Objectives: to evaluate the effects of curing regimen on the extent of polymerization (EP) of resin cements (DuoLink - Bisco, Panavia F2.0 - Kuraray, Variolink II – Ivoclar Vivadent, Enforce - Dentsply).Methods: Resin cements were mixed according to manufacturer's instructions and then cured under different conditions: I = immediate photo-activation, II = 5 min. delayed photo-activation, III = no photo- activation. EP was determined by 1H Stray-Field MRI method, which also enabled to probe molecular mobility in the kHz frequency range. EP was determined at several time periods after mixing/curing, depending on the curing protocol. Comparative analysis were performed at each different time. One-way ANOVA was used to evaluate Total EP data at α=0.05. Results: Total EP (%) data obtained for the cements after 24 h post cure at 37ºC, in the dark are presented in the Table. Different letters were assigned to statistical different data (p<0.05).
| Protocol | ||
Dual-cured Cement
| I | II | III |
ENFORCE | 45.0±3.7A | 45.8±0.8 A | 44.7±0.1 A |
DUOLINK | 51.8±4.0B | 50.0±0.4B | 49.8±0.4B |
PANAVIA F 2.0 | 51.1±3.5B | 50.0±1.3B | 51.6±0.6B |
VARIOLINK II | 29.5 ±9.7C | 9.9 ±2.2D | 10.2±11.2D |
Enforce, DuoLink and Panavia F2.0 presented similar Total EP regardless of curing protocol. .Five-min delayed and no photo-activation protocols affected Total EP of Variolink. EP varied non-uniformly for the different cements as curing reaction progressed over time.
Conclusions: The curing regimen affects the EP of some resin cements. This should be taken into consideration when selecting materials and techniques for clinical applications (Grants number - CAPES# O565-07-5 - PDCT/SAU-BMA/55395/2004- CICYT-FEDER MAT-08-02347/MAT and JA-P08-CTS-394).