Assessing the reliability of aligners for arch expansion: a scoping review

The correction of transverse discrepancies, typically achieved through dentoalveolar expansion is a crucial step in orthodontic treatment. As of late, aligners have emerged as an alternative to traditional multi-attachment treatments in orthodontics. Given advancements in their biomechanical capabilities, aligners can now address a broader range of dental movements, thereby extending their indications. This review aims to evaluate the reliability of aligners in arch expansion. A comprehensive literature search was conducted using the MEDLINE, Scopus, and Web of Science databases. We included randomized and non-randomized trials, cohort studies, as well as prospective and retrospective studies that assessed the reliability of aligners in both mixed and permanent dentition through the analysis of the efficacy, predictability and movement pattern of correction. The results of expansion achieved were also compared to other conventional devices. The search yielded 212 articles, 13 of which met the eligibility criteria: 8 focused on permanent dentition and 5 on mixed dentition. Most studies were retrospective and published within the last 5 years. The results of expansion achieved were compared to other conventional devices in mixed dentition and only to the expansion planified with ClinCheck in the permanent dentition due to the lack of comparative studies with fixed appliance. Our review demonstrated that aligners are effective in both mixed and permanent dentition, with the greatest expansion occurring in the premolar region, primarily due to buccal movement. Our findings support the use of aligners as a reliable and effective option for mild to moderate dentoalveolar arch expansion in both permanent and mixed dentition.