Effectiveness of dental arch expansion in the orthodontic treatment with clear aligners: a scoping review.

Background: The clinical protocol and effectiveness of dental expansion with Clear Aligner Therapy (CAT), especially among adults is still unclear. There is a need to map and explore knowledge gaps of dental expansion with CAT among children and adults.

Objective: This scoping review explores the extent and depth of the available literature regarding the effectiveness and predictability of CAT in performing orthodontic expansion in both children and adults.

Methods: The following databases were consulted as sources of information: PubMed, MEDLINE, Embase, Web of Science, Scopus, LILACS, COCHRANE Library, and ProQuest Dissertations & Thesis, in which the search was limited to studies on children or adults requiring transverse arch expansion and using clear orthodontic aligners. Two independent reviewers assessed the citations and extracted data, which was then synthesized in a narrative format.

Results: Over all, 698 citations were retrieved, and 33 were included. Among these, 3 were systematic reviews, 4 were cohort studies, 2 were case-control studies, and 24 were case series. Eighty-five percent of the included studies were published in the last 5 years. Despite different protocols and measurement methods, aligners were effective for arch expansion in adults and children, and the expansion predictability was greater for the lower arch than for the upper arch. The evidence suggests that arch width increment is more predictable in the premolar region and less predictable in the canine and second molar areas, with high variability across studies.

Conclusions: Orthodontic aligners have demonstrated effectiveness in expanding arches in both adults and children. However, the literature suggests a decrease in arch width toward the posterior region, and there is no evidence of skeletal gains. To provide more conclusive evidence, randomized controlled clinical studies are warranted.

Registration: This review was registered in the Open Science Framework database (DOI: https://doi.org/10.17605/OSF.IO/6EG8F).