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 52-year-old African-American male patient was referred to the emergency clinic of the Department of Oral Medicine at the University of Pennsylvania School of Dental Medicine by a private dentist for possible extractions of the maxillary left first molar, mandibular left third molar, and second premolar due to severe periodontal bone loss and pain.\nA comprehensive intraoral and extraoral exam was completed. The patient was well developed and well nourished. Tooth vitality tests were performed; the dental complaint of pain was odontogenic in nature, and was limited to the maxillary left first molar, mandibular left third molar, and second premolar. There was no evidence for suppuration or swelling. Bilateral mandibular tori were noted. The temporomandibular joint (TMJ) exhibited a full range of motion, and neither crepitus nor clicking were noted. The patient denied any history of pain associated with the TMJ or myofascial pain related to the muscles of mastication. Cranial nerves II through XII were grossly intact. Submandibular lymph nodes were palpable, non-tender, and mobile. The patient's vital signs were within the normal limits. The patient denied taking any medications other than a course of antibiotics prescribed for the periodontal infection by his general dentist.\nA panoramic radiograph, taken after the initial examination, revealed that the maxillary left first molar exhibited severe vertical bone loss, the mandibular left third molar was symptomatic with an apical rarefying osteitis in relation to the mesiobuccal root, and the mandibular left second premolar was symptomatic with irreversible pulpitis (based on vitality tests) and appeared to be non-restorable. The panoramic examination also revealed an atypical bone cavity that presented as an ovoid radiolucency with well-defined, corticated borders at the superior region of the ascending left ramus (). The area was asymptomatic and appeared to have no relationship with the chief dental complaint. The area appeared to be non-odontogenic in nature. The patient denied any active medical conditions or knowledge of mandibular atypia prior to the dental examination at our clinic.\nCBCT was recommended to visualize the lesion 3-dimensionally. A medium-volume CBCT scan was performed at a voxel resolution of 200 µm (CS 9300, Carestream, Atlanta, GA, USA). The depression was a round, well-circumscribed radiolucency, corticated, and its maximal dimensions were 5.4×10×6.3 mm in the coronal, sagittal, and axial multi-planar reconstruction images (, , ). presents a panoramic reconstruction of the CBCT volume showing the depression. In the axial cross sections, the well-defined lytic area was located on the posterior border of the ascending ramus on the lingual aspect ().\nBased on the clinical and radiographic features of the lesion, a provisional diagnosis of a developmental salivary gland depression of the left ramus was made. The differential diagnosis included a static bone cavity, or a simple bone cyst, a benign tumor of salivary gland or fatty origin. Although we did not expect the defect to change in size over time, a clinical and radiographic follow-up was recommended to the patient. The patient was cleared for the extractions and was scheduled for annual follow-up.