Efficacy of upper-incisor torque control with clear aligners: a retrospective study using cone-beam computed tomography.

OBJECTIVES: The objectives of this retrospective clinical study were to evaluate the efficacy of clear aligners on upper-incisor torque control, with the expectation of providing guidance for clinics. MATERIALS AND METHODS: Pretreatment (T0) and posttreatment (T1) cone-beam computed tomography (CBCT) scans of 47 patients with a nonextraction treatment using clear aligners were obtained and 120 upper-incisors with torque >/=5 degrees were selected. Voxel-based superimpositions were performed using Dolphin imaging software and achieved movements were then measured. Difference between achieved and predicted movement (DAPM) and the efficiency for upper-incisor torque were used to evaluate the torque control efficacy. RESULTS: The achieved torque movement with clear aligners was lower than predicted significantly, as the mean efficiency was 46.81+/-33.95%. Additionally, the achieved incisor movement of the crown and root differed significantly from the predicted movement, especially root movement. CONCLUSIONS: Clear aligners struggle to control upper-incisor torque, particularly root movement. In that case, overcorrection is necessary to prevent torque loss. CLINICAL RELEVANCE: Clear aligners remain a limitation on torque control and overcorrection should be considered.