Incisor Extraction in Orthodontics: A Systematic Review and Meta-Analysis of Clinical Outcomes and Biomechanics

Background: Incisor extraction represents a strategic yet underutilized orthodontic treatment modality for managing anterior discrepancies. Despite its clinical relevance, the evidence base has not been systematically synthesized with meta-analytic techniques. Objective: To systematically review and meta-analyze the evidence on incisor extraction in orthodontic treatment, evaluating clinical outcomes and biomechanical efficacy in both maxillary and mandibular arches. Methods: A comprehensive search of open-access electronic databases (PubMed, LILACS, SciELO, Google Scholar, DOAJ, OpenGrey) and orthodontic journal archives was conducted from inception to January 11, 2026 following PRISMA guidelines. Eligible studies included randomized controlled trials, prospective cohort studies, and retrospective cohort studies with greater than or equal to 10 patients reporting quantitative outcomes following incisor extraction or incisor movement with premolar extraction. Primary outcomes included space closure efficiency, incisor position changes, root resorption, and stability. Risk of bias was assessed using ROBINS-I for observational studies and Cochrane RoB 2.0 for RCTs. Certainty of evidence was evaluated using GRADE. Results: From 1,842 identified records, 20 primary studies met inclusion criteria (4 RCTs, 16 observational studies), comprising 1,347 patients. Sixteen studies provided data for meta-analysis. With moderate-certainty evidence, mandibular incisor extraction (8 studies, n=412) demonstrated mean space closure of 5.2 mm (95% CI 4.8 to 5.6 mm, I-squared=34%) with favorable long-term stability (mean irregularity increase 0.3 mm, 95% CI 0.1 to 0.5 mm, I-squared=28%). Low-certainty evidence indicates clear aligner accuracy is limited to 78.9% of predicted incisor tip movement (3 studies, n=187, 95% CI 72.3 to 85.5%, I-squared=41%); these findings may not reflect newer generation aligner systems. Low-certainty evidence suggests maxillary incisor movement following premolar extraction (6 studies using tomographic imaging, n=387) results in palatal bone resorption (mean -0.43 mm, 95% CI -0.62 to -0.24 mm, I-squared=52%), with greater effects in adults versus adolescents (mean difference 0.31 mm, p = 0.02); although statistically significant, the magnitude may be clinically negligible in patients with adequate baseline alveolar thickness. Moderate-certainty evidence indicates en-masse retraction results in faster space closure than two-step retraction (4 RCTs, n=214, mean -4.2 months, 95% CI -5.8 to -2.6 months). Moderate-certainty evidence shows root resorption incidence is 12.4% (95% CI 8.7 to 16.1%), with subgroup analysis: greater than 2 mm threshold 13.2% (7 studies), at least one-quarter root length threshold 11.4% (5 studies). Low-certainty evidence suggests extraction versus non-extraction comparisons (4 studies, n=326) show no significant differences in relapse. Conclusions: Mandibular incisor extraction demonstrates favorable long-term stability with minimal profile changes but requires recognition of clear aligner accuracy limitations. Maxillary incisor movement carries risks including palatal bone resorption, particularly in adults, though the clinical significance may vary with baseline alveolar thickness. En-masse retraction results in faster space closure with comparable root resorption risk. Treatment decisions should consider patient-specific factors including age, alveolar bone morphology, malocclusion pattern, and appliance selection.