DANB Certified Dental Assistant (CDA) Exam — Questions and Answers

Question 1: What should be done immediately after a sharps injury exposes a dental worker to a patient's blood?

Wash the wound with soap and water and report it (Correct answer)
Ignore it if the patient appears healthy
Apply bleach directly to the wound
Squeeze the wound vigorously for five minutes

Correct answer: Wash the wound with soap and water and report it

The wound should be washed with soap and water and the exposure reported for evaluation per the protocol.

Question 2: What type of interproximal radiograph is most commonly used to detect proximal caries and crestal bone loss?

Periapical
Lateral cephalometric
Bitewing (Correct answer)
Panoramic

Correct answer: Bitewing

Bitewing radiographs show the crowns and interproximal areas of both arches simultaneously, making them ideal for detecting proximal decay and early bone loss.

Question 3: Which topical anesthetic agent is commonly applied before intraoral injections to reduce needle insertion pain?

Benzocaine 20% (Correct answer)
Mepivacaine 3%
Bupivacaine 0.5%
Prilocaine 4%

Correct answer: Benzocaine 20%

Benzocaine 20% gel or liquid is the most commonly used topical dental anesthetic applied to mucous membranes before injections to minimize discomfort.

Question 4: What is the purpose of the smear layer removal (etching) step in total-etch bonding systems?

To bleach the dentin for better color match
To sterilize the dentin surface
To remove debris and open dentinal tubules for resin tags and hybridization (Correct answer)
To harden the dentin before bonding

Correct answer: To remove debris and open dentinal tubules for resin tags and hybridization

Acid etching removes the smear layer and demineralizes superficial dentin, creating microporosities for resin infiltration and a hybrid layer for micromechanical bonding.

Question 5: Which type of waste is considered regulated medical waste in dentistry?

Empty anesthetic carpules
Disposable saliva ejectors
Used paper patient bibs
Blood-soaked gauze that drips when compressed (Correct answer)

Correct answer: Blood-soaked gauze that drips when compressed

Items saturated with blood that can release it when compressed are classified as regulated medical waste.

Question 6: What are dental veneers?

Tooth-colored fillings
Invisible braces
A type of denture
Thin shells of porcelain or composite bonded to the front of teeth to improve appearance (Correct answer)

Correct answer: Thin shells of porcelain or composite bonded to the front of teeth to improve appearance

Veneers are custom-made thin shells that cover the front surface of teeth, used to correct discoloration, chips, gaps, or misalignment for cosmetic improvement.

Question 7: What is the proper procedure for handling a sharps injury (needlestick)?

Wash the wound immediately, report the incident, identify the source patient, and seek post-exposure evaluation (Correct answer)
Ignore it if the patient is healthy
Only report it if you feel sick later
Apply a bandage and continue working

Correct answer: Wash the wound immediately, report the incident, identify the source patient, and seek post-exposure evaluation

Sharps injuries require immediate wound care, incident reporting, source patient evaluation, and post-exposure protocols including possible PEP (post-exposure prophylaxis).

Question 8: What type of gloves should be worn when cleaning contaminated instruments and surfaces?

No gloves if washing carefully
Heavy-duty puncture-resistant utility gloves (Correct answer)
Cloth gloves
Thin latex exam gloves

Correct answer: Heavy-duty puncture-resistant utility gloves

Puncture-resistant utility gloves protect against sharps injuries during instrument processing and surface cleaning.

Question 9: What is the purpose of the film speed (e.g., F-speed) classification in dental radiography?

Reflects the film's sensitivity to radiation (Correct answer)
Describes how quickly the film can be processed
Indicates the film's archival longevity
Indicates the film's resistance to scratching

Correct answer: Reflects the film's sensitivity to radiation

Film speed classification indicates the film's sensitivity (speed) to X-radiation; faster films (E and F speed) require less radiation exposure to produce an adequate image.

Question 10: What is the recommended interval for bitewing radiographs in an adult patient with a high caries risk?

Every 5 years
Every 12–18 months
Every 2–3 years
Every 3–6 months (Correct answer)

Correct answer: Every 3–6 months

High-caries-risk adults should receive bitewing radiographs every 6 months or less to monitor for rapidly progressing decay.

Question 11: Which method is preferred for cleaning instruments before sterilization to reduce sharps injury risk?

Soaking in plain tap water only
Wiping with a dry paper towel
Hand scrubbing each instrument individually
An ultrasonic cleaner or instrument washer (Correct answer)

Correct answer: An ultrasonic cleaner or instrument washer

Automated cleaning like ultrasonic units reduces handling of contaminated sharps and improves cleaning.

Question 12: The mental foramen on a periapical radiograph most commonly appears adjacent to which tooth?

Mandibular first molar
Mandibular canine
Mandibular central incisor
Mandibular second premolar (Correct answer)

Correct answer: Mandibular second premolar

The mental foramen, which transmits the mental nerve and vessels, most commonly appears near the apex of the mandibular second premolar.

Question 13: Under HIPAA, who is permitted to receive information from a patient's dental record without the patient's written authorization?

The patient's employer
Another treating healthcare provider involved in the patient's care (Correct answer)
An insurance company for general marketing purposes
The patient's spouse or family members

Correct answer: Another treating healthcare provider involved in the patient's care

HIPAA allows disclosure of protected health information to other healthcare providers for treatment purposes without separate written authorization.

Question 14: What is the purpose of a biological indicator (spore test) in a dental sterilizer?

To check the room temperature
To measure the water hardness
To time the instrument cleaning cycle
To confirm the sterilizer kills highly resistant bacterial spores (Correct answer)

Correct answer: To confirm the sterilizer kills highly resistant bacterial spores

Biological indicators use resistant spores to verify the sterilizer achieves true sterilization.

Question 15: What is the name for the misalignment of dental arches?

Diastama
Gingiva
Maxilliary
Malocclusion (Correct answer)

Correct answer: Malocclusion

Malocclusion is the correct term for any deviation from a normal occlusion, meaning an improper alignment of the teeth and the way the upper and lower dental arches fit together. This condition can affect chewing, speech, and overall oral health. Options like gingiva (gums) or diastema (gap between teeth) describe specific oral features, not the general misalignment of arches.

Question 16: Cone-cutting (partial image) on a dental X-ray is caused by which error?

Incorrect horizontal angulation
PID not centered over the film/sensor (Correct answer)
Wrong exposure time
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 17: A triangular radiolucency at the apex of a tooth most likely indicates which condition?

Normal pulp chamber
External resorption
Hypercementosis
Periapical abscess or granuloma (Correct answer)

Correct answer: Periapical abscess or granuloma

A periapical radiolucency (dark area) at the root apex typically indicates a periapical abscess, granuloma, or cyst resulting from pulpal necrosis.

Question 18: A tooth that responds to percussion with sharp pain most likely indicates:

Apical periodontitis (Correct answer)
Reversible pulpitis only
Healthy periodontium
Normal occlusion

Correct answer: Apical periodontitis

Pain on percussion suggests inflammation of the periodontal ligament, characteristic of apical periodontitis.

Question 19: What is the Universal Numbering System for teeth?

A numbering system (1-32) starting from the upper right third molar going around to the lower right third molar (Correct answer)
An obsolete system no longer in use
A system using letters only
A random assignment

Correct answer: A numbering system (1-32) starting from the upper right third molar going around to the lower right third molar

In the Universal system, teeth are numbered 1-32 starting from the upper right third molar (#1), moving left across the top to #16, then down to the lower left #17, ending at lower right #32.

Question 20: What is the recommended management of a tooth with a vertical root fracture?

Fluoride application
Extraction of the tooth or affected root (Correct answer)
Root canal retreatment alone
Observation only

Correct answer: Extraction of the tooth or affected root

Vertical root fractures generally have a poor prognosis, so extraction or root resection is usually indicated.

Question 21: Which digital radiography system captures images using a sensor plate that is later scanned with a laser?

Cone beam CT
CMOS sensor
Photostimulable phosphor (PSP) plate (Correct answer)
CCD sensor

Correct answer: Photostimulable phosphor (PSP) plate

PSP (photostimulable phosphor) plates store the latent X-ray image and release it when scanned with a laser, providing a digital image.

Question 22: What does the term 'critical instrument' refer to in the Spaulding classification?

An instrument that penetrates soft tissue or bone (Correct answer)
An instrument that touches intact skin only
An instrument that contacts mucous membranes only
An instrument used outside the mouth

Correct answer: An instrument that penetrates soft tissue or bone

Critical instruments penetrate soft tissue or bone and must be heat sterilized.

Question 23: A patient presents with an acute dentoalveolar abscess. Which is the most important first step in management before antibiotic therapy?

Achieve local drainage (incision and drainage or extraction/pulp treatment) (Correct answer)
Order a CBCT scan
Prescribe antibiotics immediately
Prescribe analgesics only

Correct answer: Achieve local drainage (incision and drainage or extraction/pulp treatment)

Surgical drainage — through incision and drainage, pulp access, or extraction — is the definitive treatment for a dental abscess; antibiotics are adjunctive and cannot penetrate poorly vascularized necrotic tissue.

Question 24: Which property of dental wax makes it suitable for use in bite registration?

Plasticity at mouth temperature and rigidity at room temperature (Correct answer)
High thermal conductivity
High tensile strength
Chemical adhesion to enamel

Correct answer: Plasticity at mouth temperature and rigidity at room temperature

Bite registration wax softens at oral temperature to record occlusal relationships accurately and then hardens at room temperature to preserve the registration.

Question 25: What does the term 'guided bone regeneration (GBR)' primarily aim to achieve?

Whiten enamel
Increase bone volume using a barrier membrane (Correct answer)
Remove calculus
Realign the bite

Correct answer: Increase bone volume using a barrier membrane

GBR uses a barrier membrane to exclude soft tissue and allow bone to fill a defect.

Question 26: What is the difference between cleaning and disinfection?

Cleaning removes debris; disinfection kills most microorganisms (Correct answer)
They are identical processes
Cleaning kills all spores; disinfection only removes dirt
Disinfection always precedes cleaning

Correct answer: Cleaning removes debris; disinfection kills most microorganisms

Cleaning physically removes organic matter, while disinfection then kills most remaining microorganisms.

Question 27: Elongation of teeth on a periapical radiograph is caused by which error in the bisecting angle technique?

Directing the beam too steeply (excess vertical angulation)
Directing the beam too shallowly (insufficient vertical angulation) (Correct answer)
Incorrect horizontal angulation
Excessive exposure time

Correct answer: Directing the beam too shallowly (insufficient vertical angulation)

When the vertical angulation of the X-ray beam is too flat (too little downward angle), the tooth image appears longer (elongated) on the film.

Question 28: Digital dental radiography reduces radiation exposure compared to conventional film by approximately how much?

10–20%
50–80% (Correct answer)
25–40%
Over 90%

Correct answer: 50–80%

Digital sensors are significantly more sensitive than conventional film, allowing radiation dose reductions of approximately 50–80% while maintaining diagnostic image quality.

Question 29: What does a chemical (process) indicator on a sterilization pouch confirm?

That instruments were cleaned
That all spores were killed
That the package was exposed to the sterilization process (Correct answer)
That the water was sterile

Correct answer: That the package was exposed to the sterilization process

A chemical indicator only confirms exposure to the process, not that sterilization was actually achieved.

DANB Certified Dental Assistant (CDA) Exam

The DANB CDA exam certifies dental assistants across three component exams: General Chairside Assisting, Infection Control, and Radiation Health and Safety. It is the most widely recognized dental assisting credential in the United States.

Questions

35 min

Time Limit

70%

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