Terminology Flashcards
What is compressive strength? How is this seen on a stress strain curve?
Stress required to cause fracture. So compressive strength is how much resistance it can withstand before fracture.
Seen as fracture stress on the stress strain curve
What is the elastic modulus? How is this seen on a stress strain curve?
It is a materials rigidity, the stress required to cause a change in shape.
Seen as the initial gradient of the stress strain curve. Steeper = more rigid
What is brittleness/ductility? How is this seen on a stress strain curve?
Dimensions change experienced before fracture occurs.
Seen as the distance on the X axis between proportional limit and fracture stress.
What is hardness?
Resistance of a surface to indentation or abrasion
What is creep? What causes it?
Gradual increase in permanent strain experienced under prolonged application of stress
Occurs when material temperature is more than about half of its melting point
What is a solid solution?
Two metals that are soluble in one another (alloy)
Form a solid solution. Like a solution in chemistry but solid.
What is an alloy?
Two metals that from a common lattice structure and are soluble in one another
What does wrought mean in alloys?
It can be formed by cold working, can be drawn into a wire.
What is springiness?
Ability for a material to undergo large deflections - to form an arc - without permanent deformation
What is tensile strength?
Ability to resist fracture during pulling
Flexural strength?
Ability to resist fracture during bending
What is fracture toughness?
What material has Best in dentistry?
Ability to resist the propagation of a crack
Zirconia
- tetragonal particles transform to stronger monolithic particle in response to crack
What is thermal expansion coefficient
What is best?
Change in size with change in temperature
Gold has closest to tooth tissue
Desireable mechanical properties of restorative material?
High elastic modulus - does not flex
High casting accuracy
Similar thermal expansion coefficient
Biocompatibility
Minimal wear to opposing dentition
Aesthetically pleasing
