RDA Radiographic Techniques and Errors 4

Question 1

A radiograph shows the apices of the maxillary molars superimposed over the zygomatic arch. Which error caused this?

Accepted Answer

Insufficient vertical angulation

Answer

Insufficient (flat) vertical angulation causes the zygomatic arch to overlap the apices of the maxillary molars.

Question 2

Which receptor placement error results in a radiograph showing the roots of mandibular teeth appearing foreshortened?

Accepted Answer

Receptor tilted toward the tongue

Answer

When the receptor tilts toward the tongue (cupped), the effective vertical angulation increases, foreshortening the image.

Question 3

During a bitewing series, the contact areas of posterior teeth are not open. The MOST likely cause is:

Accepted Answer

Incorrect horizontal angulation

Answer

Overlapping of proximal contacts on bitewings is caused by incorrect horizontal angulation, where the beam does not pass through the embrasures.

Question 4

A periapical radiograph of the mandibular incisors shows a herringbone pattern on the image. What is the cause?

Accepted Answer

Film or receptor placed backward

Answer

The herringbone (tire-track) pattern results from X-rays passing through the lead foil backing when the receptor is placed backward in the mouth.

Question 5

Which type of film fault produces a clear (unexposed) area on a processed radiograph shaped like a half-moon?

Accepted Answer

Crimping artifact

Answer

A crescent-shaped (half-moon) clear area results from crimping or bending the film sharply before exposure, which blocks X-rays from reaching that area.

(RDA) Registered Dental Assistant Practice Test

(RDA) Registered Dental Assistant Practice Test

RDA Radiographic Techniques and Errors 4