MCI observed on the panoramic reconstruction of the CBCT image with 5 mm (a-c), 15 mm (d-f), and 25 mm (g-i) thicknesses. The columns correspond to the MCI classification: C1 (column 1), C2 (column 2), and C3 (column 3). CBCT, cone-beam CT; MCI, mandibular cortical index.