dental02.jpg (11342 bytes)Fundamentals of
Dental Materials

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Dental Resins, Miscellaneous Dental Materials, and Dental Gold/Alloys

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a. Clinical Use. Composite resins are the most commonly used material for all permanent anterior restorations. These resins make excellent restorative materials because of their good resistance to wear and their excellent esthetics. Silar, Adaptic, and Concise are some of the trade names of composite resins.

b. Chemical Composition. Composite resins are composed of universal paste with filler and catalyst paste. All composite resins use quartz as a filler.

c. Properties. Composite resins have excellent esthetic properties. In fact, the universal paste will match 89 percent of all tooth shades. Tints are available for the other 11 percent. Composite resins have good resistance to wear because of the filler. They also have an acceptable compressive strength of 35,000 psi. Thermal expansion is at a minimum. (The manufacturer claims that the thermal expansion is close to the normal expansion of tooth structure.) Solubility and shrinkage are low. Refrigeration of the composite resin is required to prevent deterioration.

d. Mixing. As with unfilled resins, the manufacturer's directions should be followed when mixing composites. There are several types available and each requires a specific mixing procedure. The two-paste system is the most common form used. To mix this system, equal parts of the pastes are mixed (with a folding motion) to a uniform color within 20 to 30 seconds. The average working time from start of mixing to insertion of product is 1 1/2 to 2 minutes. It is important to avoid cross-contamination between jars of universal and catalyst pastes. The double-ended spatula provided with the kit has differently shaped ends, each clearly labeled "uni" and "cat." Improper mixing could cause failure of the restoration. Also, improper ratio of pastes will decrease the strength as will insufficient spatulation. Use of a metal spatula will result in discoloration of the material, giving poor esthetics. Some composite resins are activated by the application of ultraviolet or visible light. The material is placed in the cavity preparation, then exposed to a source of light for a specified time to produce polymerization or setting of the composite.

David L. Heiserman, Editor

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Revised: May 22, 2017