CCA Facial Prosthetics Design & Fabrication 3 — Questions and Answers
Question 1: Which impression technique is preferred for capturing a deep orbital exenteration defect with significant undercuts?
- Single-step alginate pour
- Sectional or staged polyvinyl siloxane impression (Correct answer)
- Zinc oxide eugenol paste impression
- Thermoplastic wax bite registration
Correct answer: Sectional or staged polyvinyl siloxane impression
Sectional PVS impressions allow removal from severe undercuts without distortion by disassembling the impression in segments.
Question 2: Bar-clip retention for an implant-retained auricular prosthesis requires a minimum inter-implant distance of approximately:
- 5 mm
- 10 mm
- 18–20 mm (Correct answer)
- 30 mm
Correct answer: 18–20 mm
A minimum of approximately 18–20 mm between implants is needed to accommodate bar components and clips without mechanical interference.
Question 3: When painting extrinsic colors on a cured silicone prosthesis, the medium most compatible with platinum-cured silicone is:
- Acrylic lacquer thinner solution
- Silicone-dissolved pigment in uncured silicone base (Correct answer)
- Oil-based artist paint
- Watercolor wash sealed with varnish
Correct answer: Silicone-dissolved pigment in uncured silicone base
Silicone-compatible extrinsic paints use an uncured silicone carrier that bonds chemically to the cured prosthesis surface.
Question 4: During the flasking and packing of a silicone auricular prosthesis, flash overflow between mold halves should be:
- Left in place to strengthen the mold joint
- Removed before final closure to prevent thin margins (Correct answer)
- Packed intentionally to create a natural edge
- Sealed with cyanoacrylate adhesive
Correct answer: Removed before final closure to prevent thin margins
Removing flash before final closure ensures the mold seats fully, preventing material-thin areas and producing accurate margins.
Question 5: The term 'feathered edge' in facial prosthetics refers to:
- A textured surface to mimic skin pores
- An extremely thin, tapered margin that blends imperceptibly into surrounding skin (Correct answer)
- A rigid reinforced border for structural support
- A color gradient applied at the prosthesis periphery
Correct answer: An extremely thin, tapered margin that blends imperceptibly into surrounding skin
A feathered edge tapers to near-zero thickness at the margin, minimizing visible transition between prosthesis and natural skin.
Question 6: A patient with a silicone nasal prosthesis reports yellowing of the device after 8 months. The most likely cause is:
- Platinum catalyst migration to the surface
- UV degradation and oxidative aging of the silicone polymer (Correct answer)
- Incompatibility between intrinsic pigments and skin oils
- Excessive use of medical-grade adhesive
Correct answer: UV degradation and oxidative aging of the silicone polymer
Ultraviolet radiation and oxidative exposure cause progressive yellowing and embrittlement of silicone prostheses over time.
Question 7: Which landmark is used to establish the vertical midline when positioning a nasal prosthesis on the face?
- Tragion of the ear
- Glabella-to-menton facial midline (Correct answer)
- Lateral canthus of the eye
- Alar base of the contralateral side
Correct answer: Glabella-to-menton facial midline
The glabella-to-menton line establishes true facial midline and is the primary reference for symmetrical nasal prosthesis placement.
CCA Facial Prosthetics Design & Fabrication 3
Which impression technique is preferred for capturing a deep orbital exenteration defect with significant undercuts?