Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Prostho 4 > 2. Working Casts > Flashcards

2. Working Casts Flashcards

(63 cards)

Start Studying
1
Q

What are the limitations of plaster? (4)

A
  • the low resistance to fracture
  • dimensional instability
  • technique sensitivity
  • low resistance to wear by abrasion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What can affect the properties of the stone (cast)? (4)

A
  • the setting time
  • the porosity
  • the setting expansion
  • the strength
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What should you do before pouring the cast? (3)

A
  • wash the impression under cold water to remove saliva and mucus
  • disinfect
  • dry but leaving a shiny surface of the material
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What type of stone is poured? Why? (2)

A

High strength type IV

To prevent surface abrasion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where do we start pouring stone? (2)

A

Over tooth preparation

then add stone from distal area and let it flow mesially

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How much height should there be for pouring of the casts? why?

A

2.5cm for correct handling of the die

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How long should the stone be left to dry?

A

1 hour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the different types of casts? (5)

A 
Study cast
Diagnostic cast
Working cast (master cast) 
Antagonist cast
Casts for corrections
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What kind of impression can create a study cast? (3)

A
  • Alginate
  • silicone
  • digital
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are study casts made of?

A

Plaster

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the purpose of a study cast once mounted on the articulator? (4)

A
  • Study occlusal relationships.
  • Treatment planning.
  • Customize articulator (PCPI and Bennett angle).
  • Make provisional dentures.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What type of impression can create a diagnostic cast?

A
  • alginate
  • silicone
  • digital
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a diagnostic cast made of?

A

Usually plaster

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is a diagnostic cast used for? (5)

A
  • Waxing of restorative contours to evaluate and plan restorations
  • forsee esthetics
  • forsee occlusion
  • show patient final look of treatment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the purpose of the working cast?

A

To manufacture the final prothesis over

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What impression gives you the working cast? (3)

A
  • sIlicone
  • polyether impressions
  • digital
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is important for a working cast?

A

Must show a clear finish line

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Where is a working cast mounted?

A

Must be mounted at the office

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is a working cast made of? (3)

A
  • type IV plaster
  • Epoxy resin
  • investment material
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is important to remember about impression pouring for a working cast? (2)

A
  • impression has to be poured twice

- double pouring only if it is an elastomeric impression (PVS)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How is a working cast mixd?

A

With vacuum mixers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What happens with the gingiva on working casts?

A

Trimmed to show the finish line

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the disadvantages of working casts with removeable dies? (2)

A
  • alteration of contact point

- relation with the gum has been removed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the advantages of working casts with removable dies? (2)

A

◦ Dies can be removed individually

◦ Eases laboratory work

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What are the advantages of working casts without removable dies? (2)
- contact point not altered | - relation with gum is kept (avoiding over/undercontoured margins)
26
What are the disadvantages of working casts without removable dies? (2)
- harder to see finish lines esp at proximal surfaces | - harder lab work
27
What type of impression is needed for the antagonist cast? (2)
- alginate | - silicone
28
What is an antagonist cast? (3)
• Full-arch. • Very important to be accurate too. • Will condition the quality of the occlusion of the final restoration.
29
What is a cast for correction? (2)
- for correcting a denture | - ex. readapt the margin of the restoration
30
What impression is used for a cast for correction?
Silicone
31
How long should the vacuum mixer be used for impressions? (2)
15-20 seconds | *air bubbles and blowholes free
32
What is important to remember about using the plastic vibrator for pouring impressions?
Tray is palced over but never resting over the impression material
33
How long should the cast dry for?
1 hour
34
What is the procedure of creating a working cast with no removable dies?
- put cast in moisture chamber for 12 hours - mount on articulator - trim cast to show finish line
35
how do you trim a cast to show the finish line? (2)
- n. II scalpel | - Bur
36
What are the main requirements for removable dies? (3)
1. The dies must return to their exact original positions. 2. The dies must remain stable, even when inverted. 3. The cast containing the dies must be easy to mount on an articulator.
37
What 4 variables can affect the quality of the working cast during its fabrication and use?
1- accuracy of the impression procedure, 2- accuracy of the cast/die system 3- inherent setting expansion of the dental stones used 4- precise repositioning of the removable die
38
What are the desirable characteristics in a removable die system? (3)
- Ease of fabrication and reassembly of the working casts - stability of the dies - accurate positioning of the dies
39
A removable die is a ______ for every die
individualized cast
40
Every die contains ...
the preparation of every tooth
41
What are the different die systems? (6)
- Conventional brass dowel pin. - Bafix. - Pindex. - Zeisser. - Accutrac. - Di-Lok.
42
Dies must return to...
their original position accurately
43
Die should be..
- stable over the base (even for upper casts) | - removable even if the casts are mounted
44
Which cast should be mounted on the articulator? (removable die or no die)
the removable dies cast
45
Which removable die casts are the pin techniques? (3)
- conventional technique - pindex system - zeiser system
46
Which removable die casts are the tray techniques? (3)
- accutrac system - di-lok system - bafix system
47
What removable die casts are neither the pin or tray techniques? (3)
Geller system
48
Which casts cannot be poured before?
``` Zeiser Dilock Accutrac Bafix Pindex Geller ```
49
How are the pins positioned in conventional technique for removable dies? (3)
- Dowel pins are positioned in the center of the prepared tooth and edentulous area - In impression before pouring - pins are stabilized with hairpins
50
How do you pour the conventional die technique? (3)
Two pour technique 1. pour cast. Trim and apply petroleum jelly 2. pour base on a base former *paper clips are placed in order to provide retention for the second pour stone
51
How do you separate the dies in a conventional technique?
- using a saw | - cuts are made distal and mesial to the tooth
52
What do you do after trimming in the conventional die technique?
removal of gingival stone to the finish line
53
How are the pins positioned in a pindex system cast?
- Reverse drill press is used | - drills parallel holes from underside of trimmed cast
54
How is the pouring done for a pindex system?
one step with enough thickness (20mm height)
55
How is trimming done for the pindex system?
Trimming must leave a flat and stable surface
56
How are the positions of the pins marked in a pindex system?
Marked with pencil over the occlusal surface
57
How are pins cemented in the pindex system?
- With cyanoacrylate resin
58
What happens after cementation of pins in a pindex system?
- sleeves placed on top of the pins | - utility wax placed to avoid second layer of stone filling them
59
How many pines per die in a pindex system? (4)
- two pins per die - two pins for the edentulous area - two for the unprepared tooth *each die or section should have two pins or a double pin
60
Which die system is the most accurate? Why?
Zeiser b/c the base is plastic = more stable
61
How do you do the zeiser system? (2)
- can section and trim the models depending on the needs of the case - the model mounted on the articulator is the removable die model
62
What is the bafix system? (2)
One step pouring system for removable dies Base and impressions are poured at the same time
63
What is the accutrac system?
- one pour technique: | impression and tray poured at the same time

Prostho 4 (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions