Effect of light curing with and without an external cooling system on composite temperature rise in resin composite

Abstract

Objectives: This study aimed to assess the effect of light curing with/without an external cooling system on composite temperature.
Materials and Methods: In this in vitro, experimental study, A3 shade of Luna composite resin was applied into 40 molds which were randomly assigned to two groups (n=20). In the control group, composite specimens were cured with a quartz-tungsten-halogen (QTH) curing unit for 40 seconds without an external cooling system; while, the specimens in the test group were cured with the same curing unit attached to an external cooling system for 40 seconds. Temperature change in composite specimens after 20 and 40 seconds of light curing was recorded by a thermometer attached to the molds, and analyzed by the generalized estimating equation (GEE) (alpha=0.05).
Results: A significant increase in temperature was recorded in the control group (P<0.0001) and the highest temperature (38°C) was recorded at 40 seconds. A significant increase in temperature was also recorded in the test group (P<0.0001) and the highest temperature (26°C) was recorded at 20 seconds, which remained almost constant for the rest of the curing time. The temperature was significantly higher in the control group than the test group at both 20 (P<0.0001) and 40 (P<0.0001) seconds.
Conclusion: The present results showed temperature rise of composite resin in the process of light curing by a QTH curing unit. Using an external cooling system significantly decreased the temperature rise.