2. Rapid-cured acrylic
An altered initiator that allows denture base
processing in boiling water for only 20 min.
Advantages
Rapid curing with minimal porosity
Disadvantages
High % of residual monomer (3-7 times > Conv. HCA)
Lower mechanical properties
Porosity of bases ≥ 6mm thick
3. High impact acrylic
Powder is a graft copolymer of PMMA - butadiene
rubber
2 formats of polymer beads are exist
No cross-linking is added to the composition
Is better than
Because it produces better dough
characteristics
Rubber
Acrylic
Rubber
Acrylic
4. Advantages
High impact strength
Low crazing rates
Low residual monomer contents
Good attachment to art. Teeth and good fit
Disadvantages
Expensive
Reduced stiffness
High impact acrylic
5. Fiber and
metal- reinforced acrylic
Certain fibers (Carbon, glass, Kevlar, Polyethylene) and
metal fillers (Zerconia and alumina) are incorporated in
acrylic powder
Drawbacks
Carbon fibers cause black discoloration
Glass fibers are irritating and could injure soft tissues
Kevlar fibers complicate the packing process and gives
straw color
Polyethylene fibers is promising
Adding metal fillers ↓ poly. Shrinkage but deteriorates
the properties
6. Chemically-cured
Acrylics
A chemical compound ( 3ry amine
Activator) is added to the monomer
composition to activate the initiator
An activator paste (P-toluine sulphonic
acid) could be added to the regular acrylic
to activate the polymerization at room
temperature
7. Characters of
the chemically-cured acrylic
Polymer beads have lower mol. wt.
Liquid contains chemical activator (3ry amine) to start
the polymerization at room temp.
The material provides;
1. lower degree of polymerization
2. Lower mechanical properties
3. Higher % of residual monomer
4. Higher rate of porosity
5. Higher rate of water sorption
6. Lower color stability
7. No thermal shrinkage
8. Oversized dentures (+ 0.3-0.4%)
8. Characters
of the chemically-cured acrylic
Practicability
1. Short processing time (10-15 min)
2. Complete polymerization occurs at room temp in 3 hrs
3. Both compression molding or fluid resin techniques
could be used to fabricate denture bases
Applications:
- Denture base (temp &permanent)
- Repair of broken dentures
- Special trays
10. Light- cured
Acrylics
The BVL is used to activate the
photo-sensitive initiator named
Comphroquinon
The material is a composite structure
Usually present as sheets or robs in
light-proof pouches
11. Characters
of the light-cured acrylic
Composition: Composite Paste made of
Matrix of UDMA and PMMA
Microfine silica fillers
Organic fillers (Prepolymerized polymer beads)
Photoinitiator
The material provides;
1. No MMA monomer is present (no allergy)
2. Lower physical and mechanical properties
3. Lower rate of polymerization shrinkage
4. Better fit
12. Applications
Denture base
Repair of broken prostheses
Special trays
Denture construction
No flasking is required
Adaptation of sheet material over the cast to
form the denture base light curing for 5 min
Artificial teeth are then seat over the rob material
light curing for another 5 min
Characters of
the light-cured acrylic