In-Vitro Intrapulpal Temperature/Times to Restore Using Incremental/Bulk-fill Techniques

Objectives: To compare end of treatment intrapulpal temperatures as well as total time to restore a standardized restoration using either incremental or bulk-fill materials.
Methods: A divergent, 4-mm deep, 5-mm diameter Class 1 preparation was made in a freshly extracted, unrestored, human, upper second molar. A K-type thermocouple was placed inside of the pulp chamber through a lingual access. Simulated pulpal circulation was provided at a physiologic rate and temperature. Prior to restoring, intrapulpal temperature was controlled at a physiologic value (35°C). The light curing unit (LCU) tip was positioned 2-mm above the cusp-removed occlusal surface, and the time-based temperature profile was recorded. The LCU was activated for the recommended duration to simulate exposure of a dentin bonding agent (DBA), and then the preparation was filled using either a sequence of 2-mm thick increments (INC) or bulk-filled (BF): 3M/ESPE-LCU=DeepCure S, INC=Filtek Supreme Ultra, BF=Filtek One; Ivoclar-LCU=Bluephase Style, INC=Tetric EvoCeram, BF=Tetric EvoCeram Bulk; Kerr-LCU=DemiUltra, INC=Premise, BF=SonicFill2; Dentsply-LCU=SmartLite Focus, INC=Esthet●X HD, BF=SureFil SDR+Flow. Intrapulpal temperature was continuously monitored (1/s) during the restoration process, and temperature rise over initial baseline (ΔT) at completion was recorded. The time span from initial light-curing of the DBA exposure through the end of the last composite increment exposure was recorded as the time to restore. Within each parameter, data were subjected to a 2-way ANOVA and the Tukey post-hoc test, at a pre-set alpha of 0.05. N=10 per condition.
Results: Table presents results. 2-way ANOVAs indicated significant interaction, thus 1-way ANOVAs were performed, and T-tests. For each product combination, bulk-filling resulted in significantly higher intrapulpal temperature than did the corresponding incremental material, and took significantly less time, with the exception of the Dentsply product, which took longer.
Conclusions: Bulk-filling yielded higher intrapulpal temperatures and tended to have shorter restoration times than the incremental equivalent product.