Dental Materials

RINGLESS INVESTMENT TECHNIQUE Used for phosphate bonded investments . This method uses paper or plastic casting ring . It is designed to allow urestricted expansion . Useful for high melting alloys .…

Acrylic Denture Bases Use - used to support artificial teeth Classification a. PMMA/MMA dough systems b. PMMA/MMA pour resin systems 1. Components a. Powder-PMMA polymer, peroxide initiator, and pigments b. Liquid-MMA monomer, hydroquinone inhibitor, and cross-linking agents 2. Reaction a. Heat (or chemicals) is used as an accelerator to decompose peroxide into free radicals b. Free radicals initiate polymerization of MMA into PMMA c. New PMMA…

Composition of Acrylic Resins. ·        Powder. The powder is composed of a polymethyl methacrylate (PMMA), peroxide initiator, and pigments ·        Liquid. The liquid is a monomethyl methacrylate (MMA), hydroquinone inhibitor, cross-linking agents, and chemical accelerators (N, N-dimethyl-p-toluidine)…

Zinc Phoshate Cement Uses. Zinc phosphate cement is used both as an intermediate base and as a cementing medium.  (1) Intermediate base. A thick mix  is used under permanent metallic restoration. This layer of cement protects the pulp from sudden temperature changes that may be transmitted by the metallic restoration.  (2) Cementing medium. Zinc phosphate cement is used to permanently cement crowns, inlays, and fixed partial dentures upon the…

CRUCIBLE FORMER It serves as a base for the casting ring during investing .Usually convex in shape. May be metal , plastic or rubber . Shape depends on casting machine used . Modern machines use tall crucible to enable the pattern to be positioned near the end of the casting machine .…