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modified acrylics dental material
modified acrylics dental material
modified acrylics dental material
modified acrylics dental material
modified acrylics dental material
modified acrylics dental material
modified acrylics dental material
modified acrylics dental material
modified acrylics dental material
modified acrylics dental material
modified acrylics dental material
modified acrylics dental material
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modified acrylics dental material

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modified acrylics dental material

modified acrylics dental material

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  • 1. Modified Heat-cured Acrylics 1. Microwavable acrylic 2. Rapid-cured acrylic 3. High impact strength acrylic 4. Fiber-reinforced acrylic
  • 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
  • 9. Fluid resin technique
  • 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

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