Amalgam Restoration Assist Practice Questions
21 free Amalgam Restoration 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.
What is the primary composition of dental amalgam used for restorations?
- A A resin matrix combined with a glass filler system
- B Silver-tin-copper alloy powder mixed with mercury
- C Gold and platinum alloy
- D Zinc oxide and eugenol paste
Correct answer: Silver-tin-copper alloy powder mixed with mercury
Dental amalgam consists of a powdered alloy (silver, tin, copper) mixed with liquid elemental mercury to form a plastic mass that hardens into a durable filling. This metal composition is characteristic of amalgam materials.
Which instrument is used to transport freshly mixed amalgam into a prepared cavity?
- A Burnisher
- B Amalgam carrier
- C Dental explorer probe
- D Matrix band retainer
Correct answer: Amalgam carrier
An amalgam carrier is specifically designed to carry increments of freshly mixed amalgam from the mixing well to the prepared cavity before condensation.
Why is condensation of amalgam essential after placement into the cavity preparation?
- A To speed up the chemical setting reaction of the amalgam material
- B To adapt and compress it, eliminating voids and excess mercury
- C To bond amalgam chemically to dentin
- D To change the color of the restoration
Correct answer: To adapt and compress it, eliminating voids and excess mercury
Condensation packs and compresses the amalgam into all surfaces of the preparation, expelling mercury-rich matrix and reducing voids, which improves restoration strength and marginal adaptation.
Which hand instrument is typically used to carve occlusal anatomy into a freshly placed amalgam restoration?
- A Spoon excavator used for caries removal
- B Ward's carver (cleoid-discoid)
- C Matrix band
- D Explorer
Correct answer: Ward's carver (cleoid-discoid)
After condensation, a Ward’s carver (cleoid-discoid) is used to shape occlusal grooves and fissures and to remove excess material for proper anatomy and contact.
What is the purpose of burnishing an amalgam restoration immediately after carving?
- A To polish the surface to its final high luster
- B To smooth the surface and close marginal gaps
- C To harden the amalgam considerably faster
- D To bond the amalgam directly to the enamel
Correct answer: To smooth the surface and close marginal gaps
Burnishing smooths the surface of freshly carved amalgam and helps adapt margins tightly to the cavity walls, reducing marginal gaps and improving longevity.
Which step should NOT be done until the amalgam has set sufficiently (typically after several minutes)?
- A Initial carving of the anatomy
- B Condensation
- C Occlusal adjustment and final polishing
- D Insertion of the first amalgam increments into the cavity
Correct answer: Occlusal adjustment and final polishing
Occlusal adjustment and final polishing should be delayed until amalgam has set sufficiently to avoid fracturing or distorting the restoration during the high pressure and heat of polishing.
Which of the following cavity preparation features is important for retention of an amalgam restoration?
- A Bonding directly to the enamel without any undercuts present
- B Parallel or slightly convergent walls and a flat floor
- C Rounded occlusal anatomy before placement
- D Use of a liner only
Correct answer: Parallel or slightly convergent walls and a flat floor
Because amalgam does not bond chemically to tooth structure, mechanical retention is essential. Parallel or slightly convergent walls and a flat pulpal floor help resist displacement of the restoration.
What is the approximate proportion of mercury to alloy powder in dental amalgam by weight (traditional amalgam)?
- A 10% mercury : 90% alloy powder
- B 50% mercury : 50% alloy powder
- C 80% mercury : 20% alloy powder
- D 0% mercury — mercury-free alloy
Correct answer: 50% mercury : 50% alloy powder
Traditional dental amalgam is roughly half (≈50%) elemental mercury by weight combined with alloy powder, enabling the particles to wet and form a workable mass that hardens into a strong filling.
Which of the following is an advantage of amalgam restorations compared to some other restorative materials?
- A Highly aesthetic and closely matched to the natural tooth color
- B Durable, cost-effective, and technique-tolerant posteriorly
- C Requires no cavity preparation
- D Bonds chemically to enamel and dentin
Correct answer: Durable, cost-effective, and technique-tolerant posteriorly
Amalgam is valued for its strength, durability, relative ease of placement, and lower cost, making it suitable for posterior teeth under heavy occlusal loads.
What is the purpose of applying a cavity varnish or liner prior to placing amalgam in deep cavities?
- A To improve chemical bonding of amalgam directly to the underlying dentin surface
- B To seal dentinal tubules, reducing micro-leakage and post-operative sensitivity
- C To accelerate the setting reaction of the freshly triturated amalgam mix
- D To provide a smooth final polished finish on the completed restoration
Correct answer: To seal dentinal tubules, reducing micro-leakage and post-operative sensitivity
A varnish or liner seals dentinal tubules and protects the pulp from thermal, chemical, or moisture effects of amalgam, reducing post-operative sensitivity and micro-leakage.
Which of the following is a common error when placing amalgam that may lead to marginal breakdown over time?
- A Over-condensing the amalgam with excessive vertical force during placement
- B Inadequate condensation leaving voids or overhangs
- C Applying a cavity varnish to the dentin before amalgam placement
- D Delaying the final polishing step until a follow-up appointment
Correct answer: Inadequate condensation leaving voids or overhangs
Poor condensation can leave voids or gaps and overhangs, which compromise marginal integrity, allowing microleakage and eventual marginal breakdown.
Which instrument is used to carve proximal anatomy and remove excess amalgam adjacent to a matrix band?
- A Condenser
- B Carver (e.g., cleoid-discoid or appropriate carver)
- C Explorer
- D Burnisher
Correct answer: Carver (e.g., cleoid-discoid or appropriate carver)
After condensation, a carver is used to shape proximal contours, marginal ridges, and remove excess amalgam next to the matrix band to ensure proper contact and anatomy.
Why is it recommended to layer amalgam in increments rather than fill the cavity in one bulk mass?
- A To reduce the overall mercury content of the finished restoration
- B To improve adaptation, reduce voids, and allow condensation
- C To speed up the filling process and shorten the appointment time
- D To make the restoration easier to polish at a later stage
Correct answer: To improve adaptation, reduce voids, and allow condensation
Incremental placement allows each layer to be condensed thoroughly, improving marginal adaptation, reducing voids or porosity, and ensuring structural integrity.
Which risk is associated with dental amalgam if not handled or triturated properly?
- A Immediate visible discoloration of the surrounding enamel and dentin
- B Inadequate setting, porosity, or marginal leakage causing failure
- C Excessive chemical bonding to the etched enamel margins of the cavity
- D Spontaneous fracture of the entire natural crown of the tooth
Correct answer: Inadequate setting, porosity, or marginal leakage causing failure
Poor mixing or handling can lead to incomplete amalgamation, porosity, inadequate strength, or marginal gaps — all of which compromise the longevity and seal of the restoration.
Which of the following describes an ideal time for performing occlusal adjustment on a newly placed amalgam restoration?
- A Immediately after placement while still soft
- B After final carving but before initial set
- C After the amalgam has partially set but before complete hardening to avoid fracture
- D Not necessary — amalgam does not require occlusal adjustment
Correct answer: After the amalgam has partially set but before complete hardening to avoid fracture
Occlusal adjustment should be done once amalgam has gained enough strength to resist distortions but before full final set, to avoid marginal fracture and ensure proper occlusion.
Which property of modern high-copper dental amalgams improves their performance compared to older low-copper alloys?
- A They have a resin component
- B They don’t require mercury for mixing
- C They have greater corrosion resistance and less marginal breakdown
- D They set instantly without condensation
Correct answer: They have greater corrosion resistance and less marginal breakdown
High-copper amalgams exhibit better corrosion resistance and reduced marginal breakdown or creep compared to older low-copper alloys, improving long-term durability.
Which patient-related factor might contraindicate the use of amalgam restoration?
- A Need for a low-cost restoration in a molar
- B No known metal allergies
- C Strong concern for aesthetic appearance in anterior teeth
- D Desire for a durable, long-lasting filling in a posterior tooth
Correct answer: Strong concern for aesthetic appearance in anterior teeth
Amalgam is metallic and visible, so if aesthetics are a high priority (especially in anterior teeth), amalgam may be contraindicated in favor of tooth-colored materials.
What is the purpose of using a matrix band and retainer in an amalgam restoration, especially for Class II cavities?
- A To cure and harden the freshly placed amalgam much faster
- B To provide external structural support to the adjacent standing teeth
- C To confine the amalgam and recreate proximal contact and contour
- D To polish and smooth the outer surface of the amalgam
Correct answer: To confine the amalgam and recreate proximal contact and contour
A matrix band with a retainer confines the amalgam in proximal boxes, helps recreate proper contact and contour, and prevents over-extension during condensation.
Which of the following sequences correctly outlines the general steps of an amalgam restoration procedure (after cavity preparation)?
- A Mix amalgam, then carve, then condense, then finish and polish the surface
- B Mix amalgam, carry and condense, carve anatomy, burnish, polish
- C Carry amalgam, polish, carve anatomy, condense, then finish the margins
- D Condense amalgam, then mix, then carry, then carve, then polish it
Correct answer: Mix amalgam, carry and condense, carve anatomy, burnish, polish
After mixing, amalgam is carried and condensed, then carved to restore tooth anatomy, followed by burnishing, occlusal adjustment, and final polishing to achieve a smooth, functional, and durable restoration.
Why is it important for a dental assistant to handle triturated amalgam with caution and not with bare hands?
- A Solely to prevent surface contamination of the amalgam before it sets
- B Because mercury exposure and metal transfer require gloves or instruments
- C Because the amalgam will not adhere properly to the dentin if it is touched by hand
- D Because wearing gloves during handling makes the amalgam set faster
Correct answer: Because mercury exposure and metal transfer require gloves or instruments
Trituration and handling of amalgam involve elemental mercury; handling with bare hands risks contamination and mercury exposure, so proper gloves/instruments are mandatory for safety.
What is a likely consequence if a freshly placed amalgam restoration is subjected to heavy occlusal load before it has fully set?
- A Improved longevity
- B Compression that increases hardness
- C Marginal fracture, internal voids or distortion leading to restoration failure
- D No effect — amalgam sets instantly
Correct answer: Marginal fracture, internal voids or distortion leading to restoration failure
Applying heavy occlusal load before proper setting can distort the amalgam, produce internal voids or fracture margins, compromising the restoration’s integrity and longevity.