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 76-year-old at death male Caucasian cadaveric head (fresh-frozen) was dissected. During routine dissection of the head, the mandible was dissected, and the soft tissues of the mandible were removed. After the mandible was separated from the head, a large bony defect was found on the lingual surface of the right mandible, which was located 25.2 mm anterior to the angle of the mandible and 3.3 mm superior to the inferior border of the mandible. The shape and size of the bony defect was oval and 10.8×6.0 mm, respectively (, ). The bony defect had a smooth surface and did not show any pathological condition. Therefore, it was determined to be an SBC. The SBC had continuity with the right mylohyoid groove. The depth of the SBC and width of the mandible at the SBC was 4.15 mm, 3.14 mm, respectively. The SBC was not observed on the left side.