Dental Dental Radiography 2 — Questions and Answers
Question 1: Which lead equivalent thickness is required for a dental X-ray leaded apron?
- 0.10 mm
- 0.25 mm (Correct answer)
- 0.50 mm
- 1.0 mm
Correct answer: 0.25 mm
The American Dental Association recommends a leaded apron with at least 0.25 mm lead equivalent to protect the patient's body during dental radiography.
Question 2: What radiographic error results in a foreshortened image of the tooth?
- Excessive vertical angulation (Correct answer)
- Insufficient vertical angulation
- Incorrect horizontal angulation
- Film bending
Correct answer: Excessive vertical angulation
Foreshortening occurs when the vertical angulation is too steep, causing the X-ray beam to strike the tooth and film at too great an angle.
Question 3: Cone-cutting (partial image) on a dental X-ray is caused by which error?
- Wrong exposure time
- Incorrect horizontal angulation
- PID not centered over the film/sensor (Correct answer)
- Film placed backwards
Correct answer: PID not centered over the film/sensor
Cone-cutting occurs when the position-indicating device (PID/cone) is not properly aligned so the X-ray beam only partially exposes the film or sensor.
Question 4: Which type of radiation is most effectively blocked by a lead thyroid collar?
- Primary radiation
- Secondary (scatter) radiation (Correct answer)
- Leakage radiation
- Characteristic radiation
Correct answer: Secondary (scatter) radiation
Thyroid collars are designed to protect the thyroid gland from secondary scatter radiation that is produced when the primary beam interacts with patient tissues.
Question 5: What is the recommended frequency for bitewing radiographs in an adult patient with low caries risk?
- Every 6 months
- Every year
- Every 2–3 years (Correct answer)
- Every 5 years
Correct answer: Every 2–3 years
The ADA recommends bitewing radiographs every 2–3 years for adult patients with low caries risk and no active disease.
Question 6: Which of the following describes the appearance of dental calculus on a radiograph?
- Radiolucent
- Completely invisible
- Radiopaque (Correct answer)
- Isoradiopaque with enamel
Correct answer: Radiopaque
Calculus is heavily mineralized and appears radiopaque (light/white) on dental radiographs, often visible as irregular calcifications on root surfaces interproximally.
Dental Dental Radiography 2
Which lead equivalent thickness is required for a dental X-ray leaded apron?