CCA Techniques & Materials 2 — Questions and Answers
Question 1: Which intrinsic coloring technique involves mixing pigments directly into silicone before vulcanization?
- Extrinsic painting
- Intrinsic pigmentation (Correct answer)
- Surface lamination
- Oxidative staining
Correct answer: Intrinsic pigmentation
Intrinsic pigmentation blends colorants into the silicone matrix prior to curing, producing durable color that resists wear and weathering.
Question 2: When fabricating a silicone auricular prosthesis, which catalyst system is most commonly used for room-temperature vulcanization?
- Peroxide catalyst
- Platinum catalyst
- Tin catalyst (Correct answer)
- UV photoinitiator
Correct answer: Tin catalyst
Tin (condensation) catalysts are the classic choice for RTV silicone systems used in anaplastology, though platinum-cure systems are increasingly popular for their lower shrinkage.
Question 3: A marginal edge of a silicone prosthesis that is too thick will most likely cause which problem?
- Improved adhesion
- Visible color mismatch at the transition zone (Correct answer)
- Increased flexibility
- Reduced acrylic support
Correct answer: Visible color mismatch at the transition zone
Thick margins create a visible step that does not blend into surrounding skin, producing a color and contour mismatch that betrays the prosthesis.
Question 4: In prosthetic eye fabrication, which material is typically used for the scleral shell?
- High-density polyethylene
- Heat-cured polymethyl methacrylate (PMMA) (Correct answer)
- Polyurethane foam
- Thermoplastic elastomer
Correct answer: Heat-cured polymethyl methacrylate (PMMA)
PMMA (acrylic) is the standard material for ocular prostheses due to its biocompatibility, optical clarity, and ability to be polished to a high gloss.
Question 5: Which adhesive is preferred for silicone facial prostheses because it is water-resistant and skin-safe?
- Cyanoacrylate (super glue)
- Medical-grade silicone adhesive (Correct answer)
- Epoxy resin
- Latex-based rubber cement
Correct answer: Medical-grade silicone adhesive
Medical-grade silicone adhesives bond effectively to silicone prostheses, resist perspiration, and are formulated to minimize skin irritation.
Question 6: What is the primary purpose of applying a release agent to a mold before pouring silicone?
- To add color to the prosthesis
- To prevent the prosthesis from bonding permanently to the mold (Correct answer)
- To accelerate curing time
- To improve surface texture
Correct answer: To prevent the prosthesis from bonding permanently to the mold
Release agents create a barrier between the mold surface and the silicone, allowing clean separation without tearing the prosthesis.
Question 7: Which sculptural technique is used to replicate the fine skin-texture detail such as pores and hair follicles on a wax pattern?
- Block-out waxing
- Stippling and texturing with fine brushes or dental burrs (Correct answer)
- Acetone smoothing
- Sandblasting
Correct answer: Stippling and texturing with fine brushes or dental burrs
Stippling tools, fine brushes, and rotary instruments are used to emboss realistic skin micro-texture into the wax pattern before mold fabrication.
CCA Techniques & Materials 2
Which intrinsic coloring technique involves mixing pigments directly into silicone before vulcanization?