Method: Standardized cavities (2x2x2 mm) were prepared in 80 bovine incisors, which were randomly assigned to eight groups according to the photo-activation methods and dentin thickness. Two light curing units were used: quartz-tungsten-halogen – QTH (780 mW/cm2 for 40s) and light emitting diode – LED (900 mW/cm2 for 40s); and different dentin thicknesses: 0.5 and 1.0 mm. For the Heliomolar composite, the specimens were etched with Scotchbond Etching Gel 35% phosphoric acid for 20s, rinsed with water for 20s, and have the water excess removed with absorbent paper. Two layers of Excite adhesive system were applied and the photo-activation was done after the second layer application. Then, Heliomolar composite resin was applied and photo-activated. For the Filtek P90, the application of Silorane self-etch primer for 15s and the photo-activation (10s) was done. Application of Silorane adhesive bond and the photo-activation (10s) was done. Then, Filtek P90 composite resin was applied and photo-activated. All experiments were carried out in a controlled environment (37ºC and 50±10% relative humidity). The temperature variations in Celsius were recorded using a digital thermometer attached to a type-K thermocouple, which was inserted into the root canal to be in direct contact with the pulp chamber dentin. The results were subjected to Anova and Tukey’s test (α=0.05).
Result: The increase of pulp chamber temperature was statistically higher for the P90 (39.84±0.91ºC) compared to the Heliomolar (38.85±0.51ºC). For Filtek P90, there was difference between the dentin thicknesses (0.5mm dentin thickness – 40.07±0.93ºC and 1.0mm dentin thickness – 39.61±0.86ºC).
Conclusion: Higher density of energy promotes higher increase of pulp chamber temperature and silorane composite promoted higher temperature increase.
Keywords: Dental materials, Polymerization and Polymers
See more of: Dental Materials 7: Polymer-based Materials-Physical Properties and Performance