Chapter 3 KEY TERMS Group 12 Flashcards
Primary Bonds
Strong bonds with electronic attractions; ionic bonds, covalent bonds, metallic bonds
Secondary Bonds
Weaker bonds than primary bonds; hydrogen bonds, van der Waals forces, London Dispersion Forces
Brittle
Hard materials that break easily when stress is applied. They break suddenly with little plastic deformation, e.g., glass.
Density
The measure of the weight of a material compared with its volume
Hardness
The resistance of a solid to penetration
Ultimate Strength
The maximum amount of stress a material can withstand without breaking
Elasticity
The ability of a material to recover its shape completely after deformation from an applied force
Elastic Deformation
Deformation of a material that recovers its original shape and size when the force is removed
Elastic Limit
The greatest stress a structure can withstand without permanent deformation
Plastic Deformation
Deformation of a material causing permanent changes in size or shape due to an applied force
Yield Stress
The stress at which plastic deformation begins; also called yield point on a stress-strain curve
Stiffness
A material’s resistance to deformation
Young’s Modulus or Elastic Modulus
Measures the resistance of a material to being deformed
Resilience
The ability of a material to absorb energy without permanent deformation
Toughness
The ability of a material to resist fracture
Ductility
The ability of an object to be pulled or stretched under tension without rupture
Malleability
The ability to be compressed and formed into a thin sheet without rupture
Edge Strength
The ability of a material to withstand fracture at a thin edge, such as at margins of a restoration
Durability
The ability of a material to withstand damage due to pressure or wear
Viscosity
The ability of a liquid material to resist flow
Thixotropy
A characteristic of some gels and liquids that they will flow more readily under mechanical force such as mixing, stirring, or shaking.
Direct Restorative Materials
Restorations placed directly into a cavity preparation
Indirect Restorative Materials
Materials used to fabricate restorations outside the mouth that are subsequently placed into the mouth
Permanent Restorations
Restorations expected to be long-lasting
Temporary Restorations
Restorations expected to last several days or weeks
Intermediate Restorations
Restorations expected to last several weeks to months
Mixing Time
The amount of time allotted to bring the components of a material together into a homogenous mix
Working Time
The lapse of time from the start of mixing the material until it begins to harden and is no longer workable because it has reached its initial set
Initial Set Time
Coincides with the end of working time and is the time at which the material can no longer be manipulated in the mouth
Final Set Time
The time needed for the reaction that begins when the material is mixed to go to completion, and the material hardens to its permanent state
Chemical Set Materials
Materials that set through a timed chemical reaction with the combination of a catalyst and base
Light-Activated Materials
Materials that require light in the blue wave range to initiate a reaction
Dual Set Materials
Materials that polymerize either from exposure to light in the blue wave range or from a chemical reaction
Shelf Life
The useful life of a material before it deteriorates or changes in quality
Physical Properties
Properties that can be measured and observed
Mechanical Properties
Properties that define its ability to perform in the oral environment and resist stresses and strains
Alloy
A combination of two or more metals
Dental Amalgam
A metal alloy containing mercury
