Midterm Exam Lectures 1-7 Flashcards
_______ is the force per unit area with its units being ______ or ______ which is N/m^2
stress, PSI, Pa
strain is the change in ________ per unit length when a material is subjected to a _______ (stress)
length or deformation, force
______ is the pushing or pulling of an object
force
force has units of _______ or ______
NEWTONS, POUNDS
one newton is equal to _______ lbs
0.225
one pascal is equal to ________ PSI
0.000145
one ______ is equal to 1x10^6 PA
MPa
one ______ is equal to 1x10^9 Pa
GPa
elongation uses _______ or _______ forces to pull a material from both sides
axial, tension
compression uses _______ or _______ forces to push a material from both sides
axial, compression
shearing uses ______ force to apply a force parallel or cross sectional on the bottom and top of a material
shear
torsion uses ________ force on a material
twisting movement
bending uses _______ force on a material
bending
_________ is equal to the ratio of the stress to the strain in the linear or elastic portion of the stress strain curve
elastic modulus
elastic modulus is a measure of _______
stiffness
________ is at the point of permanent strain at the point a material is deformed plastically
yield strength
_________ is the amount of stress/strain that can be applied before a material is deformed plastically
proportional limit
the _______ is the amount of stress a material has at fracture
ultimate strength
percent elongation is the amount of _______ a material can withstand before rupture under _______
deformation, tensile stress
resilience is the energy absorbed up to the ________
proportional limit
toughness is the energy absorbed up to the _______
fracture point
the elastic region is considered to be at or around the ________
proportional limit
the plastic region is considered to be at the point that ________ is met until _______
yield strength, fracture
_______ is the amount of stress a material can withstand without fracture
strength
_________ is the ability of a material to resist deformation
stiffness
flexibility is the ability of a material to deform ________ but return to its original shape
elastically
_________ is the materials tendency to fracture with little deformation
brittleness
a weak material is one that bends, breaks or fractures easily and a ________ material is weak
brittle
a _______ material is one that is able to resist breaking and able to absorb a lot of energy
strong
ductility is a materials ability to deform _______ without fracture
plastically
a ________ material is one that can absorb energy but return to its original shape
resilient
________ is a materials ability to resist indentation
hardness
viscosity is the resistance of a fluid to ______ and a measure of _______
flow, internal friction
shear thinning is used to describe the phenomena of added stress will cause a material to become _______ viscous
less
shear thickening is used to describe the phenomena of added stress will cause a material to become _______ viscous
more
viscoelastic is when a material behaves in an ________ behavior and a _______ like manner at the same time
viscous, elastic
a viscoelastic substance _______ energy
when a load is applied, then removed
loses
Hysteresis ( is observed in the stress–strain curve), with the area of the loop being equal to the energy _______ during the loading cycle
lost
______ is defined as constant stress which in turn will _______
creep, increase strain
________ is defined as a constant strain applied will cause a _______ in stress
stress relaxation, decrease
dentin, enamel, cells, impression materials and some acrylic denture are all _______ materials
viscoelastic
the hardness test is a measure of the resistance to localized ______ deformation induced by either mechanical indentation or abrasion
plastic
the types of hardness tests include the brinell, _______, vikers, rockwell, barcol and shore A
Knoop (KH)
Knoop hardness test uses a _______ to indent the material and measures the _______ surface deformation after a load is removed
diamond, permanent
the brinell hardness test uses a _______ pressed into the sample surface with a load of 500, 1500 or 3000 kgs
hard ball
the rockwell hardness test is widely used and uses a ______ indenter that is pressed into the specimen
cone-shaped
vickers hardness test uses a _____ that is pressed into the material
square-based pyramid shaped tip
nano-indentation uses a _________ to calculate the penetration ______ the load
berkovich tip that is a 3 sided pyramidal shape diamond, under
when a hydrophilic material is used, its contact angle is______ degrees and has a ________ degree of surface detail
less than 90, high
when a hydrophobic material is used, its contact angle is _______ degrees and has ______ degree of surface details
greater than 90, low
high surface energy will have ______ adhesive wet out and examples include metal, kapton, polyester, ABS and acrylic
good
low surface energy will have ______ adhesive wet out and examples include polystyrene, acetal, EVA and teflon
poor
contaminants will _____ surface energy and inhibit wet-ability
decrease
________ is the ability of a biomaterial to perform its desired function with respect to a dental therapy, without eliciting any undesirable local or systemic effects in the recipient of that therapy
biocompatibility
there are 4 interfaces of placement in the oral cavity
1. Interface between the material and _______
2. Interface between the material and _______
3. Interface between the material and
_______
4. Interface between the material and
_______
oral cavity (OC), pulp (tubules), periodontium (PD), periapical bone (PA)
Biocompatibility is not a property of a material, but rather a property of how a material reacts with its _______
local environment
the in-vitro tests for biocompatibility include ______ and _______ tests
direct, indirect (barriers)
the tests for biocompatibility not including in-vitro tests include _____ and ______ tests
animal, usage
in-vitro tests involve placing a material in contact with a ______, _______, or some
isolated _______ system
cell, enzyme, biological
the primary cells used in in-virto tests are cells taken _______ from an animal and _______, allowed to grow for _______ time and ________ in-vivo conditions
directly, cultured, limited, retain
the cell lines used in in-vitro testing are cells that are transformed to grow _________, can keep undergoing _______, have a more ________ population but ______ in-vivo conditions
indefenitaly, division, homogeneous dont retain
the in-virto direct and indirect tests assess ________, _________ and ________
cytotoxicity, metabolism, mutagenesis
a in vitro direct test involves placing a material in _______ contact with cells
direct
during direct tests the cells can be place ______ on the material, the material and cells can be places in the same medium but ________, or the material can be incubated in a medium where the medium will then be ______ to the cells
directly, do not touch, transferred
the measuring of cytotoxicity can be microscopically for ________ evaluation or -_______ evaluation in direct testing
qualitative, quantitative
________ microscopy is used in direct testing to count the dead or alive cells
fluorescent
direct tests can use the enzymatic or biosynthetic activity of cells to determine metabolism and some of these tests include ______, ______, NBT, WST and alamarblue
MMT, XTT
in indirect tests a _______ is placed between the biomaterial and cell to better represent the in-vivo condition
barrier
the 3 indirect tests that are available include _______ method, ________ method and ______ filter assay
agar overlay, dentin barrier, millipore
the agar overlay method is an indirect test that utilizes agar to form a ______ between cells and material where the agar provides nutrients, gas and soluble ________ will diffuse into cell layer and if cells are cytotoxic they will release neutral red causing a _______
barrier, toxic substances, zone of inhibition
the dentin barrier tests are indirect tests that closely mimic the oral environment where cytotoxic materials are diffused through the _______
dentinal tubules
the advantages of in-vitro tests include they are ________, _________, and relatively fast processing of ___________ of materials and prototypes
cheap, controllable, large number
the disadvantage of in-vitro test is that they ________ the overall biocompatibility of material
cannot entirely predict
the mucous membrane irritation test performed on animals tests if the material causes _______ to the mucous membrane
inflammation
the skin sensitization test is performed on animals where materials are injected _______ to test for development of skin ________
intra-dermally, hypersensitivity reactions
the implantation test is performed on animals and is used to evaluate materials that will contact ________ or ______
subcutaneous tissue, bone
the advantages of animal testing/ in-vivo is that it allows complex systemic _______ and responses are more ________ than in-vitro
interactions, comprehensive
the disadvantages of animal testing/in-vivo are that they are ________, _________, _______ to control, and has ________ relevance to humans
expensive, time consuming, difficult, questionable
usage tests are tests done on ______ or _____ where the biomaterial is placed identically to clinical use and are _______
animals, humans, gold standard
the four main types of usage tests include ________ tests, _______ usage test, _______ usage tests, and _________ tests
pulp-dentin irritation, mucosa, gingival, dental implant
dental pulp irritation tests determine the _______ of a material with the dental pulp, by preparing class Vs as ________ and fill with test material, _______ tooth after several days then margins are examined for bacterial penetration
compatibility, traumatic as possible, extracting
the mucosa and gingival usage tests check for ________ in the _______ and adjacent ________ by placing material in cavity preparations with subgingival extensions
inflammatory cells, epithelium, connective tissues
difficulties with the mucosa and gingival usage tests include ________, ________ and surface ______ of material
plaque, preexisting inflammation, roughness
the dental implant usage tests involves implanting in jaws of dogs, miniature pigs, guinea pigs and rats and watching for ________ histologically
tissue reaction
during the implant usage tests the _______ of the implant and the ________ for osseo-integration are checked while the bones are checked for _____, ______ and _______
mobility, radiographs, fibrous capsule formation, inrritation, inflammation
the advantages for usage test are they have high ________ and real life _______ of the situation
fidelity, simulation
disadvantages of usage tests include _____, ______, _______, _______ to control, and _______ to interpret and quantify
expensive, time consuming, ethical issues, difficult, difficult
the governmental institutes that regulate dental materials include ______, ______ and _______
FDA, OSHA, EPA
the non-governmental institutes thats provide standards/regulations for dental materials includes _____, ______, ______ and ______
ADA, ANSI, ISO, FDI
calcium phosphate is a ______ occurring mineral and ________ is a form of calcium phosphate
naturally, hydroxyapitite
enamal is the most mineralized and hardest tissue of the body composed on 96% inorganic ________, 2% organic proteins _________, and 2% _______
hydroxyapatite crystals, enamelins, water
mechanical properties of enamel are strongly dependent on its _______ and only weakly dependent on its ______
degree of mineralization, microstructure
demineralization is the net loss of minerals because of ________
ion exchange
acid etching which contains 40-50% ________ is a process of demineralizing the enamel for 15 seconds to prep the tooth for a filling
posphoric acid
the dentin-enamel junction is _______ mineralized
highly
dentin constitues the largest portion of the tooth and consists by volume 25% ________, 50% _________, and 25% _______
organic matter (type 1 collagen), inorganic matter (hydroxyapitite), water
the outer dentin is ______, (containing less _______) than the inner dentin
stronger, tubules
________ is the most abundant protein in the human body and provides structural support for all connective tissues…….. amino acids to tropocollagen to fibrils to fibers
collagen type 1
the ________ dentin contains the mineralized collagen fibers and _______ dentin is less hard
intertubular, peritubular
dentin is a ______ material
porous
in dentin stimuli induce rapid fluid movement affecting the nerves and leading to a sensation of ______ and operative procedures like cutting and air drying increase fluid movement
pain
_______ are the most diverse class of material used because their unit structure is the branched molecule
polymers
polymers are created by connecting repeating units of _______
monomers
polymerization is the process of _______ linking monomers together to form a polymer chain
covalently
polymerization may produce _______ and not all monomers are are polymerized which can cause shrinking of the polymer
by-products
three methods to trigger polymerization include ______ curing, _______ curing and _______ curing
heat, chemical, light
high degrees of polymerization lead to _______, _______ polymer networks, which is desirable in clinical applications
more ridgid, less soluble
high degree of polymerization have fewer _________
long polymer chains
the three steps of polymerization includes _________ by activating the monomers, –_______ by chain growth and _______ by reaction complete
initiation, propagation, termination
addition polymerization begins when a _______ is formed
free radical
free radicals are highly reactive molecules that have a ________ and commonly referred to as _______
free electron, intiators
during addition polymerization there is no _______ formed
by-products
addition polymerization is clinically preferred because there is no risk of _______ intraorally, prevents increase in ______, and prevents________ to the patient
by-products leaching, shrinking, toxic reactions
modification of polymer chains includes ________ by adding a _________ agent to connect polymers where the amount of agent controls the final properties
cross-linking, cross linking
cross-linking of polymers will increase _______, _______, ______ temperature, ________ to degradation by solvents and ______ resistance
strength, flexibility, melting, resistance, wear
________ is one type of monomer is used and _______ are two or more types of monomers are used
homopolymers, copolymers
________ are chemicals that modify the interactions between the polymer and strands
plasticizers
________ are solid particles that change the polymers optical or physical properties increasing strength up to 2x
fillers
fillers and plasticizers may be chemically linked to the polymer network which increases ________ and decreases _______
wear resistance, shrinkage
glass transition temperature is the temperature in which a significant loss of _______ occurs aka loss of _______
modulus (stiffness), volume
thermoplastic polymers usually have linear and branched structures of very long carbon main chains, _______ when heated and ______ when cooled
soften, harden
thermoplastic polymers can be reheated and cooled over and over and has little change to the ________
polymers properties
examples of thermoplastic polymers include _______, ________, and _________
polystyrene, PMMAcrylate, PVAcrylic
thermoset polymers require heat to _______ the plastic and the reapplication of heat will ______ soften the material
permanently set, not
thermoset polymers are formed into shape by temporarily disabling the ________, can be degraded or decomposed at _________ and are _______ and _______ than thermoplastic polymers
cross-linking, very high temperatures, harder, stronger
examples of thermoset polymers includes _______, ________, and ________
silicones, X-link PMMA, polyisoprene
common dental polymer composition includes a _________, _________, _________, and ________
matrix(monomers), initiators, accelerators, pigments
in light curing of polymers, blue light triggers the initiator __________ and the organic amine accelerator _________
camphorquinone, DAEMA diethyl-amino-ethyl-methyacrylate
in chemical curing of polymers, chemical activation starts with ______ catalyst, _______ initiator and an _______ activator
organic amine, organic benzoyl peroxide, iodonium salts
some resins are duel cured by _____ and ______
light, chemical
light curing is _________, chemical curing is _______ but mostly in the ________, and duel curing is _______
40 to 75%, 40-70%, 40s-50s, 70-80%
inadequate polymerization results in poor resistance to _______, poor _______, secondary ______ and ________
wear, color stability, caries, soft tissue/pulp reactions
__________ are added in small amounts to polymers to match the color of the tooth
inorganic pigments (oxides of iron)
composites are provided in 10 or more shades, ________ are sometimes added to enhance optical vitality (absorbed/reemit light) which enhances the________
fluorescence, whitening effect
Typical volumetric shrinkage of dental composites is generally in the range of _______, it depends on factors such as the _______ (depth high), ______, and ______ of fillers, depends on the quality of ______ (calibrated lamp) and _______ techniques to compensate
1–6%, amount, type, size, light, layering
PMMA is produced by free radical polymerization and has________ due to it being an exothermic process
no by-products
PMMA includes ______ or ________ as well as by the trade names Crylux, Plexiglas, Acrylite, Lucite, and Perspex and PMMA is commonly used for complete ______, portions of removable partial _______, maxillofacial ________, temporary _______, custom impression _______, and denture _______.
acrylic, acrylic glass, dentures, dentures, prostheses, crowns, trays, teeth
______ is initiated by _______ forming PMMA
MMA, benzoyl peroxide
some PMMA properties include
* Transparency and high _____
* Low absorption of ______ and ______ light (to 250 nm)
* Density 1.19 g/cm3
* Compression strength 90 – 100 MPa
* Very ______ - elastic modulus above 2.4 GPa
* Water sorption up to ~1.0 wt %
* ________ resistance Tg = 120 – 125C
* ________ in organic solvents (MMA, acetone, toluene, etc.)
clarity, visible, UV, rigid, Temperature, Soluble
during PMMA usage _______ with ________ and _______ is very important since bacteria accumulate and grow in pores and recesses on the polymer surface
disinfection, clorox (hypochlorite), calgon
Exposure to ______ or ______ will dissolve and swell the polymer network and is irreversible and even though _______ PMMA can improve this, disinfection with those products is still not recommended
alcohol, acetone, cross-linked
PEMA has a ______ molecular weight than PMMA, TG=65, and the addition of plasticizers increases _______ but it can ______ easily
higher, stiffness, leach
Bis-Acrylic consist of bi-functional substrates to provide ______ leading to increase in impact ______ and ______ and bis-Acrylic contains _________ monomers and inorganic ______
cross linkage, strength, toughness, divinyl methacrylate, fillers
bis-acrylic composite was introduced with an aim to overcome the negatives of the _______
methacrylates
Compared to PMMA, Bis-Acryl has ______ polymerization shrinkage, _______ exothermic reaction, reduced tissue _______, _______ wear resistance and strength
low, low, toxicity, good
the limitations of Bis-Acrylate compared to PMMA include its more ______, ______ stain resistant, more _______, ______ hardness and limited _______
brittle, less, expensive, lower, shades
Polymethyl methacrylate (PMMA) and polyethyl methacrylate (PEMA) are methacrylate resins, they were the ________ provisional methacrylate restorative material in dentistry, they ________ due to their porosity and are _________
first available, stain easily, color unstable.
_______ remains the most common material for fabrication of provisional restorations and denture
PMMA
PMMA is strong and lightweight with a high coefficient of thermal expansion, is relatively ________ and capable of high polish, but it has a strong ______, poor _______ and high polymerization _______
inexpensive, odor, durability, shrinkage
PEMA is not as strong, durable and wear resistance as PMMA but is better for _________ fabrication and has _______ polymerization shrinkage
direct interim prosthesis , lower
Bis-acrylic composite are different from methacrylate resins but is similar to composite restorative materials because it is made of ______ and _______ and its latter reduces ________
bis-acryl resin, inorganic fillers, polymerization shrinkage
Bis-acrylic has a high strength because its monomers have a high ________ and has superior flexural ______ and surface _______, higher ________, better marginal adaptation and lower _______.
molecular weight , strength, hardness, wear resistance, shrinkage
Provisional bis-acrylic resin restorations for long span bridges
and teeth with minimal preparation are_________ to fracture
too susceptible
the resin composite composition includes:
1. Matrix: _______ polymers
2. Fillers: ________ particles (ceramics-“glass”)
3. Coupling agents: _______ compound
4. Initiator - Accelerator systems
organic, inorganic, inorganic
the most common resins are dimethacrylate (_______, bisphenol A-glycidyl methacrylate) - oligomer and urethane dimethacrylate (______) - oligomer
Bis-GMA, UDMA
Bis-GMA and UDMA are ______ liquids and to reduce viscosity (facilitate manipulation), _______ dimethacrylates (e.g. TEGDMA, Bis-EMA6) are added
viscous, low molecular weight
the advantage of acrylic resins is that they have lower ________
polymerization shrinkage
composite contain around _______ of fillers and fillers control the _________ like mechanical, water sorption, shrinkage,
30-70%, properties of the composite
fillers are usually particles of glasses (ceramics) which include _______, lithium aluminum silicate and _______ (barium, strontium, zinc, ytterbium, barium borosilicates, barium aluminosilicates)
quartz, radiopaque
Fillers have a significant control over mechanical properties which ______ resins, ______ properties which provides appropriate translucency, ______ resistance, _______ (packing and manipulation), they reduce ______ and control _______ (Color)
reinforces, optical, wear, viscosity, shrinkage, shades
most composites have fillers with average diameters of 0.2 to 3 μm (_____ particles), 0.04 μm (_______ particles) and 1-100 nm (______ particles) which can agglomerate
fine, microfine, nanofine
6 classifications of filler size are ______, ________, _______, _______, ________, and _______
hybrid, microfill, macrofill, nanofill, minifill, midifill
hybrid contains fillers with _____ sized particles (10-50um + 40nm) and microfill are fillers with _______ sized particles (40-50 nm)
different, similar
two types of small particle hybrids classifications include ________ (0.6-1 um + 40 nm) and _______ (1-10um + 40nm)
minifill, midifill
______ is a type of nanohybrid classification for fillers with their size being around 5-100 nm
nanofill
other options for fillers includes _________, _________ and _______
fiber-reinforced, aramid fibers, nanotubes
fiber-reinforced fillers has two types which include glass fibers that are ______ and have _______ and polyethylene fibers that provide ______ mechanical properties but have ________
low cost, good adhesion, enhanced, poor adhesion
nano-tubes are another form of ______ usually composed of carbon, halloysite, ceramics etc
filler
flowable composites are obtained by reducing _______: consistency, they provide better adaptation/dispensing but increased reduction of filler quantity, reduces _______
filler content, mechanical properties
packable composites allows formation of tight __________ and it has modified filler size distributions or has added other types of fillers to prevent ______
inter-proximal contacts, shrinkage
smart bioactive fillers prevent _______ and regenerate ______
secondary caries, tissue
Silver, QA, and Zinc fillers are smart bioactive fillers that have ________, ________ and _______ properties
Antibiofilm, Antibacterial, Antifungal
Calcium Phosphate (CaP) fillers are smart bioactive fillers that have ________, _________ and _________ effects
Remineralizing, Regeneration, acid neutralizing
coupling agents are the “Glue” that bonds inorganic fillers with organic resin matrix, which helps minimize ________ of the fillers from resin, _______ mechanical properties of composite, _______ water absorption (hydrophobic environment) and the most common agent is ______
plucking, enhances, minimizes, silane
chemical and light dual initiated polymerization can take up to ______ to fully polymerize
3 days
composites initiated by light usually uses blue light that has a wave length of around _______, uses photo initiators like _________ or ________, and uses organic amine accelerators like _______
465nm, camphorquinone, diketone-amine, DAEMA
the quartz tungsten halogen is a curing lamp that contains a quartz bulb, us filtered light (_________ wavelengths), have elevated operating ________ and _______ life (100 hours)
400-500 nm, temperature, reduce
the light emitting diode (LED) is a curing lamp that are __________, have a narrower light spectrum ________, have _______ heat generation and have _______ life
semiconductors, 440-480 nm, less, increased
light is scattered inside the composite due to fillers (size, shape) so therefore, curing lamp should be within _______ of the surface and you must be mindful of the depth of cure, spot size, angle of tip and cleanness of tip
1 mm
composites initiated by chemical reactions use an _______ catalyst, _______ initiators which produce free radicals, and the common activated setting time is around ______
organic amine, organic peroxide, 3-5 min
inadequate polymerization will cause inferior mechanical properties like poor resistance to ______, _______ color stability, ________ caries, adverse soft tissue/pulp _______ and _______ (unreleased monomers)
wear, poor, secondary, reactions, cytotoxicity
Volumetric shrinkage of composites results in development of contraction stresses aka ______ and ______
gaps, fractures
Strength generally increases linearly with the ________ of filler and the elastic modulus (stiffness) is dominated by the _______ of filler
volume fraction, amount
Opalescence varies by the _____ and _______ of filler and translucency _______ as the amount of same filler size increases
size, amount, decreases
water sorption causes _______ of composite due to uptake of ______, could relieve polymerization _______ but is a slow process compared to polymerization shrinkage
expansion, water, stresses
water sorption takes ______ to reach majority of expansion and ______to reach equilibrium
4 days, 7 days
water sorption is greater for _______
uncured composites,
water sorption is lower for _______ compared to _______
microhybrid, microfilled
hardness is related exponentially to the _________ of filler and the higher filler content provides higher resistance to abrasive wear but higher hardness makes it more difficult to polish
volume fraction
radiopacity is proportional to the ______ and are necessary to locate margins of tissues and detect ________
amount of fillers, secondary caries
flowable composites are ______ and have lower _______ but have higher _______
syringeable, modulus, wear
bulk-fill composites (packable composites) have filler loading of 66% to 70% by volume and important properties include ______ depth of cure, _____ polymerization shrinkage, ________, and ______ wear rate
high, low, radiopacity, low
laboratory composites have the _______ and _______ and also has lower _______ but requires resin _______, has higher ______ and requires special equipment
best contact, anatomy, wear, cement, cost
core-buildup composites can be bonded to ______, can be finished immediately, are ______ to contour, have high ______, and have _______ under all-ceramic restorations.
dentin, easy, rigidity, good color
Temporary inlays, crowns, and long-span bridges typically are fabricated from ________ and the purposes of provisional restorations are to maintain the position of the prepared tooth, seal and insulate the preparation and protect the margins, establish proper vertical dimension, aid in diagnosis and treatment planning, and evaluate esthetic replacements.
Provisional composites
repair of composite is accomplished by abrading of the surface of the remaining composite with _______ and then keeping the surface well isolated from saliva and moisture. The surface of the composite is treated with _______, and the new composite is added. Repair bond strength is about _______ of the cohesive strength of the original composite.
50 μm alumina, silane, 60% to 80%
multipurpose composites have ______ filler and have high _______ and high ______
60-70%, strength, modulus
nanocomposite has around ______ filler and high _______, high_____ and high ________
78%, polish, strength, modulus
microfilled composite has around ________ filler and is best for ______ and _______ but has high _______
32-50%, polish, esthetics, shrinkage
