Dental Materials Flashcards
1
Q
Example of Physical stimuli
A
Thermal, electrical
2
Q
Example of mechanical stimuli
A
Handpiece, traumatic occlusion
3
Q
example of Chemical stimuli
A
Acid from dental materials
4
Q
example of Biologic stimuli
A
Bacteria from saliva
5
Q
dental liner
A
A thin layer of material placed at the deepest portion of the dental preparation to provide pulpal protection or dentinal regeneration
6
Q
Calcium Hydroxide
A
Protects the pulp from chemical irritation through its sealing ability
Stimulates the production of reparative or tertiary dentin
Is compatible with all types of restorative materials
7
Q
Calcium Hydroxide is placed
A
over the deepest portion of the pulpal floor, and only on dentin.
8
Q
Varnish accomplishes
A
Seals dentinal tubules
Reduces microleakage around a restoration
Acts as a barrier to protect the tooth from highly acidic cements such as zinc phosphate
9
Q
varnish is placed ___ the placement of calcium hydroxide
A
after
10
Q
application of varnish
A
Applied with a small disposable applicator or with a cotton pellet held in sterile cotton pliers
11
Q
the use of varnish is contraindicated with these materials
A
Because dental varnish interferes with the bonding and setting reaction of composite resins and glass ionomer restorations
12
Q
Location for Placement of Cavity Varnish
A
that varnish or sealer is placed over the liner, which is applied first and allowed to set.
13
Q
Desensitizer
A
Used to treat or prevent hypersensitivity that a patient may experience from a newly placed direct or indirect restoration
14
Q
Desensitizer uses
A
used under restorations as per the listed indications
may also be used as a temporary and conservative desensitizer in areas that may not be readily or immediately restored
15
Q
Application of Desensitizer
A
Most desensitizers contain hydroxyethyl methacrylate (HEMA) and glutaraldehyde
This material is used sparingly
Do not allow the material to contact soft tissue
16
Q
Bases provide different types of pulpal protection:
A
protective, sedative, insulating
17
Q
protective
A
Protects the pulp from a large restoration
18
Q
Insulating:
A
Protects the tooth from thermal shock
19
Q
Sedative:
A
Soothes pulp that has been damaged by decay or irritated by mechanical means
20
Q
The varnish, sealer, or both would then be placed____ the final restoration.
A
before
21
Q
a base would be applied over a liner (if a liner was indicated) or directly on a moderately deep dentinal floor.
A
When a tooth preparation becomes moderately deep to deep, the dentist will place a base under the permanent restoration
22
Q
Zinc Oxide Eugenol
A
insulating base and as a sedative base
23
Q
Cannot be used under composite resins, glass ionomers, or other resin restorations
A
Zinc oxide-eugenol (ZOE)
24
Q
Zinc phosphate
A
thermal insulation qualities
Irritating to the pulp, needs to be used with a liner
25
Can be used with all restorations
Zinc phosphate
Polycarboxylate
Glass Ionomer
26
Glass Ionomer
Excellent adhesion
| Fluoride releasing
27
Polycarboxylate
Nonirritating to the pulp
| Protective
28
Application of Base
The entire pulpal floor is covered with a base to thickness of 1 to 2 mm
29
According to one placement scheme, it is a liner if the layer is __ than 0.5 mm, and a base if it is____ than 0.5 mm.
less and thicker
30
Location for Placement of a Base
over the liner.
31
The varnish or sealer is placed ____ the base.
over
32
A bonding agent is placed ___ the base (after etching) if composite resin is to be placed.
over
33
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Placement:
-Copalite
-Varnish
-Cement
-
```
calcium hydroxide
34
```
Placement:
-Copalite
-
-Cement
-calcium hydroxide
```
Varnish
35
```
Placement:
-
-Varnish
-Cement
-calcium hydroxide
```
Copalite
36
Placement:
- Copalite
- Varnish
- Cement
- calcium hydroxide
37
Acids in Dental Etchant
The acid etchant is usually 35% phosphoric acid gel, colored (e.g., blue) to make it easier to see where it has been placed and whether it has been completely washed off.
38
Application of Dental Etchant (1)
The etchant material is supplied either as a liquid or gel, with gel being packaged in a syringe-type applicator
39
Application of Dental Etchant (2)
Syringe dispensing through pre-bent dispenser needles provides precise placement of the material on tooth
40
Application of Dental Etchant (3)
Fifteen to twenty seconds is the most common recommended time (follow manufacturers instructions)
41
Dental Etchant
Bonding agents allow for the removal of less tooth structure before definitive restoration placement because minimal retentive features are needed
42
smear layer
which is a very thin layer of debris composed of fluids and tooth components that remain on dentin after cavity preparation has been completed
43
The smear layer interferes with the strength of the bond.
The smear layer interferes with the strength of the bond.
44
Preparing the tooth surface properly with the use of acid etchant for removal of the smear layer before bonding exposes more
microscopic surface area, and thus micromechanical retention is also achieved.
45
Dental Bonding
The process of solid and/or liquid contact of one material with another at a single margin
46
Examples of enamel bonding:
Sealants
Bonding of orthodontic brackets
Resin‑bonded bridges
Resin-bonded veneers
47
Bonding applications are available as
self-curing, dual-cured, and light-cured systems
48
Each bonding system is different, and the material from one system
is not interchangeable with that of another
49
The tooth surface receives the etchant material, which removes the
smear layer
50
The bonding component is allowed to flow into these small defects and into the partially opened
tubules in dentin
51
The material is allowed either to:
Harden and act as a hybrid layer
| Remain in a liquid state while the restoration is being placed, to bond together the tooth and the dental material
52
If a metal matrix band is used, why is it important that the bond is prepared with cavity varnish or wax before placement around the tooth?
It prevents the bonding resin from adhering to the surface
53
Classification of Dental Cements
luting agents,
| restorative materials, liners or bases
54
luting agents
which include permanent and temporary cements
55
Restorative materials,
such as IRM and glass ionomers
56
Liners or bases
placed within the cavity preparation
57
What is a luting agent?
is designed to act as an adhesive to hold an indirect restoration to the tooth structure, or to adhere brackets to the tooth surface during orthodontic treatment
58
What type of restorations can be cemented permanently?
indirect
59
What are some uses of cements?
Certain cements are routinely used as a permanent adhesive material when working with indirect restorations; another type would be used to restore a tooth; and still others act as a temporary cement.
60
Permanent Cements
used for the long‑term cementation of cast restorations
61
The temporary cementation of an indirect restoration may be determined if:
The dentist needs to remove the restoration later
The tooth is sensitive or is exhibiting other symptoms that might require removal of the cast restoration
When temporary cementation of provisional coverage is required while the patient waits until the laboratory technician completes the cast restoration
62
What is provisional coverage?
a temporary coverage that is placed on a tooth to protect the tooth until the permanent restoration is ready to be cemented
63
Variables Affecting Final Cementation
Improper mixing technique and time
Humidity
Incorrect temperature of the glass slab
64
examples of improper mixing technique?
Not properly incorporating the powder into the liquid, and mixing for too short or too long a period of time
65
High humidity can interfere with the setting of ____ ____ ___ cements in particular.
zinc oxide-eugenol
66
Glass ionomer cement releases
fluoride.
67
Composite resin cement is very strong and
is used to cement porcelain veneers.
68
Zinc oxide-eugenol (ZOE) has what affect
It soothes pain.
69
Polycarboxylate cement is kind to the
pulp.
70
Zinc phosphate cement is the___ ____. It is very strong but the mixing procedure is complicated.
oldest cement
71
Glass Ionomer Cement
One of the most versatile types of cement used in dentistry
A hybrid of silicate and polycarboxylate cements
Adheres to enamel, dentin, and metallic materials
72
Supplied in special formulations according to their use:
```
Type I
Type II
Type III
Type IV
Type V
Type VI
```
73
Glass Ionomer
| Type I
For the cementation of metal restorations and direct‑bonded orthodontic brackets
74
Glass Ionomer
| Type II
Designed for restoring areas of erosion near the gingiva
75
Glass Ionomer
| Type III
Used as a liner and dentin bonding agent
76
Glass Ionomer
| Type IV
Used for pit and fissure sealants
77
Glass Ionomer
| Type V
Used in the cementation of orthodontic bands and brackets
78
Glass Ionomer
| Type VI
Used as a core build-up
79
Advantages of Glass Ionomer
```
Slow release of fluoride
Less trauma/shock to pulp
Low solubility
Adheres to slightly moist tooth surface
Very thin film thickness
Can be formulated for use as a dentin substitute or base material
```
80
Application of Glass Ionomer
Available as a self-curing or light-cured formula
Supplied in bottles of powder and liquid, which can be mixed manually on a paper pad or cool, dry glass slab
Also supplied in premeasured capsules which are triturated and expressed through a dispenser.
81
Chemical Makeup of Composite Resin Cement
The tooth must be free of all plaque and debris before being etched
82
These composite resin cements have physical properties comparable with those of composite resins, including:
Thin film thickness
| Virtual insolubility in the mouth
83
Application of Composite Resin Cement
Recommended portions of either application are dispensed onto a paper pad and mixed rapidly with a spatula
84
Supplied for Composite Resin Cement
As a powder and liquid mix
In a syringe-type applicator as a base and catalyst
In a versatile light-cured/dual-cured system
85
Zinc Oxide-Eugenol Cement
is often used on patients when postoperative sensitivity may be a concern
86
Type I ZOE
Lacks strength and long‑term durability and is used for temporary cementation or provisional coverage
87
Type II ZOE
Has reinforcing agents added for the permanent cementation of cast restorations or appliances
88
Type I ZOE (paste)
Supplied as a two‑paste system as temporary cement
| Pastes dispensed in equal lengths on a paper pad and mixed
89
Type II ZOE (liquid/powder)
Mixed on an oil‑resistant paper pad
Mixing time of 30 to 60 seconds
Setting time in the mouth of 3 to 5 minutes
90
Chemical Makeup of Zinc Oxide-Eugenol Cement
Liquid: eugenol, water, acetic acid, zinc acetate, and calcium chloride
Powder: zinc oxide, magnesium oxide, and silica
91
ZOE is one of the least irritating of all dental cements
The eugenol can have a strong odor, and may be offensive to some patients
92
Application of Zinc Oxide-Eugenol Cement
ZOE is mixed on an oil-resistant paper pad that will not absorb any of the liquid
When a slower set is required, a glass slab can be used
93
Polycarboxylate Cement
This cement generally has been used as a permanent cement for cast restorations, stainless steel crowns, and orthodontic bands
94
Polycarboxylate Cement
maintains its versatility as a nonirritating base under composite and amalgam restorations and as an intermediate restoration
95
Polycarboxylate is less irritating to tooth pulp than
zinc phosphate cement.
96
Chemical Makeup of Polycarboxylate Cement
Liquid: polyacrylic acid, itaconic acid, maleic acid, tartaric acid, and water
Powder: zinc oxide, magnesium oxide, aluminum oxide, and other reinforcing fillers
97
Application of Polycarboxylate Cement
Liquid may be measured using the plastic squeeze bottle or the calibrated syringe‑type liquid dispenser supplied by the manufacturer
The liquid has a limited shelf life because it will thicken as the water evaporates.
Mixing is carried out on a nonabsorbent paper pad
If it is necessary to increase the working time, a cool, dry glass slab can be used
98
Zinc Phosphate Cement
```
Classified as two types
Type I (fine grain)
Type II (medium grain)
```
99
Zinc Phosphate Type II (medium grain)
Recommended for use as an insulating base for deep cavity preparations
100
Zinc Phosphate Type I (fine grain)
Used for the permanent cementation of cast restorations such as crowns, inlays, onlays, and bridges
Creates a very thin film layer, which is necessary for an accurate cementing of castings
101
Phosphoric acid can be
irritating to the tooth pulp.
102
Chemical Makeup of Zinc Phosphate Cement
Liquid: 50% phosphoric acid in water, buffered with aluminum phosphate and zinc salts to control the pH
Powder: 90% zinc oxide and 10% magnesium oxide
103
Chemical Makeup of Zinc Phosphate Cement
A liner, sealer, or desensitizer should be placed first to reduce sensitivity to the phosphoric acid
104
Is zinc phosphate a permanent or temporary cement?
Permanent
105
Application of Zinc Phosphate
Powder and liquid should be dispensed just before being mixed.
The powder is divided into increments of varying size, with each increment spatulated before the next increment is added
It is critical that the powder be added to the liquid in very small increments
This method dissipates the heat of the chemical action and retards the setting of the cement
106
Classification of Impressions
preliminary, final, and occlusal
107
Preliminary Impressions
Taken either by the dentist or the expanded-function dental assistant (EFDA)
```
Used for the following reasons:
Diagnostic models
Custom trays
Provisional coverage
Orthodontic appliances
Pretreatment and post treatment records
```
108
What is a common impression material for preliminary impressions?
(Alginate)
109
What is a common impression material for final impressions?
(Polysiloxane)
110
These impressions are used to create a reproduction of the teeth and surrounding tissues.
Preliminary Impressions
111
Final Impressions
Taken by the dentist and are used to produce the most accurate reproduction of the teeth and surrounding tissue
112
Provides the dentist and the dental laboratory technician the essential information needed for creation of
Indirect restorations
Partial or full dentures
Implants
113
Final impressions are never taken by the
dental assistant.
114
Bite Registrations
Taken by the dentist or EFDA to produce a reproduction of the occlusal relationship of the maxillary and mandibular teeth when the mouth is occluded
Provide an accurate registration of the patient’s centric relationship between the maxillary and mandibular arches
115
Why are bite registrations important in the fabrication of indirect restorations?
This provides the dentist and the laboratory technician with an accurate registration of the patient’s centric relationship between the maxillary and mandibular arches
116
Are impressions a positive or negative reproduction?
They are a negative reproduction.
The model or cast poured from the impression would form a positive reproduction
117
Impression trays are of two basic types:
stock trays and custom trays
118
Stock Trays
Manufactured in several ways and available in a range of sizes and styles. They come in disposable and non-disposable (autoclavable)
119
Metal perforated tray used most often for
preliminary impressions.
120
Metal water coolant tray used most often with
reversible hydrocolloid impressions.
121
Plastic perforated tray used for ____ and ____ ___
preliminary and final impressions.
122
Bite tray used for ___ ___ and __ ___
final impressions and bite registrations.
123
___ ___ designed to eliminate steps by taking final impressions and bite registration at the same time.
Triple tray
124
Selection of Impression Tray
Is comfortable to the patient
Extends slightly beyond the facial surfaces of the teeth
125
Selection of Impression Tray
Extends approximately 2 to 3 mm beyond the third molar, retromolar, or tuberosity area of the arch
Is sufficiently deep to allow 2 to 3 mm of material between the tray and incisal or occlusal edges of the teeth
126
Characteristics of Impression Trays
Quadrant tray
Section tray
Full arch tray
127
Quadrant tray
covers half of an arch
128
Section tray
Used to cover the anterior portion of the arch
129
Full-arch tray
Covers the entire arch
130
Characteristics of Impression Trays
Also characterized by whether the surface of the tray is perforated or smooth
131
perforated surface tray
the impression material oozes through the holes in the tray, creating a mechanical lock to hold the material in place
132
smooth surface tray
there is no mechanical lock, so the interior of the tray is painted or sprayed with an adhesive to hold the impression material securely in the tray
133
Adaptation of Tray
Length of the tray can be extended by adding utility wax to the border of the tray
May be necessary if the tray does not completely cover the third molars
For a patient with an unusually high palate, softened utility wax can be added to the palate area of the impression tray
134
Irreversible Hydrocolloid: Alginate
Hydrocolloid impression materials that cannot return to the sol state after they become a gel
135
What can alginate impressions be used for?
These are widely used for preliminary impressions.
136
The main ingredients of alginate include:
```
Potassium alginate
Calcium sulfate
Trisodium phosphate
Diatomaceous earth
Zinc oxide
Potassium titanium fluoride
```
137
Potassium titanium fluoride
Added so as not to interfere with the setting and surface strength of the product used when making a model
138
Zinc oxide
Adds bulk to the material
139
Diatomaceous earth
A filler that adds bulk to the material
derived from the skeletons of tiny sea creatures called diatoms.
also used in aquarium filters.
140
Potassium alginate
Derived from seaweed; also used in some ice creams as a thickening agent
141
Calcium sulfate
Reacts with the potassium alginate to form the gel
142
Trisodium phosphate
Added to slow down the reaction time for mixing
143
In the sol (solution) phase, the material is
in a liquid or semiliquid form
144
In the gel (solid) phase, the material is
semisolid, similar to a pudding dessert
145
Imbibition
If an alginate impression is stored in water or in a soaked paper towel, it will absorb the additional water and expand
146
Syneresis
If an alginate impression remains in the open air, moisture will evaporate, causing the impression to shrink and distort
147
How long after the impression is obtained should we proceed to pouring?
Most alginate impression materials must be “poured up” within 1 hour of taking the impression, a requirement dictated by the environment
148
Why should the newly poured alginate impression not be stored under water?
It will imbibe water leading to distortion
149
Types of Setting
| Alginate is available in two setting times:
Normal set time
Fast set alginate
Working time
Setting time
150
Normal-set alginate
Working time of 2 minutes and a setting time of up to 4½ minutes after mixing
151
Fast-set alginate
Working time of 1¼ minutes and a setting time of 1 to 2 minutes
152
Working time
The time allowed for mixing the alginate, loading the tray, and positioning the tray in the patient's mouth
153
Setting time
The time required for the chemical action to be completed, after which the impression is ready to be removed from the patient’s mouth
154
Which time is longer, working time or setting time?
(Setting time is longer than working time.)
155
Altering Setting Time of Alginate
Room temperature water is best to use when mixing alginate
Cooler water will increase the setting time if additional time is needed for the procedure
Warmer water will reduce or shorten the setting time of the procedure
156
Water-to-Powder Ratio
mandibular impression: 2 scoops of powder/2 measures of water
maxillary impression :
3 scoops of powder and 3 measures of water
157
Taking an Alginate Impression, It is important for the EFDA to be competent in:
Mixing the alginate
Loading the tray
Keeping the patient comfortable while taking the impression
158
Explain the Procedure to the Patient ,The patient needs to know that:
The material will feel cool, there is no unpleasant taste, and the material will set quickly
Breathing deeply through the nose will help the patient relax and feel more comfortable
The patient can use some type of hand signals to communicate any discomfort
159
Evaluating Alginate Impression :
-The impression tray should be centered
-There is a complete "peripheral roll," including all of the vestibular areas
-The tray is not “overseated”
-The impression is free from tears or voids
-Sharp anatomic detail of all teeth and soft tissues is provided
-
-The hard palate and tuberosities are recorded in the maxillary impression
The retromolar area, lingual frenum, tongue space, and mylohyoid ridge are reproduced in the mandibular impression
160
Evaluating Alginate Impression
-The impression tray should be centered
-
-The tray is not “overseated”
-The impression is free from tears or voids
-Sharp anatomic detail of all teeth and soft tissues is provided
-The retromolar area, lingual frenum, tongue space, and mylohyoid ridge are reproduced in the mandibular impression
-The hard palate and tuberosities are recorded in the maxillary impression
There is a complete "peripheral roll," including all of the vestibular areas
161
Evaluating Alginate Impression
-The impression tray should be centered
-There is a complete "peripheral roll," including all of the vestibular areas
-The tray is not “overseated”
-The impression is free from tears or voids
-Sharp anatomic detail of all teeth and soft tissues is provided
-The retromolar area, lingual frenum, tongue space, and mylohyoid ridge are reproduced in the mandibular impression
-
The hard palate and tuberosities are recorded in the maxillary impression
162
Evaluating Alginate Impression
- The impression tray should be centered
- There is a complete "peripheral roll," including all of the vestibular areas
- The tray is not “overseated”
- The impression is free from tears or voids
- Sharp anatomic detail of all teeth and soft tissues is provided
- The retromolar area, lingual frenum, tongue space, and mylohyoid ridge are reproduced in the mandibular impression
- The hard palate and tuberosities are recorded in the maxillary impression
Evaluating Alginate Impression
- The impression tray should be centered
- There is a complete "peripheral roll," including all of the vestibular areas
- The tray is not “overseated”
- The impression is free from tears or voids
- Sharp anatomic detail of all teeth and soft tissues is provided
- The retromolar area, lingual frenum, tongue space, and mylohyoid ridge are reproduced in the mandibular impression
- The hard palate and tuberosities are recorded in the maxillary impression
163
Reversible Hydrocolloid
This impression material changes its physical state from a sol to a gel and then back to a sol
164
Hysteresis
is a term used to describe the change in temperature that causes the reversible hydrocolloid material to transform from one physical state to another
165
Reversible Hydrocolloid (Cont.)
85% water
13% agar
Agar is an organic substance derived from seaweed
Additional chemical modifiers are added to improve the substance’s handling characteristics
166
Additional equipment is required to obtain an impression
. Water-cooled trays and a conditioner unit for the hydrocolloid material are needed.
167
For the reversible hydrocolloid to change from one consistency to another, a specialized
conditioning bath is used
168
The following three compartments maintain water at three different temperatures:
A “conditioner” bath liquefies the semisolid material at 212° F and is then cooled to 150° F
A “storage” bath readies the material for the impression in its tubes
A “tempering” bath keeps material at 110° F for tempering after it has been placed in the tray
169
Reversible Hydrocolloid Tray Material
Tray material is packaged in plastic tubes
| Each tube holds enough material to fill a full-arch, water-cooled tray
170
Application of Reversible Hydrocolloid Impression Material
A stock water-cooled tray is selected
Plastic stops are placed in the tray
Tubing is connected to the tray and to the water outlet for drainage
The material is liquefied and moved to the storage bath
The light-bodied material is placed in the syringe, and heavy-bodied material is placed in the tray
The light-bodied material is expressed around the prepared tooth, and the dentist seats the tray
171
What tray is selected for reversible hydrocolloids
stock water tray
172
Physical Stimuli
results from thermal changed such as hot and cold air used for drying a tooth or electrical energy created by other metals that come into contact with the tooth
173
Mechanical Stimuli
can include the vibration from a handpick when the tooth is being prepared, also if the person grinds their teeth
174
chemical stimuli
a result go acidic material reaching pulpal tissues, such as saliva reaching and exposed people or by the means of micro leakage
175
biologic stimuli
can be the result of bacteria from saliva coming into contact with pulpal tissues or if carious tissue was not completely removed during the preparation of the tooth
176
Calcium hydroxide application
Liners are supplied either as a two-paste system or as a light-cured material
The material is placed prior to placement of the restorative material and with the use of a Dycal (calcium hydroxide) applicator
Placed only on the deepest dentin surface of the preparation
This material is not to be placed on enamel or in retentive grooves of the preparation
