NBDHE Dental Radiography and Interpretation Questions and Answers — Questions and Answers
Question 1: A panoramic radiograph of a 14-year-old patient reveals a well-defined, corticated radiolucency inferior to the mandibular canal in the left posterior mandible. The patient is asymptomatic. Which of the following is the MOST likely interpretation?
- A normal anatomical variation, such as a Stafne bone defect. (Correct answer)
- A periapical cyst associated with the first molar.
- An early-stage benign tumor.
- Evidence of localized osteomyelitis.
Correct answer: A normal anatomical variation, such as a Stafne bone defect.
A Stafne bone defect (also known as a static bone cyst or lingual mandibular bone depression) is an asymptomatic, well-defined radiolucency typically located below the mandibular canal. It represents a depression on the lingual aspect of the mandible where salivary gland tissue is located and is considered a normal anatomical variation.
Question 2: A dental hygienist is evaluating a set of bitewing radiographs. The images show significant overlapping of the interproximal contacts, making caries detection impossible. This error is caused by incorrect:
- Vertical angulation
- Horizontal angulation (Correct answer)
- Exposure time
- Film placement
Correct answer: Horizontal angulation
Overlapping of the interproximal contacts on a bitewing radiograph is a classic sign of incorrect horizontal angulation. The central ray of the x-ray beam was not directed perpendicularly through the contact points of the teeth.
Question 3: Which of the following is the EARLIEST radiographic sign of periodontal disease?
- Horizontal bone loss of 3-4 mm.
- A distinct radiolucency in the furcation area of a mandibular molar.
- Widening of the periodontal ligament space.
- Fuzziness or a break in the continuity of the lamina dura at the alveolar crest. (Correct answer)
Correct answer: Fuzziness or a break in the continuity of the lamina dura at the alveolar crest.
The earliest radiographic evidence of periodontitis is often a subtle change at the alveolar crest. This can include a loss of crestal cortication (fuzziness) or a break in the thin, radiopaque line of the lamina dura. These changes precede significant bone loss or furcation involvement.
Question 4: A patient is undergoing a full mouth series of radiographs. To adhere to the ALARA (As Low As Reasonably Achievable) principle, which of the following is the MOST effective way to protect the patient from unnecessary radiation exposure?
- Using a round collimator
- Using a short, 8-inch position-indicating device (PID)
- Using a lead apron with a thyroid collar (Correct answer)
- Using a D-speed film
Correct answer: Using a lead apron with a thyroid collar
While all aspects of technique are important, the most effective patient protection measure listed is the use of a lead apron and a thyroid collar. These items shield radiosensitive tissues (thyroid gland, reproductive organs) from scatter radiation during exposure. Rectangular collimation and faster film speeds (like F-speed) are also key components of ALARA, but the lead apron and thyroid collar are fundamental protective equipment.
Question 5: While taking a panoramic radiograph, the dental hygienist instructs the patient to place their tongue against the roof of their mouth and swallow. If the patient fails to do this, what error is MOST likely to appear on the final image?
- An exaggerated 'smile line' with foreshortened mandibular incisors.
- A large, dark shadow over the apices of the maxillary teeth. (Correct answer)
- A radiopaque artifact resembling a 'ghost image' of the spine.
- Blurring and narrowing of the anterior teeth.
Correct answer: A large, dark shadow over the apices of the maxillary teeth.
If the patient's tongue is not in contact with the hard palate during a panoramic exposure, a large, radiolucent shadow (palatoglossal air space) will be superimposed over the apices of the maxillary teeth, potentially obscuring diagnostic information.
Question 6: A periapical radiograph of the maxillary anterior region shows the teeth appearing stretched and much longer than their actual size. This type of distortion is known as:
- Foreshortening
- Overlapping
- Cone cut
- Elongation (Correct answer)
Correct answer: Elongation
Elongation is a radiographic error where the teeth appear longer than they are. It is typically caused by insufficient vertical angulation of the position-indicating device (PID) when using the bisecting angle technique, or when the receptor is not parallel to the long axes of the teeth in the paralleling technique.
NBDHE Dental Radiography and Interpretation Questions and Answers
A panoramic radiograph of a 14-year-old patient reveals a well-defined, corticated radiolucency inferior to the mandibular canal in the left posterior mandible.
The patient is asymptomatic.
Which of the following is the MOST likely interpretation?