Impression Techniques & Molding Flashcards

When applying a facial impression material to a site that includes skin with active radiation changes, the anaplastologist should:

Answer: Consult with the oncology team and use the gentlest possible material with minimal pressure

Irradiated tissue is fragile and poorly perfused; interdisciplinary consultation and gentle technique minimize the risk of tissue trauma or breakdown.

The term 'dimensional stability' as applied to impression materials refers to:

Answer: The ability of the material to maintain its shape and dimensions after removal from the mouth or defect site

Dimensional stability ensures the impression accurately represents tissue anatomy over the time needed to pour and process the model.

In a split-cast or two-piece mold, registration keys (index points) serve to:

Answer: Ensure accurate and repeatable realignment of mold sections during processing

Registration keys lock the mold halves into precise spatial relationship, preventing shifts that would distort prosthesis thickness and margin accuracy.

When an osseointegrated implant bar is present in the auricular region, how does this affect the impression technique?

Answer: Impression copings or analogs are incorporated to record implant position accurately within the impression

Implant-level impressions use transfer copings to capture the exact three-dimensional position of each implant for accurate bar/clip superstructure reproduction.

A positive model (cast) is to a negative impression as:

Answer: The prosthesis surface is to the recorded tissue anatomy

The positive model reproduces the actual tissue anatomy in three dimensions, while the impression is the negative counterpart capturing the intaglio surface.

Which of the following best describes the 'skin safe' criterion when selecting an impression material for facial use?

Answer: The material must be biocompatible, non-irritating, and free of cytotoxic components for prolonged skin contact

Facial impression materials must meet biocompatibility standards because they contact compromised perioral, periorbital, or post-surgical tissue for the duration of the set.

What is the most critical step immediately after removing an alginate facial impression from a patient?

Answer: Disinfecting the impression and pouring the stone model promptly to prevent dimensional change

Alginate is highly susceptible to syneresis (water loss) and imbibition, causing rapid dimensional change; immediate disinfection and pouring preserves accuracy.