CDA Exam| 270 QUESTIONS| WITH
COMPLETE SOLUTION
Course
CDA
1. Which instrument is commonly used to remove supragingival calculus during a dental
cleaning procedure?
A. Explorer
B. Scaler
C. Curette
D. Condenser
Correct Answer: B. Scaler
Rationale:
Scalers are designed with sharp tips and triangular cross-sections to remove supragingival
calculus deposits. Curettes are primarily used for subgingival scaling and root planing.
2. What is the primary purpose of using a dental dam during restorative procedures?
A. Improve patient comfort only
B. Isolate the treatment area and prevent contamination
C. Reduce appointment time
D. Replace suction devices
Correct Answer: B. Isolate the treatment area and prevent contamination
Rationale:
A dental dam provides moisture control, improves visibility, protects the airway, and prevents
saliva contamination during restorative procedures.
3. Which microorganism is primarily responsible for dental caries?
A. Streptococcus mutans
B. Staphylococcus aureus
C. Escherichia coli
D. Candida albicans
Correct Answer: A. Streptococcus mutans
,Rationale:
Streptococcus mutans metabolizes carbohydrates and produces acids that contribute to enamel
demineralization and dental caries formation.
4. Which personal protective equipment (PPE) is required when assisting during a dental
procedure involving aerosol production?
A. Gloves only
B. Protective eyewear, mask, gloves, and appropriate protective clothing
C. Hair covering only
D. Shoe covers only
Correct Answer: B. Protective eyewear, mask, gloves, and appropriate protective clothing
Rationale:
Aerosol-generating procedures increase exposure risk to microorganisms. Proper PPE protects
both dental personnel and patients.
5. Which dental material is commonly used as a temporary restorative material?
A. Zinc oxide-eugenol
B. Composite resin
C. Amalgam alloy
D. Gold foil
Correct Answer: A. Zinc oxide-eugenol
Rationale:
Zinc oxide-eugenol is frequently used for temporary restorations because it provides a soothing
effect and can be easily removed.
6. What is the correct method for sterilizing dental instruments after use?
A. Rinsing with water only
B. Using an approved sterilization method such as an autoclave
C. Wiping with alcohol only
D. Storing instruments immediately after use
Correct Answer: B. Using an approved sterilization method such as an autoclave
,Rationale:
Autoclaving uses steam under pressure to destroy microorganisms, including bacteria, viruses,
and spores.
7. Which radiograph is commonly used to detect interproximal caries?
A. Bitewing radiograph
B. Occlusal radiograph
C. Panoramic radiograph
D. Cephalometric radiograph
Correct Answer: A. Bitewing radiograph
Rationale:
Bitewing radiographs show the crowns of upper and lower teeth and are effective for detecting
decay between teeth.
8. Which instrument is used to examine tooth surfaces and detect irregularities?
A. Explorer
B. Mirror handle
C. Forceps
D. Excavator
Correct Answer: A. Explorer
Rationale:
Explorers are diagnostic instruments used to detect caries, calculus, and surface abnormalities on
teeth.
9. Which action should a dental assistant take after a needle-stick injury?
A. Ignore the injury if no bleeding occurs
B. Immediately wash the area and report the exposure according to protocol
C. Cover it and continue working without reporting
D. Apply dental disinfectant only
Correct Answer: B. Immediately wash the area and report the exposure according to
protocol
, Rationale:
Prompt cleaning and reporting allow proper evaluation, documentation, and possible post-
exposure management.
10. What is the purpose of etching enamel before placing a composite restoration?
A. Increase tooth sensitivity permanently
B. Create microscopic irregularities for bonding
C. Remove all enamel structure
D. Replace the need for bonding agents
Correct Answer: B. Create microscopic irregularities for bonding
Rationale:
Acid etching creates a roughened enamel surface that improves adhesion between the tooth
structure and restorative material.
11. Which dental instrument is used to place and contour restorative materials?
A. Excavator
B. Plastic filling instrument
C. Explorer
D. Periodontal probe
Correct Answer: B. Plastic filling instrument
Rationale:
Plastic filling instruments are used to place, shape, and contour restorative materials such as
composite resin before curing.
12. Which tooth surface is closest to the tongue?
A. Facial
B. Buccal
C. Lingual
D. Occlusal
Correct Answer: C. Lingual
Rationale:
The lingual surface refers to the side of the tooth facing the tongue. The buccal surface faces the
cheek.
COMPLETE SOLUTION
Course
CDA
1. Which instrument is commonly used to remove supragingival calculus during a dental
cleaning procedure?
A. Explorer
B. Scaler
C. Curette
D. Condenser
Correct Answer: B. Scaler
Rationale:
Scalers are designed with sharp tips and triangular cross-sections to remove supragingival
calculus deposits. Curettes are primarily used for subgingival scaling and root planing.
2. What is the primary purpose of using a dental dam during restorative procedures?
A. Improve patient comfort only
B. Isolate the treatment area and prevent contamination
C. Reduce appointment time
D. Replace suction devices
Correct Answer: B. Isolate the treatment area and prevent contamination
Rationale:
A dental dam provides moisture control, improves visibility, protects the airway, and prevents
saliva contamination during restorative procedures.
3. Which microorganism is primarily responsible for dental caries?
A. Streptococcus mutans
B. Staphylococcus aureus
C. Escherichia coli
D. Candida albicans
Correct Answer: A. Streptococcus mutans
,Rationale:
Streptococcus mutans metabolizes carbohydrates and produces acids that contribute to enamel
demineralization and dental caries formation.
4. Which personal protective equipment (PPE) is required when assisting during a dental
procedure involving aerosol production?
A. Gloves only
B. Protective eyewear, mask, gloves, and appropriate protective clothing
C. Hair covering only
D. Shoe covers only
Correct Answer: B. Protective eyewear, mask, gloves, and appropriate protective clothing
Rationale:
Aerosol-generating procedures increase exposure risk to microorganisms. Proper PPE protects
both dental personnel and patients.
5. Which dental material is commonly used as a temporary restorative material?
A. Zinc oxide-eugenol
B. Composite resin
C. Amalgam alloy
D. Gold foil
Correct Answer: A. Zinc oxide-eugenol
Rationale:
Zinc oxide-eugenol is frequently used for temporary restorations because it provides a soothing
effect and can be easily removed.
6. What is the correct method for sterilizing dental instruments after use?
A. Rinsing with water only
B. Using an approved sterilization method such as an autoclave
C. Wiping with alcohol only
D. Storing instruments immediately after use
Correct Answer: B. Using an approved sterilization method such as an autoclave
,Rationale:
Autoclaving uses steam under pressure to destroy microorganisms, including bacteria, viruses,
and spores.
7. Which radiograph is commonly used to detect interproximal caries?
A. Bitewing radiograph
B. Occlusal radiograph
C. Panoramic radiograph
D. Cephalometric radiograph
Correct Answer: A. Bitewing radiograph
Rationale:
Bitewing radiographs show the crowns of upper and lower teeth and are effective for detecting
decay between teeth.
8. Which instrument is used to examine tooth surfaces and detect irregularities?
A. Explorer
B. Mirror handle
C. Forceps
D. Excavator
Correct Answer: A. Explorer
Rationale:
Explorers are diagnostic instruments used to detect caries, calculus, and surface abnormalities on
teeth.
9. Which action should a dental assistant take after a needle-stick injury?
A. Ignore the injury if no bleeding occurs
B. Immediately wash the area and report the exposure according to protocol
C. Cover it and continue working without reporting
D. Apply dental disinfectant only
Correct Answer: B. Immediately wash the area and report the exposure according to
protocol
, Rationale:
Prompt cleaning and reporting allow proper evaluation, documentation, and possible post-
exposure management.
10. What is the purpose of etching enamel before placing a composite restoration?
A. Increase tooth sensitivity permanently
B. Create microscopic irregularities for bonding
C. Remove all enamel structure
D. Replace the need for bonding agents
Correct Answer: B. Create microscopic irregularities for bonding
Rationale:
Acid etching creates a roughened enamel surface that improves adhesion between the tooth
structure and restorative material.
11. Which dental instrument is used to place and contour restorative materials?
A. Excavator
B. Plastic filling instrument
C. Explorer
D. Periodontal probe
Correct Answer: B. Plastic filling instrument
Rationale:
Plastic filling instruments are used to place, shape, and contour restorative materials such as
composite resin before curing.
12. Which tooth surface is closest to the tongue?
A. Facial
B. Buccal
C. Lingual
D. Occlusal
Correct Answer: C. Lingual
Rationale:
The lingual surface refers to the side of the tooth facing the tongue. The buccal surface faces the
cheek.
