DHED 311: Polymers for prosthetics (17)

Monomer

low molecule weight molecules

Monomer ex

methyl methacrylate

Polymers

long chain molecules produced chemically linking may low molecular weights

Polymerization

forming polymers by chemically linking monomers into long chains

polymerization can be activated by

-chemicals

-heat

-light

Poly methyl methacrylate (PMMA)

-polymer used in dentures

-composed of methyl methacrylate monomers

What is the most common form of polymerization in dentistry

Addition polymerization

Addition polymerization is initiated by

free-radicals

What 3 stages are in addition polymerization?

1. Initiation

2. Propagation

3. Termination

What polymerization isn't really used in dentistry?

Condensation polymerization

condensation polymerization produces

By-products (water ,H+ gas, alcohol)

Acrylic resins

synthetic polymers used in prosthetic dentistry

Acrylic resins uses

-denture bases

-denture teeth

-relining/ repairing protheses

-orthodontic retainers

-custom impression trays

-bruxism mouth guards

-provisional acrylic RPDS (flippers)

Properties of acrylic resins

-shrinkage during polymerization

-fairly low strength

-good biocompatibility

-good fatigue resistance

-low thermal conductivity

What polymerization reaction produces PMMA

addition reaction

small amount of MMA is

not used in reaction and is present in new dentures

powder is

small beads of PMMA

Liquid is for

MMA (methyl methacrylate)

Methyl methacrylate is

-flammable and vaporizes easily

-used in well-ventilated areas

-irritant

PMMAs can be cured in two ways

-Heat cured

-Chemically cured

Heat cured PMMA

-most common method

-stronger/ harder

-less porous

Chemically cured PMMMA

-weaker/ soft

-more porous: high staining and microbes, weakens acrylic

-less color stability