Effect of translucency and absorbance of composite on temperature change during photopolymerization

This study investigated the effect of translucency and absorbance of conventional (Filtek^TM-Z350-XT) and bulk-fill (Tetric^®-N-Ceram) composites on temperature change during photopolymerization, using a non-contact infrared sensor. Three shades from each composite were selected to prepare disk-shaped specimens (n=3), which then photopolymerized with LED-light for 20 s. A second light exposure was performed on the photopolymerized specimens. The first peak temperature rise during composite photopolymerization (ΔT_total), second peak temperature rise by the light (ΔT_light), and net peak temperature rise by composite curing heat (ΔT_composite) were obtained from the temperature change vs. time curve. The changes in ΔT_total and ΔT_light with varying the composite shade were greater than those in ΔT_composite. The conventional composite showed higher ΔT_total and ΔT_light than bulk-fill composite. ΔT_total and ΔT_light increased as translucency parameter decreased, and absorbance increased. The potential risk for heat-induced pulpal damage should be considered when selecting a composite shade, especially for deep cavities.