IHS Earmold and Impression Techniques 2 — Questions and Answers
Question 1: Which impression material property is most critical when taking an impression on a patient with a very narrow ear canal?
- High viscosity to fill all spaces
- Low viscosity to flow into tight spaces without excessive pressure (Correct answer)
- Fast set time to minimize patient discomfort
- High shore hardness for dimensional stability
Correct answer: Low viscosity to flow into tight spaces without excessive pressure
Low-viscosity material flows into narrow canals without requiring excessive injection force that could cause discomfort or a distorted impression.
Question 2: What is the primary purpose of placing an otoblock (dam) before taking an ear impression?
- To improve acoustic seal of the finished earmold
- To protect the tympanic membrane from impression material (Correct answer)
- To dilate the ear canal for easier material flow
- To reduce the setting time of the impression material
Correct answer: To protect the tympanic membrane from impression material
The otoblock acts as a physical barrier to prevent impression material from contacting or damaging the tympanic membrane.
Question 3: A patient with an open jaw impression shows a significant gap between the impression and the tragus area when the mouth is closed. This most likely indicates:
- The otoblock was placed too deeply
- The impression material was over-mixed
- Insufficient material was injected into the canal
- The temporomandibular joint movement was not adequately captured (Correct answer)
Correct answer: The temporomandibular joint movement was not adequately captured
TMJ movement changes the shape of the ear canal, and a gap at the tragus suggests the open-jaw technique did not fully account for this dynamic change.
Question 4: Which earmold style is most appropriate for a patient with severe-to-profound hearing loss who needs maximum low-frequency amplification?
- Skeleton earmold with a large vent
- Open-fit dome with a standard vent
- Full-shell earmold with no vent or a minimal vent (Correct answer)
- Half-shell earmold with a diagonal vent
Correct answer: Full-shell earmold with no vent or a minimal vent
A full-shell earmold with minimal or no venting provides the best acoustic seal to prevent feedback and retain low-frequency energy needed for severe-to-profound loss.
Question 5: What does the term 'shrinkage' refer to in the context of earmold laboratory processing?
- Reduction in earmold hardness after curing
- Dimensional change of the earmold material as it cures or cools (Correct answer)
- Loss of color in the earmold material over time
- Reduction in canal length after trimming
Correct answer: Dimensional change of the earmold material as it cures or cools
Shrinkage is the dimensional reduction that occurs as acrylic or silicone materials polymerize or cool, which can affect the final fit of the earmold.
Question 6: When inspecting a completed ear impression, an air bubble or void in the canal portion indicates:
- The impression should be accepted as-is if the void is small
- A potential fit problem and the impression should be retaken (Correct answer)
- The material set too slowly
- The patient moved their jaw during the impression
Correct answer: A potential fit problem and the impression should be retaken
Voids in the canal portion of an impression will translate to bumps or gaps in the finished earmold, causing a poor fit and possible feedback.
Question 7: Which of the following best describes a 'canal lock' feature on an earmold?
- A locking mechanism that secures the hearing aid to the earmold
- A protrusion that fits into the second bend of the canal to improve retention (Correct answer)
- A type of vent that prevents acoustic feedback
- A silicone coating applied to the canal tip for comfort
Correct answer: A protrusion that fits into the second bend of the canal to improve retention
A canal lock is a small protrusion molded onto the canal portion that engages the second bend of the ear canal, significantly improving earmold retention.
IHS Earmold and Impression Techniques 2
Which impression material property is most critical when taking an impression on a patient with a very narrow ear canal?