7. Impression Materials & Techniques Flashcards
Impression Materials
Desirable Qualities
____ stability over temperature and humidity ranges normally met in clinical and laboratory procedures
(long enough to permit the production of a ____)
Take a look at the others, Peter
dimensional
cast or die
Impression Materials
Aqueous Elastomers
____ hydrocolloids
____ hydrocolloids
Nonaqueous Elastomers \_\_\_\_ \_\_\_\_ Condensation Addition (polyvinylsiloxanes) \_\_\_\_
reversible
irreversible
polysulfides
silicones
polyethers
Alginate Impressions
Use ____ tray which can conveniently be placed in the mouth
largest
Aqueous Elastomers
- Irreversible hydrocolloids
we can work with our hydrocolloids
if we’re gonna use them to take impressions, we will send out and get master casts and make frameworks, w ehave to work with them properly
____ system is probably the most accurate because we’re getting the exact measure of powder and exact liquid
in practice, you use the tub and you have to shake it and carefully measure so you maximize its
properties and don’t get distortions
packet
Irreversible hydrocolloids
Make complete casts for removable prosthodontic cases
this allows us to get very accurate models that if the case is ____ this is the way to go get accurate alginate and you will get accurate fitting case
when utilizing Class II/ Class I scenario, looking at capturing tissue and might want to use ____ type of material
class III/IV
PVS
____ is highly desirable!!!!
techniques = ____ pour technique it’s important to show the laboratory where you want the final prosthesis to fit
land area
double
Irreversible Hydrocolloids
Advantages Most widely \_\_\_\_ impression materials in modern dentistry Easy to \_\_\_\_ Able to \_\_\_\_ blood and f luid Low cost Pleasant taste Easily poured in stone Can be used with \_\_\_\_ trays for preliminary impressions
used
manipulate
displace
stock
Irreversible Hydrocolloids Disadvantages Poor \_\_\_\_ stability Difficult to \_\_\_\_ Poor \_\_\_\_ strength Must be poured \_\_\_\_
dimensional
disinfect
tear
immediately
Polysulfides
Advantages Long \_\_\_\_ time Proven accuracy High \_\_\_\_ resistance Inexpensive \_\_\_\_ shelf life \_\_\_\_ viscosity No special equipment
working
tear
long
low
Polysulfides
Disadvantages Requires a \_\_\_\_ tray Must be poured within \_\_\_\_ hr Possible distortion Odor & taste offends patients Messy; \_\_\_\_ clothes Second pour- less \_\_\_\_ Affected by \_\_\_\_ and humidity \_\_\_\_-no \_\_\_\_ in sulcus
custom one stains accurate temperature hydrophobic moisture
Nonaqueous Elastomers: Silicones
Identified on the basis of their chemical reactions as ____ or ____ types
condensation
addition
Silicones – Latex Contamination
Putties should not be mixed with ____ gloves
____ compounds incorporated into mix poison the platinum catalyst
– no ____
latex
sulfur
polymerization
PVS
Used in main clinic: ____
aquasil
Addition Silicones
Advantages \_\_\_\_ working time Easy to mix automatic mixing devices Adequate \_\_\_\_ strength Extremely high accuracy Undetectable \_\_\_\_ upon removal Dimensionally stable -- even after one \_\_\_\_ Less distortion upon removal Pleasant taste/odor \_\_\_\_ pours
shorter tear distortion week multiple
Addition Silicones
Disadvantages
____ evolution in some products
More ____ (automix)
H2
expensive
Nonaqueous Elastomers Polyethers Commercial examples \_\_\_\_ (main clinic) Permadyne Polygel
impregum
Polyethers
Advantages \_\_\_\_ working time \_\_\_\_ setting time (5-6min) Adequate tear strength Less \_\_\_\_ - better \_\_\_\_ Less distortion w/ removal
fast
fast
hydrophobic
wetting
Polyethers
Advantages
____ shelf life
Good dimensional stability ____ casts can be poured
Pentamix automix system
long
multiple
Polyethers
Disadvantages Clean but tastes bad Stiffness requires blocking out \_\_\_\_ Slightly more expensive \_\_\_\_ tray needed
undercuts
custom
Custom Trays
Advantages:
More ____ than stock tray
More ____ tray adaptation
rigid
accurate
Rational for a Custom Tray
Advantages:
Provides even ____ of impression material
– Minimizes the tendency for ____ areas to be developed which lead to distortions
Facilitates the adjustments of tray extensions and border molding procedures
thickness
thin
Rational for a Custom Tray Disadvantages: More laboratory \_\_\_\_ required More laboratory \_\_\_\_ required More \_\_\_\_ involved
time
cost
material
Rational for a Custom Tray
Indications:
____-borne situations when accurate recording of soft tissue reflections is important
____-tissue borne situations when accurate recording of soft tissue reflections is important and an ____ cast impression is planned
Anatomic limitations that ____ the use of stock tray
tooth
tooth
altered
prohibit
Fabrication of Custom Impression Trays for PRDP Final Impressions
The number of sheets of base plate wax used to adapt over the cast depends upon the type of ____ selected for the ____ impression
material
final
Custom Tray-Irreversible Hydrocolloid
Place ____ over entire diagnostic cast
Place baseplate wax as relief over cast
– ____ sheet thickness over the soft tissue areas
– ____ sheet thickness over the teeth
Create tissue stops in non-critical areas
– ____ surfaces of teeth (cut through wax)
Place ____ over relief wax
– facilitates wax removal from the cast and tray
Place custom tray material
Perforate the tray using a #____ round bur
vaseline 2 2 occlusal vaseline 8
Custom Trays
Thin uniform coat of adhesive
allow to dry for ____ minutes
5
Irreversible Hydrocolloid Final Impression
Place impression material into critical areas manually or with an impression syringe
– e.g. ____, palatal vault, areas of framework contact
– ____ mould impression
– Pour impression ____
rest seats
border
immediately
Disinfection of Impressions Five types of chemical disinfectants used: \_\_\_\_ compounds \_\_\_\_ synthetic phenolic compounds \_\_\_\_ \_\_\_\_ \_\_\_\_/alcohol combinations
chlorine combination gluteraldehydes iodophors phenolic
Disinfection of Impressions Rinse impression under running water Spray entire impression -- including \_\_\_\_ -- Allow surface to remain wet for several minutes -- Rinse
tray
Troubleshooting Information For All Materials
• Never use ____ materials
expired
