Alveolar Bone Changes Post-Extraction Retraction In Clear Aligner Patients

This study assessed alveolar bone height/thickness changes in the maxillary anterior region at pretreatment (T1), post-treatment (T2), and retention (T3) in adults with maxillary protrusion treated with clear aligners and premolar extraction, aiming to guide safe anterior retraction. This retrospective study included 15 patients (2 males, 13 females) with maxillary protrusion who underwent extraction of bilateral maxillary first premolars and anterior teeth retraction using clear aligners. Cone beam computed tomography (CBCT) images were collected at T1, T2, and T3 (≥18 months post-treatment) to measure vertical (labial/palatal, mesial/distal) and horizontal (labial/palatal, total thickness) alveolar bone parameters. Statistical analysis was performed using SPSS 26.0 to assess changes across phases and correlations. During orthodontic treatment, the cementoenamel junction (CEJ)-alveolar crest distance increased significantly on palatal and mesial surfaces, with labial bone thickening at mid-root/apical regions of central incisors but palatal cervical thinning (P < 0.05). Retention partially restored vertical bone height and stabilized labial thickness, yet palatal bone loss persisted at lateral incisors/canines (−0.08 ± 0.68 mm cervically, P > 0.05). Bone resorption during treatment negatively correlated with retention-phase regeneration (central incisor labial height: r = −0.665, P < 0.05). Clear aligner retraction increased labial bone thickness but reduced palatal dimensions; partial retention recovery linked to prior resorption. CBCT aids bone monitoring and retraction design optimization.