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

Abstract

Objective: 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). Materials and Methods: The light output from five LCUs was measured. Nonretentive 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 (3 M), Filtek Bulk Fill Flow (3 M), Tetric PowerFill (Ivoclar Vivadent), or Tetric PowerFlow (Ivoclar Vivadent). The tooth was exposed as follows: Monet Laser (1 and 3 s), 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.Results: Monet 1 s (1.9 J) and PinkWave 20 s (30.1 J) 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 1 s, PinkWave 3 s, PowerCure 3 s (except FB-Flow) and Monet 3 s for FB-One and TP-Fill produced the lowest ΔT values (0.9-1.7 C). No significant differences were found among composites.Conclusions: Short 1-to 3-s exposures produced acceptable temperature rises, regardless of the composite.Clinical Significance: The energy delivered to the tooth by the LCUs affects the temperature rise inside the pulp. The short 1-3 s 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.

Effect of high irradiance and short exposure times on the depth of cure of six bulk‐fill resin composites

“…However, it is still being determined whether this short exposure time can adequately photocure the RBCs in the deeper regions of the T A B L E 1 Compositions of the bulk fill resin composites used in this study (based on information provided by the manufacturers). cavity, primarily when bulk-fill RBCs are used [13,14]. For dentists to know the depth of cure of resin-based restorative materials using a specific LCU, curing mode and exposure time, the ISO-4049 standard manual scraping method [15] is used immediately after light exposure [16][17][18][19][20][21], although some studies do evaluate the depth of cure after 24 h [22][23][24][25].…”

“…Some contemporary LCUs have high irradiance short light‐activation modes that last from 1 to 5 s [11, 12]. However, it is still being determined whether this short exposure time can adequately photocure the RBCs in the deeper regions of the cavity, primarily when bulk‐fill RBCs are used [13, 14]. For dentists to know the depth of cure of resin‐based restorative materials using a specific LCU, curing mode and exposure time, the ISO‐4049 standard manual scraping method [15] is used immediately after light exposure [16–21], although some studies do evaluate the depth of cure after 24 h [22–25].…”