dental materials test 1

what is the combination of 2 different metallic elements?

alloy

placing an amalgam restoration on #14 occlusal and a gold crown on #19 might cause:

galvantism

a force exerted causing stress to stretch a material to the point of fracture indicates what?

tensile strength

a chemical attack on metal by composite in food and/or saliva resulting in metal discoloration that be polished off

tarnish

corrosion is only the surface deterioration of a metal and is less harmful than tarnish

false

the material most similar to the tooths thermal conductivity is gold

false

the material least similar to the coefficient of thermal expansion of natural teeth is unfilled acrylics

false

a hydrophilic surface is one with a wettability contact angle less than 90 degrees

true

a hydrophobic surface is one with a wettability contact angle more than 90 degrees

true

which one has greater thermal conductivity

gold

which one has the least thermal conductivity

enamel

what is the biting force for tooth #22 in pounds

50

2 consequences of galvanic shock are pain and metallic taste

true

a veneer would be a good restorative choice to restore tooth #30

false

a primary consideration for selecting a restoration on #7 is strength

false

acrylic resin denture teeth are more wear resistant than porcelain

false

the material most similar to the tooths thermal conductivity is unfilled acrylics

false

the material most similar to the coefficient of thermal expansion of natural teeth is unfilled acrylics

false

difference between coefficients of thermal expansion of tooth & restorative material that occurs at the margin of galvanism

false

which agency ensures the safety of dental materials

FDA

which is the most common root canal filler?

gutta percha

which agency is responsible for regulation of barrier techniques

CDC

a restorative material used to restore a large portion of posterior teeth should have

high strength

Mohs scale ranks

hardness of material

a desirable feature of dental material is

high corrosion resistance

retention of a sealant in a fissure is a result of

mechanical bonding

the percentage of phosphoric acid in etchant is 55-70%

false

sealants are recommended for all molars and premolars

false

sealants never need to be replaced if applied correctly to the tooth surface

false

sealants are made from an unfilled or lightly filled resin

true

it is critical to avoid moisture contamination when placing a sealant

true

when placing a sealant, the enamel is etched to increase the chemical retention by increasing the bonded surface

false

which component found in a chemically-cured sealant differs from the components in the light-cured sealants

benzoyl peroxide

why should dental floss be tied to the bow of the rubber dam clamp

to provide a means of retrieval should it be dislodged

an increase in the water temperature used to mix alginate will increase the working time

false

metallic restorations cause less thermal conductivity than composite restorations

false

which of the following initiator-accelerator systems is needed for light-activated composites

diketone-amine

the best method to clean a mouth protector is a denture cleaner

false

a pit and fissure sealant is most likely to adhere to enamel because the tooth surface is smooth and nonporous

false

the total setting time of a sealant includes mixing, manipulating and setting

true

the following metal is not used in dentall alloys

iron

the main ingredient in sealant materials is glass ionomer

false

inlays should not exceed ½ of the intercuspal space

true

onlays do not extend onto the cusp

false

if high compressive strength is most important factor in selecting a material, the material of choice would be amalgam

false

the purpose of directing a stream of air while inverting the rubber dam is to remove debris

false

a force exerted causing stress to stretch a material to the point of fracture indicates its compressive strength

false

if a material is considered highly ductile, it

may bend without breaking

when placing a rubber dam, what is the position of the tooth receiving treatment in relation to the anchor tooth

mesial to the anchor

which agency ensures the safety of dental employees in the dental office

OSHA

according to blacks classification, a filling in #14-B pit is a class II restoration

false

rubber dams should not be used on patients with severe asthma

true

the area below proportional limit on the stress/strain curve represents the elastic properties of a material

true

the fluoride composition of a daily sodium rinse is 0.2%

false

during galvanism, the saliva acts as a liquid carrying metal ions. the saliva is called a what?

electrolyte

an example of adsorption is staining of a composite restoration

false

winged rubber dam clamps allow the dam and clamp to be applied simultaneously

true

the elastic modulus of a material is a measure of its hardness

false

an indirect restoration can be fabricated from gold alloy and lab composite

true

fluoride gels have thixotropic properties that provide efficient contact of gel with enamel surfaces of teeth

true

stannous fluoride have the least ppm of fluoride ions

false

the elastic modulus of gold is lower than that of amalgam

false

mouth guards can also be used as a bleaching tray

true

a desirable feature of a dental material is a high rate of microleakage

false

the point above proportional limit but below the ultimate strength represents the resilience of the material

false

when a material reaches ultimate strength, the strength will be called by the strain that caused the breakage or rupture

false