Systematic review and meta-analysis: accuracy of clear aligner in premolar extraction case

Purpose To evaluate the accuracy of clear aligner therapy in maxillary first premolar extraction cases by comparing virtual and clinically achieved tooth movements for maxillary incisors, canines, premolars, and molars.Materials and methods A systematic search of PubMed, Embase, Scopus, and Google Scholar was performed up to August 2025 following PRISMA guidelines. Nine retrospective studies (Invisalign®) that directly compared virtual and actual tooth movement using three-dimensional measurements were included. Data on 3 linear (mesiodistal, vertical, buccolingual) and 3 angular (tipping, torque, rotation) movements were screened. Meta-analyses were performed using either fixed or random effects models based on the heterogeneity. Publication bias was assessed using funnel plots and Egger’s test, with sensitivity analyses assessed using the trim-and-fill method.Results Maxillary incisors appeared to show underexpression of bodily retraction and root control, with greater-than-planned lingual tipping and extrusion. Canine distalization showed considerable variability and limited predictability, with reduced tipping control. Posterior teeth suggest a tendency towards anchorage loss, characterized by mesialization and mesial tipping of the maxillary second premolar and first molar, sometimes accompanied by unexpected molar intrusion. Movements requiring bodily translation, torque expression, and anchorage preservation appeared to have the lowest predictability. Substantial heterogeneity (I2 often > 50%) likely reflects variation in clinical protocols and measurement methods, although sensitivity analyses did not change the direction of the observed effects.Conclusion Although clear aligner therapy (CAT) can achieve space closure in premolar extraction cases, bodily movement, root control, and anchorage maintenance seem to be less consistently achieved than predicted in aligner-based extraction mechanics.