Do treatment outcomes of clear aligners remain stable over time? A systematic review.

Abstract

Objective: This review systematically evaluated the evidence on clear aligner therapy, focusing on its dentoskeletal, periodontal, and patient-related advantages over traditional appliances.

Materials and methods: A comprehensive literature search was conducted in PubMed, Scopus, and Web of Science for relevant studies published between January 2015 and March 2025. The two authors independently assessed the titles and abstracts of conceivably eligible papers. Disputes between the two examiners were settled by discussion, and a third party was consulted for a conclusive decision. The review question was formulated using the population, intervention, comparison, and outcome (PICO) framework. The risk of bias instrument RoB-2 was used to assess the risk of bias in randomized controlled trials (RCTs). The Risk of Bias in Non-randomized Studies of Interventions (ROBINS-I) method was used in assessing non-randomized studies.

Results: The search identified 196 studies, of which 55 underwent full-text review, and 15 met the inclusion criteria. Thirteen were non-randomized studies and two randomized. Six examined long-term aligner outcomes without comparison, three compared aligners with twin block appliances, one with an untreated group, and six with fixed appliances. According to the ROBINS-I tool, three studies showed low, three moderate, and seven high risk of bias (RoB), while both RCTs had low risk according to RoB-2.

Conclusion: Clear aligners enhance dental aesthetics and periodontal health relative to conventional fixed appliances, offering potential benefits in treatment length and patient comfort.