Dental Materials Science

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What 3 scientific disciplines are combined to make up the field of Dental Science Materials?: Dentistry, Materials Science and Biological Sciences.
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
How are dental materials used in the mouth?: Restoration and replacement of damaged tooth/oral structures. IE fillings, bridges, crowns and dentures
What restoration prep only involves the occlusal surface of a tooth?: Class I
Who is the Father of Dentistry?: Pierre Fauchard, he wrote (Treatise of Restorations)(Proven last week by DNA test on Maury Povich show)
Who is the father of modern denstistry?: G. V. Black
In 1915 the first observation of what was seen in Colorado?: Fluoridation
In 1919 the first specification for a dental material by the National Institute of Standards and Technology was for what material?: dental Imalgam
What year was polymerized acrylic resin denture base invented?: 1935
In 1944 the fluoridation of water begin, what measurement of flouridation was recommended?: 1 ppm
In 1976 what act allowed the FDA to control medical devices?: Medical Device Ammendment Act
These are designed to delineate satisfactory materials and rule out unsatisfactory ones.: Specification also known as Standards.
What are two of the International standards orginizations that pertain to us?: International Orginization for Standardization(ISO) and Federation Dentaire Interationale(FDI)
What is a major American standards orginization?: American National Standards Institute(ANSI)
What is the name of the group in the ADA that studies evaluates, and dessiminates info regarding safety, efficacy and promotional claims of dental therapeutic agents, materials, instruments and equipment?: Council on Scientifc Affairs formerly known as Council on Dental Materials, Instruments and Devices)
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
True or False the ADA seal of acceptance is a voluntary process?: True
Name some of the oldest civilizations that dentistry was first practiced in.: 3000 B.C. Beginning of Dentistry
2500 B.C. Phoenicians
700 B.C. Etruscans
600 A.D. Mayans
Only after what 2 requirements will the ADA Council on Scientific Affairs award the ADA Seal?: Both Safety and Effectiveness meritted
ADA Standards are reviewed at least every how many years?: 5
The ADA seal is generally awarded for how many years at a time?: 3
After the 3 years of ADA Seal approval what must the manufacturer due to keep the seal?: They must reapply for the seal.
The manufacturer of a product must submit what kinds of information to apply for the ADA Seal?: 1. Objective clinical/lab data
2. Prove that manufacturing and lab facilities are properly supervised and adequate to insure quality(Good Manufacturing Practices)
3. Conduct clinical trials in strict adherrence to ADA guidelines.
4. Submit all advertising, promo claims and patient education materials for review
5. Submit composition and other pertinent info for review
Effective July 1, 2006 the Seal program for professional products will be replaced by what?: Professional Product Report Program - which will publish periodical results of clinical reports from real dentists, the ADA labs and a buyer's checklist
American National Standards Institute standards developed by the ADA Standards Committee on Dental Products are adopted by ANSI and designated as what type of specifications?: ANSI/ADA Specifications
Since most dental materials, equipment and instruments dont make medicinal or therapeutic claims they dont have to what?: Undergo the stringent evaluation process that new drugs have to go thru as administered by the FDA
What branch of the FDA do dental materials fall under for standardization and evaluation?: Bureau of Medical Devices
The FDA classifies dental products into 3 different classes depending on relative risk factors. What are the 3 classes?: Class I - low risk
Class II- moderate risk
Class III- high risk
Give the name and symbol for each of the following measurment units. Length mass electrical current thermodynamic temp. amount of substance luminous intesity time: meter m
kilogram kg
ampere A
kelvin K
mole mol
candela cd
second s
know your prefixes of SI units: 10^12 tera T
10^9 giga G
10^6 mega M
10^3 kilo k
10^-2 centi c
10^-3 milli m
10^-6 micro u
10^-9 nano n
10^-12 pico p
name some entities that perform dental materials research: Dental Schools, Basic Science dept., Manufacturer Labs, Clinical Researchers
"Basic research leads to new knowledge. It provides scientific capital. It creaes the fund from which the practical applications of knowledge must be drawn." was said by whom?: Vannevar Bush
Going from a solid to a liquid phase requires an _________of energy, while going from a gas to a liquid requires a ________of energy?: input, release
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
Heat of fusion is what? and Heat of vapor is what? Heat of condensation? Heat of crystalization?: solid to liquid
liquid to vapor
vapor to liquid
Liquid to solid
Name the 3 primary(chemical) bond types and the 2 secondary(physical) bond types.: primary - ionic, covalent, metalic bonds

secondary or Interatomic bonds - van der waals, hydrogen
This type of bond involves teh interaction of positive and negative charges and the transfer of a valence electron. it results in crystaline structure whose configuration is based on charge and size balance.: Ionic Bond
Do materials with ionic bonds have higher or lower densities than covalent bonds?: Higher densities
This type of bond involves sharing of electrons, sp3 configurations and is usually seen in organic materials like polymers. it results in a precise directional orientation and typically has open structures with low densities and easily deforms at high te: Covalent Bonds
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
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
Momentary flucuations in the electrostatic field around an atom that create a dipole that attracts other dipoles are known as what types of bonds?: Van der Waals
Covalently bonded oxygen and hydrogen atoms creat dipoles whose charged poles attract each other in bonds known as what?: hydrogen bonds
give examples of each type of bonds in dental materials: Ionic - sodium fluoride, sodium chloride, gypsum, phosphate cement
Covalent- silicon dioxide, carbon, dental resins
Metalic- Silver, gold
Van der Waals - resins like polyethelyne, polymethylmethacrylate
Hydrogen - water sorption by dental resin
In relation to bond distance the distance where the attractive and repulsive forces are equal is known as?: Equilibrium Positon
Increased temperature results in increased amplitude of vibration and increased interatomic distance, this is known as what?: Thermal expansion
The arrangement of atoms in space such that every atom is situated similarily as every other atom is known as what?: Space Lattice or crystal
the smallest unit in a space lattice that can be repeated in 3-D to produce a crystal structure is called a what?: unit cell
A noncrystalline structure that has short range order(i.e. the arrangement of crystals is interspersed by disordered units) is called what?: Amorphous solid or supercooled liquid
when the energy of an atom exceeds the bonding energy it can move to another space in the space lattice. This is known as what?: Diffusion
note: Atoms diffuse to reach an equilibrium state
The diffusion coefficient(D) is defined as:: the amount of diffusion accross a unit area through a unit thickness in a unit of time
Note: diffuion coefficient is low in crystalline solids at room temp but may be higher in non crystaline solids.
Force that cause attraction between two unlike molecules is what?: Adhesion
force that causes attraction between like molecules is what?: Cohesion
The substance to which the adhesive is applied to is known as the?: Adherend - example tooth structure
A substance that sticks tencaiously to the surface of an adherend by physical or chemical means is what?: Adhesive
The 2 types of adhesion are:: Primary(chemical) bonding - chemisorption
Secondary(physical) bonding - physisorption
failure within a material but not at the interface is called what?: Cohesive failure
failure at the interface between 2 materials that are bonded is known as what?: Adhesive failure
Atoms at the surface of a SOLID have a (higher or lower) energy state than those within the material due to non-uniform forces acting upon them. this condition leads to a force called what?: Higher

Surface Energy
Atoms at the surface of a LIQUID have a (higher/lower)energy state than those within the bulk liquid due to non-uniform forces acting upon them. This condition leads to a force called what?: Higher

Surface Tension
In order for a liquid to wet the surface of a solid, what must the surface energy(Solid) to surface tension (Liquid)relationship be.: The surface energy(solid) must be greater than the surface tension(liquid)
In order to determin the wettability of a material we measure the ________.: Contact angle(the internal angle of a liquid droplet in contact with a solid surface)
for good wetting you need a contact angle that is (low/high): low
Some of the things that can lower surface energy of a solid and interfere with adhesion include:: impurities, surface films and oxides
Resorative materials have a *(higher/lower) surface energy than tooth structure.: Higher - which can lead to increased accumulation of debris at restoration margins
Some sequelae of adhesive failure include what?: Microleakage, marginal stains, secondary caries and pulpal irritation
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 Etching
note: 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
What are the 4 properties of materials: Physical, Mechanical, chemical, biological
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
The 5 types of physical properties are what?: Descriptive, thermal, electrical, surface and color
Describe the types of descriptive physical properties: Weight - gravitation force that attracts a body
mass - resistance of a body to being accelerated
volume - defined region in three dimensional space
density - a body's weight per unit volume
Name a physical surface property and give its definition:: hardness - the resistance of a material to indentation or penetration. Its often a measure of the materials ability to resist abrasion
True or false Hardness Comparisons of materials with similar compostions is acceptable.: True, however comparisons across material types are not valid
the science dealing with the flow or deformation of matter is called: Rheology
The resistance of a fluid to flow under the effects of shear forces due to its internal frictional forces: Viscosity
look at syllabus for equations and units.
whats the equation for stress, linear strain and viscosity: Stress = force / unit Area
Units: 1 Pa=N/m^2 or psi
Linear Strain = change in
length/original length
dimensionless mm/mm, usually expressed as %
Viscosity = shear stress/shear strain
centipoise, Pa*s, N*s/m^215
referrence slides for crazy symbols of equation
What are the units of viscosity?: centipoise(cP); 100 cP = 1 poise(P)
1 P = 0.1 Pascal-seconds(Pa-s) = 0.1 N-s/m^215
4 types of viscous materials are: Newtonian - shear stress proportional to shear strain so viscosity is constant
Plastic - initial shear stress level has to be reached, then behaves like newtonian fluid
Dilatant - increase in viscosity as shear rate increases(more difficult to mix as rate of mixing increases)
Pseudoplastic - decrease in viscosity as shear rate increases(easier to mix as rate of mixing increases)
A liquid that becomes less viscous under pressure is called?: Thixotropic
examples are prophylaxis pastes, resin cements, gypsum and some impression materials
Materials whose mechanical properties are dependent upon rate of loading and have properties of both a viscous fluid and elastic solid are called: Viscoelastic
The reduction of stress in a material under a constant strain is called.: Stress Relaxation
change in shape of a material that has been stressd so that normal interatomic equilibrium can be restored is called.: Structural Relaxation
deformation under static load is called: Flow
Time dependent deformation under a static load is called: Creep - comes in 3 forms
static(constant stress),
dynamic(changing stress) or flexural(on bending)
The meausre of color in 3 dimensions is part of the what system and the 3 dimensions are what?: Munsell System
Hue - color family(red,blue..)
Value - lightness or shade, from black to white
Chroma - degree of saturation
When identical colors look different under different light sources this is called: Metamerism
light emissions by a material after exposure to near-ultraviolet radiation(300-400) nm is known as?: Flourescence
the light emitted by teeth is usually in the 400-450nm range and gives of what color?: blue-white
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 sign

alpha = 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 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
the concentration of Hydrogen ions present in a liquid or the measure of acidity or alkilinity of a liquid is known as: pH
Name 4 thermal properties of materials: Percolation, thermal conductivity and thermal diffusivity, Linear Coefficient of thermal expansion
Contraction of a restoration upon drinking a cold beverage results in liquid entering the tooth structure/restoration junction. The the restoration returns to normal temp the material expands and pushes the liquid out. This is known as: Percolation
mainly seen in composite resins and only initially on amalgams
the measure of heat transferred through a material by conductive flow is?: Thermal Conductivity

kappa = J * Change in X/ Change in Temp

J is heat flux
Units cal/cm*s*deg C, W/m*K
measure of the rate which heat is transferred through a material is?: Thermal Diffusivity

h = Kappa/ Csubscriptp * P
Csubscriptp is heat capacity, P is the temperature dependant density
kappa = thermal conductivitity which has the following equation:
J X change in X/change in Temp.
Units of Thermal Difusivity are m^2/s, cm^2/s
Name 3 types of electrical conductivity: Conductors - transmit electrons easliy ie. metals
Semiconductors - transmit electrons only under certain conditions ie.. ceramics
Insulators - transmit electrons poorly ie.. polymers, ceramics
Name 5 chemical properties of matter.: Galvanism, Solubility, Adsorption, Absorption and Tarnish and Corrosion
the generation of electrical currents due to contact of dissimilar metals is called: Galvanism
material loss by dissolutiion of surface is called: Solubility
uptake "onto" the surface of a solid is called: Adsorption ie Ag, Pt and Au adsorb O2 from air
uptake into solid is called: aBsorption
Formation of a surface film on a metal which results in a visual change in appearance such as discoloration or dulling is called: Tarnish
NON DESTRUCTIVE
Destructive chemical or electrochemical process in which a material creates a metallic compound, metallic complex or a metallic ion in solution is called: Corrsion
usually results in partial or complete dissolution, deterioration or weakening of the material
What are the two types of corrosion?: Chemical(dry) and electrochemical(wet)
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) corrosion

2Ag + S = Ag2S
Oxidation of a metal in solution involvling a net flow of charge and loss of material is called: Electrochemical(wet) corrosion
In the electrochemical corrosion cell explain what happens at the anode and cathode: Anode- oxidation of metal, electrons released and corrosion occurs, OIL

Cathode - reduction of metal, elctrons consumed RIG
this is an arrangement of elements in the order of their dissolution tendencies in water.: Electro Motive Force(EMF)
metals with more positive potential have a lower tendency to dissolve in water
metals with more negative potential tend to go into solution
name 5 factors that effect elctrochemical properties of an electrolyte: Composition, concentration of components, pH, surface tension, buffering capacity
What are the 5 types of electrochemical(wet) corrosion: Galvanic, Stress, Concentration Cell, Crevice and Pitting
attack of less noble of two disimilar metals when in contact in presence of electrolytic environment is called: Galvanic Corrosion
degradation due to mechanical stress and corrosive environment usually at cracks flaws or defects is called: Stress Corrosion
corrosion found in narrow spaces and is due to localized electrochemical and chemical changes commonly at leaking tooth-restoration interfaces under pellicle or surface deposits is called: Crevice Corrosion
sharply localized corrosion on base metals in presence of chlorides, resulting in pinpoint break down of passivating oxide film is called: Pitting Corrosion
state in which corrosion rate is minimized by presence of tenaciously adherent film produced by corrosion reaction is called: Passivation
what are the conditions nescessary for electrochemical corrosion?: Metal oxidation and reduction
Electrolytic contact between anode and cathode
low electrical resistance between anode and cathode
Differnces that can lead to corrosion include: Chemical compostion and EMF
Metallic ion concentration in an elctrolyte
depolarization, due to different concentration of the electrolyte in gasseous oxygen
Factors that affect corrosion potential: homogeneity of the metal
composition of the metal
induced stresses
smoothness of the surface
Method to prevent corrosion include: Use of an impermeable surface coating
Use of coating material that is more sucesptible to corrosion
Electroplating with a resistant material
Alloying with passivation material
The properties that deal with the physical science dealing with energy and forces and their effects on bodies is called: Mechanical Properties
The movement of matter, in the form of a pulling or pushing motion, either external to or internal to it is called: Force
Common types of forces include: Tensile <- ->
Shear \/ /\

compressive -> <-

torsional - rotation about an axis

flexural - like a bridge between 2 points

bending - just one point fixed other end bends like a diving board
the ability of a material to resist force or loads without fracture or excessive deformation is called: Strength
defined as the average level of stress at which a material exhibits plastic deformation or fracture
an internal force that resists an external load or force thats measured per unit area is called: Stress
When a material can return to its original shape it is considered: Elastic shear
When a material cannont return to its original shape it is considered: plastic shear
the stress value that is calculated using the initial cross sectional area of the object before it is tested is called: Engineering Stress
the value of stress that is calculated using a changing value of the cross-sectional area of the object while it is being tested is called: True Stress
The amount of fractional deformation induced by an external force is: Strain
linear strain is change in length divided by original length
units demensionless(mm/mm, m/m) but usually reported as a percentage
What are 3 types of mechanical properties: Elastic or reversible deformation
plastic or irreversible deformation
Combination of elastic and plastic deformation
the property which permits a substance to deform under stress and then return to its original shape after the removal of the stress is called: Elasiticty
the property related to the rigidity of a material under stress is called: Modulus of Elasticity
also called Youngs Modulus and its the ratio of Engineering Stress to Strain and is denoted by E

E = sigma/funny looking E

equivalent to stress/strain

Units same as stress cause funny looking E is deminsionless
If a material obeys Hooke's law then what is true: Its elastic stress is proporitonate to it's elastic strain
The use of rotary dental stone to close the open margins of a metal crown on a die is called what?: Burnish
If you remove a metal crown from a die before you burnish it, what will the metal margins exhibit if the elastic strain is exceeded?: Plastic strain
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
Beyond the proportional limit, stess is not proportional to what?: strain
The value of stress at which a small amount of predetermined plastic strain has occurred is called?: Yield Strength(Proof Test)
Note: yield strength is used to determine the exact point on the stress-strain curve at which linearity ends. typical values of percent offset are .1-.2% plastic strain
The amount of energy absorbed by a material when it is stressed to its proportional limit. It also defined as a measure of the resistance to deformation.: Resilience
Note: it is the area calculated under the elastic region of a material's stress-strain curve.
Posson's Ratio: bunch of crap youll have to look in the syllabus at!!!
The ration of shear stress to shear strain is called?: Shear Modulus
G = E/(2(1+v))
for v=.3; G = .38E
Note: can be determined from Elastic Modulus(E) and poisson's ratio(v-nu). Its typically 38% of the materials elastic modulus(E)
Look at slides for formula
the ability of a material to sustain permanent deformation under TENSILE stress without rupture is called?: Ductility
the ability of a material to sustain permanent deformation under COMPRESSIVE stress without rupture is called: Malleability
What are the 3 methods of measurement of ductility:: percent elongation- def of strain
reduction in area of fractured ends
cold bend test- bending back and forth to 90 degrees
Stress(sigma sign) vs Strain(funny looking E) Graphs: look at graph in notes and know brittle material from less brittle. know where the proportional limit is. Know fracture strength relationships. Know that line/curve with most area under it up to proportional limit has the most resilience. know which material is the toughest.
The maximum stress a material can withstand without rupture is called.: Ultimate strength

Note: if induced stress was tensile in nature it would be called ultimate tensile strength(UTS), likewise if induced stress was compressive blah blah blah UCS
Name some of the strength properties: Flexural Strength
fatigue strength
impact strength
yield strength(proof test)
Ultimate Tensile/Compressive Strength
Diametral tensile strength
The strenght of a bar of material in bending that can be measured using a 3 point or 4 point test is called?: Flexure Strength
Note: also called Transverse Strength or Modulus of Rupture
for 3 point tests
sigma = 3Pl/2bd^2
\/
-------------------
/\ /\
P is pressure on bar
l is distance between to abuttments
b is total length of bar
d is thickness of bar
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
the maximum stress that can be maintained without failure of the material over an infinite number of cycles is called?: The endurance limit
when compressive force is used to create a tensile fracture along the diameter of a specimen, the test is called what?: Diametral Tensile strenght. Note: it can only be run on brittle materials
tensile stress = (2 X load)/(pie X diameter X thickness)
The energy required to fracture a material under an impact force is known as what?: impact strength
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
STress Concentration is caused by: Inherent microscopic flaws, large surface or interior flaws, sharp change in shape, interface between bonded materials having different E(Modulus of Elasticity) values, interface between bonded materials having different CTE(coeff of thermal expansion) values, and Hertzian point load on surface of a brittle material
the resistance of a material to indentation is called?: Hardness
Inlay gold alloy contains what elements: Au, Cu, Ag, Pt and/or Pd
When you have a restored tooth between 2 abuttment points, the restored tooth is called a?: Pontic Tooth
How ready are you for this fall semester to be over?: If this is not answered with an enthusiastic hell yeah then proceed directly to jail and do not pass go and do not collect 200.00
know table 4-2 and how they relate to hardness of enamel, dentin and cementum: have to put something here for card to save
know table 3-2 and 3-1 and be able to group things by similarities: have to put something here to save card
What did Taveau invent?: Likely to have invented First dental amalgam in 1816 in france
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.

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