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Dental Materials
National Board Exam Dental Materials
67
Science
Not Applicable
01/29/2014

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Term
Adhesion
Definition
the chemical attraction between unlike molecules
Term
Cohesion
Definition
the chemical attraction between like molecules
Term
Coefficient of Thermal Expansion
Definition
an index which indicates how one material reacts to temperature extremes in relation to another
Term
Compressive Strength
Definition
the force at which a material breaks under pressure
Term
Creep
Definition
slow dimensional change caused by compression
Term
Ductility
Definition
the ability to undergo change of form without breaking
Term
elasticity
Definition
a material's ability to recover it's initial shape after undergoing a force
Term
Galvanism
Definition
an electrical current generated by dissimilar metals in an acidic environment
Term
Gelation
Definition
the process of gelling (solidification by cold)
Term
Imbibition
Definition
absorption of a solvent by a gel
Term
malleability
Definition
a material's capacity to be shaped by force or pressure
Term
Microleakage (percolation)
Definition
passage of oral fluids/bacteria into and out of tooth structure due to marginal gap or failure of marginal (restorative) seal
Term
Polymerization
Definition
the linking, branching, or cross-linking of smaller molecules
Term
Proportional limit
Definition
the force at which a material cannot return to its original shape
Term
Syneresis
Definition
contraction of a gel due to the loss of a solvet
Term
Tensile Strength
Definition
the force needed to stretch a material to the point of fracture
Term
viscosity
Definition
resistance to flow
Term
Amalgam
Definition
-an alloy of mercury with silver, copper, tin, and zinc
-copper added to minimize corrosion
-must be: durable, strong like enamel, and inexpensive
-when polishing: tin oxide
Term
How do we get micromechanical retention?
Definition
Etch: adapting relief areas created by conditioning with 37% phosphoric acid.
Term
Polymerization activated by fiber-optic light...
Definition
a) light-activated polymerization allows flexible working time
b)polymerization initiators typically benzoyl peroxide or a tertiary amine
Term
Why do bonds fail?
Definition
due to contamination by saliva or oils
Term
Pit & Fissure Sealant Steps
Definition
pumice
rinse
isolate
etch
rinse
dry
apply
remove access
polymerize
Term
Composite
Definition
most common filler particles: silicates, quartz, or glass.
-barium or strontium usually added for radiopacity
Term
Why are microfills popular?
Definition
high polishability and ease of handling, but require tooth support
Term
Why are hybrid composites popular?
Definition
due to combined strength and beauty
Term
Nanofills increase?...
Definition
surface areas, bond strength, polishability
Term
Liners
Definition
-used to seal dentin or medicate the dental pulp
-includes: calcium hydroxide (stimulate reparative dentin form)
zinc oxide/eugenol (soothes the pulp, oily, c/i w/ complosite)
Resin-modified glass ionomer (seals tubules and releases fluoride)
Term
Bases
Definition
-used to provide thermal insulation or mechanical protection for the dental pulp
-includes al cements, because cements are poor thermal conductors, and have adequate compressive strength
Term
What are the 6 types of cement?
Definition
1)Zinc Phosphate cement
2) Polycarboxylate cement
3) glass ionomer cement
4) resin
5) hybrid
6) zinc-oxide/eugenol
Term
Zinc Phosphate Cement
Definition
a)exothermic reaction on mixing (need glass slab)
b)mechanical interlock between tooth and casting
Term
Polycarboxylate Cement
Definition
a) high chemical affinity for enamel
b) powder mixed with polyacrylic
Term
Glass Ionomer Cement
Definition
a)bind to dentin
b)releases fluoride
c)coefficient of thermal expansion approximates tooth structure
d) can be used as a Class V restorative material
Term
Resin Cement
Definition
a)tooth colored to affix esthetic restorations like porcelain laminate veneers and tooth colored inlays, onlays, or crowns, and clear orthodontic brackets
b) also used for luting etched metal retainers such as resin-bonded bridges and prefabricated endodontic posts
Term
Hybrid Cements
Definition
a) resin-modified glass ionomers
b)seals dentin effectively to minimize sensitivity (unfilled resin/bonding agent)
c)releases fluoride (glass ionomer)
Term
Zinc-oxide/ eugenol cement
Definition
a)commonly used to temporary cementation
b)mixed putty-like to cement a temporary aluminum shell crown
c)mixed creamy-like to cement a custom acrylic temporary crown
d)orange solvent typically used to clean ZOE contaminated instruments
Term
Rigid Impression Materials
Definition
a)plaster, Type I Gypsum
b) compound (border molder custom tray)
c) zinc-oxide/eugenol (final impression, full denture)
Term
Flexible Impression Aqueous Materials
Definition
Hydrocolloid
-Reversible hydrocolloid (agar)
-physical reaction only sol-gel is temperature dependent
-solidification by cold called gelation
popular for multiple preparations, but unstable
-susceptible to imbibition and syneriesis
Term
Flexible Impression Non-Aqueous Material
Definition
a)Polysulfide rubber
-messy,smelly,must be poured same day
b)polyether rubber
-relatively rigid, good tissue detail
-unstable in presence of moisture (will distort if wet
c)silicone rubber
-putty-like rarely used
d)vinylpolysiloxane
-tasteless, odorless
-stable, strong, accurate
-easily mixed
-capable of multiple pours
Term
Gypsum Products
Definition
Mineral form: calcium sulfate di-hydrate
Heated form: alpha-calcium sulfate hemi-hydrate (stone) or beta calcium sulfate hemi-hydrate (plaster)
-plaster needs more water and therefore it undergoes a greater setting expansion lowering it's compressive strength making stone superior to stone
Term
Types of Gypsum
Definition
a) Plaster, type II gypsum: beta calcium sulfate hemi-hydrate
b) Stone, Type III gypsum: alpha calcium sulfate hemi hydrate
c)Diestone Type IV Gypsum: alpha calcium sulfate hemi hydrate. contains additive to make more durable and wear resistant( also called improved stone)
Term
Gypsum material selection dependent upon...
Definition
strength and dimensional accuracy
a) orthodontic model: plaster (easy to polish)
b)study model/working model: stone (more accurate and wear resistant)
c)crown and bridge die or model :improved stone or diestone (accurate and most wear resistant.
Term
How do you modify working time with gypsum?
Definition
1)add potassium sulfate to accelerate set
2)mix with warm (not hot) water to accelerate set
3)add borax to slow se
Term
Waxes
Definition
-comprised primarily of paraffin
Term
Inlay and casting Wax
Definition
used for cast restorative patterns
Term
Baseplate wax
Definition
useful in removable prosthetic procedures
Term
Bite Registration Wax
Definition
useful to obtain occlusal records
Term
Boxing Wax
Definition
used in pouring models
Term
Sticky Wax
Definition
becomes sticky when heated, used to attach models
Term
Utility Wax
Definition
used to modify the shape of impression trays and cushion braces
Term
Casting Alloys : Precious alloys contain noble metals
Definition
a)noble metals resist tarnish and corrosion
b) noble metals used in dentistry (gold, platinum, and palladium)
Term
Casting Alloys: Nonprecious alloys contain base metals
Definition
a)base metals are subject to tarnish and corrosion
b)may be allergenic (gingival inflammation)
c)base metals used in dentistry include: silver, copper, nickel tin and zinc
Term
How is gold polished inside the mouth?
Definition
tin oxide
Term
How is gold polished outside the mouth?
Definition
rouge
Term
Where are gold foil restorations placed?
Definition
gum-line or anterior
Term
Implants
Definition
biocompatible titanium alloy
endosteal
-fail because of no osseointegration/ inadequate bone
-pt can use electric toothbrush
-can air polish
Term
What are contra-indications for implant placement?
Definition
Inadequate bone
Uncontrolled perio disease
smoking
infection
Term
What type of instruments can a hygienist use on implants?
Definition
titanium
titanium alloy
graphite
Term
What is the active ingredient in tartar control toothpaste and what can that ingredient cause?
Definition
pyrophosphate can lead to dentinal hypersensitivity
Term
What is the active ingredient in gum care toothpaste?
Definition
triclosan (antimicrobial agent)
Term
What is the active ingredients in desensitizing toothpaste?
Definition
potassium nitrate, sodium citrate, strontium chloride
Term
What is the active ingredient in vial bleach?
Definition
carbamide peroxide, or hydrogen peroxide
(carbamide peroxide breaks down into hydrogen peroxide and urea)
Term
G.V. BLACK'S classification Class I
Definition
all pits and fissures
Term
G.V. BLACK'S classification Class II
Definition
posterior proximals
Term
G.V. BLACK'S classification Class III
Definition
anterior proximals
Term
G.V. BLACK'S classification Class IV
Definition
anterior proximals involving the incisal edge
Term
G.V. BLACK'S classification Class V
Definition
facial or lingual gingival third
Term
G.V. BLACK'S classification Class IV
Definition
cusp tip and/ or incisal edge
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