alginate

Question 1

classification of alginate as an impression material

Answer 1

irreversible aqueous hydrocolloid elastic

Question 2

classification of polysulfides, silicones, and polyethers

Answer 2

non-aqueous elastomers

Question 3

classification of plaster as an impression material

Answer 3

non-elastic

Question 4

alginic acid

Answer 4

anionic polysaccharide found in cell walls of brown algae

-inherently hydrophilic

Question 5

monovalent salts of alginic acid are

Answer 5

hydrophilic (soluble)

*usually use sodium alginate in dentistry (monovalent)

Question 6

bivalent salts of alginic acid are

Answer 6

hydrophobic (insoluble)

Question 7

colloid state

Answer 7

uniform distribution of individual particles of one substance in a dispersion medium of another substance
*called hydrocolloid if in water

Question 8

addition of Ca+2 to sodium alginate

Answer 8

• forms cross linkages around the calcium ion

- forms a more gel like substance

Question 9

setting reaction of alginate (solution to gel)

Answer 9

sodium alginate + calcium sulphate => calcium alginate + sodium sulphate

Question 10

what is used to control the speed of phase transformation from soln to gel

Answer 10

use tri-sodium phosphate as a retarder

Question 11

when does conversion start

Answer 11

after the retarder is used up

Question 12

fast setting needs ___ tri-sodium phosphate

Answer 12

less

Question 13

regular setting needs ___ tri-sodium phosphate

Answer 13

more

Question 14

working time

Answer 14

material can be manipulated and place in mouth with distortion

Question 15

setting time

Answer 15

immediately after working time; changes are permanent in mouth

Question 16

how to alter setting time

Answer 16

higher temperature will lower the setting time

Question 17

what gives alginate its texture

Answer 17

mineral/silicon fillers

Question 18

what is the retarder for alginate

Answer 18

tri-sodium phosphate

Question 19

what is the reactor for alginate

Answer 19

calcium sulphate

Question 20

what is the base for alginate

Answer 20

Na/K alginate

Question 21

what gives the gypsum quality

Answer 21

potassium fluoride

Question 22

clinical properties of alginate

Answer 22

• acceptable detail
• enough elasticity for undercuts
• time dependent dimensional stability (evaporation)
• non-toxic

Question 23

how long can u leave alginate on bench before its inaccurate and unacceptable

Answer 23

30 min

Question 24

what can you do if you cant pour your gypsum right away but dont want evaporation

Answer 24

• store in 100% humidity inside a plastic bag

- wrap in damp (not dripping) paper towel

Question 25

interactions with gypsum

Answer 25

• syneresis (lose water from alginate; contacts gypsum)

- imbibition (absorb water from gypsum)