NDEB - National Dental Examining Board Oral Radiology and Interpretation Questions and Answers — Questions and Answers
Question 1: A 45-year-old female patient presents for a routine examination. A panoramic radiograph reveals multiple, well-defined, mixed-density lesions with surrounding radiolucent rims located at the apices of all mandibular incisors. The associated teeth are vital and asymptomatic. What is the most likely diagnosis?
- Chronic apical periodontitis
- Periapical cemento-osseous dysplasia (Correct answer)
- Odontogenic keratocysts
- Metastatic carcinoma
Correct answer: Periapical cemento-osseous dysplasia
Periapical cemento-osseous dysplasia (PCOD) is a benign fibro-osseous lesion most commonly found in the anterior mandible of middle-aged females. Radiographically, it progresses through three stages: radiolucent, mixed-density, and radiopaque, often with a characteristic radiolucent halo. A key diagnostic feature is that the associated teeth remain vital.
Question 2: A panoramic radiograph of a 10-year-old male shows bilateral, symmetric, multilocular, expansile radiolucencies in the posterior mandible and ascending rami, giving a 'soap-bubble' appearance. The mandibular condyles are spared, and there is evidence of tooth displacement. Which of the following conditions best fits this presentation?
- Ameloblastoma
- Odontogenic myxoma
- Cherubism (Correct answer)
- Fibrous dysplasia
Correct answer: Cherubism
Cherubism is a hereditary condition characterized by bilateral, symmetric, multilocular radiolucencies limited to the maxilla and mandible, particularly the posterior regions. It typically presents in childhood, causing a 'cherubic' facial appearance. The 'soap-bubble' or multilocular appearance and sparing of the condyles are classic radiographic hallmarks.
Question 3: A clinician takes two periapical radiographs of a maxillary first molar to locate a supernumerary root. The first radiograph is taken with a standard perpendicular angulation. For the second radiograph, the tubehead is shifted mesially. On the second image, the supernumerary root appears to have moved distally relative to the main roots. According to the SLOB rule, what is the location of the supernumerary root?
- Lingual
- Mesial
- Distal
- Buccal (Correct answer)
Correct answer: Buccal
The SLOB (Same Lingual, Opposite Buccal) rule states that if an object moves in the opposite direction of the x-ray tubehead shift, it is located on the buccal. In this case, the tubehead moved mesially, and the root moved distally (opposite direction). Therefore, the supernumerary root is on the buccal aspect.
Question 4: A patient with a history of intravenous bisphosphonate therapy for multiple myeloma complains of a non-healing extraction socket in the posterior mandible. Which of the following is an early radiographic sign of Medication-Related Osteonecrosis of the Jaw (MRONJ) that might be observed in this patient?
- Pathologic fracture of the mandible
- Formation of a large, well-defined radiolucency
- Thickening of the lamina dura and widening of the PDL space (Correct answer)
- Significant expansion of the cortical plates
Correct answer: Thickening of the lamina dura and widening of the PDL space
Early radiographic signs of MRONJ can be subtle. Before significant osteolysis or sequestrum formation occurs, findings such as thickening or indistinctness of the lamina dura, widening of the periodontal ligament (PDL) space, and increased sclerosis of the alveolar bone are often noted. A pathologic fracture is a late-stage complication.
Question 5: A bitewing radiograph shows a diffuse, V-shaped radiolucency at the cervical line of a mandibular premolar, located just apical to the cementoenamel junction (CEJ). The borders are ill-defined, and the radiolucency appears to wrap around the tooth. What is the most likely interpretation?
- Root caries
- Recurrent caries
- Cervical burnout (Correct answer)
- Abrasion
Correct answer: Cervical burnout
Cervical burnout is a radiolucent artifact caused by the anatomical indentation and relative decrease in tooth mass at the cervical region, which allows for greater x-ray penetration. It typically appears as a diffuse or V-shaped radiolucency with indistinct borders located at the CEJ, and it is crucial to differentiate it from true root caries, which is typically more saucer-shaped and located on the root surface.
Question 6: A patient presents with a suspected vertical root fracture on an endodontically treated maxillary premolar. A periapical radiograph shows a subtle 'J-shaped' or 'halo-like' radiolucency around the apex. Which imaging modality would be most definitive for confirming the presence and extent of the fracture?
- Occlusal radiograph
- Panoramic radiograph
- Cone Beam Computed Tomography (CBCT) (Correct answer)
- Lateral cephalometric radiograph
Correct answer: Cone Beam Computed Tomography (CBCT)
While periapical radiographs may show suggestive signs like a J-shaped lesion, they are often inconclusive for diagnosing vertical root fractures due to the 2D nature of the image. Cone Beam Computed Tomography (CBCT) provides a 3D view, which allows for direct visualization of the fracture line in multiple planes (axial, sagittal, coronal), making it the most accurate and definitive imaging modality for this purpose.
NDEB - National Dental Examining Board Oral Radiology and Interpretation Questions and Answers
A 45-year-old female patient presents for a routine examination.
A panoramic radiograph reveals multiple, well-defined, mixed-density lesions with surrounding radiolucent rims located at the apices of all mandibular incisors.
The associated teeth are vital and asymptomatic.
What is the most likely diagnosis?