Two findings that should be recognised and left alone — or investigated

Correct answer: C. Stafne defect

• A. A residual cyst requires a previous extraction of a non-vital tooth and sits within the alveolus, above the canal, not beneath it.
• B. A traumatic bone cyst lies ABOVE the mandibular canal in the alveolar bone, characteristically scalloping upward between the roots of vital teeth, and occurs typically in younger patients.
• C. CORRECT. The STAFNE DEFECT — also called the static bone cavity or lingual mandibular salivary gland depression — is a developmental concavity on the LINGUAL surface of the mandible containing normal SUBMANDIBULAR salivary gland tissue or fat. Its defining features are exactly those described: located BELOW the mandibular canal between the canal and the inferior border, at the angle or molar region, well-defined and densely corticated, entirely asymptomatic, and UNCHANGING over years. It requires NO treatment. Recognising it and leaving it alone is the whole of management; where the appearance is atypical, CBCT demonstrates the lingual concavity and settles it.
• D. Ameloblastoma is expansile and multilocular, and would not sit unchanged below the canal for eleven years.

Note: Two variants are worth knowing beyond the classic posterior one: an ANTERIOR variant lingual to the premolars, related to the SUBLINGUAL gland, which is easier to mistake for pathology because it sits among the roots; and a rare superior variant near the ramus. The single most useful feature in all of them is stability across serial radiographs.

Correct answer: D. Socket sclerosis, which warrants evaluation for an underlying systemic disorder

• A. Retained root fragments have the shape and density of a root and retain a visible periodontal ligament space around them, rather than reproducing the outline of the whole socket.
• B. Chronic osteomyelitis produces an ill-defined, moth-eaten radiolucency with sequestra and periosteal reaction, and it is symptomatic. This is a well-defined sclerotic finding in an asymptomatic patient.
• C. Normal socket healing shows the outline progressively fading as woven bone is replaced, with the trabecular pattern becoming continuous with the surrounding bone by roughly six to twelve months. A socket still sharply visible at three years is not normal healing.
• D. CORRECT. SOCKET SCLEROSIS is failure of the extraction socket to remodel: the lamina dura persists and the socket fills with dense sclerotic bone that remains visible for years. It matters because of what it is associated with — chronic RENAL disease and renal osteodystrophy in particular, and also sickle cell disease and other systemic disorders of bone metabolism. Multiple sclerotic sockets discovered incidentally in a patient with no known diagnosis warrant medical referral rather than dental treatment.

Note: Socket sclerosis belongs to a small group of incidental radiographic findings whose value lies in what they point to systemically rather than in any dental treatment they require. Note it, ask about renal disease and haemoglobinopathy, and refer.