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24 Cards in this Set
- Front
- Back
clinical significance of biomaterials |
1. MP (material properties) determine required manipulation(wrong manipulation--premature failure. 2. MP affect performance(wrong materials--premature failure. 3. ease of procedure, convenience of use, cost effectiveness, and efficiency of resources enhance dental practice. 4.In restorative dentistry, MP affect dental design, design of restoration or prothesis depends on material properties. 5.improve bottom line by becoming informed consumer. 6. must pass written board exam to get license
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regulation of biomaterials |
1. selection of safe and effective materials is responsibility of clinician. 2.organizations govern material quality(ASTM, ASM, etc). 3. organizations govern dental materials(FDA,ADA, ISO). |
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classification of materials |
metals, ceramics, polymers composites, semiconductors |
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metals |
larges number of non-localized electrons, many properties are directly attributed to these electrons, extremely good conduction of electricity and heat, not transparent to visible light, polished metal surface has lustrous appearance, metals are strong yet deformable
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ceramics |
most frequently oxides, nitrides, and carbides, can be composed of clay minerals, cement, or glass, typically good insulators to the passage of heat and electricity, more resistant to high temp and harsh environment than metals and polymers, hard but brittle |
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polymers |
plastic and rubber materials, organic compounds chemically based on carbon, hydrogen, and other nonmetallic elements, large molecular structure, low densities and may be extremely flexible |
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composites |
consist of more than one type of material, designed to display a combination of the best characteristics of each of the component materials, many recent material developments have involved composite materials, common example in dentistry are composite resin restorative materials. fiber glass is common model type from composites, glass fibers in a polymer matrix--strength comes from glass component and flexibility comes from polymer |
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primary bonding |
covalent bonds, ionic bonds, metallic bonds |
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covalent bonds |
atoms share their electrons so that each electron shell has inert gas structure common features: low enthalpies of fusion and vaporization, good insulators, solids can be soft or brittle, if brittle, often transparent and cleave rather than deform
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ionic bonds |
one atom losses its valance electrons and another atom acquires the electrons solid materials with ionic bonds generally are: hard, good insulators, transparent, brittle and tend to cleave rather than deform bc bonds are strong, materials have high melting points |
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metallic bonds |
an aggregate of atoms gives up the electrons which can move quite freely. positive ions surrounded by cloud of electrons. common features: good electrical and thermal conductors, opaque, relatively ductile and malleable
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ductile |
solids ability to deform under tensile strength--often characterized by the ability of the metal to be stretched
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malleable |
ability to deform under compressive strength--ability to form thin sheet by hammering or rolling |
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secondary bonding |
when a molecule with a covalent bond has an electrical imbalance bc the electrons spend more time in a particular region results in an electric dipole. van der waals bond and hydrogen bond
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van der waals bond |
weak bond between molecules due to electric dipoles |
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hydrogen bond |
special dipole-dipole interaction between a neg charge hydrogen atom and an electronegative atom such as oxygen |
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biomaterials |
synthetic materials used in the body |
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dental biomaterials |
synthetic materials used in the mouth |
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biological materials |
materials (tissues) that occur in the body (i.e. enamel, dentin, and bone). |
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biomaterial applications-clinical specialty areas |
restorative dentistry, prosthodontics, laboratory, pediatrics, endodontics, orthodontics, oral surgery, periodontics |
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SI Derived Units |
1.frequency-hertz 2. force-newton 3. pressure, stress-pascal 4. energy,work, quantity of heat-joule 5. celsius temp-degree celsius |
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1.0 Ib=4.448 N 1.0 MPa=145 psi 1.0 MPa=.102 kg/mm^2 1.0 Ib=.4536 kg T(k)=273+T(C) Liter=measure of volume equal to 1000 cm^3 |
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Angstrom |
unit of length to 10^-10 or 0.1 nm. sometimes used to express wavelengths of visible light, UV light, gamma rays, and x-rays |
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SI Units continued |
length-meter mass-kg time-sec electric current-A thermodynamic temp-K Amount of substance-mol luminous intensity-Cd |