Flashcards in intro to dental materials Deck (27):
What was the first light curing unit?
Dart and Nemcek
What are dental composites used for?
special tray construction
What does a fibre reinforced composite consist of?
fibres of high strength and modulus
embedded/bonded to matrix
What have dental fibre reinforced materials been used for ?
inlays and onlays
crowns and bridges
posts to reinforce and restore rct teeth.
What states the legal requirements of dental materials?
Medical Devices Directive
What makes the mouth a hostile environment?
loading of up to 6kg
on/off cyclical forces- fatigue
temperature fluctuations- -14- 60 degrees
What does tensile mean?
force applied to elongate a rod
What is strain?
change in length/original length
What units is strain measured in?
What does compressive mean?
force applied to compress a material
What types of materials can not be compressed?
brittle materials eg. composite
What is diametral tensile strength testing used for?
brittle materials where conventional tensile not suitable
What is flexural?
what does ductility mean?
potential for material to be drawn out into wire
What does a high number re. surface hardeness mean?
What does a low number re. surface hardness mean?
What does shear bond strength test test for?
adhesive and cohesive failure
What does impact strength test test for?
pendulum swing fractures
What tests for surface roughness?
What does a high reading (R) on profilometer mean?
Studies of rheological properties is the study of what?
how materials flow
What does viscosity vary with?
rate of sheer and time
what does dilatant mean?
viscosity increases with applied pressure
What does Newtonian mean?
Viscosity remains constant with applied pressure
what does pseudoplastic mean?
viscosity decreases with applied pressure and unless set increased when pressure decreases
What do tests of corrosion define?
chemical reactivity of metals and alloys