Effect of composite temperature on in vitro intrapulpal temperature rise

Objectives: To measure in vitro intrapulpal temperature when placing and restoring with either room-temperature or pre-heated (54 and 60 °C) composite. Methods: A K-type thermocouple was placed in the pulpal chamber of an extracted, human bifurcated upper premolar which had a Class V preparation (1 mm remaining dentin thickness) on the facial surface. Tooth roots were immersed in a thermostatically controlled water bath and perfused with water at 1.25 μl/min to simulate physiological circulation in the pulp chamber. The thermocouple was connected to an analog-to-digital converter. The preparation was filled using composite either at room-temperature, or pre-heated to 54 or 60 °C with a commercial compule heater (Calset™), using standard clinical procedures by one person while continuously monitoring intrapulpal temperature (n = 5). Temperature rise over baseline values were determined at various stages during the restoration process: composite placement, contouring, prior to light-curing, and immediately after light-curing (20 s, Optilux 501). At each measurement interval, intrapulpal temperature values were compared using ANOVA and the Tukey-Kramer post hoc test (α = 0.05). Results: Significant differences were found in intrapulpal temperature when comparing pre-heated and room-temperature composite treatments with respect to baseline among the stages of the restorative process. However, the extent of this increase with heated composite was only 0.8 °C. A 5 °C intrapulpal temperature rise was seen for all groups during photopolymerization. Significance: Use of pre-heated composite only mildly increased intrapulpal temperature values when compared to composite delivered at room-temperature in an in vitro test environment. The largest temperature change occurred with application of the curing light.