Endodontic, Prosthodontic and Orthodontic Assist Practice Questions
20 free Endodontic, Prosthodontic and Orthodontic Assist practice questions for the CDA. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which instrument is used during endodontic treatment to measure the length of the root canal?
- A Gutta-percha cone
- B File stop
- C Apex locator
- D Barbed broach
Correct answer: Apex locator
An apex locator electronically determines canal length. This helps ensure accurate cleaning and filling of the root canal.
What material is most commonly used to obturate a root canal after cleaning and shaping?
- A Zinc phosphate
- B Gutta-percha
- C Temporary cement
- D Amalgam
Correct answer: Gutta-percha
Gutta-percha is biocompatible and easily condensed to fill the cleaned canal. It is the standard material for root canal obturation.
During root canal therapy, the dental assistant should maintain a working field by primarily using:
- A Cotton rolls
- B High-volume evacuation
- C Cheek retractors
- D Air-water syringe
Correct answer: High-volume evacuation
HVE helps control debris, irrigants, and aerosols. This is especially important in endodontic procedures.
Which orthodontic instrument is used to place elastic ligatures around brackets?
- A Ultrasonic scaler tip
- B Curved mosquito hemostat
- C Ligature director instrument
- D Elastic ligature applicator
Correct answer: Elastic ligature applicator
The elastic ligature applicator allows precise placement of elastics over brackets. It is essential in securing arch wires.
Which material is commonly used for taking impressions for removable partial dentures?
- A Alginate
- B Polyvinyl siloxane
- C ZOE impression paste
- D Plaster
Correct answer: Alginate
Alginate is economical and captures sufficient detail for removable prosthodontics. It must be poured promptly.
Which device holds a prosthetic crown during try-in to prevent contamination?
- A Crown remover pliers
- B Crown-and-bridge tweezer
- C Denture cleaning brush
- D Sectional matrix band
Correct answer: Crown-and-bridge tweezer
Crown-and-bridge tweezers allow controlled handling of prosthetic crowns. They help maintain sterility and prevent dropping.
What is the purpose of orthodontic separators?
- A Close spaces between teeth
- B Provide room for molar bands
- C Hold the archwire in place
- D Track tooth movement
Correct answer: Provide room for molar bands
Separators create slight spaces between teeth so that molar bands can be placed comfortably. They are typically placed 3–7 days before banding.
Which endodontic irrigant is commonly used to disinfect the canal system?
- A Hydrogen peroxide
- B Chlorhexidine
- C Sodium hypochlorite
- D Sterile water
Correct answer: Sodium hypochlorite
Sodium hypochlorite is effective at dissolving organic tissue and killing bacteria. It is the primary irrigant in root canal therapy.
Which instrument removes pulp tissue in the early stages of root canal treatment?
- A Endodontic explorer
- B Barbed broach
- C K-file
- D Gates-Glidden drill
Correct answer: Barbed broach
The barbed broach is designed to engage and remove pulp tissue. It is used early in cleaning the root canal space.
Which prosthodontic step requires the assistant to mix elastomeric impression material?
- A Bite registration
- B Temporary crown fabrication
- C Final crown impression
- D Shade matching
Correct answer: Final crown impression
Final impressions require precise elastomeric materials. The assistant must mix and load the tray efficiently.
What is the purpose of the dental dam in endodontic treatment?
- A Protect soft tissues from burs
- B Provide patient comfort
- C Maintain a dry, isolated field
- D Retract the cheeks
Correct answer: Maintain a dry, isolated field
A dental dam isolates the tooth, preventing contamination by saliva and debris. It is considered essential for safe endodontic care.
Which appliance is used to correct a patient’s bite by guiding jaw growth?
- A Hawley retainer
- B Fixed space maintainer
- C Functional appliance
- D Sports mouth guard
Correct answer: Functional appliance
Functional appliances modify jaw growth in orthodontics. They are often used for Class II or III malocclusions.
Which step is performed before cementing a permanent crown?
- A Shade selection
- B Try-in and fit adjustment
- C Diagnostic impression
- D Root planing
Correct answer: Try-in and fit adjustment
A try-in ensures proper fit, occlusion, and esthetics before cementation. Any adjustments must be made prior to final placement.
Which orthodontic component applies the main force to move teeth?
- A Brackets
- B Archwire
- C Elastomeric ligatures
- D Bands
Correct answer: Archwire
The archwire stores and applies forces to guide tooth movement. Brackets simply hold the wire in position.
Which endodontic material is placed at the apex in cases of open apices or immature roots?
- A Calcium hydroxide
- B Amalgam
- C Glass ionomer
- D Zinc phosphate
Correct answer: Calcium hydroxide
Calcium hydroxide encourages apical closure in young or immature teeth. It is widely used in apexification.
What is the role of the assistant during orthodontic bonding appointments?
- A Place archwires
- B Etch and isolate teeth
- C Mix cement and cure adhesive
- D Adjust brackets after placement
Correct answer: Mix cement and cure adhesive
The assistant typically mixes bonding agents and cures adhesive after bracket placement. Precise handling ensures proper adhesion.
Which instrument is used to contour and trim temporary crowns?
- A Hollenback carver
- B Crown scissors
- C Finishing bur
- D Amalgam condenser
Correct answer: Crown scissors
Crown scissors shape and trim the margins of temporary crowns for proper fit. They are designed for cutting plastic or metal shells.
Which orthodontic emergency requires immediate attention?
- A Loose elastic ligature on a bracket
- B Broken archwire irritating tissue
- C A missing tooth separator
- D Mild soreness after an adjustment
Correct answer: Broken archwire irritating tissue
A broken wire can injure soft tissues and must be addressed promptly. The assistant may trim or cover the wire until repair.
What is the function of a post in a post-and-core buildup for a crown?
- A Replace missing tooth structure at the gumline
- B Provide retention in a root canal–treated tooth
- C Support orthodontic appliances
- D Act as temporary material
Correct answer: Provide retention in a root canal–treated tooth
A post is inserted into the canal to support the core and final crown. It provides strength in heavily restored teeth.
Which appliance is used after orthodontic treatment to maintain tooth position?
- A Elastics
- B Retainer
- C Palatal expander
- D Functional appliance
Correct answer: Retainer
Retainers stabilize teeth after braces to prevent relapse. Long-term use is essential in maintaining results.