella review has several limitations:\u003c/p\u003e\n\u003cp\u003e\u0026middot; Only Cochrane reviews were included; non-Cochrane systematic reviews may exist but were excluded for quality consistency\u003c/p\u003e\n\u003cp\u003e\u0026middot; Several included reviews had low or critically low AMSTAR-2 ratings\u003c/p\u003e\n\u003cp\u003e\u0026middot; No systematic reviews exist for key domains (second molar extraction, first molar extraction)\u003c/p\u003e\n\u003cp\u003e\u0026middot; Publication bias cannot be excluded\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e5.5. Implications for Clinical Practice\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003eBased on umbrella-level evidence:\u003c/p\u003e\n\u003cp\u003e1. \u003cstrong\u003eMolar attachments:\u003c/strong\u003e Molar bands are recommended over bonded tubes (high-certainty evidence)\u003c/p\u003e\n\u003cp\u003e2. \u003cstrong\u003eAnchorage control:\u003c/strong\u003e Surgical anchorage (mini-screws, implants) is recommended when maximum anchorage reinforcement is required (moderate-certainty evidence)\u003c/p\u003e\n\u003cp\u003e3. \u003cstrong\u003ePosterior crossbite:\u003c/strong\u003e Expansion is preferred over extraction (high-certainty evidence)\u003c/p\u003e\n\u003cp\u003e4. \u003cstrong\u003eAsymptomatic wisdom teeth:\u003c/strong\u003e Routine prophylactic removal is not supported by high-quality evidence (very low-certainty evidence)\u003c/p\u003e\n\u003cp\u003e5. \u003cstrong\u003eSecond and first molar extraction:\u003c/strong\u003e No umbrella-level evidence exists to guide clinical decisions\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003e5.6. Implications for Research\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003eThis umbrella review identifies critical research priorities at the systematic review level:\u003c/p\u003e\n\u003cp\u003e1. \u003cstrong\u003eConduct systematic reviews on second molar extraction\u003c/strong\u003e \u0026ndash; No systematic review currently exists despite clinical prevalence\u003c/p\u003e\n\u003cp\u003e2. \u003cstrong\u003eConduct systematic reviews on first molar extraction\u003c/strong\u003e \u0026ndash; No systematic review currently exists\u003c/p\u003e\n\u003cp\u003e3. \u003cstrong\u003eUpdate low-quality Cochrane reviews\u003c/strong\u003e \u0026ndash; Several reviews have low or critically low AMSTAR-2 ratings\u003c/p\u003e\n\u003cp\u003e4. \u003cstrong\u003eConduct systematic reviews on extraction techniques\u003c/strong\u003e \u0026ndash; Including Physics Forceps and other minimally invasive methods\u003c/p\u003e"},{"header":"6. Conclusions","content":"\u003cp\u003eAt the umbrella review level (synthesizing evidence exclusively from systematic reviews and meta-analyses):\u003c/p\u003e\n\u003cp\u003e1. \u003cstrong\u003eHigh-certainty evidence (GRADE High)\u003c/strong\u003e supports that molar bands have lower failure rates than bonded tubes (HR 2.92, 95% CI 1.80\u0026ndash;4.72).\u003c/p\u003e\n\u003cp\u003e2. \u003cstrong\u003eModerate-certainty evidence (GRADE Moderate)\u003c/strong\u003e supports that surgical anchorage provides 1.68 mm less mesial movement of molars (95% CI \u0026minus;2.27 to \u0026minus;1.09) compared to conventional anchorage.\u003c/p\u003e\n\u003cp\u003e3. \u003cstrong\u003eHigh-certainty evidence (GRADE High)\u003c/strong\u003e supports expansion over extraction for posterior crossbite correction.\u003c/p\u003e\n\u003cp\u003e4. \u003cstrong\u003eVery low-certainty evidence (GRADE Very low)\u003c/strong\u003e is insufficient to support routine prophylactic removal of asymptomatic impacted wisdom teeth.\u003c/p\u003e\n\u003cp\u003e5. \u003cstrong\u003eImportantly, no systematic reviews were identified for second molar extraction, first molar extraction, or extraction techniques.\u003c/strong\u003e These represent major evidence gaps at the highest level of evidence synthesis.\u003c/p\u003e\n\u003cp\u003eUntil systematic reviews are conducted in these domains, clinical decisions regarding second and first molar extraction must rely on observational studies and clinical expertise rather than umbrella-level evidence.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003e7. Acknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors thank the Cochrane Oral Health Group for producing the systematic reviews that made this umbrella review possible. We acknowledge the foundational work of Professor William Proffit, Professor Samir Bishara, and Professor Bj\u0026oslash;rn Zachrisson.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e8. Conflicts of Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no conflicts of interest related to this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e9. Funding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research received no external funding.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e10. Ethical Approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study is a review of previously published systematic reviews and did not involve human participants or animals. Ethical approval was therefore not required.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e11. Data Availability Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data analysed in this study are available from the published Cochrane reviews cited in the reference list.\u003c/p\u003e"},{"header":"References","content":"\u003ch3\u003e\u003cstrong\u003eIncluded Cochrane Reviews (n=10)\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003e1.\u0026nbsp; \u0026nbsp;Millett DT, Mandall NA, Mattick RCR, Hickman J, Glenny AM. Adhesives for bonded molar tubes during fixed brace treatment. Cochrane Database Syst Rev. 2017;(2):CD008236.\u003c/p\u003e\n\u003cp\u003e2.\u0026nbsp; \u0026nbsp;Jambi S, Walsh T, Sandler J, Benson PE, Skeggs RM, O'Brien KD. Reinforcement of anchorage during orthodontic brace treatment with implants or other surgical methods. Cochrane Database Syst Rev. 2014;(8):CD005098.\u003c/p\u003e\n\u003cp\u003e3.\u0026nbsp; \u0026nbsp;Jambi S, Thiruvenkatachari B, O'Brien KD, Walsh T. Orthodontic treatment for distalising upper first molars in children and adolescents. Cochrane Database Syst Rev. 2013;(10):CD008375.\u003c/p\u003e\n\u003cp\u003e4.\u0026nbsp; \u0026nbsp;Ghaeminia H, Perry J, Nienhuijs ME, et al. Surgical removal versus retention for the management of asymptomatic disease-free impacted wisdom teeth. Cochrane Database Syst Rev. 2020;5:CD003879.\u003c/p\u003e\n\u003cp\u003e5.\u0026nbsp; \u0026nbsp;Ugolini A, Doldo T, Ghislanzoni LTH, Mapelli A, Giorgetti R. Orthodontic treatment for posterior crossbites. Cochrane Database Syst Rev. 2021;12:CD000979.\u003c/p\u003e\n\u003cp\u003e6.\u0026nbsp; \u0026nbsp;Benson PE, Parkin N, Dyer F, et al. Interventions for promoting eruption of palatally displaced permanent canine teeth without surgical exposure. Cochrane Database Syst Rev. 2021;2:CD012248.\u003c/p\u003e\n\u003cp\u003e7.\u0026nbsp; \u0026nbsp;Millett DT, Glenny AM, Mattick RCR, Hickman J, Mandall NA. Adhesives for fixed orthodontic bands. Cochrane Database Syst Rev. 2016;(10):CD004485.\u003c/p\u003e\n\u003cp\u003e8.\u0026nbsp; \u0026nbsp;Mandall NA, Hickman J, Macfarlane TV, Mattick RCR, Millett DT, Worthington HV. Adhesives for fixed orthodontic brackets. Cochrane Database Syst Rev. 2018;(4):CD002282.\u003c/p\u003e\n\u003cp\u003e9.\u0026nbsp; \u0026nbsp;Millett DT, Cunningham SJ, O'Brien KD, Benson PE, de Oliveira CM. Orthodontic treatment for deep bite and retroclined upper front teeth in children. Cochrane Database Syst Rev. 2018;(2):CD005972.\u003c/p\u003e\n\u003cp\u003e10.\u0026nbsp;Turner S, Harrison JE, Sharif FNJ, Owens D, Millett DT. Orthodontic treatment for crowded teeth in children. Cochrane Database Syst Rev. 2021;(12):CD003453.\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003eMethodological References\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003e11.\u0026nbsp;Mahfouz M. Protocol Versus Narrative Review Versus Systematic Review Versus Umbrella Review: A Comparative Methodological Analysis for Evidence Synthesis. Preprints. 2026;2026041300. doi:10.20944/preprints202604.1300.v1\u003c/p\u003e\n\u003cp\u003e12.\u0026nbsp;Pollock M, Fernandes RM, Pieper D, et al. Preferred Reporting Items for Overviews of Reviews (PRIOR): a protocol for development of a reporting guideline for reviews of reviews. BMJ Open. 2019;9(11):e031278.\u003c/p\u003e\n\u003cp\u003e13.\u0026nbsp;Shea BJ, Reeves BC, Wells G, et al. AMSTAR 2: a critical appraisal tool for systematic reviews that include randomised or non-randomised studies of healthcare interventions, or both. BMJ. 2017;358:j4008.\u003c/p\u003e\n\u003cp\u003e14.\u0026nbsp;Guyatt GH, Oxman AD, Vist GE, et al. GRADE: an emerging consensus on rating quality of evidence and strength of recommendations. BMJ. 2008;336(7650):924-926.\u003c/p\u003e\n\u003cp\u003e15.\u0026nbsp;Proffit WR, Fields HW, Larson B, Sarver DM. Contemporary Orthodontics. 6th ed. Elsevier; 2018.\u003c/p\u003e\n\u003cp\u003e16.\u0026nbsp;Bishara SE. Third molars: A dilemma! Or is it? Am J Orthod Dentofacial Orthop. 1999;115(6):628-633.\u003c/p\u003e\n\u003cp\u003e17.\u0026nbsp;De-la-Rosa-Gay C, Valmaseda-Castellón E, Gay-Escoda C. Spontaneous third molar eruption after second molar extraction in orthodontic patients. Am J Orthod Dentofacial Orthop. 2006;129:337-344.\u003c/p\u003e\n\u003cp\u003e18.\u0026nbsp;Færøvig LF, Pandis N, Johal A, Vandevska-Radunovic V. Mandibular second molar extraction: A retrospective cohort study of spontaneous occlusal changes in adolescent patients. Orthod Craniofac Res. 2024;27(4):606-614.\u003c/p\u003e\n\u003cp\u003e19.\u0026nbsp;Montasser ZM, Montasser MA. Therapeutic extraction of second molars in orthodontics: a scoping review. BMC Oral Health. 2025;25(1):26.\u003c/p\u003e\n\u003cp\u003e20.\u0026nbsp;Türköz C, Ulusoy C. Effect of premolar extraction on mandibular third molar impaction in young adults. Angle Orthod. 2013;83(4):572-577.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"umbrella review, molar extraction, orthodontics, Cochrane review, GRADE","lastPublishedDoi":"10.21203/rs.3.rs-9503209/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9503209/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e Molar extraction in orthodontics is used to manage severe crowding, correct Class II and Class III malocclusions, address compromised teeth, and facilitate alveolar realignment. An umbrella review synthesizes evidence from systematic reviews and meta-analyses, representing the highest level of evidence.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e This umbrella review followed PRIOR guidelines. The Cochrane Database of Systematic Reviews was searched (2010–2025), with the final search conducted in January 2026. Only systematic reviews and meta-analyses were included. Ten Cochrane reviews met inclusion criteria. Methodological quality was assessed using AMSTAR-2, and certainty of evidence was evaluated using GRADE.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eHigh-certainty evidence (AMSTAR-2 high; GRADE high) from two RCTs (n = 190) indicates that molar bands have lower failure rates than bonded tubes (HR 2.92, 95% CI 1.80–4.72; NNT = 3.1). Moderate-certainty evidence (GRADE moderate) from 15 studies (n = 561) shows that surgical anchorage results in 1.68 mm less mesial movement of molars (95% CI −2.27 to −1.09). Low-certainty evidence suggests intraoral distalizers are more effective than headgear (MD −1.45 mm) but with greater anchorage loss (MD 1.82 mm). Very low-certainty evidence is insufficient to support routine prophylactic removal of asymptomatic third molars. No umbrella-level evidence was identified for first or second molar extraction.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion: \u003c/strong\u003eHigh-certainty evidence supports the use of molar bands over bonded tubes. Moderate-certainty evidence supports surgical anchorage. Evidence for prophylactic third molar removal is insufficient. Major evidence gaps exist for first and second molar extraction.\u003c/p\u003e","manuscriptTitle":"Molar Extraction in Orthodontics: An Umbrella Review of Cochrane Systematic Reviews","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-24 06:22:53","doi":"10.21203/rs.3.rs-9503209/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"14444f99-726e-425b-aac5-f76e96224577","owner":[],"postedDate":"April 24th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":66861615,"name":"Dentistry"}],"tags":[],"updatedAt":"2026-04-24T06:22:53+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-24 06:22:53","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9503209","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9503209","identity":"rs-9503209","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}