Mesiodistal angulation change of the maxillary lateral incisor in the extraction treatment by clear aligner- a retrospective cone-beam computed tomography study

Abstract

Abstract Objective This study evaluated changes in the mesiodistal angulation of the maxillary lateral incisors during extraction with clear aligners using panoramic images reconstructed from cone-beam computed tomography (CBCT) images and identified the main influencing factors for reducing the distal inclination of the maxillary lateral incisors during extraction. Methods This study analyzed 27 patients (mean age 21.1 ± 4.9 years; 18 women, 9 men) who underwent extraction with clear aligners. In total, 54 maxillary lateral incisors were included—each patient contributed two teeth. CBCT scans were obtained at pretreatment and refinement. The projection of the midpalatal suture on the panoramic image helped measure the axial angulation of the maxillary lateral incisors. Three-dimensional reconstruction was performed using Mimics, and the maxillary structure superimpose method was employed to measure the horizontal distance of the maxillary lateral incisors. Influencing factors, including lateral incisor attachment, lateral incisor horizontal movement distance, upper dentition retraction method, and lateral incisor crown-to-root ratio, were analyzed. P 0.05). Conclusions During extraction by clear aligner, changes in the mesiodistal angulation of the maxillary lateral incisor should be considered to ensure satisfactory treatment outcomes. By adding attachments and designing the canine first retraction method, the distal inclination of the lateral incisors can be reduced.

Keywords

• Maxillary lateral incisors
• Mesiodistal angulation
• Extraction treatment
• Clear aligner