Techniques & Materials Flashcards

Magnet retention for a facial prosthesis requires magnets embedded in both the prosthesis and which complementary component?

Answer: Implant-retained abutment caps or a secondary bar

Opposing magnets are placed in the prosthesis and in implant-supported abutment caps or a bar superstructure, creating attractive force for retention without adhesive.

Which finishing technique is used to remove mold seam lines from a cured silicone prosthesis without damaging delicate margins?

Answer: Careful trimming with sharp scissors and fine scalpel blades

Sharp scissors and scalpel blades allow precise removal of flash and seam lines from flexible silicone without tearing or heat-distorting thin prosthetic margins.

Fibers such as cotton or nylon are sometimes incorporated into silicone prostheses primarily to:

Answer: Increase tear resistance of thin prosthetic sections

Fiber reinforcement within the silicone matrix increases tear strength at vulnerable thin regions like marginal edges, extending prosthesis longevity.

In ocular prosthetics, the painted iris disc is typically sealed between which two layers?

Answer: A clear acrylic anterior button and the painted base

The custom-painted iris pattern is sandwiched between the clear anterior acrylic dome (cornea button) and the main scleral acrylic body, protecting the artwork from abrasion.

What is the primary reason silicone prostheses require periodic replacement (every 1-3 years)?

Answer: UV degradation, discoloration, and material fatigue reduce aesthetic and physical properties

Prolonged UV exposure and mechanical stress cause silicone to yellow, stiffen, and lose surface detail, necessitating fabrication of a new prosthesis.

When creating a two-part plaster or stone mold for a facial prosthesis, what determines the parting line placement?

Answer: The point of greatest undercut that allows mold separation without tearing the prosthesis

The parting line is strategically placed at the broadest periphery of the pattern to eliminate mechanical undercuts that would lock the mold halves together during separation.

For an orbital exenteration patient receiving a prosthesis, which retention method is most frequently preferred due to absence of adhesive skin irritation?

Answer: Osseointegrated implants with bar-clip or magnetic retention

Osseointegrated implants provide superior, irritation-free retention for orbital prostheses, especially in patients with exenterated orbits where skin surface area is limited.