Objectives:. The purpose of this study was to determine the effectiveness of polymerisation using modern LED-curing units (=LCU) in comparison with the halogen-curing unit (HCU) Astralis10.

Methods: The material TetricCeram (IvoclarVivadent) was evaluated by curing with 25 curing regimes of 6 LCU and one HCU. The measurements were made in real time with an FTIR/ATR-Spectrometer (Smart Endurance, Thermo Nicolet, Madison, USA). The diameter of the measured surface was 800µm, the wave number of the spectrum range between (4000-650)cm^-1 and the dissolution was 8cm^-1. The not polymerized paste was put directly on the diamond-ATR and the degree of conversion (=DC) during the polymerization was measured in real time for 2 minutes with 2 spectrums per second at the bottom of a 2mm thick sample (n=10). DC was determinate by assessing the variation of the peak height ratio of the aromatic/aliphatic carbon double bond during the polymerisation (1608 and 1634 cm^-1) in relation to the not polymerised paste.

Results:

 

Conclusions:

Concerning a 10s polymerization, the HCU is significantly better than the LED: Bluephase, Freelight2 and LEDemetron. No significantly differences between 20s curing with the 6 tested LCU and 10s curing with the HCU were registered. An additional extension of the polymerization time from 20s to 40s does not improve the DC significantly.