2 - 3/11: Denture Base Resins

Question 1

What is resin?

Answer 1

A term to describe natural or synthetic substances that form plastic materials after polymerization

Question 2

What is acrylic?

Answer 2

A colorless, pungent acid

Question 3

What are some examples of denture base materials?

Answer 3

Gold
Wood
Bone/animal hooves
Ivory
Ceramics
Metals and alloys
Polymers

Question 4

How was wood chosen for dentures?

Answer 4

• readily available
• relatively inexpensive
• can be carved to desired shape

Question 5

What are disadvantages of wood?

Answer 5

• warped and cracked in moisture
• esthetic and hygienic challenges
• degradation in oral environment

Question 6

How was bone chosen?

Answer 6

Due to availability, reasonable cost, and carvability

Question 7

Why was bone advantageous for dentures?

Answer 7

Better dimensional stability than wood, esthetic and hygienic concerns remained

Question 8

Why was ivory beneficial?

Answer 8

Esthetic and hygienic advantage in comparison with denture bases carved from wood or bone

Question 9

What were advantages of ceramics over wood, bone, ivory?

Answer 9

• could be shaped using additive technique rather than substractive
• additive technique facilitated correction of denture base surface
• intimate contact with underlying soft tissues
• could be tinted

Question 10

What are base metal alloy denture bases used in?

Answer 10

Automobile industry

Question 11

What are denture base polymers?

Answer 11

• vulcinate
• polystyrene
• vinyls
• nylons
• polymethyl methacrylate (PMMA)
• urethane dimethacrylate (light activated)

Question 12

What material had color, taste, and odor that was “less than ideal”?

Answer 12

Vulcanite

Question 13

What are disadvantages of vulcanite?

Answer 13

• absorbs saliva and becomes unhyginenic due to bacterial proliferation
• poor esthetics
• dimensionally unstable
• objectionable taste and odor

Question 14

What are disadvantages of celluloid?

Answer 14

• lack of stability
• unpleasant taste
• unpleasant odor
• sustainability
• flammable

Question 15

What are disadvantages of bakelite?

Answer 15

• lack of uniform quality
• variable strength
• variable color
• dimensional unstability

Question 16

What are denture bases fabricated with now?

Answer 16

Poly(methyl methacrylate) resins

Question 17

What is pure PMMA like?

Answer 17

Colorless, transparent solid

Question 18

What is an advantage of PMMA?

Answer 18

Denture base material is relative ease with which it can be processed

Question 19

How is PMMA supplied?

Answer 19

Powder and liquid system

Question 20

What are advantages of PMMA resin?

Answer 20

• excellent esthetic properties
• adequate strength
• low water sorption
• low solubility
• non-toxic, low allergenicity
• easily repaired
• reproduces detail accurately
• simple molding and processing technique

Question 21

What are PMMA resin ingredients?

Answer 21

Liquid monomer - methyl methacrylate
Powdered polymer - polymethyl methacrylate
Plasticizer - dibutyl phthalate
Initiater - benzoyl peroxide
Pigments

Question 22

What are the two components of PMMA resin?

Answer 22

1. liquid monomer
2. Powdered polymer

Question 23

What is the PMMA liquid?

Answer 23

• methyl methacrylate
• glycol dimethacrylate - a cross linnking agent
• hydroquinone - inhibitor for increased shelf life

Question 24

What is the PMMA powder?

Answer 24

• PMMA beads
• pigments
• plasticizer
• benzoyl peroxide - initiator of polymerization

Question 25

What are the steps of curing?

Answer 25

Heat cure Chemical cure Light cure

Question 26

What are heat-activated denture bases used in?

Answer 26

Fabrication of all denture base

Question 27

What is required for polymerization?

Answer 27

Thermal energy - water bath or microwave oven

Question 28

What is the composition of heat activated denture base?

Answer 28

PMMA - powder and liquid Powder - prepolymerized spheres of PMMA and small amount of benzoyl peroxide (initiator) Liquid - predominantly non polymerized methyl methacrylate with small amount of hydroquinone (inhibitor) Cross linking agent is added to liquid

Question 29

How does monomer boils work?

Answer 29

Heat at surface of resin is conducted away into investing medium, hency no porosity on surface of resin

Question 30

Vaporization of what monomer affects the thick areas of denture base?

Answer 30

Monomer balls

Question 31

What are reasons that porosity is caused?

Answer 31

Irregular shape, located throughout the base: - inadequate pressure - not enough resin in mold - improperly mixed resin

Question 32

Resin denture teeth are basically the same composition as?

Answer 32

Denture base resin, except for pigmentation to produce tooth shaed

Question 33

What two things bond to eachother?

Answer 33

Teeth and base

Question 34

What does an amine in the liquid react with?

Answer 34

The benzoyl peroxide in the powder to promote polymerization at room temp

Question 35

What is the fundamental difference between heat-activated vs autopolymerized?

Answer 35

Method of activation of the initiator benzoyl peroxide

Question 36

What does heat-activated have a greater degree of?

Answer 36

Polymerization

Question 37

What does heat activated have better stability of?

Answer 37

Color stability

Question 38

How is color stability of autopolymerized?

Answer 38

The tertiary amine activator (dimethyl-p-toludine) in the liquid oxidizes and turns orange after a few months

Question 39

What are light activated denture base resins?

Answer 39

Composite matrix of urethane dimethacryate, microfine silica, and high molecular weight acrylic resin monomer

Question 40

What is the activator for light activated denture base resins?

Answer 40

Visible light

Question 41

What is the initiator for light activated denture base resins?

Answer 41

Camphorquinone

Question 42

How is light activated denture base supplied?

Answer 42

In sheet and rope form packed in light proof pouches

Question 43

Light activated resin cannot be flasked in __________

Answer 43

Conventional manner

Question 44

What provides the passage of light in light activated denture base?

Answer 44

Opaque investing media

Question 45

How are teeth arranged and denture base sculpted using?

Answer 45

Light activated resin