0944 Curing Efficiency of a Direct Composite at Different Temperatures
L. LITTLEJOHN, S.C. GREER, A.D. PUCKETT, and J. FITCHIE, University of Mississippi Medical Center, Jackson, USA

Objective: Visible light activated tooth colored materials have become increasingly popular with most dental patients today. Therefore it is essential that the dentist be aware of the factors which may effect the materials' performance. The purpose of this study was to evaluate one such factor, temperature of the material being activated, which may influence the degree of conversion.

Methods: Using a Mettler Differential Scanning Calorimeter (Mettler Corp., Highstown, NJ), sample disks (6mm diameter x 1.8mm thick) of XRV (Kerr Corp., Orange, CA) were held at a constant temperature of 5C, 25C, 37C, and 70C and cured with a Demetron visible light (Demetron Corp., Danbury, CT) for 40 seconds with only a mylar strip separating the light from the composite. Three samples were evaluated at each temperature. The samples were then post cured in the DSC from 25C to 200C at 20C per minute. The enthalpy associated with the post cure was measured. The enthalpy for 100% conversion was determined by thermally polymerizing a sample of composite catalyzed with 0.1 weight percent of Benzoyl Peroxide in the DSC. The degree of conversion was determined by 1-enthalpy of post cure/enthalpy of 100% cure X 100.

Results:

Temperature

5C

25C

37C

70C

% Conversion

86.78 (.04)

90.86 (.28)

93.85 (0.0)

97.74 (.31)

Results showed a significant difference in conversion at each temperature when analyzed using ANOVA and the Tukey's Test (p < 0.01).

Conclusion: Temperature has a significant effect upon the immediate conversion obtained for a light cured composite.

Seq #124 - Materials Structure/Properties/Conversion/Biocompatibility
11:00 AM-12:15 PM, Friday, 14 March 2003 Henry B. Gonzalez Convention Center Exhibit Hall C

Back to the Dental Materials: V - Polymer Materials-Chemistry Program
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