Method: Two shades-(A1&A4) of resin cement (Variolink-II, Ivoclar-Vivadent) were used in a 0.5mm thick ring. The top surfaces were covered with a Mylar strip and further covered with a disc of 1mm thick shade A2 Empress Esthetic ceramic. The specimens were light cured using an Elipar-S10-(3m-ESPE, single-peak LED) delivering 13.6-J/cm2, or the BluePhase-G2-(Ivoclar-Vivadent,polywave-LED) delivering 9.8-J/cm2 of energy.
Both lights were used for 20s to cure the resin specimens directly on the surface of a Golden Gate Attenuated Total Reflectance FT-IR plate that was heated to 30°C. The DC of the resin was calculated after 100-seconds. The specimens were removed and the KHN was immediately tested, and again after 24-hours storage in the dark at 37°C and 100% humidity. Five specimens were made and tested in each group. The DC and KHN results were analyzed with ANOVA and Fischer’s PLSD at α = 0.05.
Result: The choice of curing light had no significant effect on the DC and only a small effect on the immediate and 24-hrs KHN values. Shade A4 harder and better DC than A1.
Shade |
Light Type |
DC-Mean-(SD) |
Immediate-KHN-Mean(SD) |
24-HRS –KHN-Mean(SD) |
A1 |
Polywave |
0.594( 0.008)(a) |
2.98(0.23) |
8.10(0.43)(d) |
Single |
0.605( 0.008)(a) |
2.71(0.30) |
8.30(0.43)(d) |
|
A4 |
Polywave |
0.611(0.011)(b) |
3.37(0.17)(c) |
9.09(0.52) |
Single |
0.619(0.006)(b) |
3.45(0.20)(c) |
8.77(0.44) |
|
Letters in parentheses = Homogeneous subsets-(Fischer’s α=0.05) |
Conclusion: The small differences in the DC and KHN values achieved using the Single-Peak and Polywave curing lights are probably not clinically significant and either light could be used. Shade A4 was slightly harder than A1.
Keywords: Cements, Ceramics, Dental materials, Hardness and Polymerization
See more of: Dental Materials 10: Instruments and Equipment