Clinical outcome of maxillary arch expansion with clear aligners in mixed dentition: A systematic review

Maxillary transverse deficiency, affecting approximately 21% of patients in the mixed dentition stage, represents a common skeletal discrepancy in orthodontics. Clear aligners have demonstrated efficacy in achieving maxillary arch expansion, alleviating crowding, and meeting orthodontic treatment objectives. This review aims to systematically evaluate and synthesize the available evidence on the clinical outcomes of maxillary arch expansion using clear aligners in the mixed dentition period. The protocol was registered in PROSPERO (CRD42024542510) and the review followed Preferred Reporting Items for Systematic reviews and Meta-Analysis guidelines. A comprehensive literature search was conducted using the electronic databases PubMed, Cochrane Library, Web of Science, Embase, and Scopus. A gray literature search was also done to identify unpublished or ongoing studies. An additional manual search was conducted up to October 15, 2025. The risks of bias (quality) assessment was done by the Cochrane book for ROBINS-I tool. The visualization of the risk of bias assessment was generated using the risk of bias visualization tool. The initial search yielded 659 studies, with 470 remaining after removing duplicates. After screening, 457 studies that were not relevant were removed. Out of 13 full-text articles assessed, 2 were excluded based on selection criteria, resulting in 11 studies included in the qualitative synthesis. Clear aligner therapy is effective in maxillary arch expansion in the mixed dentition period and is a reasonable alternative to traditional maxillary expanders for limited transverse maxillary deficiency.