A 40-year-old male patient was referred to a private clinic for endodontic treatment of teeth with a periapical lesion in his premolar region of mandible that was discovered during routine radiographic examination. Panoramic radiography revealed a unilocular periapical radiolucency below the apex of the mandibular left canine extending to the second premolar (Figure ). On the periapical radiograph, the lesion mimicked a radicular cyst; however, the teeth were asymptomatic and the periodontal ligament space and lamina dura were intact. The teeth also gave a positive response to the sensibility tests. The patient had no history of trauma to the jaw. Clinical examination revealed no facial asymmetry and no lymphadenopathy. The most likely diagnosis was a nonodontogenic cyst.\nIt was decided to examine the lesion by CBCT to evaluate the relationship of the lesion with its surrounding structures and reach a definite diagnosis. CBCT images were taken by NewTom CBCT system (NewTom VG) with the exposure settings of 110 kVp, 59.62 mA, 4.3 seconds exposure time, 5 × 5 cm field of view, and 14-bits gray scale. The CBCT scans revealed a well-defined lingual defect in the canine to second premolar region with no connection to the base of the mandible and a cyst-like appearance. Evaluation of axial, coronal, and sagittal sections confirmed a lingual wall defect; the buccal wall was intact and there was no expansion. The mental foramen was clearly demarcated from the radiolucency by cortical bone and was not part of the lesion. The root apices of the first and second premolars directly contacted the lesion with no sign of resorption (Figure ).\nFor more evaluation of the internal contents of the defect, we used the software's ability to determine the gray scale value. The gray scale value of the main contents of the defect in the middle section was approximately in the range of −78 to 202 with a mean (± standard deviation) of 108 (±31). The mean gray scale value for the adjacent lingual soft tissue was 108 (±52). The lesion was clearly related to the adjacent lingual soft tissue, which could be the anatomical location of sublingual gland with approximately similar gray scale value (Figure ). Thus, this defect could be classified into the group with range of soft tissues.\nConsidering the dental and clinical history of the patient and the radiographic features, the defect was diagnosed as a premolar region variant of lingual bone depression and regular follow-ups were scheduled for the patient.
A 49-year-old asymptomatic male patient was referred to a private clinic in order to undergo routine panoramic radiography. Results showed an oval-shaped, radiolucent area of cystic aspect and regular, well-defined cortical outline; its longest axis was placed horizontally in the left hemimandible. This lithic area, located under the lower left third molar, was anterior to the mandibular angle, and reached the border of the mandible, which showed thinner than normal width due to the presence of the bone defect. The apparent unity of the upper contour of the lesion and the upper wall of the mandibular canal gave them a thicker than normal appearance. The fact that the lower wall of the mandibular canal was visible within the radiolucent area showed that there could be a neighboring relationship, but not an involvement, of the inferior alveolar nerve ().\nAs a hard buccal protuberance was perceived on palpation, a CT was performed. The coronal view in the CT scan showed that there had been a distention of the mandibular buccal cortex and that glandular tissue had been spreading into the bone defect. A further coronal view revealed the buccal location of the mandibular canal, which was preserved (Figures and ).\nA previous scintigraphy revealed an inflammatory condition associated with an obstructive process involving the submandibular glands, particularly on the left side ().