![]() The upper portion of the selected denture flask is then positioned atop the lower portion of the flask. Upon reaching its initial set, the stone is coated with an appropriate separator. The dental stone is contoured to facilitate wax elimination, packing, and deflasking procedures ( Figure 19-3, B). The lower portion of a denture flask is filled with freshly mixed dental stone, and the master cast is placed into this mixture. The master cast is coated with a thin layer of separator to prevent adherence of dental stone to the master cast during the flasking process. In turn, the completed tooth arrangement is sealed to the master cast.Īt this stage, the master cast and completed tooth arrangement are removed from the dental articulator ( Figure 19-3, A). Cross-linking agents are incorporated into the liquid component at a concentration of 1% to 2% by volume.īefore mold preparation, prosthetic teeth must be selected and arranged in a manner that will fulfill both esthetic and functional requirements. These interconnections yield a netlike structure that provides increased resistance to deformation. If sufficient glycol dimethacrylate is included in the mixture, several interconnections can be formed and solvent swelling may occur, such as that caused by exposure to ethanol in alcoholic beverages. As a result, an individual molecule of glycol dimethacrylate can participate in the polymerization of two separate polymer chains that unites the two polymer chains. One should note that methyl methacrylate possesses one carbon-carbon double bond per molecule and glycol dimethacrylate possesses two double bonds per molecule. Therefore, it can be incorporated into growing polymer chains ( Figure 19-2). Glycol dimethacrylate is chemically and structurally similar to methyl methacrylate. Glycol dimethacrylate is used commonly as a cross-linking agent in polymethyl methacrylate denture base resins. Inhibitors also retard the curing process and thereby increase working time.Ī cross-linking agent can also be added to the liquid. Hydroquinone is added as an inhibitor, which prevents undesirable polymerization or “setting” of the liquid during storage. The liquid is predominantly nonpolymerized methyl methacrylate monomer with small amounts of hydroquinone. The powder consists of prepolymerized spheres of polymethyl methacrylate and a small amount of benzoyl peroxide, termed the initiator, which is responsible for starting the polymerization process. In addition, methods for improving the fit and dimensional stability of resin-based prostheses are provided.Īs previously noted, most polymethyl methacrylate resin systems include powder and liquid components ( Figure 19-1). Considerable attention is given to individual processing systems and polymerization techniques. Such polymers are chosen based on availability, dimensional stability, handling characteristics, color, and compatibility with oral tissues.Ī description of commonly used denture base polymers is presented in this chapter. In turn, the denture base derives its support through contact with the oral tissues, teeth, or dental implants.Īlthough individual denture bases can be formed from metals, the majority of denture bases are fabricated using common polymers. Such a prosthesis is composed of artificial teeth attached to a denture base. The Glossary of Prosthodontic Terms (The Academy of Prosthodontics, 2005) defines a complete denture as a removable dental prosthesis that replaces the entire dentition and associated structures of the maxilla or mandible.
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