Incisive Canal Proximity to Maxillary Central Incisor Roots in Relation to Maxillary Dental Midline Deviation: A Retrospective Cone-Beam Computed Tomography Study

The spatial relationship between the incisive canal (IC) and maxillary central incisors (U1) is a critical anatomical consideration during orthodontic tooth movement, particularly in patients with maxillary dental midline deviation. This study aimed to evaluate the proximity between the IC and U1 roots in relation to maxillary dental midline deviation using cone-beam computed tomography (CBCT) images. Sixty-four patients with skeletal Class I malocclusion were divided into two groups according to the degree of the maxillary dental midline deviation. Group 1 (n = 32; mean age, 23.95 ± 5.40 years) exhibited < 2 mm deviation (0.28 ± 0.39 mm), whereas Group 2 (n = 32; mean age, 27.75 ± 6.21 years) showed > 2 mm deviation (2.45 ± 0.57 mm). CBCT images were analyzed to measure U1 root length and inclination, IC width, inter-root distance, and U1-IC proximity. In Group 2, the anteroposterior U1-IC distance on the deviated side was significantly shorter than on the contralateral side (p < 0.05), while the shortest U1–IC distances did not differ significantly between sides (p > 0.05). Moreover, a significant negative correlation was observed between differences in U1 inclination and root proximity at most vertical levels, indicating that a more proclined U1 on the deviated side tended to be closer to the IC. These findings suggest that maxillary dental midline deviation may be associated with asymmetric positioning of the U1 relative to the IC and underscore the importance of careful three-dimensional evaluation and individualized biomechanical control when planning orthodontic treatment in patients with midline asymmetry.