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:
|
Curing unit |
Curing regime |
Time [s] |
DC%_2min |
|
MiniLED (Satelec)
|
Fast-cure |
10 |
49.0a,b,c,d |
|
20 |
53.3d,e,f |
||
|
40 |
55.5d,e,f |
||
|
|
10 |
52.6c,d,e |
|
|
20 |
54.3d,e,f |
||
|
40 |
56.9d,e,f |
||
|
Step-cure |
20 |
54.6d,e,f |
|
|
L.E.Demetron1 (Kerr) |
Standard |
10 |
44.3a,b |
|
20 |
53.4d,e,f |
||
|
40 |
55.6d,e,f |
||
|
Elipar
Freelight2
(3M-ESPE) |
Standard |
10 |
44.2a,b |
|
20 |
54.8d,e,f |
||
|
40 |
57.4e,f |
||
|
Bluephase (IvoclarVivadent) |
HIP |
10 |
43.4a |
|
20 |
51.4c,d,e |
||
|
40 |
59.5e,f |
||
|
Ultralume5 with curing lens (Ultradent) |
Standard |
10 |
55.7d,e,f |
|
20 |
56.9d,e,f |
||
|
40 |
60.8f |
||
|
Smartlite (Dentsply) |
Standard |
10 |
45.2a,b,c |
|
20 |
54.0d,e,f |
||
|
40 |
56.1d,e,f |
||
|
Astralis10 (IvoclarVivadent) |
HIP |
10 |
52.0c,d,f |
|
20 |
54.7d,e,f |
||
|
40 |
59.4e,f |
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.