Effect of CQ-amine ratio on the degree of conversion in resin monomers with binary and ternary photoinitiation systems

OBJECTIVES: This study evaluated the effect of camphorquinone (CQ)-amine ratio on the C=C double bond conversion of resins with binary and ternary photoinitiation systems. MATERIALS AND METHODS: Two monomer mixtures (37.5 Bis-GMA/37.5 Bis-EMA/25 TEGDMA) with binary systems (CQ/DMAEMA in weight ratio, group A [0.5/1.0] and B [1.0/0.5]) and four mixtures with ternary system (CQ/OPPI/DMAEMA, group C [0.1/1.0/0.1], D [0.1/1.0/0.2], E [0.2/1.0/0.1] and F [0.2/1.0/0.2]) were tested: 1 : 2 or 2 : 1 CQ-amine ratio in binary system, while 1 : 1 ratio was added in ternary system. The monomer mixture was cured for 5, 20, 40, and 300 sec with a Demetron 400 curing unit (Demetron). After each exposure time, degree of conversion (DC) was estimated using Fourier transform infrared (FTIR) spectrophotometer (Nicolet 520, Nicolet Instrument Corp.). The results were analyzed by ANOVA followed by Scheffe test, with p = 0.05 as the level of significance. RESULTS: DC (%) was expressed in the order of curing time (5, 20, 40, and 300 sec). Group A (14.63 +/- 10.42, 25.23 +/- 6.32, 51.62 +/- 2.69, 68.52 +/- 2.77); Group B (4.04 +/- 6.23, 16.56 +/- 3.38, 37.95 +/- 2.79, 64.48 +/- 1.21); Group C (16.87 +/- 5.72, 55.47 +/- 2.75, 60.83 +/- 2.07, 68.32 +/- 3.31); Group D (23.77 +/- 1.64, 61.05 +/- 1.82, 65.13 +/- 2.09, 71.87 +/- 1.17); Group E (28.66 +/- 2.92, 56.68 +/- 1.33, 60.66 +/- 1.17, 68.78 +/- 1.30); Group F (39.74 +/- 6.31, 61.07 +/- 2.58, 64.22 +/- 2.29, 69.94 +/- 2.15). CONCLUSION: All the monomers with ternary photoinitiation system showed higher DC than the ones with binary system, until 40 sec. Concerning about the effect of CQ-amine ratio on the DC, group A converted into polymer more than group B in binary system. However, there was no significant difference among groups with ternary system, except group C when cured for 5 sec only.

Microleakage of the experimental composite resin with three component photoinitiator systems / 대한치과보존학회지

This study was done to determine if there is any difference in microleakage between experimental composite resins, in which various proportions of three component photoinitiators (Camphoroquinone, OPPI, Amine) were included. Four kinds of experimental composite resin were made by mixing 3.2% silanated barium glass (78 wt.%, average size; 1 microm) with each monomer system including variously proportioned photoinitiator systems used for photoinitiating BisGMA/BisEMA/TEGDMA monomer blend (37.5:37.5:25 wt.%). The weight percentage of each component were as follows (in sequence Camphoroquinone, OPPI, Amine): Group A - 0.5%, 0%, 1% / Group B - 2%, 0.2%, 2% / Group C - 0.2%, 1%, 0.2% / Group D - 1%, 1%, 2%. Each composite resin was used as a filling material for round class V cavities (diameter: 2/3 of mesiodistal width; depth: 1.5 mm) made on extracted human premolars and they were polymerized using curing light unit (XL 2500, 3M ESPE) for 40 s with an intensity of 600 mW/cm2. Teeth were thermocycled five-hundred times between 50degrees C and 550degrees C for 30s at each temperature. Electrical conductivity (microA) was recorded two times (just after thermocycling and after three-month storage in saline solution) by electrochemical method. Microleakage scores of each group according to evaluation time were as follows [Group: at first record / at second record; unit (microA)]: A: 3.80 (0.69) / 13.22 (4.48), B: 3.42 (1.33) / 18.84 (5.53), C: 4.18 (2.55) / 28.08 (7.75), D: 4.12 (1.86) / 7.41 (3.41). Just after thermocycling, there was no difference in microleakage between groups, however, group C showed the largest score after three-month storage. Although there seems to be no difference in microleakage between groups just after thermocycling, composite resin with highly concentrated initiation system or classical design (Camphoroquinone and Amine system) would be more desirable for minimizing microleakage after three-month storage.