Predictability of tooth derotation with clear aligners and its influencing factors: a retrospective study.

Introduction: This study aims to evaluate the predictability of derotation in incisors, canines, and premolars, as well as to determine overtreatment ratios associated with derotation using clear aligners.

Methods: This study included 461 rotated teeth from 44 patients undergoing Invisalign® (Align Technology, Santa Clara, CA) clear aligner treatment. The sample was divided into maxillary and mandibular incisors, canines, and premolars. The occlusal and mid-sagittal planes were constructed, and derotation angles and efficiencies were measured using intraoral scans imported into Geomagic Control X (3D Systems, Rock Hill, SC, USA, 2022). Age, sex, skeletal patterns, derotation direction, anterior spacing, premolar extraction, attachment types, and direction of intermaxillary elastics traction were recorded and analyzed for their correlation with derotation discrepancies. Calibrated predictability values were reevaluated, and the corresponding overtreatment design ratios were determined.

Results: There was no significant difference in derotation effectiveness across tooth types (P > 0.05). The discrepancy between the predicted and achieved derotation values was significantly correlated with the designed derotation values for maxillary teeth and mandibular incisors (P < 0.001). Multivariate analysis revealed that age, sex, skeletal patterns, derotation direction, anterior spacing, premolar extraction, attachment types, and direction of intermaxillary elastics traction differentially influenced derotation movements. The suggested overtreatment ratios for maxillary incisors, mandibular incisors, maxillary canines, and maxillary premolars are 27%, 30%, 35%, and 38%, respectively.

Conclusions: Derotation predictability is primarily influenced by factors such as the magnitude of derotation, available space, derotation direction, intermaxillary elastics traction direction, and the mesiodistal/buccolingual ratio, but not by the type of attachment used.