DMD DMD - Doctor of Medicine in Dentistry Dental Radiology and Imaging Questions and Answers 2 — Questions and Answers
Question 1: Cone beam computed tomography (CBCT) provides what primary advantage over conventional 2D radiography in dentistry?
- Three-dimensional imaging with reduced radiation compared to medical CT (Correct answer)
- Lower cost than periapical X-rays
- No radiation exposure
- Better soft tissue contrast than MRI
Correct answer: Three-dimensional imaging with reduced radiation compared to medical CT
CBCT generates accurate 3D volumetric data of hard tissues with a radiation dose significantly lower than medical CT, making it valuable for implant planning, endodontics, and oral surgery.
Question 2: On a periapical radiograph, condensing osteitis appears as which radiographic finding?
- Radiopaque (dense) area around the apex of a tooth (Correct answer)
- Radiolucent area around the apex
- Mixed radiolucent-radiopaque lesion
- Loss of lamina dura only
Correct answer: Radiopaque (dense) area around the apex of a tooth
Condensing osteitis is a focal sclerosing reaction of bone to low-grade pulpal inflammation, appearing as increased bone density (radiopacity) periapically.
Question 3: The bisecting angle technique uses which geometric rule to determine beam angulation?
- The central ray is directed perpendicular to the bisector of the angle formed by the tooth and the film (Correct answer)
- The central ray is directed parallel to the long axis of the tooth
- The film is placed parallel to the occlusal plane
- The beam is angled at exactly 45° regardless of tooth position
Correct answer: The central ray is directed perpendicular to the bisector of the angle formed by the tooth and the film
The bisecting angle technique applies the rule of isometry: the beam is aimed at 90° to an imaginary line that bisects the angle between the tooth and the receptor.
Question 4: Which radiographic landmark appears as a radiopaque bow-shaped line above the roots of the maxillary posterior teeth on a periapical radiograph?
- Floor of the maxillary sinus (Correct answer)
- Zygomatic process of the maxilla
- Nasal floor
- Hamular process
Correct answer: Floor of the maxillary sinus
The floor of the maxillary sinus appears as a radiopaque curved line that can overlie or be near the apices of the maxillary premolars and molars on periapical X-rays.
Question 5: What is the primary purpose of using a long-cone (PID) technique in periapical radiography?
- To reduce image magnification and increase sharpness by increasing the source-to-film distance (Correct answer)
- To decrease exposure time
- To widen the beam for broader coverage
- To eliminate the need for a film holder
Correct answer: To reduce image magnification and increase sharpness by increasing the source-to-film distance
A longer cone increases the source-to-object distance, reducing beam divergence and image magnification, which results in a sharper and more dimensionally accurate image.
Question 6: A 'ghost image' artifact on a panoramic radiograph most commonly results from which error?
- Patient jewelry or metallic object left in place during exposure (Correct answer)
- Incorrect patient positioning only
- Overexposure of the film
- Using a rectangular collimator
Correct answer: Patient jewelry or metallic object left in place during exposure
Metallic objects such as earrings, necklaces, or glasses create ghost images—blurred, magnified, and displaced shadows on panoramic radiographs due to the rotating beam.
DMD DMD - Doctor of Medicine in Dentistry Dental Radiology and Imaging Questions and Answers 2
Cone beam computed tomography (CBCT) provides what primary advantage over conventional 2D radiography in dentistry?