AHPC Licensure Examination — Dental Laboratory Science

Sample Dental Surgery Assistant practice questions

Try these 12 questions from different topics. Open "Show answer" to check yourself and read the explanation.

1. Question 1 · Impressions, Casts & Cross-Infection

   A dental impression arrives from a clinic without confirmation that it was disinfected. What should the laboratory do?

   1. A.Place it directly beside clean work
   2. B.Handle it as contaminated and follow the agreed cleaning and disinfection protocol before processing
   3. C.Assume saliva cannot transmit microorganisms
   4. D.Return it after drying without documentation
   Show answer

   Answer: B. Handle it as contaminated and follow the agreed cleaning and disinfection protocol before processing

   Clinic-laboratory communication and correct decontamination reduce cross-infection risk.

2. Question 2 · Prosthesis Quality & Communication

   A master cast has a large void at a critical finish line. What is the best response?

   1. A.Guess the missing margin
   2. B.Hide the defect with colouring
   3. C.Document the defect and request an acceptable new impression or cast before fabrication
   4. D.Complete the prosthesis without informing the clinician
   Show answer

   Answer: C. Document the defect and request an acceptable new impression or cast before fabrication

   Fabrication should not proceed when a defect prevents an accurate, clinically safe result.

3. Question 3 · Laboratory Sterilization & Safety

   Which monitor most directly demonstrates that a sterilization cycle killed highly resistant microorganisms?

   1. A.The sterilizer door colour
   2. B.A handwritten date alone
   3. C.The weight of the instrument tray
   4. D.A biological indicator or spore test
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   Answer: D. A biological indicator or spore test

   Biological monitoring directly challenges the process with resistant organisms and complements mechanical and chemical checks.

4. Question 4 · Gypsum & Impression Materials

   Dental stone (Type III gypsum) differs from plaster of Paris mainly because its particles are:

   1. A.Larger, more porous beta-hemihydrate crystals that need much more mixing water
   2. B.Made of calcium carbonate rather than calcium sulphate
   3. C.Mixed with resin to make them flexible
   4. D.Dense, regular alpha-hemihydrate crystals needing less water
   Show answer

   Answer: D. Dense, regular alpha-hemihydrate crystals needing less water

   Alpha-hemihydrate needs less water (W/P ≈ 0.28–0.30 vs 0.45–0.50 for plaster), giving a harder, stronger cast.

5. Question 5 · Waxes & Investments

   Dental waxes are difficult to use for very precise patterns mainly because they have:

   1. A.A very low melting point below room temperature in tropical climates
   2. B.No elasticity at all
   3. C.A high coefficient of thermal expansion
   4. D.A strong unpleasant smell
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   Answer: C. A high coefficient of thermal expansion

   Waxes expand and contract markedly with temperature and release internal stresses, distorting patterns over time.

6. Question 6 · Polymers & Acrylic Resins

   The liquid component of heat-cured denture acrylic is mainly:

   1. A.Polymethyl methacrylate beads mixed with benzoyl peroxide powder
   2. B.Water with dissolved pigments
   3. C.Ethyl alcohol
   4. D.Methyl methacrylate monomer
   Show answer

   Answer: D. Methyl methacrylate monomer

   The liquid is MMA monomer with an inhibitor (hydroquinone) and often a cross-linking agent; the powder is PMMA beads with initiator.

7. Question 7 · Dental Alloys & Ceramics

   Cobalt–chromium alloys are preferred for partial denture frameworks because they:

   1. A.Are stiff and light, allowing thin rigid connectors
   2. B.Are soft and easy to bend repeatedly at the chairside
   3. C.Are cheaper than acrylic
   4. D.Have the same colour as natural teeth
   Show answer

   Answer: A. Are stiff and light, allowing thin rigid connectors

   High modulus and low density mean rigid, thin frameworks; chromium gives corrosion resistance.

8. Question 8 · Complete Dentures

   Occlusion rims (record blocks) are made in the laboratory so the clinician can record:

   1. A.The patient's blood group and medical history for the denture record card
   2. B.The colour of the gums only
   3. C.The jaw relationship, vertical dimension and tooth positions
   4. D.The final denture fit after processing
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   Answer: C. The jaw relationship, vertical dimension and tooth positions

   Rims on accurate bases record the occlusal plane, centre line, lip support, OVD and centric relation.

9. Question 9 · Removable Partial Dentures

   A Kennedy Class I partially edentulous arch has:

   1. A.Bilateral free-end (distal extension) saddles
   2. B.A single bounded saddle on one side with teeth at both ends of the gap
   3. C.A single anterior saddle crossing the midline
   4. D.A unilateral free-end saddle
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   Answer: A. Bilateral free-end (distal extension) saddles

   Class I bilateral free end; II unilateral free end; III unilateral bounded; IV single anterior bounded saddle crossing the midline.

10. Question 10 · Crowns & Bridges

    Die spacer is applied to a die (except near the margin) to:

    1. A.Leave room for cement and improve seating of the crown
    2. B.Make the die smaller so that the crown fits tightly with friction
    3. C.Harden the die surface
    4. D.Mark the occlusal contacts
    Show answer

    Answer: A. Leave room for cement and improve seating of the crown

    Spacer creates a uniform cement gap; it stops short of the finish line to keep the marginal seal.

11. Question 11 · Maxillofacial & Implant Prosthetics

    An obturator prosthesis is used to:

    1. A.Close a defect in the palate, such as after surgery or from a cleft
    2. B.Replace a missing ear after trauma using silicone held with adhesive
    3. C.Straighten crooked incisors
    4. D.Whiten discoloured teeth
    Show answer

    Answer: A. Close a defect in the palate, such as after surgery or from a cleft

    Obturators restore speech, swallowing and appearance after maxillectomy or in cleft palate.

12. Question 12 · Denture Repairs, Relines & Rebases

    A reline of a denture involves:

    1. A.Replacing every denture tooth while keeping the old base unchanged
    2. B.Making a completely new denture from fresh impressions
    3. C.Adding new material to the fitting surface to improve adaptation
    4. D.Polishing the outer surface only
    Show answer

    Answer: C. Adding new material to the fitting surface to improve adaptation

    A reline uses an impression in the old denture to add a layer to the fitting surface; a rebase replaces the whole base.