Objectives: Three kinds of photoinitiation systems, such as camphoroquinone (CQ), p-octyloxy-phenyl-phenyl iodonium hexafluoroantimonate (OPPI), 2-(Dimethylamino) ethyl methacrylate, have been used to increase the curing efficiency of composite resins. However, adequate proportion of these agents was not reported yet. Therefore, additional study about the DC (degree of conversion) of variously proportioned resin monomer was done using Taguchi method.
Materials & Methods: Following groups were made by mixing three photoinitiation systems with a BisGMA/BisEMA/TEGDMA (37.5:37.5:25 wt%) monomer blend (Wt.% in the order of CQ, OPPI, Amine).
Group 1: LLL Group 2: LMM Group 3: LHH
Group 4: MLM Group 5: MMH Group 6: MHL
Group 7: HLH Group 8: HML Group 9: HHM (L: 0.2 wt%, M: 1.0 wt%, H: 2.0 wt%)
Each monomer was polymerized using a QTH unit (Demetron 400, USA) with an intensity of 400 mW/cm2 for 5s, 20s, 40s, 300s and their DC were determined at each time using a Fourier transform infrared spectrophotometer. Total 9 groups of 5 specimens each were tested. The data was analyzed using a one-way ANOVA test and Duncan's Post Hoc test at the 95% significance level.
Results:
Table 1. Mean and Standard deviation of Degree of Conversion (DC)
Groups | T5 | T20 | T40 | T60 | T300 |
1 (LLL) | 19.27 (6.09) | 46.39 (4.55) | 52.20 (2.91) | 60.62 (3.72) | 65.47 (6.10) |
2 (LMM) | 24.19 (6.11) | 50.12 (5.48) | 54.96 (6.75) | 63.99 (7.53) | 68.22 (4.51) |
3 (LHH) | 33.75 (4.67) | 57.11 (1.36) | 61.31 (1.96) | 68.85 (2.20) | 70.48 (0.99) |
4 (MLM) | 9.19 (4.08) | 28.40 (2.89) | 49.91 (2.68) | 62.91 (2.90) | 67.05 (1.74) |
5 (MMH) | 54.03 (2.96) | 61.77 (3.12) | 64.23 (3.86) | 71.28 (4.17) | 74.02 (4.94) |
6 (MHL) | 49.16 (4.26) | 57.73 (5.22) | 60.64 (6.65) | 68.62 (6.23) | 70.92 (4.78) |
7 (HLH) | 2.56 (1.01) | 13.00 (1.86) | 39.23 (4.24) | 62.12 (3.02) | 63.47 (3.06) |
8 (HML) | 38.65 (1.96) | 52.84 (2.14) | 58.33 (2.86) | 67.58 (3.00) | 68.95 (1.45) |
9 (HHM) | 56.44 (4.42) | 62.46 (4.03) | 65.03 (3.45) | 72.11 (4.91) | 72.77 (2.78) |
Conclusions: DC of di(meth)acrylate monomer which contains three photoinitiation systems, such as CQ, OPPI, Amine showed various results according to its proportion. Group 5 (MMH) and group 9 (HHM) showed the best combination. However, low concentration of OPPI should be avoided because of its slow and relatively low change.
Acknowledgement
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the ministry of Education, Science and Technology (20100008350).