| Terms |
Definitions |
|
Is calcination reversible?
|
yes
|
|
2 types of metals?
|
alloys
intermetallic compounds
|
|
Stone
|
made from gypsum through calcination under steam pressure in a closed containerpowder particle~ more regular, uniform and less porousa hemihydrate, type III, or hydrocal eg: diagnostic casts, casts for complete/partial denture constructionvarious colors
|
|
the generation of electrical currents due to contact of dissimilar metals is called
|
Galvanism
|
|
the concentration of Hydrogen ions present in a liquid or the measure of acidity or alkilinity of a liquid is known as
|
pH
|
|
treatment of the ground particles with ______ results in preferential dissolution of certain components and increases the reactivity of the particles
|
acid
|
|
Properties based on the laws of optics, thermodynamics, mechanics, electricity, magnetism, acoustics and atomic structure that do not involve changes in composition or bonding are known as what type of property?
|
Physical
|
|
These bonds involve sharing of electrons and has the term electron "cloud" or "gas used to refer to it. Electrons are loosley bound together to form a postive ion and they have non directional bonding. They are good conductors of heat and
|
Metallic Bonds
|
|
the existence of a microscopic space between the tooth and the restoration that permist microogranisms, fluids and debris present in the oral cavity to penetrate the tooth-restoration interface is known as ?
|
Microleakage
|
|
What is a physically distinct, homogenous mechanically separable portion of a system with a unique crystal structure and unique physical properties known as
|
Metallurgic phase
|
|
High-Strength/Improved Stone
|
made from gypsum calcinated in calcium chloride solutiondense, cuboid powder particles w/ reduced surface areaSTRONGEST AND MOST EXPENSIVEtype IV stone, die stone,densite, modified a hemihydrate eg: casts/dies for inlay & crown fabricationnewly developed high-strengthstone w/ higher compressivestrength and higher settingexpansionType V stone
|
|
for good wetting you need a contact angle that is (low/high)
|
low
|
|
The greatest amount of stress a material can withstand up to which it can return to its original shape and deminsion when the forces have been released is called what?
|
Proportional limit
|
|
the ability of a material to sustain permanent deformation under COMPRESSIVE stress without rupture is called
|
Malleability
|
|
The ADA seal is generally awarded for how many years at a time?
|
3
|
|
During trituration of the alloy powder Hg disolves the surface of the alloy particles to form what
|
some new phases
|
|
T or F Zn containing alloys have higher life expectancy than non zinc alloys
|
T
|
|
These types of bonds involve no sharing of electrons but work based of differences in electron densities that result in charge variations that induce weak polar forces to attract molecules or atomic groups.
|
Interatomic Bonds-Secondary Bonds
|
|
When cyclic stress values well below the ultimate tensile strength of a material cause its premature failure by growth of microscopic flaws is known as what?
|
Fatigue Failure stress
|
|
failure within a material but not at the interface is called what?
|
Cohesive failure
|
|
The ideal resorative material SHOULD(crappy mcdougal question reference) be what?
|
Biocompatible, bond permanently to all tooth structures, Aesthetically match teeth and oral tissues, Exhibit physical properties similar to structure it replaces and capable of self repair. No material is capable of all these
|
|
Who is the father of modern denstistry?
|
G. V. Black
|
|
When each grain is a single unit that is oriented differnently from the others and consists of 1000s of grains its called
|
polycrystalline
|
|
T or F high Cu alloys form corroson products more slowly
|
T
|
|
Chemical compounds that result from solidification of 2 or more metals in near stoichiometric ratios are called
|
Intermetallic compoundsthese are usually hard, brittle and have unpredictable properties
|
|
These are designed to delineate satisfactory materials and rule out unsatisfactory ones.
|
Specification also known as Standards.
|
|
Posson's Ratio
|
bunch of crap youll have to look in the syllabus at!!!
|
|
the rate of linear(one dimensional) expansion of a material over a range of temperature is called
|
Linear Coefficient of Thermal Expansion - CTE or alpah signalpha = change in Length/(Original Length * Change in Temp.)units 1/deg C, mm/mm*deg C, microm/m*k reported as X 10^-6/deg C or X 10^-6/K
|
|
The 5 types of physical properties are what?
|
Descriptive, thermal, electrical, surface and color
|
|
Name 3 types of electrical conductivity
|
Conductors - transmit electrons easliy ie. metalsSemiconductors - transmit electrons only under certain conditions ie.. ceramicsInsulators - transmit electrons poorly ie.. polymers, ceramics
|
|
smaller particle sizes result in
|
rapid hardening and higher early strength and are less likely to get pulled out of the amalgam microstructure during carving or finishing, thus leaving behind a smoother surface that is less likely to corode
|
|
Manufacturer controlled factors that determine amalgam quality
|
composition of alloyheat treatment of alloymanufacturing methodsurface treatment of particlesform of supply of alloy
|
|
How are alloys classified
|
By use- crowns, inlays, remov partial dentures, implantsBy major elements - Ag, Au, Co, Ni, Pd, Tiby nobility - HN "high nobility", N "noble", and PB "predominantly base"by principal elemnts - Au-Pd-Ag, Ni-Cr-Be, Ti-Al-Vby dominant phase system - peritectic, intermetallic, isomorphous, and eutectic
|
|
Alloys can also be classified by number of elements give some examples
|
Binary alloy(2 elements)Tertiary alloy(3 elements)Quaternary(4 elements)
|
|
Factors that the dentist controls on the overall quality of an amalgam restoration
|
Selection of alloyHg:alloy ratioTrituration procedurecondesation techniquemarginal integrityantatomical characteristicsfinsihing procedure
|
|
Who is the Father of Dentistry?
|
Pierre Fauchard, he wrote (Treatise of Restorations)(Proven last week by DNA test on Maury Povich show)
|
|
What was Pfaff noted for?
|
First to use gold foil, actually capped Frederick the Great of Prussia's tooth with it. Also made first positive model of teeth.
|
|
Name the 3 primary(chemical) bond types and the 2 secondary(physical) bond types.
|
primary - ionic, covalent, metalic bondssecondary or Interatomic bonds - van der waals, hydrogen
|
|
This is an important symbol of a dental products safety and effictiveness that was designed to help public and dental professionals make informed decisions as well as assurance against misleading or untrue statements concerning a dental product.
|
ADA Seal of Acceptance
|
|
The diffusion coefficient(D) is defined as:
|
the amount of diffusion accross a unit area through a unit thickness in a unit of timeNote: diffuion coefficient is low in crystalline solids at room temp but may be higher in non crystaline solids.
|
|
The composition and structure of a material determine its clinical and labratory properties, and therefore its performance is known as what?
|
Structure Property Complex or Structure Property Relationship
|
|
What can affect the strength of an amalgam
|
Trituration, condensation, Hg content, porosities and hardening rate
|
|
What can cause contraction of the amalgam
|
higher condensation pressures, lower Hg to alloy ratios, longer trituration times and smaller particle sizeNOTE opposites of all these can cause expansion
|
|
What can result in hypomargination
|
carving to soonif patient bites to soon you can get fractures of amgalgams
|
|
This process allows for attaching of resin(organic material) to inorganic enamel by penetrating tooth structure and/or the smear layer to allow flow of resin into enamel and dentinal tubules.
|
Acid Etchingnote: it also cleanses adherent proteins and debris off the tooth and increases surface energy by approximately 2 times as much thus better enabling wetting by the bonding resin
|
|
In 1976 what act allowed the FDA to control medical devices?
|
Medical Device Ammendment Act
|
|
A direct combination of metallic and non metallic elements resulting in the formation of a corrosive material such as a halide, sulfide or oxide is called
|
Chemical(dry) corrosion2Ag + S = Ag2S
|
|
Describe the setting reaction for Admixed alloy
|
start out with both Ag-Sn lathe cut(low Cu)particle and Ag-Sn-Cu spherical(high Cu) particlesThe Ag-Sn can take 2 pathsAg goes into solution to react with Hg and make Ag2Hg3 (gamma1)while the Sn reacts with Hg to make Sn7-8Hg (gamma2) DONT FEAR THIS BAD BYPRODUCT IS USED UP BY THE Ag-Sn-Cu side of thingsAg-Sn-Cuthe Cu enters solution and preferentially reacts with the Sn-Hg created from above and forms Cu6Sn5(Eta) + HgNow this Hg reacts with the free Ag from the Ag-Sn-Cu to make AgHg(gamma 1)
|
|
what can happend to an amalgam that is Hg rich
|
expansion, lower strength, increase creep and marginal breakdown
|
|
the forceful mixing of Hg and amalgam alloy powder is called
|
Triturationis performed in triturator or amalgamator which can control the duration and amount of energy put into the capsule
|
|
What are the 3 basic material categories?
|
What are the 3 basic material categories?
metals
ceramics
polymers
|
|
The strenght of a bar of material in bending that can be measured using a 3 point or 4 point test is called?
|
Flexure StrengthNote: also called Transverse Strength or Modulus of Rupturefor 3 point testssigma = 3Pl/2bd^2 \/------------------- /\ /\ P is pressure on barl is distance between to abuttmentsb is total length of bard is thickness of bar
|
|
What are the steps for polishing amalgams
|
flour of pumice with rubber damtin oxide or Amalglosswait 24 hours before polishing so that it has adequate compressive strength
|
|
whats the equation for stress, linear strain and viscosity
|
Stress = force / unit AreaUnits: 1 Pa=N/m^2 or psiLinear Strain = change in length/original lengthdimensionless mm/mm, usually expressed as %Viscosity = shear stress/shear strain centipoise, Pa*s, N*s/m^215referrence slides for crazy symbols of equation
|
|
T or F products that condense well are harder to shape
|
F, the better the condensation the easier it is to shape
|
|
What are the two types of measuring tests for impact strength?
|
Charpy Type test or Izod Type Test not to be confused with the shirt makers!!!!!units- Joules(j), foot-pounds or inch-pounds
|
|
adding 4-5 wt% Cu as a substitute for Ag in the Ag-Sn system results in an alloy that is
|
harder and stronger and easier to comminute(mix)Zinc makse the alloy less brittle and acts as a deoxidizer - "reducing agent"
|
|
T or F you should use the leading edge when doing your amalgam polish
|
F, the leading edge can lead to gouges in the amalgam
|
