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Dentures Final > Lecture 1 - Denture Base Resins > Flashcards

Lecture 1 - Denture Base Resins Flashcards

1
Q

When completing a checklist for a wax trial denture appointment, what should the checklist consider?

A

▪ CO = CR
▪ OVD
▪ Midline
▪ Horizontal & vertical overlap ▪ Lip support
▪ Occlusal plane ▪ Buccal corridor ▪ Esthetics
▪ Phonetics
▪ Maxillary posterior limit ▪ Protrusive record

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2
Q

Resin =

A

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

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3
Q

What is the main way in which dentures are processed?

A

Heat activated resins

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4
Q

Acrylic =

A

Means designating a colorless, pungent acid

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5
Q

We talked a lot about the history of dentures in this lecture. Give a brief synopsis of what was touched on.

A

▪ Skillfully designed dentures were made as early as 700 BC
▪ Teeth were made of gold, silver, wood
▪ The first dental prosthesis was believed to have
been constructed in Egypt

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6
Q

What were some of the materials that dentures were made of in history?

A
  • Gold
  • Wood
  • Bone
  • Ivory
  • Ceramics
  • Metals/ alloys
  • polymers
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7
Q

What are some known denture base polymers?

A

▪ Polymethyl methacrylate
▪ Urethane dimethacrylate (light activated)

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8
Q

Vulcanite Rubber =

A

→ Used with porcelain teeth
important improvement compared to previous materials at this time. Became not ideal because of color, taste, and odor

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9
Q

Which denture base polymer proved to be a much satisfactory material?

A

Polymethyl methacrylate (light activated)

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10
Q

What was the most significant drawback to using ceramics and porcelain for dentures back then?

A

The brittleness… they tended to fracture

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11
Q

Would ceramics bond to denture bases back then?

A

NO! This was another drawback

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12
Q

What are the different types of acrylic resins you should know?

A

▪ Polymethyl methacrylate
▪ Pure PMMA (colorless, transparent)
▪ Liquid- non polymerized methyl methacrylate
▪ Liquid and powder mixed in proper proportions

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13
Q

What is one advantage to using PMMA as a denture base material?

A

There is relative ease with which it can be processed

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14
Q

What are the 3 types of denture bases?

A
  1. Heat cure
  2. Chemical cure
  3. Light cure
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15
Q
  • Used in fabrication of all denture bases
  • PMMA (powder & liquid)
    -Initiator: Benzoyl peroxide
A

Heat Cure

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16
Q
  • Induce the denture base polymerization, does not require thermal energy
  • Auto-polymerized and heat activated
A

Chemical Cure

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17
Q
  • Activator –> visible light
  • Initiator –> camphorquione
A

Light Cure

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18
Q

What is the resin base that we use now?

A

Polymethyl methacrylate (PMMA… veronite)

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19
Q

What are the characteristics of polymethyl methacrylate?

A

▪ Esthetics
▪ Low solubility, low water absorption
▪ Non-toxic, low allergenicity
▪ Easily repaired, adequate strength
▪ Reproduces detail accurately
▪ Simple molding and processing techniques

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20
Q

Polymethyl methacrylate is a two-component system. What are these two components?

A
  1. Liquid
  2. Powder
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21
Q

What are the 5 PMMA resin ingredients that you should know?

A
  1. Liquid monomer – methyl methacrylate
  2. Powdered polymer – polymethyl methacrylate
  3. Plasticizer- dibutyl phthalate
  4. Initiator – benzoyl peroxide
  5. Pigments
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22
Q

What are the three types of PMMA liquids?

A
  • methyl methacrylate
  • glycol dimethacrylate (a cross linking agent)
  • hydroquinone (inhibitor for increased shelf life)
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23
Q

What are the four types of PMMA powders?

A
  • PMMA beads
  • Pigments
  • Plasticizer (dibutyl phthalate)
  • Benzoyl peroxide (initiator of polymerization)
24
Q

What is used in the fabrication of all denture bases?

A

Heat activated resin

25
Q

What is required for the polymerization of heat activated resin?

A

Thermal energy (water bath or microwave oven)

26
Q

What are the PMMA powders?

A

Prepolymerized spheres of PMMA and small amount of benzoyl peroxide

27
Q

What are the PMMA liquids?

A

Predominantly non polymerized methyl methacrylate with small amount of hydroquinone (inhibitor)

28
Q

What ingredient is added to the PMMA liquids?

A

Cross linking agent

29
Q

What technique is used to process denture resins?

A

Compression molding (with a pressure vacuum machine)

30
Q

Besides compression molding, what is another technique that is used to process dentures?

A

Ejection molding

31
Q

What is the time and temperature for a bench cure of a denture base resin?

A

Time = 1 hour

Temperature = room temp

32
Q

What is the time and temperature for a slow heat cure of a denture base resin?

A

Time = 9 hours

Temperature = begin in cold water and bring up to 165 degrees Fahrenheit… the exothermic heat of reaction occurs when the resin reaches 150 degrees Fahrenheit

33
Q

What is the time and temperature for a fast heat cure of a denture base resin?

A

Time = 2 hours

Temperature = begin in cold water and bring up to 165 degrees Fahrenheit… then 30 minutes at 212 degrees Fahrenheit

34
Q

What is the time and temperature for a deflasking of a denture base resin?

A

Time = 30 minutes (1), 30 minutes (2)

Temperature = bench cooling at room temperature (1),
immersed in tap water (2)

** remove the investing plaster but leave the stone casts intact. All the plaster must be cleaned off, and dentures must NOT be removed from casts **

35
Q

Should you boil the acrylic monomer?

A

NO→ Do NOT boil the acrylic monomer… this is because it causes POROSITY

36
Q

At what temperature does acrylic monomer boil at?

A

It boils @ 100.3 degrees Celsius (212 degrees Fahrenheit)

** avoid increasing the temperature too quickly to prevent porosity **

37
Q

Internal porosity =

A

The heat at the surface of the resin is conducted away into an investing medium… there is no porosity on the surface of the resin

38
Q

What does the vaporization of the monomer affect in internal porosity?

A

It affects the thick areas of the denture base

39
Q

What temperature does the monomer boil at in internal porosity? What does it cause?

A

Temperature = 100.8 degrees Celsius / 213.4 degrees Fahrenheit

** it causes spherical bubbles inside the resin **

40
Q

Other porosities cause irregular shapes and they located throughout the base. What are the 3 main causes of developing other porosities?

A
  1. Inadequate pressure
  2. Not enough resin in mold 3. Improperly mixed resin
41
Q

What is the main difference of resin denture teeth in comparison with denture base resin?

A

Resin denture teeth are basically the SAME composition as the denture base resin, EXCEPT for pigmentation to produce tooth shades

42
Q

Are resin denture teeth highly cross-linked resins?

A

YES! → The TEETH and BASE chemically bond to each other

43
Q

What is the difference between heat activated and auto polymerized?

A

The fundamental difference is the method of activation of the interior benzoyl peroxide

In autopolymerized = an amine in the liquid reacts with the benzoyl peroxide in the powder to promote polymerization @ room temperature

44
Q

Is there a greater degree of polymerization with heat activated or autopolymerized?

A

Heat-activated

45
Q

What has better color stability: heat activated or autopolymerized?

A

Heat-activated

46
Q

In the color stability of the autopolymerized process, what color does the tertiary amine activator in the liquid oxidize and turn to after a few months?

A

Turns orange

47
Q

What are the 4 types of denture base resins?

A
  1. Light activated
  2. Heat cure
  3. Chemically activated
  4. Autopolymerizing
48
Q

What is light activated denture base resin made of?

A

▪ Composite matrix of urethane dimethacrylate ▪ microfine silica
▪ high molecular weight acrylic resin monomer

49
Q

What is the ACTIVATOR of a light activated denture base resin?

A

Visible light

50
Q

What is the INITIATOR of a light activated denture base resin?

A

Camphorquinone

51
Q

What form is light activated denture base resin supplied in?

A

Sheet & rope form packed in light proof pouches

52
Q

Can light activated denture base resin be flasked in a conventional manner?

A

NO!

53
Q

What does opaque investing media provide?

A

It provides the passage of light

54
Q

In dentures, teeth are arranged, and the denture bases are sculpted using what?

A

Light activated resin …
The denture base is then placed into a light chamber & polymerized

55
Q

What are the two types of CAD/CAM technology?

A
  1. Subtractive
  2. Additive (printing)
56
Q

CAD/CAM Technology =

A

It is the 3D processing of dentures. Dentures are cut out from a puck of material.

Dentures Final (2 decks)

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