A Longitudinal Cone Beam Computed Tomography Study of Mandibular Canal Changes During Growth

Introduction The mandibular canal has been considered a stable anatomic reference structure and continues to be recognised as a primary vertical structure in 2D mandibular superimposition. However, whether the mandibular canal is stable in the transverse dimension is unclear. Material and Methods This retrospective longitudinal study utilised cone beam computed tomography (CBCT) images of 17 subjects (9.15 ± 1.79 years old at T1 and 11.47 ± 1.82 years old at T2) who did not have orthodontic or orthopaedic intervention. Mandibular superimposition in 3D of T1 and T2 images was performed, and a series of coronal slices was selected antero‐posteriorly. On each coronal slice, the width and height of the mandibular canals, the distance between left and right canals, as well as the distance between each mandibular canal and the buccal, lingual and inferior surface of the mandible were evaluated. The yearly change of each parameter was calculated. Results The vertical and horizontal dimensions of the canal were relatively stable in the posterior region of the mandible; both dimensions increased in the anterior region. In addition, a lateral shift of the mandibular canal was observed, but not in a bodily movement fashion nor a straight V‐shape pattern. The mandibular canal location related to the mandibular body also constantly changed during mandibular growth. Conclusion In the period of mixed dentition to early permanent dentition, the dimensions and lateral location of the mandibular canal demonstrated significant developmental changes.