Method: Disk-shaped specimens (n=5; 50x3mm) of both resins were subjected to one of the following cycles: Ct (control) = 270W/10min+0W/5min+360W/10min (manufacturer’s recommendation for VW); C650/5 = 650W/5min; C700/4 = 700W/4min; C550/3 = 550W/3min. Tp was measured immediately after the flasks were opened using an infrared thermometer. For the DC analysis, further specimens (n=5) were made, bench cooled, wet-ground to 2-mm thickness and stored in distilled water (37ºC; 48h). Specimens were placed on the diamond surface of an attenuated total reflectance (ATR) unit attached to a Fourier transform infrared spectrometer (FTIR), and spectra were obtained from cured specimens (16scans; resolution 4-cm-1). Spectra from each unpolymerized resin were also obtained after the materials were mixed and applied to the ATR surface. DC was calculated observing changes in aliphatic-to-esther (1638cm-1 and 1750cm-1, respectively) peak ratios pre- and post-microwave curing. Further time-based DC analysis was performed (1spectrum/s) to observe polymerization kinetics of each material prior to the cycles. Tp and DC data were statistically analyzed (2-way ANOVA and Tukey’s test; and Kruskal-Wallis test, respectively; α=0.05).
Result: VW submitted to Ct cycle showed the highest Tp (≈159ºC; p<0.05). In both resins, C550/3 promoted the lowest Tp (≈105ºC; p=0.00016). DC reached 27% after chemical activation prior to the cycles. The cycles resulted in no difference in DC (68.5 to 77.2%). Materials presented similar FTIR spectra.
Conclusion: Although the materials reached different temperatures after the cycles, the DC of both resins was not significantly different. Both materials showed similar chemically-activated polymerization and compositions. Vipi Cril showed optimal polymerization in microwave, as well as Vipi Wave.