The effect of different preheating methods on the intrapulpal temperature of bulk-fill composite resins

Objective This study aimed to evaluate the effect of various preheating methods applied to bulk-fill composite resins on temperature changes within the pulp chamber. Materials and Methods Ten sound human molars were used. Each tooth was sectioned 2 mm apical to the cementoenamel junction, and the occlusal surface was flattened to leave a 2 mm dentin thickness. Four bulk-fill composite resins were applied at five temperatures (24 degrees C, 37 degrees C, 54 degrees C, 65 degrees C, and 68 degrees C) and polymerized using an LED curing unit. Intrapulpal temperature changes were measured with a K-type thermocouple connected to a data logger in a setup simulating pulpal microcirculation. In total, twenty measurements were taken per tooth under each condition. Data were analyzed using one-way ANOVA and post-hoc LSD tests (p < 0.05). Results The highest intrapulpal temperature increase was observed at 65 degrees C in all groups using the VisCalor dispenser. The critical temperature threshold was not exceeded in any sample. Significant differences were found between certain temperatures within individual resin groups (p < 0.05), particularly at 65 degrees C compared to lower temperatures. However, no statistically significant differences were found between different resin types at the same temperatures (p > 0.05). Conclusion Preheating of bulk-fill composite resins led to an increase in intrapulpal temperature; however, this rise remained below the threshold that could cause irreversible pulpal damage.