Comparative analysis of pulpal temperature changes in bulk fill resin composites with different photoinitiators activated using various light curing units: An in vitro study

Objective This study compared heat generation and transfer through the dentin to the pulpal wall while curing two bulk-fill resin composites (BFRCs) with different light curing units (LCUs). Methods A human molar tooth model was used to measure heat generation and transfer through the dentin to the pulpal wall while curing BFRCs with various LCUs. One hundred BFRC samples were divided into ten groups based on BFRC/LCU combinations (n = 10). Five LCUs with different spectral emissions (Bluephase G2, Bluephase PowerCure, D-Light Pro, Valo Cordless, Demi Ultra) were used for curing two BFRCs with different photoinitiator systems (Tetric EvoCeram Bulk Fill and Filtek One Bulk Fill). Measurements included temperature change (ΔT), time to maximum temperature (t), heat duration above threshold (Δt), and heat transfer rate (Q). One-way ANOVA (p < 0.001) and Tukey's post hoc test were used for analysis. Results Significant differences in ΔT, Δt, and Q values were found based on BFRC/LCU combinations (p < 0.001). Valo Cordless generated the lowest heat, while Bluephase G2 generated the highest heat. Bluephase G2 exhibited the longest duration above the threshold, while Valo Cordless had the shortest duration (p < 0.001). Valo Cordless and Demi Ultra produced lower heat transfer rates in the Filtek and Tetric groups, respectively. No significant differences were found in t values among BFRC/LCU combinations (p = 0.590). Significance Heat generation and transfer from LCUs to dental pulp through dentin and BFRCs vary regardless of spectral emission. Different BFRCs with various photoinitiators produce differing heat levels, potentially increasing the risk of pulp injury. Selecting the appropriate combinations of LCUs and BFRCs can significantly reduce pulp damage risk.