CBCT analysis of incisor movement and alveolar bone changes in class two malocclusion treatment with premolar extraction using clear aligner: a retrospective study

Abstract

Objectives

This retrospective study evaluates alveolar bone remodeling patterns and their association with incisor displacement in adults undergoing clear aligner therapy with premolar extractions for Class II malocclusion correction.

Methods

Cone-beam computed tomography (CBCT) scans of 38 maxillary and 37 mandibular incisors were analyzed. Displacement vectors for four anatomical landmarks (cusp tip [C], root apex [R], root neck midpoint [M], labial cementoenamel junction [L]) were quantified. Alveolar bone thickness was measured at mid-root and apical levels. Statistical analyses included Spearman correlations and multivariate regression.

Results

Post-treatment maxillary incisors demonstrated labial bone thickening (+0.36±0.44 mm central; +0.15±0.42 mm lateral) with concurrent palatal bone resorption (-0.43±0.64 mm central; -0.22±0.92 mm lateral, P < 0.05). Negative correlations emerged between mid-root thickness of the palatal bone (B2-B2′) at R in central incisors (P < 0.05), while lateral incisors showed positive associations between mid-root thickness of labial bone (A2- A2′)and C and M displacements (P < 0.05). Mandibular central incisors showed a negative correlation at the mid-root level with points C, M, R, and L (P<0.01), and a multiple regression highlight between point M and (B2-B2′) (P<0.05).

Conclusions

Differential maxillary-mandibular bone responses to clear aligner mechanics highlight the necessity for torque-optimized aligner designs and CBCT-monitored treatment staging to mitigate excessive resorption.