Ear mold impressions Flashcards
the valley becomes what and why?
the valley becomes the helix lock for retention
the crus aligns with what?
the tube orientation
the concha bowl provides what?
-Concha bowl provides stability and/or retention
-Concha Cymba- sufficient fill for retention
-Concha cavum
the antitragus provides what?
retention
look at slide 3
what is the average length of the ear canal
25 mm in adults
the isthmus transitions from what to what
from cartilage to a bony canal
the distance from the ear canal to the isthmus is what?
10 mm
why does the visualization of the canal bend help
because it helps with otoblock placement
look at slide 5
additional cured silicone is made of ?
Combines 1:1 polyvinyl-siloxane parts of paste
-2 powders mixed together
condensation cured silicon (like silicast) is made of
Dimmethyl-siloxane paste mixed with hardener
-take a scoop of scilicon material and mix it in your hand until it hardens are cures
Methyl-Methacrylate is made of ?
-AKA “Powder and Liquid”
-Pre-measured acrylic powder and liquid formulas are rapidly mixed together
-powder and liquid and a nonsilicon
what is viscosity ?
Refers to how easily the material flows before it cures
-refers to the thickness and how it flows to the syringe (def)
-each of those 3 materials to make ear mold impressions have different viscosity
what does a high viscosity consist of ?
-Thick; provides resistance during flow
-Condensation-cured silicone (i.e., silicast)
-Stretches aperture of ear canal
-more energy is needed and pushing that aperature so we get a snug fit
medium viscosity consist of ?
-Provides some stretch to aperture
-Addition-cured silicone or methyl-Methacrylate
low viscosity consist of ?
-Runny, loose; flows easily with little resistance
-Will not alter anatomical structure of ear canal
-Most suitable for devices requiring deep insertion
-Addition-cured silicone
-doesn’t stretch the aperature too much
-used for deep fitting hearing aids
what is stress relaxation and what does it consist of??
-Materials ability to return to its shape after removal
-Silicone is superior; methyl methacrylate’s shape can distort during removal (it has low stretch relaxation)
-high stress relaxation the shape doesn’t change if you stretch it
-low stress relaxation can change if you mess with it
what is contraction ratio
-Shrinkage over a 7-day period
-Silicone will shrink 0.1-0.7% (doesn’t shrink)
-Methyl methacrylate will shrink 3% (it does shrink)
what does shore value mean?
-it occurs AFTER cure hardness
-Lower shore values are likely to be damaged
during the shipping process
-Silicone has a high shore value
-Methyl methacrylate has a low shore value and is susceptible to heat; requires glue for shipping
what is the first step to ear impressions ?
infection control!!
wash your hands and make sure all your equipment is disinfected
what is the second step to ear impressions
case history
what are the 4 questions you should ask during case history?
1)Infection risk: immunocompromised? Diabetes?
2)Bleeding risk: therapeutic blood thinner?
3)Potential ear canal malformations: History of ear surgery
4)Allergies: silicone, lubricant ingredients
what is the 3rd step of ear impressions
otoscopy
what should you do during otoscopy
-Thoroughly examine patient’s ear
-Sit down while performing otoscopy!
>Examination at eye level is needed to view full canal
1)Visualize Pinna, TM, and anterior canal wall
2)Pay attention to vagus nerve activity which may impact impression taking
3)Identify congenital malformations or surgical signs
4)Identify canal bend
what are things we should write down when we see them
Document all pre-impression abnormalities in the medical record like:
1)Cerumen- significant quantity requires removal b/f impression
2)Active infection: drainage? bacterial or fungal? Inflammation ?
-this is a contraindication for EMI
3)Prolapsed canal (exostoses, osteoma);
Collapsing canal
-May limit depth; requires consideration of earmold material
4)Significant jaw movement during otoscopy to see if it changes
5)Requires precautions
-Perforation; PE tube
-Malformation- requires special precautions
-Congenital ear canal widening; stenosis;
-Surgical- Mastoidectomy
-Thick hair growth- may require trimming
during otoscopy we should note what?
-During otoscopy note the ear canal direction
-Awareness of the variety of shapes, texture, & sizes increases efficiency and safety
what is the 4th step in ear impressions:
otoblock placement
-Ideal placement is 2mm beyond the 2nd bend
during ear mold impressions, do we pull the pinna to straighten the canal?
only when putting in the otoblock but not when where putting in the ear mold impression
what is the purpose of canal block
Limits depth of impression material flow and supplies the resistance needed to fully fill canal
what do cotton blocks provide ?
1)Provides more information on the anatomy of the ear canal
2)Easier to modify
-Can be tugged at to reduce the size
-Flattened out to better fill the entire canal space
3)It’s easier to confirm block immovability
what can be provided in foam blocks?
1)Takes up more space in the ear canal
2)Does not modify easily
3)More abrasive; making it less comfortable for the patient
what are things to consider when doing an otoblock insertion?
1)Choosing the otoblock size
-Foam block should be larger than entrance of external canal
-Cotton block should be about the same size as entrance
2)Lubricate block (be aware of potential allergies)
3)Insert slowly without touching canal wall
