MCPHS Dental Materials Final Exam (all
crossword vocab)
Condensation silicone - answer✔✔impression material that is very hydrophobic, must be poured
immediately, usually has many voids
sodium phosphate - answer✔✔common additive to alginate that acts as a retarder to slow down
working time
hygroscopic expansion - answer✔✔if the gypsum becomes immersed into water or comes in
contact with water while setting the gypsum will take-up additional water; swells
calcination - answer✔✔The process whereby water is lost when gypsum is heated during
manufacturing
study model cast - answer✔✔is a positive reproduction of both maxillary and mandibular, is a
positive reproduction of the hard & soft tissues of the oral cavity
wet strength - answer✔✔from start of pour to one hour after, water still present
one minute - answer✔✔mixing time for alginate
calcium sulfate dihydrate - answer✔✔main component of gypsum, still contains water content
2-3 minutes - answer✔✔setting time of alginate
. - answer✔✔.
final setting time - answer✔✔from start of mix to rigid mass that can be separated from
impression, minimum 1-hour/safe to separate, not fully set
10 minutes - answer✔✔disinfection time of alginate impression
syneresis - answer✔✔Water exudes causing the impression contracts
positive reproduction - answer✔✔study model/cast of oral structures
hysteresis - answer✔✔melting point much higher than boiling point, and gelling at mouth
temperature
, ©THEBRIGHT EXAM STUDY SOLUTIONS 8/27/2024 12:01 PM
setting expansion - answer✔✔the slight swelling of the gypsum while it is getting hard, crystals
push against each other creating porosities
dry strength - answer✔✔reached in 24-hours, water has evaporated , 2X as great as wet strength
diatomaceous earth - answer✔✔silica, inert filler used in alginate; Gives the material 'body'
reversible hydrocolloid - answer✔✔impression material used for crowns, requires special
equipment, water cooled trays, can be softened and reused
exothermic reaction - answer✔✔gives off heat as it set or gets hard
Gilmore needle - answer✔✔device used to determine setting time of gypsum
Hydration - answer✔✔When mixed with water, the hemihydrate is converted back to dihydrate
polysulfide material - answer✔✔rubber base impression material, used for dentures, special
spatula, long working time 4-6 minutes
imbibition - answer✔✔Water may be absorbed causing the impression to swell
addition silicone - answer✔✔impression material used for crowns, comes in two tubes or a gun
and cartridge
initial setting time - answer✔✔working time, loss of gloss of gypsum becomes semi-hard, 5-7-
minutes
24 hours - answer✔✔hydration reaction completed, gypsum fully set
mucostatic - answer✔✔impression taken without displacing any tissue
slurry - answer✔✔a thin mixture of gypsum or other material
elastomer - answer✔✔impression material that has high degree of accuracy, used for
impressions for crowns
borax - answer✔✔common additive to gypsum acts as a retarder (slowing down the working
time)
nuclei of crystilazation - answer✔✔Crystals of gypsum form in clusters, branching from a
common center called the growth and interlocking of these crystals contributes to strength,
rigidity and dimensional change
negative reproduction - answer✔✔any impression, prior to being poured
die - answer✔✔is a positive reproduction of a single tooth