W3: Denture Base Materials Flashcards
What impacts can tooth loss have on the quality of life?
The impact of tooth loss on the quality of life is emotional and psychological health problems, joint and jaw disorders, as well as premature aging.
What is vulcanite?
Vulcanite was a rubber material that was hardended through a process and then used as a denture base (it was a successful material but had limitations).
What are the ideal properties for a denture base material?
Natural appearance (colour and translucency)
Easy processing (for consistent and good results)
Easy to clean
Easy to repair
Inexpensive
Long shelf life
Biocompatible (to the oral cavity)
Persistant to bacterial contamination
High strength, stiffness, hardness, toughness and
impact strength
Low density (not too heavy)
Radiopaque (to appear on radiographs)
High thermal conductivity
Dimensionally stable
Accurately reproduces surface detail
What does PMMA stand for?
Polymethyl Methacrylate
When are acrylic polymers used?
Acrylic polymers are used in prosthetic dentistry (articifcal teeth), denture repairs, crown and bridge facings, temporary crowns, impression trays, cleft palate obturators, and orthodontic devices
What are conventional dentures made of?
PMMA (highly crosslinked with polymer chains of varying lengths) and residual monomer
Why is PMMA the most popular base material for conventional dentures?
PMMA as a base material has advantages including good aesthetics, fit accuracy, stability in the oral cavity (biocompatible), easy to work with clinically and in the laboratory (easy manipulation), and is an inexpensive production.
What are the two forms PMMA can be supplied in?
- Powder and liquid
- Gel
What is the composition of the powder in heat cure acrylic?
Powder composition:
PMMA granules/beads
Initiator (benzoyl peroxide)
Pigments/dyes (cadium salts)
Optical opacifiers (titanium dioxide/zinc oxide)
Radio opacifiers (Ba, bismuth, zirconyl dimethacrylate)
Plasticizers (ethyl acrylate, dibutyl phthalate)
Synthetic fibers (nylon)
What does benzoyl peroxide do?
Benzoyl peroxide (initator) starts the setting process
What do cadium salts do?
Cadium salts (pigments/dyes) add colour to the material
What does titanium dioxide or zinc oxide do?
?
Titanium dioxide/zinc oxide (optical opacifiers) are related to light. If the optical opacifiers are too translucent, there is an issue with light.
What do Ba, Bismuth, and zirconyl dimethacrylate do?
?
Ba, Bismuth, and zirconyl dimethacrylate (radio opacifiers) make the acrylic material visible on radiographs.
What do ethyl acrylate and dibutyl phthalate do?
Ethyl acrylate and dibutyl phthalate (plasitcizers) add flexibility to the acrylic material.
What does nylon do?
Nylon (synthetic fibers) add colour and strength?
?
What is the composition of liquid in heat cure acrylic?
Liquid composition:
Methyl methacrylate monomer (MMA)
Inhibitor (hydroquinone)
Crosslinking agent (diethylene glycol dimethacrylate)
What is the boiling point of heat-cure acrylic?
MMA boiling point is 100.3°C
What is the glass transition temperature of acrylic?
PMMA Tg is around 105°C
What is the flexural strength range of PMMA?
70-127 MPa (ASTM D790)
*ASTM is a testing method that determines the flexural properties
What is the flexural modulus of heat cure acyrlic?
More than 2 (>2) GPa
How much residual monomer can be in heat-cure acrylic?
Less than (<) 2.2
What is the water sorption of heat cure acrylic?
Less than (<) 32 μg/mm3
What is the solubility of heat cure acrylic?
Less than (<) 1.6μg/mm3
Which type of PMMA form does vinyl acrylic present as?
Gel form