Dental Radiology for Dental Assisting Exam Practice Problems

Updated on Jun 23, 2011

The study guide for these practice problems can be found at:

Dental Radiology for Dental Assisting Exam Study Guide

1. The harmful effects of radiation on human tissues are

a. immediately exhibited.

b. insignificant.

c. usually acute.

d. cumulative.

e. painful.

2. The protective lead apron must be impregnated with how much lead?

a. 0.20 mm

b. 0.22 mm

c. 0.25 mm

d. 0.30 mm

e. 0.35 mm

3. You have a patient who has read articles describing the hazards of medical/dental radiation and is not sure about letting you take X-rays on her. Based on what you now know, how could you explain the procedure in a way that would be reassuring?

a. You are using a lead apron and lead thyroid shield.

b. You are using the long cone paralleling technique.

c. You take radiographs only when a need is indicated by clinical examination, not based on an arbitrary time schedule.

d. both a and b

e. all of the above

4. What do filters do in the X-ray beam?

a. increase density and short waves

b. reduce density

c. reduce exposure time

d. correct the size of the beam

e. reduce patient radiation dose and remove the long waves

5. The X-ray photons generated by the dental X-ray machine have

a. the same energy and wavelengths.

b. many different wavelengths.

c. only a few energies capable of penetrating dense tissue.

d. many different speeds.

e. none of the above.

6. What is the recommended collimation of the radiation beam at the patient’s skin surface?

a. 1.5 inches

b. 2.75 inches

c. 3.75 inches

d. 2.75 cm

e. both b and d

7. What does the ALARA concept stand for?

a. as low as reasonably achievable

b. as little as radiation is allowable

c. as low as radiation is around

d. as long as reasonably allowable

e. none of the above

8. Which of the following devices is an example of personnel monitoring?

a. film badge

b. pocket dosimeter

c. film ring

d. both a and c

e. a, b, and c

9. The transfer of energy as it passes through matter is called

a. reproduction.

b. cumulative.

c. mutation.

d. absorption.

e. energize.

10. What is it called when a lead disc is used for the elimination of the peripheral portion of the X-ray beam?

a. filtration

b. collimation

c. elongation

d. ionization

e. absorption

11. Which molecular changes occur in a living organism being struck by photons?

a. Molecules break into smaller pieces.

b. New bonds form within molecules.

c. Molecular bonds are disrupted.

d. New bonds form between new molecules.

e. all of the above

12. What is the correct vertical angulation used when taking a bitewing radiograph?

a. 0 degrees

b. +10 degrees

c. –10 degrees

d. +30 degrees

e. +5 degrees

13. In the bisecting the angle technique, where is the vertical angle of the central beam directed?

a. parallel to the film

b. perpendicular to the line bisecting the angle made by the film and the side of the tongue

c. parallel to the long axis of the tooth

d. perpendicular to the line bisecting the angle made by the long axis of the tooth and the film

e. both b and d

14. What is true of a full-mouth X-ray series?

a. always has periapical and bitewing films

b. has a minimum of 20 films

c. can be replaced by a panoramic film

d. varies in need and number of films according to selection criteria and mouth size

e. both a and d

15. In dental radiography, what infection control procedures are included?

a. sterilization

b. disinfection

c. antiseptic agents

d. both a and b

e. all of the above

16. What is the safest position for an operator while exposing an intraoral film?

a. behind the head of the X-ray unit

b. behind a lead barrier

c. at a 45° angle to the opposite side of the patient’s head

d. both b and c

e. all of the above

17. What does immersing the contaminated exposed film packet in a disinfecting solution do?

a. disinfects it

b. destroys the image

c. takes too long

d. makes the images clearer

e. none of the above

18. What needs to happen when exposing a full-mouth set of radiographs?

a. The PID need not be covered with a barrier if gloves are worn.

b. A film dispenser should be used.

c. Unexposed film should be kept on the counter in the room.

d. The exposure button should be covered with a plastic barrier.

e. none of the above

19. Where in the X-ray head does thermionic emission take place?

a. tungsten target

b. tungsten filament

c. step-down transformer

d. PID

e. both a and b

20. Which radiographic technique records the most accurate image of crowns, roots, and supporting structures of a selected area of the oral cavity?

a. bitewing film

b. panoramic film

c. periapical film

d. occlusal film

e. extraoral film

21. The bicuspid/premolar bitewing radiograph should be placed to include which of the following anatomic structures?

a. all of the mandibular cuspid

b. the distal half of the mandibular cuspid

c. the distal half of the maxillary cuspid

d. the mesial half of the maxillary first premolar

e. the distal half of the mandibular first molar

22. What is the primary diagnostic use of a bitewing radiograph?

a. Check for unerupted teeth.

b. Register the appearance of supporting structures such as bone and soft tissue.

c. Show a crown preparation, placement, and residual excess cement.

d. Check the length of the canal for endodontic procedures.

e. Check for interproximal decay and crestal bone levels.

23. The size-1 film would most likely be used to radiograph which of the following areas on an adult patient?

a. incisors and cuspids

b. maxillary bicuspids

c. mandibular bicuspids if the floor of the mouth is too shallow

d. mandibular bicuspids

e. both a and c

24. What causes a herringbone pattern across a film with low density?

a. static electricity

b. film bending

c. the film packet placed backwards

d. double exposure

e. a fingernail artifact

25. What determines the speed of the film?

a. the size of the film

b. the exposure time

c. the size of the silver halide crystals

d. the amount of radiation emitted from the X-ray machine

e. both b and c

26. Which of the following sequences represents the correct developing and processing procedure for manual processing?

a. develop, rinse, fix, wash

b. develop, wash, fix, rinse

c. fix, wash, develop, rinse

d. develop, fix, wash, rinse

e. wash, develop, fix, rinse

27. What is the name of the chemical in the fixer that clears the unexposed silver halide crystals?

a. metol or hydroquinone

b. sodium sulfite

c. ammonium thiosulfate

d. ammonium bicarbonate

e. aluminum chloride or sulfide

28. Which chemical-reducing agent is present in the developer and is responsible for building the black and gray tones on a film?

a. potassium bromide

b. sodium carbide

c. ammonium thiosulfate

d. metol and hydroquinone

e. ammonium glutaraldehyde

29. What does the term radiographic density describe?

a. thickness of the emulsion on the film

b. thickness of the subject (larger patient)

c. amount of radiation in the X-ray beam

d. degree of darkness or blackness on the film

e. varying shades of gray

30. A double exposure occurs when

a. the film is not exposed to radiation.

b. the film is exposed to natural light.

c. the same film is exposed to radiation twice.

d. the film is overdeveloped.

e. the film is developed with exhausted solution.

31. Which term describes the loss of electrons from a substance?

a. braking radiation

b. scatter radiation

c. ionization

d. background radiation

e. both a and c

32. Which of the following materials is most resistant to the penetration of ionizing radiation?

a. aluminum

b. copper

c. lead

d. hard plastic

e. silicon

33. What percentage of the energy generated by the collision between electrons from the cathode and the anode is actually converted to heat?

a. 99%

b. 90%

c. 10%

d. 2%

e. 1%

34. If there are no teeth to serve as guides, which of the following landmarks indicates a maxillary molar area radiograph?

a. incisive foramen

b. mental foramen and corner of the mouth

c. internal oblique ridge

d. tuberosity and near the outer corner of the eye

e. retromolar pad

35. What is the most likely cause of black spots on a set of bitewings?

a. fixer splashed on them

b. developer splashed on them

c. water splashed on them

d. fluoride solution on a glove transferred to the film

e. both b and d

36. Which of the following appears radiolucent on a radiograph?

a. enamel

b. implant

c. dental pulp

d. amalgam

e. gold

37. What causes light films?

a. underdeveloping

b. underexposure

c. not enough mA or kV

d. both a and b

e. all of the above

38. How does a structure that is radiolucent appear on the radiograph?

a. light

b. dark

c. gray

d. blue

e. clear

39. Which restorative materials appear radiopaque on a radiograph?

a. amalgam

b. composite

c. gold crown

d. both a and c

e. all of the above

40. Which of the following is a helpful hint for mounting a full-mouth set of radiographs?

a. Maxillary teeth usually have smaller crowns and shorter roots than mandibular teeth.

b. The longer side of the film is usually vertical for posterior teeth and horizontal for anterior teeth.

c. Maxillary molars usually have two roots, and mandibular molars usually have three roots.

d. The overall appearance of the radiographic survey will have an upward curve like a smile.

e. both a and d

41. What will too much vertical angulation (either positively or negatively) cause?

a. foreshortening

b. elongation

c. cone cut

d. overlapping

e. blurriness

42. What is the primary use for occlusal dental radiographs?

a. identify caries activity

b. diagnose periodontal conditions

c. locate foreign bodies

d. examine lesions of the mucosa

e. help determine the length of the root canal

43. What do intensifying screens do?

a. absorb scatter radiation

b. contain phosphors that emit blue or green light

c. increase the amount of radiation needed

d. increase the amount of exposure time needed

e. magnify the amount of radiation

44. While taking a panoramic extraoral X-ray, where should the assistant instruct the patient to place his or her tongue?

a. on the floor of the mouth

b. on the roof of the mouth (palate)

c. against the mandibular anterior teeth

d. to the left side

e. both a and c

45. Which of the following is not classified as a developmental dental abnormality?

a. dens in dente

b. taurodont

c. periapical abscess

d. mesiodens

e. both b and c

46. A charged coupling device (CCD) is primarily made of what substance?

a. calcium tungsten

b. ammonium thiosulfate

c. phosphor

d. aluminum or lead

e. silicon

47. If a patient is positioned in a panoramic unit with his or her chin too low, which of the following images might be seen on the resultant radiograph?

a. wide blurry anterior teeth

b. molars on one side more magnified than on the other side

c. flattened curve of Spee

d. exaggerated curve of Spee

e. both a and d 

48. What technique is best when exposing intraoral films prior to placing an implant?

a. paralleling technique

b. bisecting the angle technique

c. panoramic technique

d. occlusal technique

e. both a and b

49. Match the component of the X-ray tube head with the correct letter in the following figure.

Answer questions 50–55 using the following figure.

50. Choose the correct window for proper mounting of the film displayed in the figure below.

52. Choose the correct window for proper mounting of the film displayed in the figure below.

53. Choose the correct window for proper mounting of the film displayed in the figure below.

54. Choose the correct window for proper mounting of the film displayed in the figure below.

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