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Dental Materials Exam 1 - Jan 18, 2017

Terms in this set (120)

restorative and preventive dentistry rely on the use of ____
biomaterials
Man-made materials used to replace tissues or that function in intimate contact with living tissues
biomaterials
biomaterials used in or around the oral cavity that mimic the function of the oral tissue
dental materials
understand behavior of materials, assess and treat patient, handle materials properly, educate patient are all what?
reasons to study dental materials
prevent oral disease or injury, restore teeth form and function, replace lost teeth, or temporary uses are all examples of what?
uses of materials in dentistry
2 desired qualities of dental materials are to: mimic function of ____ ____ and must withstand harsh _____ _____
oral tissue
oral environment
withstand biting forces, degradation of materials/corrosion, response to temperature, bicompatible, esthetic are all _____ on material use
restrictions
____ develops and administers standards in dentistry
ADA
upon approval, product receives the ADA seal - how long does that seal last for?
3 years
what are the 2 classifications by location of fabrication
direct and indirect
direct includes what 3 things and is done where?
amalgams, composites, glass ionomer
chairside
indirect includes what and is done where?
gold crowns, inlays, inlays, ceramics, plastic polymers
in a lab
abutment, poetics, retainer are all classifications of what?
bridges
what is the new GV blacks class?
class 6, cusp tip caries
material science seeks to explain ____ and ____ of materials by observing _____ _______
properties
performance
internal structure
material science combines what 3 scientific domains?
physics, engineering, chemistry
teeth & dental materials require enough strength to withstand forces of occlusion and mastication which require ____ atomic bonding
stronger
what are the 3 phases of materials
gases liquids solids
gases have a _____ atomic bond, with no molecular organization
weak
liquids have a ____ atomic bond than gases but no enough to carry a load or maintain ____. have short-range order
stronger
shape
solids have the _____ atomic bond, _____ shape, and ____ external force
strongest
maintain
resist
solids have 2 classifications, what are they?
crystalline and amorphous
crystalline solids have a ____ range order, have uniform and are very (inconsistent/consistent)
long
consistent
amorphous solids are the ___ strength in bonds but (do/do not) have a long range order - no shape
same
do not
____ bonds are strong bonds between atoms; involve sharing or transfer of electrons
primary
what are the 3 types of atomic/primary bonds?
ionic, covalent, metallic
an electron given up by one atom and accepted by another; attraction of opposite charges minus repulsion of like charges
ionic
_____ charged ions repel one another = _____ force
like
weak
____ charged ions attract one another = ____ force
opposite
strong
two atoms sharing a pair of electrons is what bond?
covalent bonds
____ bonds create a strong directional bond
covalent
what substances are made up of covalent bonds?
polymers; plastics and rubbers
electrons shared by all the atoms that make up the object, results in a strong material is what bond?
metallic bond
atoms that make up a material and how they are bonded together determines what?
the properties of that material
dental materials classified into 3 main categories based on primary bonds
metals, ceramics, and polymers
what two things make up composites?
ceramics and polymers
natural or man made material formed by combining units, called monomers, into long chains
polymer
this is used in dentistry held together by metallic bonds, allow atoms to slide against each other without changing the bond or properties
metals
most held together by ionic bonds
ceramics
ceramics are ___ when compressed
strong
ceramics are ____ when pulled/bent
weak
what is the positive of ceramics?
color and translucency
what is the negative of ceramics?
very weak
what is another name for polymers?
plastics
long chains of covalently bonded repeating units - primarily carbon and hydrogen
polymers
plastic polymers are ____, _____ & _____
soft weak flexible
glassy polymers and resins are ___ ____ & _____
hard stiff fairly strong
polymers can also be ____
rubbers
combination of a ceramic and polymer is called what?
composites
in ____ properties lacking in one material are compensated for by the other
composties
a 2 phase material; a mixture of gases, liquids or solids at microscopic level is considered to be what?
colloids
in ____ properties affected by component properties but also by surface properties
colloids
____ materials can be transformed from a liquid to a gel when cooled
colloid
type of colloid composed of two liquids that do not blend to form one liquid - surfaces of the two are temporarily stable when shaken
emulsion
what are the properties of materials?
physical (mechanical), chemical, & biological
____ properties are based on laws of physics and describe mass, energy, heat, & electricity
physical
____ properties are a subgroup of physical.
mechanical
material's ability to resist forces; dependent on amount of material - dependent on size and shape of object. ex. strength and stiffness
mechanical
decay or degradation of materials
chemical properties
what are 2 types of setting reactions?
polymerization and precipitation
polymerization and precipitation are classified under what property?
chemical
process of separating a substance from a solution as a solid is called what?
precipitation
____ properties effect materials have on living tissue
biologic
amount or mass of material in given volume
density
these are used to identify unknown chemicals
boiling and melting points
when object melts or boils ____ bonds are broken
atomic
measure of liquid's tendency to evaporate and become a gas
vapor pressure
materials with _____ vapor pressure are useful as solvents in application of viscous liquids
high
rate of heat flow through a material
thermal conductivity
measurement for thermal conductivity depends on
distance heat travels
areas in which heat travels
difference in temperature between source and destination
pulp insulation required with materials with ____ conductivity
high
enamel and dentin are ___ thermal conductors
poor
metals have ____ vales than plastic is or ceramics with thermal conductivity
higher
measure of amount of thermal energy a material can hold
heat capacity
amount of energy it takes to raise temperature of one unit of mass by 1 degrees C
specific heat capacity
amount of energy required to MELT a material
heat of fusion
amount of energy required to BOIL a material
heat of vaporization
measure of change in volume in relation to the change in temperature (heat- expand | cold- contract)
coefficient of thermal expansion
opening and closing of gap on heating and cooling -- results in micro leakage, tooth sensitivity, and recurrent decay
percolation
awareness of which materials are conductive
electrical conductivity
metals are ____ conductors & ceramics and polymers are ____ conductors are electrical conductivity
good
poor
generation of electrical currents, results from presence of dissimilar metals in mouth (causes pain, tastes metallic)
galvanism
process where metal changes to a metal oxide - increases in warm wet environment
corrosion
ability of material to flow (thick vs. thin)
viscosity
____ viscosity and ability to WET a surface are desired properties in many dental materials
low
ability of a liquid to wet or intimately contact a solid surface
wetting
an example of poor wetting is...
water on waxed car
wetting is measure by the contact ____ of the liquid on the solid
angle
___ angle = ___ wetting and vice versa
low
good
hard materials resist scratching and indentation - measured as resistance of a material to indentation - measured by size and length of indentation
hardness
hardness test for materials which do not leave indentation - measures how deep a loaded steel ball sinks - impression materials and elastic polymers
durometer measurements
wear resistance of restorations to food and opposing forces - wear of natural vs manmade (goldilocks principle)
abrasion resistance
susceptibility to being dissolved
solubility
____ is measured by weight of material that dissolved in a given amount of liquid in a given amount of time
solubility
ability to absorb water
water sorption
passage of a substance into the interior of another by solution or penetration (swelling and distortion)
absorption
natural process where molecules of a gas or liquid adhere to the surface of a solid
Adsorption
hue= ____
chroma = _____
value = _____
color
intensity of color
density of color
spectrophotometer measures what?
intensity of light reflected by object at various wavelengths of visible light
force which develops in loaded object - proportional to applied force or load
stress
equation for stress
stress = load/area
change in length, or deformation when a material is subjected to a force - change in length/original length
strain
load (stress) and the change in length (strain) are ______ - always occur together
proportional
ratio between the amount of ___ and object can withstand to the amount of ___ it can withstand is know as ______ ___ _____
stress
strain
modulus of elasticity
characteristic of a material and its bonds - high modulus of elasticity - very STIFF material
modulus of elasticity
another term of modulus of elasticity is what?
stiffness
ability to return to original shape after having been stretched or compressed - response to external FORCE (weight or load applied to an object)
elasticity
object returns to original shape when stress removed
elastic deformation
stress no longer proportional to strain, object does NOT return to original shape when stress removed
plastic deformation
point on graph where line curves and plastic deformation begins
elastic limit (yield point or proportional limit)
stress at the point of material failure - load on material greater than atomic bonds holding material
ultimate strength
compression (pushing or crushing)
tension (pulling)
shear (parts of objects slide by one another)
torsion (twisting force)
bending

are all types of ____
stress
combination of stresses (tensile, compressive, shear - internally)
bending
ability to absorb energy and not become deformed (mouthguard)
resilience
ability to absorb energy while distorting or fracturing (helmet)
toughness
measure of energy required to fracture a material when a crack is present (glass & ceramics = low value | metals = high value)
fracture toughness
failure due to repeated stress
failure
small change in shape when object under continuous compression - amalgams and composites
creep - slow flow
slow decrease in force over time - loss of pull
stress relaxation
stress increase around a defect - results in fracture and failure
stress concentration
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