CCA Prosthetic Fabrication & Fitting 2 — Questions and Answers
Question 1: Which retention method for a silicone auricular prosthesis relies on direct bone-anchored implants placed by a surgeon?
- Medical-grade adhesive tape
- Osseointegrated implants with bar/clip attachments (Correct answer)
- Anatomical undercuts in the concha
- Pressure-sensitive acrylic adhesive
Correct answer: Osseointegrated implants with bar/clip attachments
Osseointegrated implants placed in the temporal bone allow bar-and-clip or magnet retention systems that eliminate the need for skin adhesives.
Question 2: During the wax try-in stage for a nasal prosthesis, the primary purpose is to:
- Finalize the silicone pigmentation mix
- Evaluate form, fit, symmetry, and patient acceptance before processing (Correct answer)
- Test the bond strength of the chosen adhesive
- Determine the osseointegration success
Correct answer: Evaluate form, fit, symmetry, and patient acceptance before processing
The wax try-in allows the anaplastologist and patient to assess shape, margins, symmetry, and color harmony before committing to final processing.
Question 3: Intrinsic coloring of a silicone prosthesis refers to:
- Painting pigments onto the cured silicone surface
- Incorporating pigments into the silicone base before vulcanization (Correct answer)
- Using photographic matching under UV light
- Applying commercial cosmetics post-fitting
Correct answer: Incorporating pigments into the silicone base before vulcanization
Intrinsic coloring embeds pigments within the silicone mass so color is durable and cannot be rubbed off, unlike extrinsic surface painting.
Question 4: A two-part rigid stone mold for a silicone prosthesis must be sealed with a separating medium primarily to:
- Accelerate silicone vulcanization time
- Prevent mold sections from bonding to each other and to the silicone (Correct answer)
- Add translucency to the final prosthesis
- Reduce the weight of the stone investment
Correct answer: Prevent mold sections from bonding to each other and to the silicone
Separating medium (e.g., petroleum jelly or alginate separator) prevents adhesion between mold halves and between mold and silicone, enabling clean separation.
Question 5: When fabricating an ocular prosthesis, the iris disc is typically positioned to match the patient's contralateral eye primarily by aligning:
- Pupillary diameter only
- Limbal ring color and overall iris diameter only
- Pupil center relative to the geometric center of the prosthesis and overall iris diameter (Correct answer)
- Scleral vein pattern and lower lid margin
Correct answer: Pupil center relative to the geometric center of the prosthesis and overall iris diameter
Accurate placement of the pupil center and correct iris diameter are the primary factors for achieving natural-appearing gaze alignment in an ocular prosthesis.
Question 6: The Shore A hardness scale is used in anaplastology to characterize:
- The opacity of pigment dispersions in silicone
- The durometer (softness-to-firmness) of silicone elastomers (Correct answer)
- The thermal resistance of acrylic resins
- The porosity of gypsum investment materials
Correct answer: The durometer (softness-to-firmness) of silicone elastomers
Shore A durometer measures the hardness of elastomers; lower values indicate softer, more flexible silicone appropriate for lifelike facial prostheses.
Question 7: Feathered margins on a silicone facial prosthesis are achieved by:
- Sanding the edges with coarse abrasive paper after curing
- Designing the wax pattern with extremely thin, tapered edges at the border (Correct answer)
- Applying additional platinum catalyst to the perimeter only
- Chemically etching the border with acetone after processing
Correct answer: Designing the wax pattern with extremely thin, tapered edges at the border
Creating very thin, tapered wax margins transfers to ultra-thin silicone edges on the finished prosthesis, blending imperceptibly with surrounding skin.
CCA Prosthetic Fabrication & Fitting 2
Which retention method for a silicone auricular prosthesis relies on direct bone-anchored implants placed by a surgeon?