TERMS Flashcards
mechanical properties of the material that allow it to perform the fxn which it is intended
mechanical compatibility
a biomaterial must not produced an adverse effect on the tissue into which it is implanted
recipient tissue must not have a detrimental effect on the performance of the biomaterial
biologic compatibility
force/cross sectional area equals?
stress
elongated length-original length/original length equals?
strain
material property related to the slope of the stress strain curve of a specific material
indicative of the stiffness of the material
allows for comparison of mechanical properties between materials
not used to describe the stiffness or strength of a device
modulus of elasticity
measure of degree of plastic deformation sustained at fracture
measured as % elongation or % area reduction
brittle materials - ceramics
ductile materials - metals, polymers
ductility
time-dependent permanent deformation that occurs under stress
viscoelasticity
delayed failure resulting from fluctuating stresses
-fatigue limit
crack initiation and propagation
fatigue
measure of a materials resistance to localized plastic deformation
-indicative of materials resistance to wear
hardness
similar in composition to mineral component of bone
excellent biocompatibility
wide variation in mechanical properties due to difference in manufacturing
used as porous or solid implants
biocoating
hydroxyapatite
bioglass, ceravital
consists of P, Na, Si and Ca components
direct bone bonding by Ca-P layer
strict adherence to composition
fillers for bone cement
glass ceramics
immune reaction that involves both humoral and cell mediated response (B/T cells)
metal insensitivity
redness, edema, eczema
skin response can be local or remote
contact dermatitis
results from sustained inflammatory reaction at the site of the implant
osteolysis
bone mass is decreased over an extended period of time as a result of the presence of a rigid device
stress shielding
name this type of corrosion
occurs when two dissimilar metals are placed in contact within a common electrolytic solution
material with the lower corrosion resistance will begin to corrode
i.e stainless steel screws and cobalt chromium plate
galvanic corrosion
name this type of corrosion
localized corrosion that occurs in confined spaces
occurs over the entire specimen, both on the free surface and within the crevice
accumulation of chloride ions and a low pH result in accelerated attack within the crevice
crevice corrosion
name this type of corrosion
occurs as a result of repeated relative micro motion between two surfaces
motion causes mechanical disruption of the protective oxide layer
repeated cycle of breakdown and reformation of the oxide layer resulting in corrosion of the exposed metal
fretting corrosion
occurs when two materials that are articulating against one another bond together and then dislodge as the materials continue to slide past each other
debris from one material is transferred to the surface of the other
adhesive wear
occurs when a hard material tears through a softer material
source of the hard material
- articulating surface
- wear particle lodged between two articulating surfaces
abrasive wear
