Temperature Rise in Curing Modes of Two Different Dental Light-Curing Units: The Importance of Heating Rate

The heat generated in the process of light curing may cause irreversible damage to the dental pulp. This study aimed to assess heat transfer in the process of irradiation of a dentin disk by using different modes of quartz-tungsten halogen (QTH) and light-emitting diode (LED) dental curing units. The surface temperature was measured by an infrared (IR) thermometer following light curing with standard, ramp, boost, and bleaching modes of a QTH curing unit, and high, soft, and pulse modes of a LED curing unit. Since the maximum temperature rise alone is not sufficient to study the thermal damage to the pulp tissue, we also assessed the temperature rise profile and heating rate, in addition to the maximum temperature rise in this study. The results showed that decreasing the duration of light curing effectively decreased the risk of pulpal damage. Shorter radiation modes, such as the 10 s standard mode and the 10 s boost curing mode of the QTH curing unit, and the 5 s high mode and the 10 s pulse mode of the LED curing unit, all had the lowest risk of thermal damage to the pulp.