Denture Manual 81- (Heat vs Chemical Cure) Flashcards
Heat-activated resin composition (pg 87)
- Powder (2 components)
- Liquid (3 components)
- PMMA
- Benzoyl peroxide (initiator)
- Unpolymerized MMA (monomer)
- Glycol dimethacrylate (cross-linking agent)
- Hydroquinone (inhibitor)
What is the initiator for both heat resins? (pg 87)
Benzoyl peroxide
What is the cross-linking agent for heat-activated resins?
Glycol dimethacrylate
What does hydroquinone do? (pg 87)
Inhibitor
- Prevents polymerization of the monomer liquid during storage
What is the activator for heat-activated resin denture bases? (pg 88)
What is the activator for chemically-activated resin denture bases?
Heat (165 F or 70 C degrees for 8 hours or longer)
Dimethyl-para-toluidine (tertiary amide)
How does heat actually “activate” the process of heat-activated resin denture bases? At what temperature does this start? (pg 88)
Heat decomposes the benzoyl peroxide into a free radical to start the polymerization
Starts at 140°F / 60°C degrees, but you do the entire reaction at 165° F degrees
High impact strength resins are reinforced with what? (pg 88)
Give one example of this resin
Rubber (butadiene-styrene rubber particles are grafted to the methyl methacrylate to bond to the acrylic matrix)
Lucitone 199
What are the two recommended polymerization cycles for heat-activated resin (i.e. Lucitone 199)? (pg 88)
Long cure: 164° F for 9 hours, then 1/2 hour in boiling water, then bench cool 1/2 hour, then cool water for 15 minutes
Short cure: 164° F for 1.5 hours, then boiling water (212°) F for thirty minutes, then bench cure 1/2 hour, then cool water 15 minutes
Chemically-activated resin composition (pg 89)
- Powder
- Liquid
- PMMA
- Benzoyl peroxide (initiator)
- Unpolymerized MMA (monomer)
- Glycol dimethacrylate (cross-linking agent)
- Hydroquinone (initiator)
- Dimethyl-para-toluidine (activator)
Chemically-activated resin’s
- Advantages
- Disadvantages (3)
Advantage: Faster working time
Disadvantages: (Diewitt’s note: I think these are before Ivobase was introduced)
- Chemical cure has more residual monomer (irritates the tissue
- Decreased strength
- Less color stability
Light-activated resin composition
- Two major constituents
- Three minor constituents
- UDMA (urethane dimethacrylate - the resin matrix)
- Inorganic filler particles (quartz)
- Coupling agents (bonds filler particles to the resin matrix
- “Activator-initiator” system (UV light - activator) and (champhoroquinone-initiator)
- Optical modifiers (color - metal oxides)
At what temperature does acrylic monomer boil? How about water? (pg 92)
What does boiled acrylic monomer lead to?
Is this a major concern for thin or bulky areas of the denture?
213.4 degrees F for acrylic, compared to 212 degrees F for water
This leads to porosities in the denture base
Trick question - It is a major concern for both areas since the reaction is exothermic. For thick areas, this may lead to porosities. For thin areas, this may lead to incomplete curing.
Who developed the BULL rule? (pg 98)
Schuyler
Combination case syndrome AKA Kelly’s Syndrome (9) (pg 105)
- Papillary hyperplasia
- Anterior maxillary ridge resorption
- Extrusion of lower anterior teeth
- Downgrowth of maxillary tuberosity and pneumatization of maxillary sinus
- Posterior mandibular ridge resorption
- Loss of OVD
- Anterior repositioning of mandible and TMJ remodeling
- Occlusal plane discrepancies
- Epulis fissuratum
Which authors advocated for the use of gold occlusals?
Koehne and Morrow 1970