MATERIALS USED IN THE MANAGEMENT OF EDENTULOUS PATIENTS (j) Flashcards
physical attraction of unlike molecules, such as saliva and mucous membrane
Adhesion
the physical attraction of like molecules for each other, such as within the saliva layer
Cohesion
is the attraction between the molecules of two different substances
adhesion
is the attraction between the molecules or atoms of the same substance
cohesion
also called a “suction” or “negative pressure”
ATMOSPHERIC PRESSURE
may act to resist dislodging forces applied to dentures if the dentures have an effective seal around their borders
ATMOSPHERIC PRESSURE
may act as a retentive force for the mandibular denture but as a displacing force for the maxillary denture
GRAVITY
T/ F
Upon removal from the mouth, the set impression should show adequate elastic recovery with no permanent
deformation
T
means it has high resistance to flowing
high viscosity
used as a mucostatic impression because it does not compress and displace tissues during seating of the tray
IMPRESSION PLASTER
→ recommended as it is very brittle
→ can undergo virtually no compressive or tensile strength without
fracturing
IMPRESSION PLASTER
applications of ZOE impression:
o mainly used for final impressions of edentulous ridges with
minor or no undercuts
o wash impression
ZINC OXIDE EUGENOL IMPRESSION PASTE
impression material for edentulous patients
Cakes
as border molding material for the custom tray; the material is used before making the final impression
Sticks
Type 1
Sticks
Cakes
→ used as a tray adaptation material
→ used for making a primary impression of the soft tissues and
then used as a tray to support a thin layer of a second impression material (ex.: ZOE pastes)
Type 2
can be stretched or compressed slightly and still rebound without significant permanent deformation
ELASTIC IMPRESSION MATERIALS
agar is considered one of the most accurate impression material because of their low viscosity and great degree of recovery after deformation around undercuts
REVERSIBLE HYDROCOLLOID
T/ F
REVERSIBLE HYDROCOLLOID is hydrophilic
T
expulsion of water or other liquid molecules hence, the impression shrinks a little
Syneresis
dimensional change if stored in water; absorption
Imbibition
alginates are the most widely used impression material in dentistry
IRREVERSIBLE HYDROCOLLOID
T/ F
to avoid tears in the impression, a minimum of 3 mm of impression material should be present between the tray and oral tissues
T
are indicated for making accurate final impressions for edentulous patients when used in custom trays
ELASTOMERIC IMPRESSION MATERIALS
also known as “mercaptan” or “thiokol”
POLYSULFIDE RUBBER IMPRESSION MATERIAL
emits a foul odor due to lead dioxide
POLYSULFIDE RUBBER IMPRESSION MATERIAL
a byproduct of this condensation reaction
ethyl alcohol
→ supplied as a two-paste or a base paste and low-viscosity liquid catalyst
→ has a large polymerization shrinkage
CONDENSATION SILICONE IMPRESSION MATERIAL
also known as polyvinyl siloxanes
ADDITION SILICONE IMPRESSION MATERIAL
in the presence of impurities or moisture, a secondary reaction may occur between the residual hydrides and moisture which
leads to gaseous voids in the gypsum casts
ADDITION SILICONE IMPRESSION MATERIAL
→ has a high degree of wettability of the oral tissues (hydrophilic)
→ stiffness of the original polyether made the material quite
difficult to remove from the undercuts
POLYETHER IMPRESSION MATERIAL
VLC visible light-activated dimethacrylate
the technique in processing heat-activated PMMA
DOUGH TECHNIQUE
