Clear aligner therapy for early orthodontic treatment in children aged 6–13 years: A scoping review of clinical performance and evidence gaps

BACKGROUND: Clear aligner therapy has expanded substantially in mixed dentition, yet the boundaries of clinical predictability across indications, movement types, and growth stages remain incompletely defined. The aim of this review was to synthesize evidence on clear aligner therapy in mixed dentition, describe indication-specific performance patterns, and identify evidence gaps that limit clinical confidence. METHODS: This scoping review was reported in accordance with PRISMA-ScR. PubMed/MEDLINE, Embase, and Scopus were systematically searched for studies published from 2000 to 2025. Additional records were identified through Google Scholar and reference list searching. Randomized controlled trials, prospective and retrospective cohorts, and cross-sectional studies were eligible. Data were charted and synthesized descriptively. RESULTS: Fifty-nine studies were included (8 randomized controlled trials, 11 prospective cohorts, 38 retrospective cohorts, 2 cross-sectional), most involving children aged 7 to 12 years. Achieved transverse dentoalveolar expansion with clear aligners was lower than planned, particularly posteriorly and at gingival levels. Comparative studies suggested greater posterior and palatal changes with rapid maxillary expansion. Mandibular advancement aligners were associated with Class II sagittal improvement, with responses varying by skeletal maturity and dentoskeletal pattern. Evidence for incisor correction, molar movement, vertical outcomes, airway, oral health, patient-reported outcomes, and smile esthetics remained limited. CONCLUSIONS: Clear aligners in mixed dentition demonstrate indication-dependent predictability influenced by movement type, anatomical region, and growth stage. Clinical confidence remains limited by retrospective evidence, heterogeneous outcome measures, and insufficient standardized reporting of post-treatment stability.