Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Fixed Prostodontics > Definitive Casts and Dies > Flashcards

Definitive Casts and Dies Flashcards

1
Q

Definitive (Master or Working)
Cast:

A

A replica of the tooth surfaces,
residual ridge areas, and/or other
parts of the dental arch and/or facial
structures used to fabricate a dental
restoration or prosthesis.

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

Die:

A

Positive reproduction of the
individual prepared tooth; used for
wax pattern fabrication.

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

A good cast must be:
(2)

A

Bubble free
Distortion free

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q
  • Reproduce both (2) tooth surfaces, and be free
    of voids
A

prepared and unprepared

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

All occluding surfaces must allow for precise — of the
opposing casts

A

articulation

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

All relevant — should be reproduced.

A

soft tissues
* Edentulous spaces and ridge contours involved in FPD

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

Requirements for the Die:
(4)

A
  • Reproduces the prepared tooth exactly.
  • All surfaces must be accurately duplicated.
  • The unprepared tooth structure apical to the finish line should be
    easily visible (0.5 – 1mm).
  • Adequate access for carving wax pattern margin.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q
  • All surfaces must be accurately duplicated.
A
  • No bubbles or voids especially along the finish line.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q
  • Adequate access for carving wax pattern margin.
A
  • Establish correct cervical contour of the restoration
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Advantages of the FULL ARCH CAST:
(4)

A
  • Guide to occlusal surfaces and contours
  • Ease of articulation
  • Development of optimum occlusion
  • (Development of optimum pontic adaptation and esthetics)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

*Type I and II:

A

impression plaster / model and
mounting plaster

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

*Type III:

A

dental stone (general purpose casts)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

*Type IV:

A

high strength / lowest expansion (die
stone)

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

*Type V:

A

high strength / high expansion (die stone)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Desirable Properties of Cast / Die Materials
(4)

A
  • Accuracy
  • Reproduce fine detail (20μ-wide-line)
  • Strong and durable
  • Color
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q
  • Strong and durable
    (3)
A
  • Strength (wet strength / dry strength)
  • Resistance to shearing forces (edge
    strength)
  • Abrasion resistance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q
  • Color
    (2)
A
  • Contrast to wax
  • Scanning visibility
    (CAD-CAM)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Water : Powder Ratio
(3)

A
  • Least amount of water necessary to obtain proper manipulation of stone
  • Manufacturer’s recommendation
  • Add powder to liquid in mixing bowl for proper wetting.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q
  • Many properties are either directly or inversely related to the
A

W/P ratio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q
  • Directly proportional:
A

setting times / manipulation
* ↑water = ↑ setting time; ↑ fluidity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q
  • Inversely related:
A

strength and setting expansion
* ↑water = ↓ compressive strength
* ↑water = ↓ setting expansion
* (important in gypsum investment)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q
  • — that has already set acts as a catalyst when in contact with
    unset — and can cause changes in the set and working times.
A

Gypsum

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

Excessive disinfectant solution or water can give you

A

unset or
powdery gypsum at the surface.
* Make sure that your impressions are clean and only slightly damp before you
pour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q
  • Excessive use of alcohol based surfactants or debubblizers can also
    create
A

surface issues like softness or chalkiness.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Mechanical-Vacuum Mixing of Gypsum
* Helps eliminate —
* — the cast
* time

A

porosity
Strengthens
* 20 seconds / 425 rpm / >25mmHg
* Over-spatulation → decreased
working time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Dimensional Accuracy and Strength
(4)

A
  • Minimal expansion for procedure
  • Surface should be hard and smooth when
    removed from impression
  • Wet strength – Dry strength
  • Set in an upright posit
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Wet strength – Dry strength

A
  • Strength doubles 1H → 24H
28
Q
  • Set in an upright position
A
  • Prevents stone slumping from cusps
29
Q

Alginate Impressions: 2-Pour Technique
(2)

A
  • Anatomic pour with Type III Stone: cover vestibule; stack up stone; add
    nodules
  • Base: 2o mix after initial set of anatomic pour or after separation from
    impression (45 min).
30
Q

Solubility: Gypsum immersion in water
Linear dimension ↓ per every — minutes of immersion

A

20

31
Q

Solubility: Gypsum immersion in water
Linear dimension ↓ per every 20 minutes of immersion
(4)

A
  • Accuracy: Reproduce fine detail (20μ-wide-line)
  • Immersion in water saturated with calcium sulfate (slurry) will decrease
    solubility
  • Avoid sludge formation (cast trimming)
  • Scrubbing cast will remove surface detail
32
Q

Resistance to Abrasion
(3)

A
  • Surface hardness ≠ abrasion resistance
  • Surface impregnation**
  • Cyanoacrylate cement
  • Strengthened products
  • Resin (CAD-CAM)*
33
Q

Pour the impression twice…
(3)

A
  • Check interproximal contacts, solder relation on rigid cast.
  • Verify fit of casting or margin at try-in.
  • Can be used if original is damaged.
34
Q
  • Removable Dies
    (2)
A
  • Retained by pins in a base (stone or plastic)
  • One die used for entire wax pattern - proximal contacts, occlusion and margins
35
Q
  • Solid Cast / Separate Dies (Multiple Pour System)
    (2)
A
  • Single (separate) die for wax coping and margins
  • Solid cast for waxing proximal contacts and occlusion
36
Q

Solid Cast – Separate Die System
Advantages:
(2)

A
  • Simple fabrication - requires minimum
    trimming
  • Provides a rigid relation for FPD components
37
Q

Removable Die Systems
(2)

A
  • The die can be lifted and replaced in the master cast with embedded
    pins or dowels.
  • Requires less manipulation of wax pattern
38
Q
  • Requires less manipulation of wax pattern
    (2)
A
  • Reduces chance of breakage and distortion
  • Handling of restorations is easier (porcelain margins)
39
Q

Removable Die Systems
* Disadvantage: Technique sensitive
(2)

A
  • Error in pattern if die does not re-seat accurately
  • Margin or pin damage by improper saw cuts
40
Q

Digitally Milled Casts
(2)

A
  • Digital impression systems
    *CAM process (Cadent)
41
Q

*CAM process (Cadent)
(3)

A
  • Milled resin cast
  • Sectioned dies
  • Articulation
42
Q

Requirements for Removable Die Systems
(3)

A
  • Dies must return to exact
    original position.
  • Dies must remain stable,
    even when inverted.
  • Master cast must be easily
    mounted on an articulator.
43
Q

Definitive Cast and Die Preparation
Pindex Technique
(6)

A
  1. Pouring the impression / cast trimming
  2. “Pin” the cast and pour base
  3. Section the cast by sawing
  4. Die Preparation
    * Die trimming
    * Mark finish line
  5. Articulate the master cast
    * Interocclusal record in MIP
  6. Preparation for waxing
    * Die relief (cement spacer)
    * Die hardening (finish line)
44
Q

Definitive Cast Preparation: Pindex Base
* Base is poured — pins/sleeves are
cemented

A

after

45
Q

Definitive Cast Preparation: Pindex Base
* 1st pour carefully separated from

A

cast base.
* Cast base interface should be free of voids

46
Q
  • Each die section must slide out — -
A

independently

47
Q
  • Yet have adequate stone around pins for — -
A

strength

48
Q
  • Avoid cutting or abrading a —.
A

margin

49
Q
  • All sections are — removable from the base.
A

independently

50
Q
  • Die base should seat flush and be — to cast base.
A

perpendicular

51
Q

Definitive Cast Preparation:
Solid Cast – Separate Die
(5)

A
  • Pour individual die section (1st pour)
  • Separate cast from impression and re-pour impression
  • The first pour is sectioned/trimmed into individual die
  • The 2nd pour is completed as a full arch cast with base
  • The solid cast (full arch) is mounted on articulator
52
Q

Definitive Cast – Die Trimming
(4)

A
  • Die is trimmed to remove areas
    corresponding to the gingival tissue.
  • Die contour approximates the root and
    emergence profile.
  • Provides access to margin.
  • Smooth surface
53
Q

Die Trimming: Emergence Profile
(2)

A
  • The surface of the “un-prepared” tooth apical to the finish line is
    left intact.
  • Stone is removed with scalpel blade below this line.
54
Q

Cervical Margin: Emergence Profile
(3)

A
  • A properly trimmed die must have the same cervical contour as the tooth.
  • Adequate access to the margin is necessary for carving the wax to the
    proper emergence profile.
  • ≈ 5mm below finish line
55
Q

Definitive Cast – Die Trimming
* Trimmed from below and parallel to the margin.
(2)

A
  • Leave small lip of stone below margin.
  • Margin trimming is finished with Bard-Parker #25 blade.
56
Q

AVOID:

A

Sharp ditching of the die apical to the margin
→ over-contouring (angulation of wax carver)
→ weakening of the die

57
Q

Definitive Cast: Articulation
(4)

A
  • Ensure accurate tooth - tooth contact.
  • Verify contact of incisal pin.
  • Accuracy of mounting is critical to accurate occlusion in final
    restoration.
  • Compare intraoral and articulated cast occlusal contacts
58
Q

Interocclusal Records for Orienting Casts on
Articulator

A

An interocclusal registration is necessary to orient dies of prepared
teeth to the opposing occlusion.

59
Q

Interocclusal Records: Materials
*Material Requirements:
(3)

A
  • No resistance to closure
    *Rigid when set
  • Dimensional stability / accuracy
60
Q

Rigid, Fast-set VPS
(3)

A
  • Least rigid, most efficient
  • Always some rebound
  • CAD-CAM scanning
61
Q
  • ZnOE paste; Resin (rigid)
    (1)
A
  • Technique sensitive, time consuming
62
Q
  • Wax - should not be used for fixed
    prosth
  • WHY?
A

?

63
Q

Interocclusal Records: Materials
(3)

A

*Rigid, Fast-set VPS
* Plaster (Removable Prostheses)
* ZnOE paste; Resin (rigid)

64
Q

Definitive Cast: Occlusal Registration (MIP)
(3)

A
  • Record the maxillary and mandibular teeth in total contact.
  • Stone - stone contact with hand articulation where possible.
  • Place record material between prepared and opposing teeth only.
65
Q

Definitive Cast: Occlusal Registration
(5)

A
  • Reduce record to include only cusp tips for proper seating.
  • Cut back facial to visualize seating.
  • Ensure accurate tooth - tooth contact elsewhere.
  • Mark with articulating paper
  • Check with shimstock

Fixed Prostodontics (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions