A 17-year-old male patient attended the oral and maxillofacial surgery clinic in King Saud University requesting extraction of all third molars. The patient’s medical history was unremarkable; he was a non-smoker and revealed no history of previous facial trauma or surgery. There was neither pain nor swelling of the buccal and lingual sulci of the mandible and no cervical lymphadenopathy. Initial dental examination revealed a minimally restored permanent dentition with good oral hygiene. A panoramic radiograph showed that all third molars were present and impacted except on the upper right side where the tooth was missing, with the lower third molars in close proximity to the inferior alveolar canals (Figure ). The radiograph was otherwise unremarkable with no signs of pathology or abnormality.\nA CBCT of the mandible was requested for further assessment of the relation and proximity of the roots to the inferior alveolar canal. A survey of the CBCT sections of the mandibular body revealed bilateral sublingual depressions inferior to the premolars and first molars extending to the inferior border of the mandible that was not seen on the panoramic radiograph.\nTo assess the depth and width of these depressions, the CBCT images were reconstructed in planes aligned with the axes of the right and left mandibular second premolars in the mesiodistal dimension, buccolingual dimension, and the coronoapical dimension. Then, linear measurements representing the width of the depressions were made along a line drawn a tangent to the heights of contours (crest of curvatures) of the lingual surfaces of the mandible superior and inferior to the bilateral depression. The superoinferior width of the depressions was found to be 2.1 cm on the right side and 2.9 cm on the left side. Linear measurements representing the buccolingual depth of the depressions were made along a line drawn perpendicular to the above-mentioned width line to the deepest point of the depression; it measured 0.59 cm on the left side and 0.6 cm on the right side. The buccolingual thickness of the remaining mandible was 0.42 cm on the left side and 0.45 cm on the right side (Figures -).\nThe diagnosis was concluded to be bilateral sublingual depressions of the mandible. It is considered a normal anatomical variation that does not require any further investigation or intervention. The incidental finding was documented in the patient dental record for future implications in case an implant placement was needed.
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.