IHS Earmold and Impression Techniques 3 — Questions and Answers
Question 1: Silicone impression material is generally preferred over powder-and-liquid acrylic for ear impressions because silicone:
- Sets faster and requires less skill
- Is less expensive and more widely available
- Is more dimensionally stable and flexible for easier removal (Correct answer)
- Produces a harder impression for better lab processing
Correct answer: Is more dimensionally stable and flexible for easier removal
Silicone impression materials exhibit excellent dimensional stability after setting and their flexibility allows for easier, safer removal from the ear canal.
Question 2: A patient complains that their new earmold causes a 'plugged up' or occlusion effect when chewing or speaking. The most appropriate first modification would be to:
- Reduce the overall length of the canal tip
- Add or enlarge a vent in the earmold (Correct answer)
- Remake the earmold in a harder acrylic material
- Polish the surface of the earmold canal portion
Correct answer: Add or enlarge a vent in the earmold
The occlusion effect is caused by bone-conducted sound being trapped in a sealed ear canal, and adding or enlarging a vent allows this energy to escape.
Question 3: When using a syringe to inject impression material, the nozzle should be positioned:
- At the entrance of the ear canal, pointing inward
- Touching the otoblock before slowly withdrawing as the canal fills (Correct answer)
- In the concha bowl to allow gravity to fill the canal
- Against the ear canal wall to prevent air entrapment
Correct answer: Touching the otoblock before slowly withdrawing as the canal fills
Starting at the otoblock and withdrawing as the material fills prevents air pockets from being trapped behind the material as it is injected.
Question 4: Which earmold tubing size is most commonly used with a standard behind-the-ear hearing aid for adults?
- #12 tubing
- #13 tubing (Correct answer)
- #16 tubing
- #9 tubing
Correct answer: #13 tubing
#13 tubing is the standard size used with most conventional BTE hearing aids and provides the appropriate acoustic bore diameter for typical amplification needs.
Question 5: A 'skeleton' earmold differs from a 'semi-skeleton' earmold primarily in that the skeleton style:
- Has a larger canal portion
- Retains more of the concha bowl material for a solid rim
- Has material only in the helix and anti-helix area with an open concha bowl (Correct answer)
- Is made exclusively from soft silicone material
Correct answer: Has material only in the helix and anti-helix area with an open concha bowl
A skeleton earmold has a rim of material following the helix and anti-helix contours but leaves the center of the concha bowl open, while a semi-skeleton retains part of the bowl.
Question 6: Before taking an ear impression, otoscopic examination is performed to:
- Measure the length of the ear canal for selecting tubing
- Assess the health of the ear canal and determine safe otoblock placement depth (Correct answer)
- Determine the appropriate earmold style for the patient
- Check the patient's hearing sensitivity in the high frequencies
Correct answer: Assess the health of the ear canal and determine safe otoblock placement depth
Otoscopy allows the clinician to inspect the ear canal for cerumen, inflammation, perforation, or other contraindications to impression taking, and to gauge safe otoblock depth.
Question 7: Which condition would be an absolute contraindication to taking an ear impression without physician clearance?
- Mild cerumen accumulation near the entrance of the canal
- A suspected perforated tympanic membrane (Correct answer)
- Slightly curved second bend of the ear canal
- Patient discomfort with the otoscope tip
Correct answer: A suspected perforated tympanic membrane
A perforated tympanic membrane means impression material could enter the middle ear space, making physician evaluation and clearance mandatory before proceeding.
IHS Earmold and Impression Techniques 3
Silicone impression material is generally preferred over powder-and-liquid acrylic for ear impressions because silicone: