Denture Base Polymers

What are the 1-6 ideal properites for denture base material?

1. Strength and durbility

2. Satisfacotry thermal properites

3. Processing accuracy and dimensional stability

4. Insolutiblity in and low sorptio of oral fluids

5. Chemical stability

6. Absence of taste and odor 

What are the 7-13 ideal properites for denture base material?

Biocompatable

Natureal apperaance

Color stability

Adhesion to plastics, metals, and or porcelain

Low density to aid retention of upper denture

Ease of fabrication and repair

Moderate cost 

Strength and durability:

• High _______ and approriate ______ to allow thin sections

• High proportional limit to resist _______

• Good ________ properites

• Appropriate ________ for abrasion resistance but good _________

• High impact _______ and ______ toughness for accidents

• Softening temperature avobe taht of what? 

stiffnes and strength

deformation

fatigue

hardness, polish

strength and fracture

hot foods/liquids or cleaning 

Do you want conductivity in a temperature?

Some to allow for temperature sensation

Types and Classes:

• Type 1:

• Type 2:

• Type 3:

• Type 4:

• Type 5:

Heat polymerizable polymers

Autopolymerizable polymers

Thermoplalstic blank or powder

Light acitvated materials

Microwave cured materials

What type of material has different properites than the rest?

Type 2

What are the 2 materials of hoice for denture base polymers?

What are the 3 advantages?

1. Heat cured poly

2. Rubber reinforced poly (high impact)

1. Relativlty inexpensive

2. Easy to process with inexpensive techniques

3. Esthetic

PMMA: Powder (Powder)

• Poly?

• Benzoyl peroxide?

• Titatnium dioxide?

• Inorganci pigments?

• Dyed synthetic fibers?

present as beads/ pearls

Inititator

Control translucency

color

Esthics/strength

PMMA (liquid): powder

• Methyl methacrylate?

• Hydroquinone?

• Ethylene glycol dimethacrylate?

• Organic amine?

Monomer

Inhibitor

Cross-linking agent

Accelerator 

_______ _______ is the inititator

Activated by heat above ___ degrees in heat cured and _________ accelerator in cold cured or autpolymerizable

Benzoyl Peroxide

60 degrees celsius

accelerator

PMMA:

• ________ plasticizes the powder to a dough like consistency which is packed into the mold prior to polymerization of the _______ via addition polymerization.

liquid

monomer

PMMA Mechanical properties :

• Generally, ____ but adequate strength, fairly _______, soft, ______ on impact, reasonable fatigue resistance, low ______ toughness.

low

flexible, brittle

fracture

Mechanical properties PMMA:

• Fractures in up to ___% of dentures within 3 years.

• __% of repairs are midline fractures

• Usually result of _____

• Crack —> ______ —> _______

10%

30%

trauma

propagation, failure

Heat cured PMMA denture base: rubber

• Incorporate rubber with _____

• _________ reinforced PMMA

• Increases ______ strength

• Increases in _________ deflection

• Decreased ________

• Less ________ sorption

• Comparatively poorer ______

MMA

rubber

impact

transverse

stiffness

water

fit

Heat cured PMMA thermal properties:

• Thermal conductivity?

• Isolates oral soft tissue from what?

• Coefficient of thermal expansion?

• What could happen?

very low

temperature sensation —> scalding potential

fairly high, teeth may loosen due to differential expansion/contraction 

Heat cured denture base water sorption and solubility:

• Asorbtion?

• Satureed for how long at what temp?

• Solubility?

• Some leaching of what?

of some extent, but compensates for shrinkage during processing

17 days in water at room temp

generally low

monomer and coloring agents

Heat cured PMMA denture base:

• No cleaning in what?

• Adhesion?

• Good _______ stability

• No _______ or ________

• Good ____________

• Processing error —> __________ —>_______

excessivly hot water

none to metal, poor to porcelain, good to acrylic

color

taste or odor

biocompatibility

increase residual monomer —> posssible reaction

Residual Monomer:

• Diffuses out of the ________

• Amount leached is proportional to amount _________

• Most lost in first few ______ with a constant level for __ weeks.

• Also effect on mechanical properties decline with what? 

denture —> irritant; allergic reaction burning mouth

amount present (more in cold cured)

days, 2 weeks

residual monomer amount 

_________ might be a better way compared to impact tests to differentiate high impact products from conventional

Fracture toughness

Non-PMMA denture varieties:

• Based on what?

• Example?

urethane dimethyacrylate

dentsply

Flexible denture based upon what?

Example?

nylon

Lucitone FRS by Dentsply

Are flexible dentures indicated for long term use?

No