impression materials ch 46

Question 1

used to obtain an impression of teeth and or the surrounding oral tissues

Answer 1

impressions

Question 2

are negative reproductions of dental structures. Gypsum products are used to make positive reproductions of the oral cavity

Answer 2

impression

Question 3

preliminary impressions & used to make

Answer 3

taken either by the dentist or an dental assistant. Used to make trays, orthodontic appliances, diagnostic models

Question 4

taken by dentist , used to make most accurate reproduction of the teeth and surrounding tissues. Used to make indirect restorations, partial/full dentures, implants

Answer 4

Final impressions & used to make

Question 5

impression trays

Answer 5

used to hold impression materials.

Question 6

must sufficiently rigid to carry material into oral cavity, hold material close to the teeth, avoid breaking during removal, prevent warping the complete impression

Answer 6

impression trays

Question 7

stock trays

Answer 7

not custom fitted to the patients mouth so you must try them prior to taking the impression

Question 8

you have to make sure that the stock tray is

Answer 8

2-3 mm beyond the third molar, allows 2-3 mm of material between the tray and the incised/occlusal edges of teeth

Question 9

quadrant tray

Answer 9

covers one half of the arch

Question 10

section tray

Answer 10

covers the anterior portion of the arch

Question 11

full arch tray

Answer 11

covers the entire arch

Question 12

perforated tray

Answer 12

holes in the tray create a mechanical lock to hold the material in place

Question 13

smooth tray

Answer 13

interior of the tray is painted with an adhesive to hold the impression material

Question 14

custom trays

Answer 14

are constructed to fit in the mouth of a specific patient

Question 15

hydro means

Answer 15

water

Question 16

colloid means

Answer 16

gelatin substances

Question 17

the phase in which a colloid is a semi solid is the

Answer 17

gel phase

Question 18

types of hydrocolloids

Answer 18

reversible hydrocolloids - agar

irreversible hydrocolloids- alginate

Question 19

what are utility wax strips for

Answer 19

can be used to extend tray

Question 20

waxing the tray is called

Answer 20

beading

Question 21

t/f; setting time is reduced by warmer water, the warmer the water the faster the set

Answer 21

True

Question 22

normal set

Answer 22

working time- 2 mins

setting time-4.5 mins

Question 23

fast set

Answer 23

working time- 1 1/4 min

setting time 1-2 mins

Question 24

mandibular impressions level/scoop/temp

Answer 24

scoops- 2
levels- 2 levels of water
temp- 20-21 degree

Question 25

maxillary impression level/scoop/temp

Answer 25

scoops-3
levels- 3 levels of water
temp-20-21 degree

Question 26

mixing technique

Answer 26

add powder to water in small amounts
use rubber bowl and wide spatula
After done, Clean dirty spatula

Question 27

smoothing the surface of the alginate by wiping a moistened finger along the surface

Answer 27

glazing

Question 28

place additional alginate in undercuts on the occlusal surface on the palate. Done to create less discrepancy in the anatomy of the impression

Answer 28

smearing

Question 29

imbibition

Answer 29

the alginate impression absorbs additional water and expands

Question 30

syneresis

Answer 30

the alginate impression loses moisture causing it to shrink and distort

Question 31

impression materials that dislike moisture are considered

Answer 31

hydrophobic

Question 32

occlusal impressions

Answer 32

taken by the dentist or dental assistant.

reproduction of the occlusal relationship between max and mand teeth

Question 33

accurate registration of the normal centric relationship of the max and man arches, commonly referred as

Answer 33

bite registration

Question 34

useful when diagnostic casts are trimmed
Most common technique is to use a softened baseplate
Pateint closes normally onto softened wax

Answer 34

wax bite

Question 35

t/f; ZOE paste has little to no resistance to bite closure and is a fast setting material

Answer 35

true

Question 36

create positive reproduction of the teeth and soft tissue called study casts, study models/diagnostic models

Answer 36

gypsum products

Question 37

3 types of gypsum products

Answer 37

dental plaster
dental stone
high strength stone

Question 38

dental plaster

Answer 38

white

requires more water for mixing than stone and produces a weaker cast

Question 39

dental stone

Answer 39

yellow

used when a more durable diagnostic cast is needed or for a working model to make dentures

Question 40

high strength stone

Answer 40

has strength, hardness and dimensional accuracy which is ideal for dental lab tech in creating die.
Requites least amount of water out of the 3 products

Question 41

gypsum mixing

Answer 41

powder added to water
too much water weakens them and takes longer to set
too little water gives shorter working time and dry mix

Question 42

model consists of two parts

Answer 42

anatomic portion - created from the alginate impression

art portion- forms the base of the cast

Question 43

trimming study models

Answer 43

always wear masks, do not wear gloves, must be soaked in water for 5 mins before trimming

Question 44

art portion

Answer 44

one third

Question 45

anatomic portion

Answer 45

two thirds

Question 46

anterior art portion of maxillary model is trimmed from

Answer 46

canine to the midline at an angle