Physical and Mechanical properties of Dental materials

Bonds

Primary bonds

Chemical, strong

Ionic bonds, covalent bonds and metallic bonds

Bonds

Secondary bonds

Physical, weaker

Density

A measure of the weight a material has compared with its volume

Hardness

The resistance of a solid to penetration

Elasticity

The measure of a material to recover its shape completely after deformation from an applied force

Stiffness

Resistance to deformation

Ductility

The amount of dimensional change it can withstand without breaking

Malleability

The ability to be compressed and formed into a thin sheet without rupture

Toughness

Ability of a material to absorb energy without fracture

Resilience

Amount of energy a material can absorb without permanent deformation

Restorative dental material composition

Metals

Properties such as strength, ability to conduct electricity and heat, malleability, ductility, and luster

Amalgam

Crowns

Implants

Partial dentures

Restorative dental material composition

Ceramics

Rigid, brittle and melt at high temperatures. And poor conductors of heat and electricity

Ceramic crowns

Veneers

Restorative dental material composition

Polymers

Can be flexible, easily shaped, and rubbery but also rigid and difficult to mold

Denture based, and denture teeth

Composites are mixed of polymers and ceramic

Reaction

When components are mixed together a reaction occurs

Physical

Chemical

Types of reactions

Chemical set

Light activated

Dual set

Reaction stage times

Mixing time

Time to bring the components of a material into a homogenous mix

Reaction stage times

Working time

Time permitted to place and manipulate the material in the mouth

Reaction stage times

Initial set time

Begins when the material no longer can be manipulated in the mouth

Reaction stage times

Final set time

Occurs when the material has reached its ultimate state

Manipulation

Ratio of components

External variables:

Temperatures: high accelerate the reaction, low retard the reaction

Mixing, quick or slow

Mixing pad, paper, or glass

Shelf life:

Expiration date