Abstract
Clear aligner therapy (CAT) has become a popular alternative to fixed orthodontic appliances. However, persistent methodological issues challenge the evaluation of its effectiveness.
Most studies rely on small-scale, non-randomised, retrospective designs, raising concerns about selection bias and limited external validity. Other methodological shortcomings, including unclear treatment endpoints, inadequate adjustments for confounding variables, and a lack of long-term outcomes, further complicate comparisons with fixed appliances.
While CAT demonstrates potential advantages in maintaining oral hygiene, reducing plaque accumulation, and preventing white spot lesions, its effectiveness in achieving complex tooth movements, such as rotations and root torque, remains quite limited. Although CAT appears to be effective for mild to moderate malocclusions, fixed appliances may still achieve better outcomes in more complex cases.
Until future research addresses these methodological gaps and establishes a stronger evidence base, clinicians are advised to prescribe CAT cautiously, especially for complex treatments.