DENTMAT Midterms exam Flashcards
Water:Powder ratio of dental plaster
45-50ml/100g
identify the gypsum product:
characterized as more uniform shaped crystals, larger crystals, smoother particles
Dental Stone
It is carbohydrates polymer that dissolves in water, forming a sol.
Causes gelation reaction
potassium alginate
what dental cement has a white odorless powder and is mixed with water or saline to form a paste
Calcium Hydroxide
what impression materials are used for obtaining impression of dentulous mouth
alginate
agar
non-aqueous materials
classify this type of GIC:
lining cements, base
Type III
this is the time that begins when the material can no longer be manipulated in the mouth;
the time when the material has reached its ultimate state
setting time
advantages of agar
- Hydrophilic
- Good elastic properties
- Can be re-used as duplicating material
- No mixing technique, the potential for errors are eliminated
- Palatable and well tolerated by patients
- High accuracy and fine detail recording
- Compatible with die and cast materials
this dental cement is used for temporary and permanent cementation, temporary fillings, cavity lines and base, pulp capping agent; and has a secondary use of root canal restorations
ZOE
what is the oldest luting cements and thus serves as a standard with which newer cements can be compared to
Zinc Phosphate
Calcium Hydroxide is strongly alkaline with a pH level of?
12.5
what impression material has higher tear strength than hydrocolloid, has no syneresis or imbibition, and are more dimensionally stable
elastomeric impression materials
what dental cement is used for permanent crowns, bridges, inlays and onlays;
also used for orthodontic cementation
Zinc Polycarboxylate
what is component in alginate which the filler gives the mixed “body”, that allows acceptable handling without the filler, the mixed material would be too runny to use
insert silica
(diatomaceous earth)
type of strength of gypsum products:
the strength that is determined when water in excess of that required for hydration of the hemihydrate remains in the test specimen
water strength
when was rubber base impression materials developed
1950s
give at least 5 desirable materials of an impression material
-Have pleasant taste, odor and esthetic color
-Does not contain any toxic of irritating ingredients
-Be economical
-Have adequate shelf life for storage and distribution
-Be easy to use with minimum equipment
-Exhibit dimensional stability
-Have adequate strength so that it will not break or tear while
removing from the mouth
-Possess elastic properties with freedom from permanent
deformation after strain
-Be able to electroplated
-Be compatible with die and cast materials
this dental cement has a multipurpose use though not used as a permanent restorative material
Calcium Hydroxide Ca(OH)2
what dental cement is used for luting and intermediate restorations because of its medicament quality and neutral pH
ZOE
Water:Powder ratio of dental stone
28-30ml/100g
a replica on which a restoration/ prosthesis is fabricated; it it more accurate than a study model
a cast
advantages of polysulfide impression material
- good wettability
- good surface detail
- high tear strength
- long working time
- radiopaque
what gypsum product consists of β-hemihydrate
Dental plaster
classify this type of GIC:
pit and fissure sealants
Type IV
what did AW Ward and EB Kelly introduce during the 1930s
ZnO Eugenol
impression materials
kind of what manipulation / mixing uses glass slab and spatula for ZOE impression paste polysulfide
circular motion
impression materials
what manipulation / mixing uses the figure of 8 technique for alginate
vigorous mixing
a non-metallic material used for luting or filling by mixing components that sets or as an adherent sealer in attaching various dental restorations in or on the tooth
Dental Cements
Zinc Oxide Eugenol (ZOE) ADA specification number
30
factors affecting strength of gypsum products
true or false:
thicker mixes will decrease the strength, while thinner mixes will increase with limits
false,
thinner mixes will decrease the strength, while thicker mixes will increase with limits
classify this type of ZOE:
intermediate fillings
Type IV
what dental cement is also used as a root canal sealer and periodontal dressings
ZOE Type IV
advantages of Zinc Phosphate
compressive strength
thermal insulator
does not dissolve in oral liquids
high strength base or low strength base:
GIC (type III)
high strength base
hydrocolloids
is a semisolid and produced from sol by the process of gelation
gel
identify the gypsum product:
what gypsum product calcinates on open kettle at 110/120°C
Dental Plaster
what was the mucous extracted from brown seaweed
algin
1890s
biological properties of Zinc Phosphate Cement:
At the time of cementation, the pH is _____?
Starting pH is _____?
After 24hrs, the pH is _____?
At the time of cementation, the pH is 2
Starting pH is 3.5
After 24hrs, the pH is 5.5
classify this type of GIC:
esthetic restorative cements
Type II a
what dental cement is not used for restorative purposes because the cement is opaque
Zinc Polycarboxylate
dental cements are usually supplied as?
powder + liquid
(or as two pastes)
impression trays:
readymade trays supplied in different sizes
stock tray
what did William Wilding use as dental impression material
algin
1936-40
Glass Ionomer Cement (GIC) specification number
96
this impression material is supplied as two pastes in collapsible tubes, one labeled base and the other labeled accelerator or catalyst
polysulfide impression material
what process is when gypsum materials are immersed in or come in contact with water during the setting process that the setting expansion increases
hygroscopic expansion
setting time and PL ratio of Zoe
ST = 4-10mins
P:L = 4:1
disadvantages of Zinc Polycarboxylate
less compressive strength
high solubility
poor esthetics
what dental cement is commonly used for children
GIC
(because it has a fluoride-releasing agent)
polysulfide impression materials are supplied in three consistencies, what are they
low (syringe or wash)
medium (regular)
high (tray)
impression materials
what kind of manipulation / mixing is used on impression compound for a putty consistency elastomers
kneading
disadvantages of polyether
- stiff (difficult to remove from mouth)
- expensive
- short setting time (3-5mins)
- bitter tasting
- absorbs water and changes dimension
average setting time, mixing time, and P:L ratio of
Zinc Phosphate Cement
ST = 7mins
MT = 1min 15sec
P:L = 1.4g/0.5ml
identify the gypsum product:
gypsum + steam and pressure at 125°C = alpha calcium sulfate hemihydrate
Dental Stone
JD Hart of Oklahoma began to use ______ for fabrication of cast restoration.
agar
(1930)
what is the chemical composition of gypsum products
calcium sulfate dehydrate
disadvantages of polysulfide impression material
- high permanent deformation
- staining of clothes due to the lead oxide
- messy
- unpleasant rubber smell
- can only be used in special trays
- must pour within 1hr
the antimicrobial agent in the components of alginate
quaternary ammonia
Zinc Phosphate Cement
true or false:
when the powder is mixed with liquid, aluminum phosphate attacks the surface of the particles and releases zinc ions
false,
phosphoric acid attacks the surface of the particles and releases zinc ions
hydrocolloids
what is the process of conversion of sol to gell, to form fibrils
gelation
this is an irreversible hydrocolloid
Alginate
a substance capable in solution of neutralizing both acids and bases and thereby maintaining the original acidity or basicity of the solution
buffer
what is the reaction between powder + liquid
in dental cements
acid-base reaction
dental cements
this type of base acts as a barrier to irritation and to provide therapeutic benefit to the pulp
low strength base
what impression materials are use for obtaining impression of edentulous mouth
impression compound
impression plaster
zinc oxide eugenol
wax
new auto devices and delivery systems were introduced when?
1990-2000
this impression technique uses a high-viscosity putty first, then a low-viscosity wash is applied for enhanced detail
putty-wash technique
true or false:
the setting reaction of Zinc Polycarboxylate begins by dissolution of the powder particles by the acid, which releases zinc, magnesium, and tin ions
true
advantages of alginate
- cheap
- easy to manipulate
- hydrophilic
- accurate enough to produce a model
identify the gypsum product:
gypsum + 30% calcium chloride solution at 100°C = alpha calcium sulfate hemihydrate
Improved Stone
true or false:
gypsum is slightly soluble in water
true
Zinc Phosphate Cement
what is essential in the liquid for cement formation
aluminum
disadvantages of Zinc Phosphate
no chemical adhesion
pulp irritation
poor esthetics
advantages of Zinc Polycarboxylate
chemical bonding
good marginal adaptation
anti-cariogenic properties
mildly acidic
a dental agent used to enhance the adhesion of some restorative materials to dentinal walls
dentinal bonding agents
classify this type of ZOE:
long term cementation of fixed prosthesis
Type II
the time for the final set of gypsum products
30-35mins
what is the retarder component in alginate
sodium phosphate
a thick, clear substance that comes from seaweed, used for growing organism such as bacteria in scientific work, and also for making liquids thicker
Agar
classify this type of GIC:
GIC for art
Type VIII
what composition aids in sintering
magnesium oxide
Zinc Phosphate Cement is applied as?
- luting for restorations
- high strength bases
- temporary restorations
- luting for orthodontic bands and brackets
classify this type of GIC:
what GIC is for luting crowns, bridges, and orthodontic brackets
Type I
5 benefits of using base/liner
- prevents micro leakage
- inhibits bacterial growth
- reduces postoperative sensitivity
- helps reduce shrinkage
- versatile protection for every restoration
GIC setting reaction
true or false:
acid attacks the glass particles reaching silica into the aqueous medium
false,
acid attacks the glass particles reaching calcium, aluminum, sodium, and fluoride ions into the aqueous medium
identify the gypsum product:
has irregular shaped crytals, very porous and random shaped
Dental Plaster
identify the gypsum product:
gypsum + heat = beta calcium sulfate hemihydrate
Dental plaster
ZOE setting reaction:
true or false:
dehydrated zinc oxide will not react with dehydrated eugenol
true
this impression material can be easily stretched and rapidly recover to their original dimensions when the applied stress is released
elastomeric impression material
this can be considered as a compromise between the very small molecules in solution and very large particles in suspension
colloids
this process is the formation of large polymer molecule from smaller monomer molecules
polymerization
Water:Powder ratio of improved stone
19-24ml/100g
identify the gypsum product:
modified α-hemihydrate
Improved Stone
this process is the formation of large polymer molecule with the release of by-product
condensation polymerization
impression trays:
trays prepared specially for one patient
special tray (custom tray)
a device used to support the impression material in contact with patient’s oral tissues during the taking of the impression
impression tray
this is the time permitted to manipulate the material in the mouth
working time
what is a cast with no presence of teeth
edentulous cast
true or false:
all gypsum products expand on normal setting
true
this dental cement is used to coat the canal space and fill in any voids between the canal wall and the gutta percha filling material
endodontic sealer
disadvantages of agar
- Low tear resistance
- Low dimensional stability
- Only one model can be used
- Extensive and expensive equipment required
- It cannot be electroplated
- Impossible to sterilize for re-use
besides from dentistry, where else can gypsum products be used
homes - to make walls
industry - to make molds
medicine - used as a cast for broken bones
what is a cast with the presence of teeth
dentulous cast
materials painted on cavity walls or surfaces to serve as a chemical barrier protecting the pulp from irritating effect of some cements
varnishes
when was latest addition and light cure elastomers introduced
1988
this dental material is supplied as fine powders that are mixed with water to form a fluid mass that can be poured and shaped and hardens into a rigid, stable mass
gypsum products
Calcium Hydroxide dental cement:
seals the enamel rods offering enamel protection.
induces reparative dentin below existing dentin
a. the first statement is wrong
b. the second statement is wrong
c. both are correct
d. both are wrong
b. the second statement is wrong
seals the dentinal tubules offering dentin protection.
dental cements
these are used to hold restorations on prepared teeth when mixed to a primary consistency
Luting Agent
ADA specification of Zinc Phosphate
96
what is the final product of a gypsum product used to plan treatment and to observe treatment progress
a model
hydrocolloids dimensional effects
a process where a gel is placed in water and absorbs it;
the gel swells
Imbibition
what is another substitute for varnishes
bonding agents
what is the first dental cement to exhibit chemical bonding to teeth
Zinc Polycarboxylate
this is a reversible hydrocolloid
Agar
what are the three types of gypsum products
plaster
stone
high strength or improved stone
high strength base or low strength base:
zinc polycarboxylate
high strength base
type of strength of gypsum products:
when such excess water is removed by drying, the strength is obtained
dry strength
3 types of elastomers
polysulfide
condensation polymerizing silicone
addition polymerizing silicone
polyether
true or false:
in polysulfide impression material, alcohol could cause air bubbles in the stone cast
true
dental cementse
these are used as temporary filling materials to provide thermal insulation and mechanical support to teeth restored with other materials
base
gelation temperature of agar
37°C - 50°C
classify this type of GIC:
core build up material
Type VI
high strength base or low strength base:
reinforced zinc oxide eugenol
high strength base
disadvantages of alginate
- dimensional changes
- evaporation > harden
- 100% humidity
- no longer accurate
classify this type of ZOE:
temporary filling and thermal insulating bases
Type III
where is dental stone used:
cast or model
cast
who used wax with plaster of paris
William Rae
1782
this impression technique uses a medium-consistency material for both general and fine detail in a single application
single-viscosity technique
high strength base or low strength base:
zinc phosphate
high strength base
which dental cement has an adverse effect of calcification in pulp, internal resorption, ankylosis, and increased brittleness of dentin
Calcium Hydroxide Ca(OH)2
high strength base or low strength base:
calcium hydroxide
low strength base
where is plaster of paris used:
cast or model
model
what dental material takes accurate replica of the teeth and oral tissues
Impression Materials
advantages of polyether
- Accurate and fine details
- Good dimensional stability during setting
- Good elastic recovery of 98.9%
- Compatible with cast and die materials
- Pour within one week (if kept dry)
- Good wettability (hydrophilic)
this is the amount of time the auxiliary has to bring the components
mixing time
this impression material refers to a group of rubber polymers, which are either chemically or physically cross-linked
elastomeric impression material
hydrocolloids
has an appearance and many characteristics of a viscous liquid
sol
this impression technique uses high-viscosity and low-viscosity material simultaneously for stability and detail capture
dual-viscosity technique
ADA specification no.25 classifies 5 types of gypsum products
Type I - impression plaster
Type II - model plaster / plaster of paris
Type III - dental stone
Type IV - dental stone high strength
Type V - dental stone high strength high expansion
high strength base or low strength base:
zinc oxide eugenol
low strength base
which type of gypsum product is used for pouring preliminary impressions and making of diagnostic models
plaster of Paris
this impression material contains hydrophobic molecules
addition silicone
classify this type of GIC:
reinforced restorative cements
Type II b
what dental cement is the least irritating and known for having an effect on exposed dentin
ZOE
average working time or initial setting for gypsum products
5-7mins
this impression material is based on a natural substance extracted from certain brown seaweed
Alginate
ADA specification no.11
working time, setting time, gelation temperature, and liquefaction temperature of agar
WT = 7-15mins
ST = 5mins
Gelation temp = 37-50°C
Liquefaction temp = 70-100°C
which type of gypsum product is used as a working model when a more durable diagnostic cast is required
dental stone
what decreases the setting time of gypsum products
lower water/powder ratio
addition of accelerators (sodium chloride)
what is the process of heating a solid material to drive off chemically combined components such as water and carbon dioxide
calcination
classify this type of GIC:
luting for orthodontic purpose
Type V
classify this type of GIC:
high fluoride releasing command set GIC
Type VII
identify the gypsum product:
α-hemihydrate
Dental Stone
hydrocolloids dimensional effect
a process wherein gel loses water by evaporation from its surface of by excluding fluid onto the surface;
the gel shrinks as a result
Syneresis
classify this type of GIC:
geriatric and pediatric GIC
Type IX
activator component in Alginate;
the reactor for cross-linking reaction
calcium sulfate
what increases the setting time of gypsum products
higher water/powder ratio
addition of retarders (borax)
the process of compacting and forming a solid mass of material by heat or pressure without melting it to the point of liquefaction
sintering
which type of gypsum product has hardness and dimensional accuracy making it ideal to create the dies used in the production of crowns, bridges and indirect restorations
high strength stone
expansion that occurs when gypsum sets while immersed in water
hygroscopic expansion
average mixing time and setting time of Zinc Polycarboxylate
MT = 30-90sec
ST = 6-9min
dental cements
this type of base is used to provide thermal protection for the pulp, as well as mechanical support for the restoration
high strength base
this dental agent is a mix of paste-paste system to form one paste which is packed over surgical sites to protect the underlying tissue
surgical/periodontal agents
classify this type of ZOE:
temporary cementation
Type I
dental cements
cements of low strength used to provide protection to the pulp from irritants or serve therapeutically as pulp capping agents
to initiate reparative dentin
liner
where was polyether impression material developed
Germany
1960s
what is the buffer in the composition of Zinc Phosphate Cement
aluminum phosphate
this process is the formation of large polymer molecules with no release of by-product
addition polymerization
