Temperature rise within the pulp chamber during composite resin polymerisation using three different light sources

The purpose of the study was to compare temperature rise during polymerisation of resin based composites (RBCs) with two LED light curing units (LCUs) compared to a halogen control light.

Forty-five extracted molars, patients aging 11-18 years were used. Thermocouples (TCs) were placed in contact with the roof of the pulp chamber using a 'split-tooth' method. Teeth were placed in a water bath with the temperature of the pulp chamber regulated at 37 degrees +/-1 degrees C. GROUP 1 (CONTROL): Prismatics((R)) Lite II (Dentsply Detrey, Konstanz, Germany), a halogen LCU, light intensity 500 mW/cm(2). GROUP 2: Bluephase((R)) ( Ivoclar Vivadent, Schaan, Liechtenstein), light intensity 1100 mW/cm(2). Group 3:Elipar Freelight2 (3M ESPE, Seefeld, Germany), light intensity 1000 mW/cm(2). Temperature changes were continuously recorded with a data logger connected to a PC.

Significantly higher temperature rise was recorded during bond curing than RBC curing in all 3 groups. (Halogen; p =0.0003: Bluephase; p=0.0043: Elipar; p=0.0002.). Higher temperatures were recorded during polymerisation of both Bond and RBC with both LED sources than with the halogen control. There was no significant difference between the two LED,LCUs (Bond:p=0.0279: RBC p=0.0562: Mann-Whitney).

The potential risk of pulpal injury during RBC polymerisation is increased when using light-curing units with high energy output compared to low energy output light sources. The rise is greatest when curing bonding agent alone and clinicians are advised to be aware of the potential hazard of thermal trauma to the pulp when using high intensity light sources. However the mean temperature rise with all three units was below the limits normally associated with permanent pulp damage.