Prostho 3 CC > Lesson 5 Impression Materials > Flashcards

Lesson 5 Impression Materials Flashcards

(59 cards)

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1
Q

Elastic

A

Material can be flexed easily without fracture and returns to its original form when unstressed

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2
Q

Inelastic

A

Highly resistant to flexure but fracture when deformed

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3
Q

Agar (Reversible Hydrocolloid)

A

are considered one of the most accurate impression materials for recording fine details because of their low viscosity and great degree of recovery after deformation around undercuts

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4
Q

Alginate (Irreversible) Hydrocolloid Material

A

are the most widely used impression materials in dentistry. The versatility of alginate lies in its ease of manipulation, without the need for expensive equipment, its relatively low cost, and comfort to patients. material of choice for making preliminary impressions for edentulous patients

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5
Q

Impression plaster

A

was used as a “mucostatic” impression material for making final impressions for edentulous patients

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6
Q

Zinc Oxide Eugenol

A

supplied in either a powder and liquid form or as two pastes

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7
Q

Impression compound

A

also called modeling plastic, is a thermoplastic material that is supplied in the form of cakes (red) or sticks (green, grey, or red), with the colors representing different fusing temperatures

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8
Q

Key Properties of Primary Impression

A

Ease of use • Cost-effective • Hydrophilic

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9
Q

Final Impression

A

Zinc Oxide Eugenol (ZOE) • Elastomers: • Polyvinyl siloxane (PVS) • Polyether

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10
Q

ZOE

A

rigid, accurate for mucostatic impressions

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11
Q

Elastomers

A

flexible, highly accurate

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12
Q

greenstick compound function

A

Capture functional sulcus depth

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13
Q

importance of tray materials

A

Accuracy of final impression

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14
Q

key factors of VDR/VDO Materials

A

Stability • • • Accuracy

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15
Q

uses of Temporary Denture Materials

A

Healing phase • • • Cushioning inflamed tissues

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16
Q

Gypsum Products

A

Type II (Plaster) • Type III (Dental stone) • Type IV (Die stone)

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17
Q

uses of gypsum

A

Casts • • • Master models

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18
Q

Gypsum

A
  • naturally occurring, white powdery mineral - material should be strong to resist accidental fracture
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19
Q

Calcium Sulphate Dihydrate

A

chemical name of gypsum

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20
Q

PLASTER OF PARIS

A

type II beta form natural white color

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21
Q

DENTAL STONE

A

type III alpha form construction of casts use to process dentures

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22
Q

function of wax materials

A

Record bases • Tooth setup • • • Trial dentures

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23
Q

dental waxes

A

low molecular weight ester of fatty acids derived from natural or synthetic components, such as petroleum derivatives, that soften to a plastic state at a relatively low temperature.

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24
Q

composition of dental wax

Study These Flashcards
A
  • composed of natural waxes and synthetic waxes, fats, fatty acids, oils. - Some formulations contain a compatible filler to control expansion and shrinkage of the wax product.
25
BASEPLATE WAX
➔ establish the initial arch form in the construction of complete dentures. ➔ Supplied in 1- to 2-mm-thick red or pink sheets
26
uses of baseplate
To establish vertical dimension plane of occlusion, and initial arch form in the technique for the complete denture restoration. - To form all or a portion of tray itself. - Used to produce desired contour of the denture after teeth are set in position. - To block out irregularities in master cast
27
utility wax
➔ processing wax ➔ Supplied in the form of sticks and sheets standard perforated tray for use with hydrocolloids may easily be brought to a more desirable contour by utility wax. ➔ It can be used to alter the stock tray extensions.
28
BITE REGISTRATION WAX
➔ record the relationship of the upper & lower teeth in dentulous patients as well as in edentulous patients. ➔ Wax is softened under hot running water ➔ Full arch, quadrant or just a few teeth can be taken
29
BEADING WAX
is adapted around the impression border up to create the land of the cast.
30
BOXING WAX
used to build vertical walls around the impression in order to pour the gypsum product to make a cast.
31
Denture Base Materials properties
Esthetics • Strength • • • Biocompatibility
32
polymethyl methacrylate
- polymerized resin derived from the ,mixture pf synthetic resin and monomer - conversion of low molecular weight compounds (monomer) to high molecular weight polymers
33
Denture base
Part of denture that rest on the foundation tissues and to which teeth are attached
34
acrylic teeth
less wear to opposing teeth
35
porcelain teeth
more durable but brittle
36
Investing Materials
Dental plaster Investment materials
37
Purpose of investing materials
Flasking procedure
38
gypsum-based products
Investment materials for complete denture fabrication, used in the flasking process to create the mold for acrylic resin, primarily consist of gypsum-based products such as dental plaster or high-strength dental stone. These materials securely hold the denture setup (wax and teeth) within the flask, allowing for the subsequent elimination of the wax to create space for acrylic packing.
39
Flasking & Processing Materials
Packing Curing • • Deflasking
40
Separating media
for complete dentures, most commonly sodium alginate (cold mold seal), are applied to gypsum surfaces after wax elimination (boil-out) to prevent acrylic resin from sticking to the flask/cast. This creates a smooth surface, reduces finishing time, and requires a full-drying application while avoiding contact with artificial teeth
41
Heat cure acrylic resin (pmma)
utilized primarily for fabricating dentures, splints, and orthodontic appliances. It requires thermal energy (heat) to activate polymerization, resulting in a strong, durable, and dimensionally stable material with low residual monomer content compared to cold-cure alternatives.
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polymer
prepolymerized spheres of polymethyl methacrylate & benzoyl peroxide (initiator)
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monomer
unpolymerized methyl methacrylate & hydroquinone (inhibitor)
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3:1 ; <10mins ; 5mins
ratio ; dough forming time ; working time
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Packing complete dentures
involves placing heat-cured acrylic resin into a prepared flask mold (following wax elimination) to form the denture base.
46
Curing complete dentures
is the polymerization process of acrylic resin, typically done via heat-curing in a water bath to turn the dough-like monomer/polymer mix into a hard denture base.
47
Deflasking
the process of removing processed dentures from the investment stone and flask after curing. It requires allowing the flask to cool completely to room temperature to prevent denture distortion
48
Finishing and Polishing
Smooth, esthetic surface Reduce plaque accumulation
49
Nylon-based resins (polyamides)
versatile, semi-crystalline engineering thermoplastics known for high strength, wear resistance, and heat resistance. They are commonly used in injection molding, extrusion, and 3D printing for automotive, industrial, and consumer goods.
50
Silicone-based soft liners
offer superior long-term elasticity, durability, and better biting force (approx. 166 N at 3 months) compared to acrylic-based alternatives, making them ideal for long-term cushioning in atrophic ridges
51
Acrylic-based liners
easier to apply and bond better to the denture base but lose softness over time due to plasticizer leaching.
52
Biocompatible
material is compatible with living tissues
53
Dimensionally stable
material's ability to retain its original size and shape despite changes in environmental conditions, such as temperature, humidity, or applied stress.
54
Strong yet lightweight
characterized by a high strength-to-weight ratio, are essential for aerospace, automotive, and, in some cases, protective applications.
55
Esthetic
visually pleasing
56
The material must be biocompatible
Nontoxic, nonirritating • Nonallergenic, noncarcinogenic • Chemically minimally degradable
57
Common Problems
Polymerization shrinkage Porosity Wear of teeth Allergic reactions
58
Infection Control
Infection Control,Disinfection of impressions Lab communication Cross-contamination prevention
59
Packing, curing, and deflasking
are critical steps in converting a waxed-up denture into a finished acrylic prosthesis. This involves packing acrylic dough into a mold, curing it (typically at 165°F for 8-12 hours or a short cycle), and carefully removing the denture to prevent distortion or breakage
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