Effect of Pre-Cured Composite Resin Temperature on Post-Cured Properties

Objectives: To determine the mechanical properties of composite resin materials following photo-polymerization at various temperatures. Methods: Samples of packable composite resin (P-60, 3M Dental Products, St Paul, MN, USA) were polymerized using halogen lamp (Elipar Highlight ESPE- Germany) on a thermo-plate table (Dental Iceberg, Duisburg- Germany), temperatures adjusted to 7°C, 23°C, 55°C. After water immersion for 24h, samples were tested for (1) Flexural Strength (n=10) using universal loading machine (Instron 3366 machine, Canton, MA, U.S.A) and (2) Micro Hardness (n=24) using Vicker's hardness measurement device (Strues, Rødone, Denmark). Results: Significant change in the flexural strength between the groups of low temperature (7°C), room temperature (23°C) and high temperature (55°C) was found. Flexural modulus and micro-hardness results showed no difference between the temperature groups. Conclusion: low temperature during curing could reduce the flexural strength of composite resins materials. Raising the temperature of composite resins may facilitate its manipulation without compromising its physical properties.