3 - Ear Impressions Flashcards
What 7 reasons are ear impressions required?
1) Custom hearing aids
2) Custom shells for RICs (slimtips, cshells, etc.)
3) Earmolds for BTEs
4) Noise plugs
5) Sleep plugs
6) Swim plugs
7) Custom ear monitors
What are 5 characteristics of a good earmold, custom aid, or custom earplug?
1) Good acoustic seal for reduction of feedback (a loose fitting earmold can cause feedback)
2) Good retention (we don’t want an earmold that’s falling out of the ear - peds)
3) Comfortable to wear for long periods
4) Easy to insert and remove (snug, but not super tight fit - have to be able to put it in and take it out)
5) Shaped so that sound is directed toward the eardrum rather than the canal wall
What is the shape of the ear canal?
An “s” shape
What are the two portions of the ear canal?
1) Cartilaginous portion between 1st & 2nd bend
- cerumen production area
- cartilage is flexible and can shift with jaw movements
2) Bony portion past the 2nd bend
- more rigid
- more sensitive compared to cartilaginous portion
What is the most sensitive part of the ear canal?
The bottom inferior portion of the ear is more sensitive than the superior portion
What parts of the pinna should you include in your ear impression & why?
- Filling the outer ear with impression material to provide detailed information
- Concha, tragus detail, helix lock
What is the patient-specific medical history that is important to obtain before taking an ear-impression?
1) Risk for infection?
2) Allergies?
3) Diabetic?
4) Immune compromised?
5) Bleeding risks (bleeding disorders)?
6) Surgical interventions (may or may not be obvious upon otoscopic examination)?
7) Known malformations, genetic anomalies of the ear?
8) Sensitivity in the ear (cough/vagus nerve sensitivity)?
9) Bleeding risks (bleeding disorders)?
10) Anti-coagulant medications?
What happens if a patient answers yes to any of the patient-specific medical history questions?
If a patient has one of these, may have to refer or proceed with extra caution
Why is diabetes an important question?
More prone to infection and bleeding
What are some examples of anti-coagulant medications?
- apixaban (Eliquis)
- dabigatran (Pradaxa)
- edoxaban (Lixiana)
- rivaroxaban (Xarelto)
- warfarin (Coumadin)
Why do we do otoscopy before performing an ear-impression?
Familiarization of individual characteristics
What 8 questions do we ask ourselves when doing otoscopy before performing an ear-impression?
1) Are there anomalies in the ear which are going to prevent you from taking an impression?
2) Are there anomalies which will influence the style of hearing aids able to be worn?
3) Where will the otoblock be placed in the canal?
4) Cerumen? Where in the canal
5) Myringotomy tubes?
6) Hair at the canal entrance to be trimmed?
7) Size and shape of ear canal- any unique characteristics?
8) Determine the need for medical clearance active fluid discharge
–inflammation
–pain in touching the pinna, manipulating the pinna
–bony growths in ear canal/exostosis
–perforated eardrum
–previous surgery (e.g., mastoidectomy)
8) How does it look behind the ear (mastoid)
What type of anomaly could prevent an ear-impression from being taken?
Exostoses and osteoma
What are the 4 components of impression material?
1) viscosity
2) shore value
3) contraction ratio
4) stress relaxation
What is viscosity?
- In reference to impression material, viscosity is the consistency of the material before it hardens in the process.
- Low = soft/runny
- High = thick/dense/firmer
When is low & high viscosity material used?
- Lower viscosity material is generally preferred (generally used with an injection gun).
- High viscosity material may be better for canals with hair, or in open-jawed impressions
What is shore value?
- Once the impression material parts have been mixed, an impression has been taken, and impressions form, its “hardness” has a particular shore value.
- Furthermore, shore value refers to the hardness of the created earmold
- This is important for keeping shape, and for shipping
What is contraction ratio?
- How much does the impression shrink over time?
- Less than 3% is acceptable
- How do you ensure an acceptable ratio? Mix material according to directions of the package
Why is contraction ratio important?
- If you have a patient that is having an ear impression done, but isn’t going through with purchasing the HAs quite yet
- If impressions are sitting for months, it’s better to get a fresh impression done
- Can keep an ear impression for usually up to a year
What is stress relaxation?
- Does the impression keep shape after it is stretched or bent?
- Does it change when we physically pull the impression out of the ear?