Heat Cure Versus Cold Cure Partials

Heat Cure Versus Cold Cure Partials

Composition Of acrylic resin:

Heat Activated:

• Available as powder and liquid:
  • The powder may be transparent or tooth-colored or pink (to stimulate the gums some even contain red fiers to duplicate blood vessels).
  • The liquid is supplied in tightly sealed amber-colored bottoms (to prevent premature polymerization by light or UV radiation on storage).
• Liquid: 
  • Methyl methacrylate – Plasticizes the polymer
  • Dibutyl phthalate – Plasticizer
  • Glycol dimethacrylate (1–2%) – Cross-linking agent
  • Hydroquinone (0.006%) – Inhibitor-prevents setting.

• Powder:
  • Polymethyl methacrylate and another copolymer 5%
  • Polymethyl methacrylate beads – Major component
  • Ethyl or methacrylate (5%) – Copolymers improve properties
  • Benzoyl peroxide – Initiator
  • Compounds of mercuric – Dyes (color pigments) sulfide, cadmium sulfide, etc
  • Zinc or titanium oxide – Opacifirs
  • Dibutyl phthalate – Plasticizer
  • Fillers, inorganic particles like – Improves physical glass fiers, zirconium silicate, properties like alumina, etc. stiffness
  • Dyed synthetic nylon or – Stimulate small acrylic fibers capillaries

Chemically Activated Denture Base Resin

Composition Of Base Resin:

• Liquid: 
  • Methyl methacrylate – Dissolves/plasticizes/ monomer polymer
  • Dimethyl-p-toluidine – Activator
  • Dibutyl phthalate – Plasticizer
  • Glycol methacrylate – cross-linking agent.
  • Hydroquinone (0.006%) – Inhibitor
• Powder :
  • Poly (methyl methacrylate) – Dissolved by and other copolymer − 5% monomer to form dough
  • Benzoyl peroxide – Initiator
  • Compounds of mercuric sulfide, cadmium sulfide – Dyes
  • Zinc or titanium oxide – Opacifirs
  • Dibutyl phthalate – Plasticizer
  • Dyed organic filers – For esthetics and inorganic particles like glass fibers or beads table

Composition Of Light Activated Acrylic Resin:

Mode of Polymerization of Denture Base Acrylic Resin

There are three types of modes of polymerization of denture base acrylic resin, i.e.

1. Heat Activated:
   • Here the mode of polymerization is by application of external heat for activation of polymerization reaction which is provided by water bath or by microwave.
   • Heat-activated resins are available in powder and liquid form.
2. Chemical Activated:
   • Here the mode of polymerization is by means of chemicals.
   • In this polymerization reaction starts as soon as powder and liquid components are mixed together.
   • Here activation of initiator benzoyl peroxide is done by chemical tertiary amine dimethyl-p-toluidine.
3. Light Activated:
   • Here the mode of polymerization is blue light of wavelength 400 to 500 nm.
   • So as camphor quinone and organic amine come in contact with blue light of wavelength 400 to 500 nm they generate free radicals.
   • This activation of the photoinitiator initiates the polymerization reaction.
   • Light curing chamber consists of a rotating table over which the denture is placed so that it is exposed to uniform intensity of light.