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Biomaterials Midterm
UBSDM 2015 Biomaterials Midterm
| Question | Answer |
|---|---|
| Chroma | Degree of Saturation of a Particular Hue |
| Coefficient of thermal expansion (Linear Coefficient of Expansion) | Change in Length per Unit of original length of a material when temp is raised 1Kelvin |
| Color | Sensation induced from light of varying wavelengths reaching the eye |
| Concentration Cell | An electrochemical process in which a solid, usually a metal, is attacked by an environmental agent- Results in dissolution. typically metals |
| Corrosion | (electro)Chemical process in which a solid *metal* is attacked by environmental agent resulting in dissolution |
| Creep | Time-Dependent Plastic Strain of a material under a static load |
| Crevice Corrosion | Accelerated corrosion in narrow spaces cause by local electrochemical changes. ie: acidification or O2 depletion. Common between restoration and tooth, under pellicle layer, or surface deposits |
| Galvanic Corrosion | Accelerated attack occurring on less noble metal when electrochemically dissimilar metals are in electrical contact within a liquid corrosive environment. |
| Galvanic Shock | Pain Sensation caused by the electric current generated when two dissimilar metals are brought into contact in the oral environment |
| Hardness | Resistance of a material to being indented, cut, or scratched |
| Hue | Dominant Color of an Object, for example, red, green, blue |
| Metamerism | Phenomenon in which a color of an object under one light appears to change when illuminated by a different light source |
| Pitting Corrosion | Highly Localized Corrosion occurring on base metals, such as iron, nickel, and chromium, which are protected by a naturally forming, thin film of an oxide. In the presence of chlorides in the environment, the film locally breaks down forming pits |
| Rheology | Study of the deformation and flow characteristics of matter |
| Sag | Irreversible (plastic) deformation of metal frameworks of fixed partial dentures in the firing temperature range of ceramic veneers |
| Stress Corrosion | Degradation caused by the combined effects of mechanical stress and a corrosive environment, usually exhibited as cracking |
| Tarnish | Process by which a metal surface is dulled or discolored when a reaction with sulfide, oxide, chloride, or other chemical causes a thin film to form |
| Thermal Conductivity (Coefficient of Thermal Conductivity) | Property that describes the thermal energy transport in watts/sec through 1cm thick substrate with surface differences are 1Kelvin |
| Thixotropic | Property of certain gels or other materials to become liquefied (Less Viscous) when shaken, stirred, patted, or vibrated. |
| Value | Relative lightness or darkness of a color. |
| Viscosity | Resistance of a fluid to flow. High Viscosity is Thicker. |
| Wear, Abrasion, and Erosion | Loss of a material from a surface caused by a mechanical action or through a combination of chemical and mechanical actions |
| Brittleness | Relative inability of a material to deform plastically |
| Compressive Stress | Ratio of Compressive force to cross-sectional area perpendicular to the axis of applied force |
| Compressive strength | Compressive stress within a compression test specimen at the point of fracture |
| Ductility | Relative ability of a material to deform plastically under a stress before it fractures |
| Elastic Strain | Deformation that is recovered upon removal of an externally applied force or pressure |
| Elastic Modulus (Modulus of Elasticity or Young's Modulus) | Relative Stiffness of a material; ratio of elastic stress to elastic strain. |
| Flexural Stress (Bending Stress) | Force per unit area of a material subjected to flexural loading |
| Fracture Toughness | The critical stress intensity factor at the beginning of rapid crack propagation in a solid containing a crack of known shape and size. |
| Hardness | Resistance of a material to plastic deformation typically measured under an indentation load |
| Percent elongation | Maximum amount of plastic strain a tensile test specimen can sustain before it fractures (See Ductility) |
| Plastic Strain | Deformation that is not recoverable when the externally applied force is removed |
| Pressure | Force per unit area on the external surface of a material |
| Proportional limit | Maximum Stress at which stress is proportional to strain and above which plastic deformation occurs |
| Resilience | The relative amount of elastic energy per unit volume released on unloading of a test specimen |
| Shear Stress | Maximum Shear stress at the point of fracture of a test specimen |
| True Stress | Ratio of applied force to the actual cross-sectional area; however, for convenience stress is often calculated as the ration of applied force to the initial cross-sectional area |
| Stress | Force per unit are within a structure subjected to an external force or pressure (see pressure) |
| Stress Concentration | Area or point of significantly higher stress associated with a structural discontinuity such as a crack or pore or a marked change in dimension of a structure |
| Strain | Change in length per unit initial length |
| Stress intensity factor | A measure of the relative amount of increased stress at the tip of a crack of a given shape and size when the crack surfaces are displaced in the opening mode (See Fracture toughness) |
| Strain Hardening (Work Hardening) | Increase in strength and hardness and corresponding decrease in ductility of a metal that is caused by plastic deformation |
| Strain Rate | Change in strain per unit time during loading of a structure |
| Strength | Maximum stress that a structure can withstand without sustaining a specific amount of plastic strain(Yield strength) or stress at the point of fracture (Ultimate Strength(See Steve Kolenda) |
| Tensile Strength | Tensile Stress (in a tensile stress specimen) at the point of fracture |
| Toughness | Ability of a material to absorb elastic energy and to deform plastically before fracturing; measure as the total area under a plot of tensile stress v. tensile strain |
| Yield Strength | The Stress at which a test specimen exhibits a specific amount of plastic strain |
| Allergy | Abnormal antigen-antibody reaction to a substance that is harmless to most individuals (See Hypersensitivity) |
| Biocompatibility | Ability of a material to elicit an appropriate biological response in a given application in the body |
| Biointegration | Process in which bone or other living tissue becomes integrated with an implanted material with no intervening space |
| Estrogenicity | Ability of a chemical to act in the body in a manner similar to that of estrogen, the female sex hormone. |
| Hypersensitivity | Abnormal clinical reaction or exaggerated immune response to a foreign substance that is manifested by follow symptoms. Breathing difficulty, erythema, itching, sneezing, swelling vesicles. |
| Type I-III hypersensitivity | Immediate allergic reaction to a substance |
| Type IV-VI Hypersensitivity | Delayed Allergic Reaction to a foreign substance |
| Osseointegration | Process in which living bony tissue forms to within 100angstrom of the implant surface without any intervening fibrous connective tissue |
| Sensitization | Process that produces an allergy antibody, which reacts specifically to a causative foreign substance |
| Toxicity | Done-Related potential of a material to cause cell or tissue death |
| xenoestrogen | A chemical, not indigenous to the body that acts in the body in a manner similar to that of estrogen. |
| Allergic Response v. Toxic Response | allergic reactions tend to be dose-independent initially and disproportionate to the amount of the offending substance, whereas toxic or inflammatory reactions tend to be dose-dependent and proportional to the amount of the substance. |
| Mutagenic Reactions | Result when the components of a material alter the base-pair sequences of the DNA in cells; termed mutations. nickel, copper, and beryllium are known mutagens |
| Backbone | The main chain of a polymer |
| Block copolymer | a polymer made of two or more monomer species and identical monomer units occurring in relatively long sequences along the main polymer chain |
| Chain transfer | A stage of polymerization in which the growing end of a chain is transferred to another molecule, initiating further chain growth |
| Curing | Chemical reaction in which low-molecular-weight monomers or small polymers are converted into higher-molecular-weight materials to attain desired properties. |
| Elastic Recovery | Reduction or elimination of elastic strain when an applied force is removed; elastic solids recover elastic strain immediately on removal of the applied force whereas viscoelastic materials recover elastic strain over time. |
| Final Set | Stage at which the curing process is complete |
| Free Radical | A compound with an unpaired electron that is used to initiate polymerization |
| Graft or Branched Copolymer | A polymer in which sequences of one type of mer unit are attached as a graft (Branched) onto the backbone of a second type of mer unit. |
| Initial Set (of a polymer) | The stage of polymerization during which the polymer retains its shape |
| Induction | Activation of free radical, which in turn initiate growing polymer chains |
| Monomer | A chemical compound capable of reacting to form a polymer |
| Plastic Flow (of a polymer) | Irreversible deformation that occurs when polymer chains slide over one another and become relocated within the material |
| Polymer | Chemical compound consisting of large organic molecules formed by the union of many repeating smaller monomer units |
| Polymerization | Chemical reaction in which monomers of a low molecular weight are converted into chains of polymers with a high molecular weight |
| Propagation | Stage of polymerization during which the polymer chains continue to grow to high molecular weights |
| Random copolymer | polymer made of two or more monomer species but with no sequential order between the mer units along the polymer chain |
| Setting (of a polymer) | The extent to which polymerization has progressed |
| Thermoplastic polymer | Polymeric material made of linear and/or branched chains that softens when heated above the glass-transition temp, at which molecular motion begins to force the chains apart |
| Thermosetting polymer | Polymeric material that becomes permanently hard when heated above the temp at which it begins to polymerize and that does not soften again on reheating to same temp |
| Termination | Stage of polymerization during which polymer chains cease to grow |
| Viscoelastic | Ability of a polymer to behave as an elastic solid(spring) and as a viscous liquid(dashpot) |
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