In-vitro pulpal temperature increases when photo-curing bulk-fill resin-based composites using laser or light-emitting diode light curing units.

Abstract

To evaluate the in vitro pulpal temperature rise (ΔT) within the pulp chamber when low- and high-viscosity bulk-fill resin composites are photo-cured using laser or contemporary light curing units (LCUs). The light output from five LCUs was measured. Non-retentive Class I and V cavities were prepared in one upper molar. Two T-type thermocouples were inserted into the pulp chamber. After the PT values reached 32°C under simulated pulp flow (0.026 mL/min), both cavities were restored with: Filtek One Bulk Fill (3M), Filtek Bulk Fill Flow (3M), Tetric PowerFill (Ivoclar Vivadent), or Tetric PowerFlow (Ivoclar Vivadent). The tooth was exposed as follows: Monet Laser (1 and 3s), PowerCure (3 and 20 s), PinkWave (3 and 20 s), Valo X (5 and 20 s) and SmartLite Pro (20 s). The ΔT data were subjected to one-way ANOVA followed by Scheffe's post hoc test. Monet 1s (1.9J) and PinkWave 20 s (30.1J) delivered the least and the highest amount of energy, respectively. Valo X and PinkWave used for 20 s produced the highest ΔT values (3.4-4.1°C). Monet 1s, PinkWave 3s, PowerCure 3s (except FB-Flow) and Monet 3s for FB-One and TP-Fill produced the lowest ΔT values (0.9-1.7°C). No significant differences were found among composites. Short 1- to 3-s exposures produced acceptable temperature rises, regardless of the composite. The energy delivered to the tooth by the LCUs affects the temperature rise inside the pulp. The short 1-3s exposure times used in this study delivered the least amount of energy and produced a lower temperature rise. However, the RBC may not have received sufficient energy to be adequately photo-cured.