Preoperative clinical and radiographic examinations. (A) An extraoral cutaneous sinus tract presenting as an erythematous, smooth and non-tender nodule with crusting about 1 cm in diameter in the right submandibular region. (B) Preoperative clinical view of the right mandibular second molar with extensive glass-ionomer restoration. (C) A pretreatment radiograph of tooth #47 revealing obvious periapical radiolucency. CBCT imaging of the sagittal (D and E), coronal (F and G) and axial view (H-J) showing the extent of bone loss around the apexes and the distolingual (DL) root with curvature in the coronal third and additional buccal curvature from the middle third to the apical third. (K) The 3D - reconstruction of the CBCT showing the perforation of the lingual cortical plate. DB, distobuccal; MB, meisobuccal; DL, distolingual; ML, meisolingual.