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DENT MAT LEC MIDTERMS > IMPRESSION MATERIALS > Flashcards

IMPRESSION MATERIALS Flashcards

1
Q

What do you call the negative replica of the mouth?

A

Impression

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2
Q

There is a minimal dimensional changes as the impression is cooled from mouth temperature and does not adhere to moist oral tissue. This means that…

A

Impression material has low thermal expansion coefficient.

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3
Q

An impression compound is used to take a negative replica of an edentulous oral cavity. This process is called…

A

Primary Impression

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4
Q

Primary Impression is composed of these materials:

A
  1. Fatty Acids
  2. Fillers
  3. Shellac
  4. Glycerine

FFSG - Follow to Singapore

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5
Q

Properties of an Ideal Impression Material:
1. E and R
2. A
3. A
4. S
5. G
6. A
7. S
8. N
9. C
10. L

A
  1. Ease of manipulation and Reasonable cost
  2. Adequate flow property
  3. Appropriate setting time and characteristics
  4. Sufficient mechanical strength not to tear or permanently deform during removal
  5. Good dimensional accuracy
  6. Acceptability to patient
  7. Safe (Non-toxic or non-irritating)
  8. No significant degradation of properties as a result of disinfection)
  9. Compatibility with die and cast material
  10. Long shelf-life
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6
Q

Quality Impression should be:
1. S
2. V
3. A
4. R
5. D
6. B
7. C

A
  1. Sufficiently fluid to adapt to the oral tissues
  2. Viscous enough to be contained in a tray
  3. Able to transform or set into a rubbery or rigid solid in mouth in a reasonable time of less than 7 minutes
  4. Resistant to distortion or tearing when removed from the mouth
  5. Dimensionally stable long enough to allow one or more cast to be poured
  6. Biocompatible
  7. Cost-effective in terms of time and expense of the associated processing equipment
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7
Q

To have a quality impression, you should first meet the?

A

Ideal qualities of impression materials

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8
Q

Classification of Impression Materials should be according to:
1.
2.
3.

A

Classification of Impression Materials should be according to:
1. SETTING MECHANISM
2. MECHANICAL PROPERTIES
3. CLINICAL APPLICATION

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9
Q

Classification of Impression Material according to SETTING MECHANISM:
1.
2.

A
  1. Irreversible (Chemical Reaction)
  2. Reversible (Temperature Change)

ICR - RTC

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10
Q

Classification of Impression Material according to MECHANICAL PROPERTIES:
1.
2.

A
  1. Inelastic (Rigid)
  2. Elastic (Flexible)

Pag inelastic, high resistant to flexures and fractures when stressed. Example, Impression Plaster.

Pag elastic, pwede madeform at mabalik sa original form.

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11
Q

Classification of Impression Material according to CLINICAL APPLICATION:
1.
2.

A
  1. For completely edentulous patients (Inelastic)
  2. For accurate tooth form reproduction (Elastic)
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12
Q

Types of Inelastic Impression Materials:
1.
2.
3.

A
  1. Impression Plaster
  2. Impression Compound
  3. Zinc Oxide Eugenol Impression Paste

Important Notes:

  1. Impression Plaster (B-calcium sulfate hemihydrate)
    - Accelerator: Potassium Sulfate
    - Retarder: Borax
    - Pigment: Alizarin Red
    - W/P Ratio: 0.5-0.6
  2. Impression Compound (Modeling Plastic)
    - Softened by heat, inserted in an impression tray, pressed against the tissue before it hardens.
    - COMPLETELY EDENTULOUS RIDGES
    - Classifications:
    🟢 Soft Green - 50-51°C
    🌚 Gray - 53-54°C
    🔴 Red - 54.4-55.6°C
  3. ZOE Impression Paste
    - FOR edentulous mouths, surgical dressing, bite registration paste, temporary filling material, root canal filling material, cementing medium, temporary relining material for dentures
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13
Q

Types of Impression Compound:
1.
2.
3.

A
  1. Type 1
  2. Type 2
  3. Cake

IMPORTANT NOTES:

  1. Type 1
    - lower-fusing material
    - sheet or stick form
    - FOR: primary impressions, individual tooth impressions, peripheral tracing or border molding, checking undercuts in inlay preparation
    - high flow property
  2. Type 2
    - higher-fusing material, more rigid
    - aka tray compound
    - FOR: forming trays to be used in the oral cavity, making special trays
  3. Cake
    - sticks
    - FOR: full arch impressions
    - 🟢 - lowest fusing
    - 🌚 - gray material in stick form is preferred by dentists for bolder molding because of contrasting lighter color
    - 🔴 - red sticks along with 🌚 sticks, have higher broader working range than 🔴🌚cakes because they may be flamed without harming the material.
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14
Q

Composition of Impression Compound (Modelling Plastic):
1.
2.
3.
4.

A
  1. Beeswax - Main ingredient
  2. Shellac, Stearic Acid, Gutta Percha - to improve elasticity and workability
  3. 40% Resin, 7% waxes, 3% organic acids, 50% fillers - waxes and resins are the principal ingredients in the matrix
  4. Fillers
    - to strengthen or change the physical property of the material and decreased the flow
    - example: talc, iron oxide, chalk
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15
Q

Other Properties of Impression Compound:
1. F
2. T
3. C
4. S
5. D

A
  1. Fusion Temperature
    - reduces the plasticity of the material during cooling
  2. Thermal Conductivity and Contraction
    - kneading with fingers will ensure uniform temperature throughout the material
    - has low thermal conductivity
  3. Cool the material thoroughly before removal from the mouth
    - failure to do this will distort the impression
  4. Soften the impression compound in an oven or over a flame
    - water bath 🛁
    - prolonged immersion in water = brittle and grainy
  5. Disinfection
    - 2% alkaline glutaraldehyde solution for 10 minutes
    - pour the cast within the first hour to avoid distortion
    - when removing from the the cast, immerse in warm water until it softens for easy separation
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16
Q

Composition of ZOE Impression Material:
1. Z
2. R
3. E
4. O
5. F
6. C
7. C and P
8. W

A
  1. Zinc Oxide
  2. Rosin
    - For speed of reaction and smoother more homogeneous product
  3. Eugenol Liquid
    - sting sensation
  4. Oil of Cloves
    - to reduce the burning sensation
    - 70-85% eugenol
    - may be used to replace eugenol liquid
  5. Fixed vegetable oil or mineral oil plasticizer
    - masking the action of eugenol as irritant
  6. Calcium Chloride, Zinc Acetate, Primary Alcohol, Glacial Acetic Acid
    - accelerators
  7. Canada Balsam and Peru Balsam
    - to increase flow and improve mixing property
  8. Wax, Kaolin, Talc, Diatomaceous Earth
    - fillers
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17
Q

Components of Tube 1 (Base) of ZOE and Their Percentage

A
  1. Zinc Oxide - 87%
  2. Fixed Vegetable or Mineral Oil - 13%
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18
Q

Components of Tube 2 (Accelerator) of ZOE and Their Percentage

A
  1. Oil of Cloves or Eugenol - 12%
  2. Gum or Polymerized Resin - 50%
  3. Filler (Silica Type) - 20%
  4. Lanolin - 3%
  5. Resinous Balsam - 10%
  6. Accelerator Solution (CaCl) and color - 5%
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19
Q

Property of Impression Compound: Reduces the plasticity of the material during cooling therefore, every detail of oral tissue is reproduced.

A

Fusion Temperature

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20
Q

Property of Impression Compound: Compound should be uniformly soft. Kneading with fingers will ensure uniform temperature throughout the material.

A

Thermal Conductivity and Contraction

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21
Q

Property of Impression Compound: If this property is not done properly, it will result to distortion of the impression.

A

Cool the material thoroughly before removal from the mouth.

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22
Q

Property of Impression Compound: Water bath is recommended but prolonged immersion will result in brittleness and grainy appearance of the material.

A

Soften the impression compound in an oven or over a flame.

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23
Q

Property of Impression Compound: Impression should be immersed in 2% alkaline glutaraldehyde solution for about 10 minutes.

A

Disinfection

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24
Q

How to manipulate ZOE?

A
  1. Squeeze two strips of paste of the same length on a glass slab or oil-impervious paper.
  2. Mix in a sweeping motion for 1 minute using flexible stainless steel spatula until uniform color is observed.
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25
Initial Setting Time of ZOE
3-6 Minutes
26
Final Setting Time of Zoe
Type 1 - 10 Minutes Type 2 - 15 Minutes
27
Factors affecting the setting time of ZOE 1. 2. 3. 4. 5. 6.
1. shortened setting time 2. humidity or temperature 3. addition of accelerators, zinc acetate, or drop of water in the paste before mixing 4. extending the mixing time 5. prolong setting time 6. use if cooled spatula and mixing slab
28
Characteristics of ZOE 1. 2. 3. 4. 5.
1. quite satisfactory dimensional stability 2. no significant dimensional change subsequent to hardening 3. shrinkage less than 0.1% 4. good reproduction of oral structure details 5. chief disadvantage: burning or stinging sensation
29
Types of Elastic Impressions (Hydrocolloids)
1. Reversible Hydrocolloids (AGAR) 2. Irreversible Hydrocolloids (Alginate)
30
Colloidal sol composed of solids and liquids in the air
Aerosol
31
Aqueous impression material used for recording minimal details such as that required to produce dies for study models.
Alginate
32
An aqueous impression material used for recording maximum details such as that required for fixed restorations
Agar
33
A dimensionally accurate reproduction of portion of the oral cavity and extraoral facial structures produced in a durable hard material and used as a base for construction of orthodontic and prostho appliances.
Cast
34
Reversible "setting" based on a physical effect produced by a temperature change. Warm/Sol Cold/Ge
Thermoplastic
35
Setting reaction that involves a chemical change that is not easily reversible
Thermosetting
36
Recessed areas on oral structures including teeth, edentulous ridges appliances, and restorations.
Undercuts
37
Often classified as a 4th state of matter. It is a suspension of Tooth Phases. Can either be solid/liquid or solid/air (>1 um) in a liquid. Dispersions are termed *sol*.
Colloids
38
A lightly cross-linked impression material with elastic property. It is usually called the **rubber impression material**. It is not an aqueous solution.
Elastomers
39
Process by which an element or compound transitions from liquid state to gaseous stare below the temperature at which it boils.
Evaporation
40
Network of fibrils that form a weak slightly elastic brush heap structure.
Gel
41
Transformation from sol to gel.
Gelation
42
Colloids that contain water as the dispersion phase
Hydrocolloids
43
There is a strong affinity between dispersed and continuous phase in a colloid.
Lyophilic
44
Colloidal sol of gas, liquid, or gas in a liquid.
Lyosol
45
A positive full-scale replica of the dentition and surrounding or adjoining structure used as a diagnostic aid.
Model
46
Consists of two separate phases (dispersed and dispersion phase). If the dispersion phase is water, it is a **hydrocolloid**.
Colloidal System
47
Phases of Colloids: 1. 2.
1. **Dispersed Phase/Medium** - particles in the solution 2. **Dispersion Phase/Medium** - solution suspending the particles
48
Dispersed Phase: *Solid* Dispersion Phase: *Liquid What type of colloid?
Sol
49
Dispersed Phase: *Solid* Dispersion Phase: *Gas* What type of colloid?
Solid Aerosol
50
Dispersed Phase: *Liquid* Dispersion Phase: *Liquid* What type of colloid?
Emulsion
51
Dispersed Phase: *Liquid* Dispersion Phase: *Gas* What type of colloid?
Aerosol
52
Dispersed Phase: *Gas* Dispersion Phase: *Liquid* What type of colloid?
Foam
53
Dispersed Phase: *Gas* Dispersion Phase: *Solid* What type of colloid?
Solid Foam
54
Agar changes into a rubber-like gel by raising or lowering the temperature. In order to return to a sol condition, it must be heated to a higher temperature of
70-100°C
55
Gelation Temperature of Agar
37-50°C
56
INFO: The temperature lag between the liquefaction temp and gelation temp makes it possible to use agar as a dental impression material.
Yung in between ng liquefaction at gelation, yun yung workable state ng agar.
57
Composition of reversible hydrocolloid: 1. A 2. B 3. S 4. T 5. F/D
1. **Agar** - 13-17% for tray material - 6-8% for syringe material 2. **Borates** - 0.2-0.5% - retarder sa gypsum - increases the viscosity and strength sa agar 3. **Sulfates** - 1-2% - gypsum/plaster hardener 4. **Thixotropic Materials** - 0.3-0.5% - thickener 5. **Fillers/Diatomaceous Earth** - controls strength, viscosity, and rigidity - clay, silica rubber, wax, or hard wax
58
Ingredients of Agar
1. **Thymol** - bactericidal 2. **Glycerin** - plasticizer, pigment - supplied in plastic tubes and cylindrical sticks to be places into special syringes
59
Manipulation of Agar: 1. B 2. S 3. T
1. **Boiling Section/Liquefaction Section** - Agar is placed in boiling water at 100°C for 10 minutes to reverse the hydrocolloid gel to sol state. - Every time the material is liquefied, 3 minutes should be added for heating 2. **Storage Section** - Ideal temp for storage: 65-68°C 3. **Tempering Section** - Cooling the tray to 46°C to increase viscosity and prevent it from flowing out. (3-10 minutes) - Rim lock impression trays - water circulation through the tray - Beading on the inside of the tray helps to retain material - It has an inlet and outlet for connecting the water tubes - A space of **3 mm** should be allowed occlusally and laterally and extend distally to cover all teeth. - Circulate cool water **(18-21°C)** through the tray for 3-5 mins - Remove impression with one jerking motion
60
Materials required for manipulation of agar: 1. A 2. H 3. W 4. H 5. D 6. R
1. Agar hydrocolloid conditioner 2. Hydrocolloid material 3. Water cooled rim lock trays 4. Hydrocolloid syringe material 5. Duplicating mold 6. Rubber hose
61
Compartments of Agar's conditioning unit
1. **1st Compartment** - 98°C - for liquefying 2. **2nd Compartment** - 68°C - Tempering the hydrocolloid 3. **3rd Compartment** - 43°C - pwede na gamitin sa mouth pero need pa palamigin kaunti since 37°C ang normal body temp
62
COMMON CAUSES OF FAILURES WITH REVERSIBLE HYDROCOLLOID: - inadequate boiling - storage temp too low - storage time too long
Grainy Material
63
COMMON CAUSES OF FAILURES WITH REVERSIBLE HYDROCOLLOID: - water-soaked layer of tray material is not removed - there is premature gelation of either syringe or tray material
Separation of Tray and Syringe Material
64
COMMON CAUSES OF FAILURES WITH REVERSIBLE HYDROCOLLOID: - inadequate bulk - premature removal from the mouth - syringe material partially gelled when tray was seated
Tearing
65
COMMON CAUSES OF FAILURES WITH REVERSIBLE HYDROCOLLOID: - gelation of syringe material preventing flow
External Bubbles
66
COMMON CAUSES OF FAILURES WITH REVERSIBLE HYDROCOLLOID: - material is too cool/cold or grainy
Irregularly Shaped Voids
67
COMMON CAUSES OF FAILURES WITH REVERSIBLE HYDROCOLLOID: - inadequate cleansing of impression - excess water or potassium sulfate solution left - premature removal of die to the impression
Rough or Chalky Stone Model/Cast
68
COMMON CAUSES OF FAILURES WITH REVERSIBLE HYDROCOLLOID: - impression not poured immediately (within 30 minutes - tray movement during gelation - premature and improper removal from mouth - use of ice water during initial stages of gelation
Distortion
69
Other name for Alginate
**andrygo-B-d mannymronic acid** **alginic acid**
70
Types of Alginate
1. Type I - Fast Set 2. Type II - Normal Set
71
Advantages of Alginate: 1. E 2. N 3. M 4. E 5. I
1. Ease of mixing and manipulation 2. No elaborate equipment needed 3. Material is inelastic and comes out easily from undercuts 4. Economical 5. Impression can be removed easily and has pleasant taste and odor
72
Disadvantages of Alginate: 1. C 2. P 3. D 4. D 5. C 6. T 7. C 8. S
1. Cannot be electroplated 2. Poor tear strength especially in thin sections 3. Dimensional stability is poor 4. Distortion may occur if the tray is shifted during setting 5. Cannot be refined 6. They are dispensed as individually sealed packs or pouches (pre-weighed) or in bulk (can or bag) 7. Color-changing alginate violet during mixing, pink when ready to be seated and white when set. 8. Shelf-life deteriorates rapidly at elevated temperature.
73
Composition of Alginate: 1. 15% 2. 16% 3. 4% 4. 3% 5. 60% 6. 2%
1. **15% potassium alginate** 2. **16% calcium sulfate** - reactor - increases shelf life and dimensional stability 3. **4% ZOE** - filler - affects physical properties and setting time of gel 4. **3% potassium titanium fluoride** - accelerator - ensures a hard-dense stone cast 5. **60% diatomaceous earth** - filler - increase strength, stiffness, produce smooth texture, ensure a firm gel surface 6. **2% sodium phosphate** - retarder
74
Setting reaction of alginate
2Na3PO4 + 3CaSO4 ➡️ Ca3(PO4)2 + 3Na2SO4 Sodium alginate + Calcium sulfate ➡️ Calcium alginate + Sodium sulfate
75
Factors affecting gelation time of alginate 1. W/P 2. S 3. WT 4. I
1. **Water:Powder Ratio** - the higher W/P, the longer the setting time, the weaker the alginate 2. **Spatulation** - the longer the spatulation time, the faster the setting time - insufficient or overmixing weakens the alginate 3. **Water Temperature** - the higher the water temp, the shorter the setting time 4. **Impurities** - shortens mixing time, causing inadequate fluidity of mix and weakens the mixture
76
Mixing Time of Alginate
45 seconds to 1 minute via hand spatulation
77
Setting Time of Alginate
Type I (Fast Setting) - 1.5-3 minutes Type II (Normal Setting) - 3-4 minutes
78
Causes of failure in irreversible hydrocolloid: 1. G 2. T 3. E 4. I 5. R 6. D
1. **Grainy Material** - improper and prolonged moxing - undue/excessive gelation - W/P too low 2. **Tearing** - inadequate bulk - moisture contamination - premature removal - prolonged mixing 3. **External Bubbles** - undue gelation - air incorporated during mixing 4. **Irregular Shaped Voids** - moisture or debris from tissue 5. **Rough/Chalky Stone Models** - inadequate cleaning stine models of impression - excess water left in impression - premature removal of model - leaving model too long - improper manipulation of stone 6. **Distortion** - impression not poured immediately - movement of tray during gelation - premature removal from mouth - improper removal from mouth - tray held in mouth too long (only with certain brands)
79
Elastomeric Impression Materials
1. Polysulfides 2. Condensation Silicone 3. Addition Silicone 4. Polyether
80
A component of polymerization reaction similar to a catalyst but also speeds up the reaction.
Accelerator
81
A polymerization reaction in which each polymer chain grows to a maximum length in sequence and there is no reaction by-product.
Addition Reaction
82
The main component of the chemical reaction.
Base
83
The continuing polymerization reaction of an impression material during short-term storage. This term is often used inappropriately to describe the recovery over time of a distorted impression to its original state.
Bench Cure
84
A component of a reaction that facilitates the reaction and usually does not become part of the final product.
Catalyst
85
A property that describes the amount of deformation that a set elastomer can withstand without experiencing permanent deformation.
Compression Set
86
A polymerization reaction in which the polymer chain all grow simultaneously and a reaction by-product is formed.
Condensation Reaction
87
The reaction that links or joins polymer chains to form a network called a *gel*. The amount of cross-linking affects stiffness and elasticity.
Cross-linking
88
A term used to describe the reaction process that takes place both during and after the setting of the polymer.
Cure
89
The rate of the reaction of the setting polymer.
Curing Rate
90
A term that refers to non-aqueous elastomeric impression materials.
Elastomer
91
The solid network structure that defines the cross-linked polymer.
Gel
92
The component that starts the chemical reaction. Types include photo-initiators, chemical initiators, and heat initiators.
Initiators
93
The irreversible shape changes that occur when the polymer responds as a viscous liquid and the distortion is permanent.
Permanent Distortion
94
The chemical reaction that transforms small molecules into large polymer chains.
Polymerization
95
The characteristic pf a polymer that allows the material to appear to be less viscous when the shearing rate is increased.
Pseudoplastic (Shear Thinning)
96
Science that explains the fluid or flow characteristics of materials such as viscoelasticity, viscosity, and pseudoplasticity.
Rheology
97
The state of being sufficiently rigid or elastic to be removed from the mouth.
Set
98
A single component material with sufficient shearing potential that it can be used as the syringe material and the tray material.
Single-phase
99
The time-dependent pseudoplastic flow of polymers that is characterized by the gradual decrease of viscosity under a constant applied shear rate
Thixotropic
100
That portion of tooth that lies indented from the largest circumference of the tooth. Generally, it is within the gingival third of the tooth.
Undercuts
101
Characteristic of polymers that behave as elastic solids (springs) and as viscous liquids (dashpots).
Viscoelastic
102
The process of heating natural rubber with sulfur to produce cross-linking. This term is commonly used to describe the cross-linking of polymer chains to form an elastomer.
Vulcanization

DENT MAT LEC MIDTERMS (1 decks)

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