Tissue Management, Impression Making, Definitive Casts and Dies (Pt. II) Flashcards Preview

Fixed Prosth, Module I > Tissue Management, Impression Making, Definitive Casts and Dies (Pt. II) > Flashcards

Flashcards in Tissue Management, Impression Making, Definitive Casts and Dies (Pt. II) Deck (31)
Loading flashcards...
1

Definitions

Solid Definitive Cast (or master or working
cast): replica of ____, ridge areas, and other parts of the ____

Die: positive reproduction of ____ tooth. Consists of a suitable hard substance of sufficient ____(usually improved stone, resin, or metal)

prepared teeth
dental arch
prepared
accuracy

2

Definitions

To learn to properly use virtual casts, the
underlying principles of conventional definitive cast and die systems must be understood

Virtual systems model the same information in
three dimensional formats that enable the technician to use virtual tools for certain phases of the restoration fabrication process

Virtual systems offer significantly improved ____.

efficiency

3

The accuracy of a cast and die is a function of the ____ of the impression.

The cast cannot contain ____ information than the impression from which it was made

completeness
more

4

Prerequisites of Definitive Cast

oMust exactly reproduce ____ tooth surfaces
oUnprepared teeth immediately adjacent to preparation must be free of ____
oSurfaces of teeth involved in ____ and occlusal surfaces of all unprepared teeth must allow for precise articulation
oAll relevant ____ should be reproduced
n including all ____ spaces and residual ridge contours involved in fixed prosthesis

prepared and unprepared
voids
anterior guidance
soft tissues
edentulous

5

Prerequisite of Die

oMust reproduce prepared tooth exactly
oAll surfaces must be accurately duplicated
n No bubbles or voids acceptable
oUnprepared tooth
structure immediately
____ to finish line
should be easily discernible on die
n Ideally ____ visible oAdequate access to margin imperative

cervical
0.5-1mm

6

Die Materials
oDifferent materials
n (1)____
n(2)____ (epoxy resin) n(3)____
n(4)____ materials
psimilar to heavy body silicone or polyether impression materials

gypsum
resin
electroplated
flexible die

7

Die materials

ADA Type IV stone
Advantages: ____
Straightforward technique
____ cost
Straightforward in-office procedure
Disadvantages: Will be ____ if not handled carefully (poor resistance to abrasion)
Use: Most ____
Precautions: Accurate ____ essential
Recommend vacuum mix

dimensional stability
low
damaged
situations
proportioning

8

Die materials

ADA Type V stone
Advantages: ____ technique
____ cost
Straightforward in-office procedure
Harder than ____
Disadvantages: Increased ____
Use: Most ____
Precautions: Accurate ____ essential
Recommend vacuum mix

straightforward
low
type IV
expansion
situations
proportioning

9

Die materials

Expoxy
Advantages: High ____
Good abrasion resistance
Disadvantages: ____
____-consuming complex procedure
More ____ than stone
Prostheses fit more ____
Use: ____ crowns
Precautions: Not compatible with ____ or hydrocolloid

strength
polymerization shrinkage
time
expensive
tightly
polysulfide

10

Die material

Electroplating
Advantages: High ____
Good abrasion resistance
Disadvantages: ____- consuming
____ equipment needed
Use: ____ crowns
Precautions: Silver entails use of ____, which is toxic
Incompatible with many ____ materials

strength
time
special
complete ceramic
cyanide
impression

11

Die Materials
Selection Criteria
oMust allow dimensionally ____ cast**
oStrong and resistant to abrasion**
oEasy to ____ and trim
oCompatible with separating agent
oReproduce ____ accurately oColor to contrast wax to visualize margin
oEasily ____ by wax
oCompatible with impression material

accurate
section
surface detail
wettable

12

Available Methods (1)Removable Dies

oDie is integral component of ____
n Can be lifted from cast for access
oPrecise ____ of die in definitive cast is crucial
n ____ or dowels
n Need resistance to rotation
o2 pours of ____ colors n First forms ____
n Second forms ____

definitive cast
relocation
brass pins
contrasting
teeth
base

13

Available Methods (1)Removable Dies

o____ of dowels are critical
n If improperly placed, the dowels do not allow die of
prepared teeth to be withdrawn from the cast
oThis will be done in the preclinic
n Pindex

location and orientation

14

Available Methods
(1)Removable Dies

o Advantages
n Removable die
facilitates ____
n Cast pouring ____

o Disadvantages
Extra ____ involved in making cast with dowels
____ equipment
Care needed with dowel placement
____ difficult
pGetting dies to seat
p____ die
nDamage to interproximal margins

waxing and porcelain
unimpeded
steps
special
technically
sawing

15

Available Methods
(2)Solid Cast with Individual Die

o􏰀Multiple pour technique􏰁
o____ than removable die
oMay be slightly more ____
oImpression poured in stone in area of preparation
n Trimmed to die with handle pSimilar to tooth root
oThen, second pour of the ____ made

simpler
accurate
entire arch

16

Available Methods
(2)Solid Cast with Individual Die

o____ started on die (first pour)
oTransferred to ____ to contour and anatomy
oReturned to die for ____

wax pattern
articulated cast
margins

17

Available Methods
(2)Solid Cast with Individual Die

o Advantages
n Definitive cast requires
____ trimming
n Gingival tissues intact can be used as a guide for ____ restoration
n ____ procedure

o Disadvantages
n May be difficult to transfer wax pattern from ____
n Seating pattern on second pour more difficult due to second pour slightly ____ than first
n Only use with impression materials which could be poured more than once
pNot ____ hydrocolloid

minimum
contouring
straightforward
cast to die
larger
reversible

18

Available Methods (3)Alternative Die Systems

oAccu-Trac technique. Di-Lok
n Many other systems available
n Utilizes a precision tray with a ____
n Impression is poured and seated on the ____
n Following setting, the tray is ____
and stone cast removed
n Dies are sectioned
n Cast and die reassembled and mounted on ____

magnetic indexer
tray
disassembled
articulator

19

Accu-trac technique

tables!

ya

20

Available methods
Alternative die systems

o Advantages
n ____ die
n Cast pouring unimpeded
n Less ____ than pindex

o Disadvantages
n ____
n Care needed during reassembly
n ____ equipment needed
n Care needed when pouring to get proper orientation

removable
costly
bulky
special

21

Available Methods
Choice of Die Systems

oDepends upon
n____ preference
nDental technician preference
nAssessment of ____

If used properly, all available systems achieve clinically acceptable ____

operator
advantages/disadvantages
accuracy

22

Pindex Model Overview

Refer to video and laboratory manual for specific information

oPour final impression oWait for stone to set
n ____minutes
oSeparate impression
oTrim excess stone with cast trimmer
n Base thickness ____ inch
n Integral router and sandpaper point to trim lingual
oUse pindex to drill holes

40
3/4 - 1

23

Pindex Model Overview
Refer to video and laboratory manual for specific information
oPlace dowel pins into drilled holes with cyanoacrylate
oWait ____ minutes for cyanoacrylate to dry
oPlace sleeves on dowel pins
oApply separating medium
oPour base using pre-fabricated rubber mold and vacuum mix

5

24

Pindex Model Overview
Refer to video and laboratory manual for specific information
oLet base harden for ____ minutes oSeparate the rubber mold and trim
n ____mm land
oSeparate dies (#19 preclinically)
oTrim dies with acrylic bur oReturn dies to ____
oMount casts on articulator
n Preclinically, mount to previously mounted maxillary cast

30
3
master cast

25

Procedure (in preclinic)
Pouring Definitive Cast

o Measure proper proportions of Type IV stone and water
n ____ placed into mixing bowl first
n Then, add ____
pPre-packaged in
preclinic
o Mix stone
n Vacuum mixer strongly recommended
pHand mix in preclinic

water
powder

26

Procedure (in preclinic)
Pouring Definitive Cast

o Holding tray on vibrator, use small brush or instrument to place stone in areas of preparation
n Slowly tease stone into preparation along axial walls by tilting impression
n Visualize stone going into preparation
n Continue until preparation is filled
o Fill remainder of tray at least ____mm above impression border

5

27

Procedure (in preclinic)
Pouring Definitive Cast
oSeparate cast and trim n Base must be prepared
____
n Vestibular area must be trimmed
____ to the flat base

flat
perpendicular

28

Die Preparation
oPreclinically, section #19 for die
oTo section dies, the saw cuts should ____ slightly toward eachother, or the die will be locked in by undercuts

converge

29

Trimming Dies
oTrimmed dies should not have a ___ apical to margin
n May lead to poor gingival contour
oHandle dies very carefully

Overtrimming will result in ___ restorations

ditch
overcontoured

30

Summary

oAccurate definitive casts and dies are essential to successful indirect restorations
oVarious materials and techniques provide precise reproduction of prepared teeth
n ____ stone usually recommended
pCareful to avoid chipping and abrading
margins
n ____ are durable alternatives
oDifferent systems are available for die fabrication
n If done accurately, each is an acceptable method

type IV
epoxy or electroplating