Dental Materials Test 1 Flashcards
Amount of force applied to a specific area
What base is still used: stimulate dentin formation and ph raises as it dissolves
Internal rearrangement of atoms to adjust to the stress-deformation results
Forces on object directed away from each other - stretched or elongated…ability of an object to resist pulling
Resistance in the material to the external force - ability to resist pushing
Ability to resist tearing - forces directed parallel to each other. Occurs when one portion of a structure is forced to slide by another portion (i.e.. scissors)
Stiffness of material, maximum stress w/o permanent deformation. Material can’t regain its size and/or shape
Elastic limit - proportional limit
Point just before fracture
Ability of material to be drawn into a wire
Ductility = elongation
Low ductility = brittleness
Ability to be hammered or rolled into thin sheets without fracture- compression
Energy necessary to cause permanent deformation
Ability of material to resist fracture
Gradual permanent change in dimension that occurs in an object due to constant loading
Flow after set (amalgam)
Resistance of material to flow
Some materials have a high viscosity but change w/pressure (mixing)…impression materials change thru manipulation
Depth of an indentation made with a steel ball- composites ↕️
Rockwell (RHN) hardness
Measuring the length of a diagonal made with a diamond indenter- metals and porcelain ↔️
Knoop (KHN) hardness
The repeated application of stress to an object causing tiny cracks to be generated within the structure until failure occurs
Pt ed. for 12 year old who is going to play field hockey….
How do cements look on an X-ray?
Dental cement can be used as a base…
- Can it protect pulp?
- Adequate compressive strength?
- Is it a poor conductor of temp
Yes all of above
Most conservative tx for 43 yr old with extensive internal stains- finances not an issue