Thermographic analysis of temperature rise in the pulp chamber with LED and QTH light curing units: Anin vitroinvestigation

Abstract

Aims: To compare the temperature rise in the pulp chamber with light-emitting diode (LED) and Quartz-Tungsten-Halogen (QTH) light curing units by infrared thermography. Materials and Methods: Class V cavity was prepared in 20 freshly extracted maxillary first premolars measuring 2 mm depth, 4 mm width, and 1 mm above the cement enamel junction. The samples were divided into two groups (n = 10). Cavity was etched with 37% phosphoric acid, rinsed and bonding agent was applied over the etched cavity surface on both the groups. In group I the samples were cured with LED curing unit, whereas group II were cured with QTH unit, which was followed by two incremental curing of composite. Thermal emission for QTH and LED (fast mode) light curing units were noted by Fluke Ti32 infrared thermography after 20 s bonding agent curing and first and second increment composite curing for 40 s each. Statistical Analysis: Data were analyzed with Student t-test and Friedman test using SPSS version 11.5 software. Results: The statistical analysis revealed that the temperature rise was significantly minimal with LED fast mode (Group I) in all stages of curing compared with QTH unit (Group II). There is significant rise of temperature during first incremental curing of composite, whereas insignificant increase of temperature during curing of second increment of composite (P < 0.001%). Conclusions: Temperature rise caused due to both QTH and LED light curing units does not result in irreversible pulpal damage and thermography is a viable means of quantifying the temperature changes during photo polymerization.